Great video, a galon of gas have aprox. 33,7Kw/h of energy, your conversion has 12,5% eficiency. Pretty good for modied alternator predator powered generator set! Thanks for Share!!
That method doesn't do any justice be cause its an equivalency in raw power to compare to electric vehicles. ICE are roughly 20% efficient. Typically when generating power from a gallon of gas you get between 4 and 7 kwh. for a small generator this is actually not to bad. The fact its put together a garage is also outstanding.
This has to be my favourite series of DIY on UA-cam currently. You've done such a great job for all us hobbyists explaining all the little tid bits so that we can all have a crack at it. Thank you so much for all the effort!
I really like all the detailed info. If you're only taking 2.2kw from the alternator, you should get a smaller pulley for the alternator or a bigger one for the engine, then you can turn the throttle down and still spin the alternator at the same speed. You have more engine than you need, so it doesn't need to run at full speed. A smaller engine could make better fuel efficiency also...something like a 160cc would be good for 2.2kw. You should try playing with the voltage to the rotor, between that and RPMs you may be able to adjust it to run cooler or at a different speed with different voltages.
that a good point dose it need to run so fast. if it was slowed by the ues of a bigger pully it as a possibility to save fuel by running it slower. been equal to the Honda generator by mens of . efficiency. their is serval different ways to carol of rotter sculpt with a Verica in the siystom. grat thinking son .
I would go the other way. Run the alternator at 50+ A and direct air cool it with 12V fans. That way, you can run the current motor at a higher efficiency level. He said the motor had over 6 horse power, so a bigger or even two alternators, could also work better.
Different approach same result. My home made 48 vdc generator/charger contains a 80's, 10 horse Hatz diesel engine and a permanent magnet hubmotor of an electric scooter/moped. I run the diesel at a slow 1400 rpm driving the hubmotor at about 650 rpm with a belt, put the 3 phases directly through a rectifier and like you did, the DC + and - through capacitors to smooth it out. I can make 2200 watts without stuff overheating, the hubmotor gets about 50C but I'm limited by the bridge rectifier that needs forced cooling at this point, but i can get a whopping 2.7 kwh out off 1 liter of diesel which is about 27% efficiency (One liter is 10kwh) and i was blown away by that result as it is an old NA diesel and some hubmotor i had laying around. With some duty free diesel i can charge my batteries for about 0,45 euro per kWh, which is not bad concidering that gasoline cost me at least double that per kWh....in Europe i might add where gasoline is liquid gold. It would be nice to make a gasoline genny with the same hubmotor setup, i would be curious how efficient that would be, the system would be much simpler, no need for a buck converter to generate an output, the amount of RPM decides how much current is flowing as the engine and hubmotor are loaded up once you hit battery voltage.
Great videos, just a few comments from an old engineer. Small engine carburetors only provide optimal mix for a single RPM, load, air temperature, air density, and fuel variant. Fuel injection (like newer Hondas) would substantively improve fuel efficiency. You might be able to get an FI kit, or set one operating rpm/load for battery charging and jet/set the carb optimally for your RPM/load point and altitude, and adjust seasonally.
The alternator is 3 phase. The way that the phases overlap greatly reduces the output ripple . Even if you don’t use any smoothing cap at all, the ripple in the output is low enough that it probably could go to the charge controller as is.
Maybe, but why risk damaging a pricey charge controller when capacitors are so cheap? If nothing else, the internal monitoring software will not be expecting pulsing input voltage and may become inaccurate with some noise. Even with external measuring devices, the system is easier to measure with less ripple. I don't see why anyone would go through all this trouble just to save a few bucks on a capacitor.
@@kellyj1464 The 1000uF capacitor feeding 25A to the load is a 25V/ms slew rate when the 85VDC system already has only about 10V of peak-to-peak ripple at 500-600Hz which is 1.5-2ms. If you put an oscilloscope on this or simulated it in something like LTSpice, you would find that it makes no meaningful difference on voltage waveforms. What the capacitor does do though is wreck stator and diode current waveforms.
One note David: If your gas stays cold, the motor is more efficient. Especially if it has a fuel injection CDI ignition instead of carburetor. But nice project. And practice
@@teardowndan5364 Dude 10V of peak-to-peak ripple is pretty bad, that's 10% of the output voltage. If it means a little bit of current spikes that's fine, with the high ESR of a big electrolytic like that a little 100A current spike for half a millisecond won't do anything anyways. Those bridge rectifier packs are usually good for 1500A spikes, 200-300A continuous. But yeah, really he should've made a resonant LC network to perfectly cancel the ripple without causing huge current spikes.
The output control depends on control of the rotor excitation. With permanent magnets you would need to figure out some other means of control. Or oversize the charge controller to potentially handle hundreds of volts.
Permanent magnets could give you a better efficiency, as used in wind turbines, no waste of energy in having to input current to get the thing going. Your controller of course needs to be able to handle the voltage output and could be more costly depending on the specifics.
12v @ 5a loss, so 60 Watts lost energy - as compared to a permanent magnet alternator. Have you tried reducing the Stator feed voltage? High stator power is typically only needed at low RPM conditions, and will cause more magnetic drag and energy loss at normal RPM conditions. That DC to DC converter is probably adjustable, most are. You are also wasting power by using passive silicon bridge rectifiers... about 120 Watts lost, since each diode loses about 1.5 Volt during conduction, and you always have 2 of them in full conduction. 40 Amps x 1.5v x 2 diodes is 120 Watts. Using synchronous rectification would reduce that to about 10-15 Watts, but would be expensive.
using a controller you get a flat output vs speed where as using a permanent magnet you get a means(bell curve) output. if you are trying to figure this out then look for car dynamo outputs for autos pre 1978
Your fuel economy result answers the largest question that I've long had. I seems that my 90-120 hours of winter battery charging by an AC generator is not such a inefficient solution compared to a possible DC charging option. Many thanks for all your work and sharing with us.
We have a remote cabin and have been using a Honda 2000 to charge the batteries when the sun isn’t good for over 20 years. With the eco throttle I don’t think any other generator will charge the batteries as efficiently because as the battery charge tapers off the generator runs slower. I set the charger in the inverter to 10amps AC max to keep from overloading the generator because you should never run a generator more than 75% of its rated output continuously.
Commented on last video. A lot of effort and expense here for a 48 volt charger. What i did was take a 'broken' inverter generator, where the inverter wasn't making power anymore. Used a bridge rectifier right off the AC windings to convert the direct output of the AC into 250 volt DC. Then Wired up MC4 plugs to go to my charge controller. To the charge controller, it just looks like a solar array. Generator was $200 broken, $50 for the bridge rectifier or so. So for a 48 volt charger, cheaper to reuse a 'broken' genny and use a rectifier than to completely build one
When you mostly need this setup in winter, it would be nice to gain the heat, too. Even when you only can gain half the heat and the other half is lost, it would double the efficency. Maybe a generator with water cooling and putting the heat in the house water heating system? Maybe an enclosure with a air/water heat exchanger and another heat exchanger in the shop?
for kick-starting the alternator i think there's a couple of things you can do. The less obvious is to find a way to embed a perminent magnet in to the rotor somewhere so that when it spins it seeds the magnetic flux in the stater before the buck converter comes on and the closed loop takes over feeding the winding. A second and less invasive approach would be a small kickstart battery and a latching relay circuit Use a relay with a minimum closing voltage of 12v and tie it to the rotor winding circuit. Connect the buck converter output via the relay's 'normally open' side and the relay coil. Connect the battery to the normally closed side Connect the center contacts to the rotor windings. When there's enough voltage on the output to pull that relay closed it will disconnect the battery from the circuit and switch over to the buck converter, allowing the closed loop to take over feeding current to the rotor. As a bonus, You can cut the battery off when not in use with any kind of switch that serves as the 'ignition' switch for the generator so it doesn't go flat when not in use. as a small bonus, why not add a small trickle charger in there somewhere to keep the battery topped up =)
@@bumbarabun: Not really. I think in the first video he said that the engine is 6 horsepower. If that’s true, that means the engine can do 4.41kW of power; and his tests showed getting about 4.2. Is worth chasing 210 watts of power? Probably not.
@jacob seria kW/gal, não kWh a comparação. Que análises excelentes, parabéns pelo vídeo!! 👏👏👏👏 Eu planejo fazer um com automações de partida, desligamento e sensores para um gerenciamento na manutenção do motor.
Thanks David! Very interesting and informative test. In Alaska connected the exhaust of air and water cooled generators to a coil stainless steel and copper tubing, and immersed the coil as crude stack robber and estimated I was able to recover up to about 20% of the thermal heat energy from the engine. I mounted the generators above the heat exchanger coil inlet and plumbed the outlet out the bottom of a spray-foam insulated fiberglass or steel tanks so the exhaust condensate would drain out. On water cooled generators from 7kw to 600kw we installed coolant heat exchangers to the engine coolant system, removed the engine thermostats and used AMOT valves (Thermostats) in the heat exchanger loop to maximize heat recovery. Combing engine heat recovery with commercial exhaust to water stack robbers recovered up to 60% of the engine heat, so basically the fuel cost of our electric load provided heat most of our space heating. I was thinking a heat recovery might project might be interesting for viewers, and I would be happy to provide insights from my experience if needed.
@@DavidPozEnergy That was back in the 90's so I don't have a website or videos. Heat generator heat recovery hydronic heating in Alaska was somewhat common. I worked with a variety of hydronic heating and recover systems from what might be used to heat a small trailer from 2kw to large oilfield camps of several hundred men and megawatts of power generation, and depending on the scale of application you would be interested in I can provide information as the design depends varies greatly depending on the size of the system. The smallest system I did that might apply to a home system used a pair of 2800w air-cooled Honda generators. Basically, I welded threaded fittings to the exhaust outlets of the generators. As I recall the exhaust outlet of the Honda was about 3/4" diameter, and used 3ft of of 1.5" dia. flexible stainless steel tubing to reduce the vibrational stresses on the generator exhaust, insulated it with fiberglass high temp and connected the other end of the flex to, two coils of about 20' of 1.25 copper tubing immersed in a 350 gal steel tank that was about 3ft tall by 3ft. wide and 5 ft. long filled about 2.5ft. full ,and insulated with spray foam. I mounted the generators on a platform just above the top of the tank, and routed the flexible stainless tubing through a sleeve below the water level and connected it to the threaded fitting to one end of the copper tubing coil, and the other end of the tubing to a outlet in the bottom of the tank, so any condensate would drain out the end and into a drip pan. In the Alaskan arctic, in sub-zero temps there was little humidity so little condensate was produced, but in above zero temps you could see a gallon in a day that had had some soot. We used a locally produced gasoline that was more like white-gas / naphtha mix that had few additives and burned pretty clean. so the condensate was likely not too hazardous. The tank was open to the air and I used a small Grundfos pump (UPS15-58FC 1/25 HP 115-Volt 3-Speed Circulator Pump) on a thermostat at the bottom of the tank to pump hot water to baseboard heating element lengths with a fan to heat a small mobile trailer office, the generator delivered about 2000w of power for lights, a microwave, fridge, radios and a couple of 1500w electric heaters, and a few other things. The office was a well insulated ATCO trailer about 28ft long by 10ft wide that had about 3" of spray foam added to on the outside. The generators ran pretty much 24hours, and the system was pretty much self balancing down to about -25f, as the more electrical heating load produced more hot water. The grundfos pump was set to turn off when the tank temp got below 135f. below -30F we typically needed to use a 12V webasto gasoline heater to keep the trailer comfy We used glycol water mix but in warmer some applications water might be ok if you don't have to worry about freezing your coils or tank. I would estimate that the system recovered a about 2000 watts of heat from the combined generator exhausts when they were running at about 50% load. In warmer temps we only ran one generator. I'm thinking that you might be able to recover 1000 watt-hours or more of heat from the from a 4kwh run of your portable generator, and that would be pretty easy to calculate by measuring temp rise in a water tank. it might also be possible to plumb up some iron or steel water pipe for a direct exhaust heat exchange if you were sure to prevent exhaust leaks. If you want to chat about recovery systems and how to use AMOT water cooled generator recovery let me know.
Yes a part two!! I literally built the same thing with a few of the same parts. It works pretty good at higher throttle I can pull about 2,800 Watts found a little constant current adjustable regulator where I can adjust the current going to the field windings so it doesn't bog down The motor too much. Works great. I found about 2.1 amps to be a good output for my alternator. It's literally just an alternator from an '87 mustang
With regards to the flexing that we see of the motor plate with the mounted alternator, it seems that a piece of angle iron going perpendicular to the angle iron alternator mount may reduce that flex. Adding some more angle iron to make an "X" or a cross of angle iron in approximately the middle of your plate. I'd bet that would stiffen things up so you wouldn't see that flexing we see in the video due to the harmonics. All in all a GREAT project, one that I think many of us (myself included) have thought of "what if I built this?" and you did! Even though it's not as efficient on a gallon of gas when compared to the Honda inverter generator, not everyone can afford to put down the funds needed for a big Honda inverter generator like that. As you said, folks may have a spare engine and alternator lying around in their stash. Thank you, David!
Thanks for the nice comment. I appreciate you watching to the end. After each version, there are more modifications to be made. I wish I had the time for all of it.
For almost all buck/boost converters, the two negative connections are actually untouched/commoned. This is because these circuits modulate voltage on the positive side in reference to this common negative rail. To double check, just check for continuity between -IN and -OUT on your converter. Hope this helps!
You can probably get more power by increasing the RPM of the alternator. 8000 RPM is not really optimal. Alternators can normally go to 15000RPM. in the vehicle, the ratio is like 1:3 or 1:4, so 6000*3. But nice setup, congratulations.
Needs a smaller motor. You're getting only ~3 hp of output from a ~7 hp engine. You could probably use a more fuel efficient 160 cc engine with proper pulleys. Also increase motor pulley size or decrease generator pulley size to increase voltage output while lowering amperage or increasing generator's output while maintaining same heat levels. You have a lot more efficiency available in this DC setup. It just requires more experimentation to find the proper balance. Honda beats yours currently because they've done the performance to output testing in their design.
Thank you very much for the follow up video, and thank you in general for making video's, here in South Africa we have multiple times of power outage per day, thanks to loadshedding from 2 hours to 16 hours a day. So doing stuff diy really helps especially when solar pannels is always out of stock and inverter generators is quite scares aswell, but thanks again for the follow up video.
Another south African here! I knew some Saffas would check this out. It is a kak spul there. Mom is still left there, she refused to leave. I packed up in 2019 and came to USA. Mom is off grid with 7kw lithium and 5kw inverter and 1800l JoJo. Just sponsored her with some ecoflow goodies and solar panels for the caravan trip to Scottburgh. I am off grid too, my yacht is on solar power and only needed to run the generator once in last 20 days due to a 5 days of rain. I have a 100amp alternator on my 55hp Diesel engine, and a 20amp and 40 amp DC to DC charge controller for my 6kw of lithium on my sailboat. I can charge all 6kw with 3.5 liter of petrol in the Honda generator in 8 hours. In conclusion of this video, Not worth the effort and cost to go directly DC charging on another engine, although a single cylinder diesel Lister would be lots of fun to play with
I built a generator like this probably 15 years ago, I used a 5HP B&S engine with a spare alternator from my Suburban. I kept it 12V because thats what the solar system at the cabin was set up for. One thing I found really helped was dropping the engine RPM, it allowed me to still pull about 40A at 12V, but I could run it at just above idle, it did a good job of juicing the batteries without blowing my eardrums out. I still have it, I'm going to rebuild it this summer, I really like the modifications you made as far as reducing vibration and I'm going to incorporate many of those features. Good series, liked it a lot, learned a few things.
@@DavidPozEnergy would you consider providing more details maybe by a series of video/s at a beginner level on the secondary components or electronic components that you have on this unit? Thank you!
@@DavidPozEnergy Great suggestion Drew, and great video, David. Most of the store-bought generators seem to rate their run times at half-load. The trade-off seems to be the slower you go, the higher the effiency. Of course this only works if you have the time - most people don't drive down the freeway at 35 MPH, even though we'd save on gas. Choices are good, though. Appreciate the work giving us the information to make better decisions. 🙂
I also built similar only using a 8hp B&S and a GM alternater charging 3 semi batterys running 3 2500 watt inverters barely above an idle ran my fridge heat lights ect and would only burn 5 gallons of gas at almost 51 hrs of runtime still have this setup for my backup Peace
I have no intention to heart anyone’s feelings. But this is a terrible terrible terrible idea!!. Why are you trying to reinvent the wheel? You can’t. you just can’t!! You can’t reinvent something that is already invented. I have seen way too many video’s connecting a trimmer engine (two strokes) or mower engine (4 stroke) connected to either a car alternator (like yours, brushed motor bad on ware and tare, using a 12V stater waste of energy) or to a brushless electric generator (like wind turbines generators. Fixed stater, rotating permanent magnets. No brushes ware and tear). None of these projects were cheaper than just a standard Gas or propane electric generators that you can buy from any store including harbor fright. The off the shelf generators have an “Automatic RPM adjustments”, has belt in circuit breakers and other safeties that being ignored in these projects in general (including yours). First of all, you are thinking doing this will get you of the grid. You are lying to yourself. You will be off “the electric grid” but now you are connected to “the Gas Grid” (that’s 4 times more expensive) or “the propane Grid” (about 2 to 3 times expensive). The only time you are truly off the grid only if you are doing solar or wind (which u do have solar). But then how much do you save that depends on where you are and the weather and how reliable the equipment’s you are using (equipment life expectancy). This is an open debate for the past 10 years or so. And still going… Let me explain the “Automatic” RPM systems. In any electric generators you need to run it at 3600RPM (60 hz per sec * 60 sec). there are two types “Mechanical” and that’s a spring-loaded arm in front of the cooling air blower of the Engine. When you start without load the throttle will be at idle and when you add load, the load will cause the generator to slow down to let’s say 3200RPM, that will slow the air from the blower and the spring will bring the arm closer to the engine and the arm connected to the Carb and it open ‘s it up. By adding more throttle, it adds more torque, adds more RPM and it goes back to 3600RM. The more load the less RPM, the arm opens more throttle, more torque until the RPM goes back to 3600 RPM. When you remove the load the RPM increases pushing the arm further way from the engine reducing the throttle until the RPM goes down to 3600 RPM. This happens so fast in milliseconds and in every second keeping the engine running at 3600 RPM regardless of the load. The “electronic automatic” type uses an electronic TACO meter to control the throttle. It’s more efficient than the mechanical and more accurate and faster to reach the target RPM. Now, if you still keen on your idea, you should have tried this. Buy off the shelf Gas or propane Electric generator. Get a 120V AC to 120VDC full rectifier (I get them from any broken computer or TV power supplies. Or you can buy them online). Use couple of 200V capacitors for the ripples, then connect that directly to your solar charger. That’s it!! Done. You don’t even need to add circuit breakers because you will have them on the generator anyway. Again, I have no intention to heart anyone’s feelings.
I would not have ever imagined the efficiency with either setup could be that bad! A US Gallon is 3.8L. A litre of petrol contains close enough to 10 KWH of energy. You therefore burned 38 KWH of energy to get 4.2 and 5. whatever KWH out of that. I knew there were losses but I never imagined that much! The fact the Honda did not do that much better just shows how poor all the conversions are. I am making a Small Diesel Driven setup and going to make it co-gen or combined heat and power to supplement my solar system in winter. Looks like using the waste heat will have potential for huge efficiency gains due to what must be at least 10 Kwh of waste heat. Car alternators with their base electronic controls I knew were inefficient even though the design itself being claw pole is capable of good efficiency. I would have thought the setup you did would be much better but obviously not. The Honda is direct drive and inverter so not going to get much better than that. Where I am, electricity is .30C KWH. Fuel is currently $6.85 a Gallon. To get say 4 KWH out of a gallon of fuel makes the cost of the electricity here a Whopping $1.71 Kwh! Glad I will be running the engine on free waste veg oil! Thanks for the very informative vid. A real eye opener! Really shows me doing the heat capture side of the setup will be worth while far more than I thought!
Glad to help. I agree that co-gen will be great. I have plans to convert my water-cooled diesel genset (MEP-802A) into a co-gen as well. It's just going to take awhile to get there.
@@DavidPozEnergy it's a simple principal but when you start going through all the sub systems it needs, it's quite involved. I think the payoff will be worth it though in reclaimed energy.
Back in 1965, I modified the 55 amp alternator on a 55 Dodge station wagon. I setup 12 to 14 volts on the stator field and got out 150 volts at 4000 engine rpm, gauging pulley ratios from 1955 memory, likely 3 to 1 so 12000 rpm. The 1/4 hp variable speed universal brush motor on the drill worked fine except that it wouldn't turn off. Had to unplug it. What did I know, I was just a kid. Anyway, for short term use, 50 amps times 150 volts would be 7500 watts possible or about ten horsepower off that car engine. Half that 7500 or 3750 would be going into the load and the other half would be lost into the field windings. I'm fairly sure your setup was much more stable than mine was. That phone measuring and adjusting the power rating was really cool. Not available back in 1965. Anyway, your alternator was prepared to operate at full capacity in a much overheated engine compartment, with safety margins on their capacities as well. You said yours was a 215 amp alternator, and you ran it at 50 amps and the field ran up to 100 deg Centigrade, but the field rating was 160 deg C, my guess might be linear relationship so 50 amps times 160 deg divided by 100 deg might ask ya to test long term monitoring at 80 amps, certainly within the 215 amp device capacity. I'm also thinking Amperage squared times resistance would suggest 1.6 squared or 2.5 times as much heating, but at higher temperature you have more dissipation. Maybe change motor pulley size to get it up towards 12000 rpm as rated and get more alternator internal fan cooling. (also you'd have more max voltage, not needing as much current for the same power rating. You could certainly draw more power out of that gas motor with your system) Looks like great fun, thanks for letting us watch your exploration!
Thanks for the fuel economy part it cost you $.80 approx per KWH much more than the grid at $.14 per KWH in my area. you are over cap on filtering for two reasons one it is 3 phases the other it is higher than 60 hz more like 400 hz +. You did right on the 12 vdc rotor voltage if you had driven it with the stator voltage you would have got way over voltage on everything.
I love the Ingenuity man and just getting to do Hands-On projects like this are so fun it's easy for anybody to go out and just buy something to do the job and that's totally fine I'm not against that if you are not comfortable trying to build something like this by all means don't there's nothing wrong with that but it's so much more fun to try and build it and make it work yourself the end result is always much more satisfying sure you might not use that DIY unit you built all the time or maybe you will but the point is you had a lot of fun building it you learn you discover through trial and error and it just makes it all so worth it great job love the videos on this!
@@DavidPozEnergy This was a REALLY cool project man! Kudos! I know I'm late to the party, but I have a question. When you were measuring the capacitor current, were you measuring AC amps, or DC amps? Potentially, especially if you took the measurement in DC, it's probably nowhere near accurate? Also, depending on the frequency of the ripple, and whether or not that meter reads in RMS, that 180-190 mA may also be anywhere near accurate? If I were anywhere near you, I'd offer to bring one of my Oscilloscopes over to have a look at the output waveform, just for shoots and giggles. Either way man, very cool project, loved it!
So what if you use the permanent magnet alternator from a inverter generator. Without using the 120v inverter. You can hook the 3 phase stator to a rectifier and capacitor then to the pv input of your chage controller. It will remove one power inverter out the picture and should increase 10%-15% efficiency.
Nice demonstration David!! If you wanted to measure the conversion efficiency of the alternator + charge controller, you could replace the petrol motor with an electric motor, measure the power required to drive the electric motor and then see how much power you get out of the alternator (before the charge controller). I think the 100oC on the alternator amounts to a substantial amount lost energy going to heat. You will need to factor in the efficiency of the electric motor, but I suspect that will be greater than 90%. Mayby part 3?
That is quite interesting. The total heat output potential of 1 US gallon (As opposed to an Imperial gallon) of "gas" is 35.96 KwH. That makes this setup 11.68% efficient.
Would you share the maths behind this please? I'm running an inverter generator to charge 48v lifepo4, and wondering if a 48v alternator on my diesel engine will be more cost effective.....
One more suggestion: The belt -will- stretch with use. Why don't you add any typical alternator idler puller/belt tensioner that will always maintain the optimum belt tension ? This will also act as a shock absorber of sorts and reduce vibration.
You need a fan on the alternator. Many alternator just use a small fan behind the pulley for forced air cooling. This would allow you to extract more amps and run cooler which should be more efficient. Also, as you stated before, direct drive rather than a belt.
Have you considered testing the affect of raising or lowering the stator voltage? I know you're already gauging 40A as the max safe output by temperature, but it would be interesting to see if 15v for example could provide 40A at a lower RPM. Given the fan would be spinning more slowly, it would get hotter even if the same amount of heat is created. Since the heat created is based on current, I was thinking increasing the voltage may allow it run more efficiently, with the same amount of power delivered in higher voltage and lower current. Alternatively (pun intended), lowering the stator voltage may allow you to run the engine at higher RPM for the same current output and allow the motor to operate at a more efficient part of its power curve.
Connect a bicycle to the alternator and not a gas engine. Wanna see if its viable for a 2 years after the fall situation sort of electricity generation when all the gas is bad. Can a normal guy do it or do you need to be Lance Armstrong.
Stock alternators are about 40-50% efficient on average due to their 12 volt rectifiers. It will be interesting to see how external 48v rectifiers change that.
I think an ohms check will confirm that the buck converter's input and output negative terminals are tied together so that other experimenters may indeed be able to use the internal diodes. Great follow up video.
But in your case external diodes are still a good call. Newer alternators use diodes that avalanche around 20 to 40 volts. Finding this spec on an unknown alternator can be tough so external diodes remove any doubt.
Thanks so much. I have to say you could see your worry about Heat. LOL. Amazing and completely understandable. You answered all my questions. Once again Thank You.
Between the two generators what’s the cost difference? 4.2kw vs. 5.8kw but at what added cost for the 5.8kw? Sub’d and thanks a bunch for all your videos.
It would be neat to capture the heat from running it and use it for heating. Since you only plan on running it in the winter months, you need heat anyways. For 4kWh of electricity you should have about 29kWh of heat produced. If you can capture this then you're using it as a heater as well as a power generator
I often wonder why we burn natural gas at atmospheric pressures to heat our homes... it would make more sense to generate electricity for heat and capture the heat
I've wondered about this, although obviously CO poisoning is the reason people don't do it. I suppose connecting an exhaust line to the engine would help - but in practice these Harbor Freight engines' mufflers do not have an easily-accessible pipe to hook onto. I suppose if you built an adapter it might work, but removing the muffler and running indoors might be a nightmare on the ears. Also, what would you realisticly heat? Water going through a heat exchanger into the house? I'm actually curious if you have some thoughts on this. It seems difficult in practice.
@@benniethejew Do to economy of scale. It is much much much cheaper to run a big powerplant, than a bunch of tiny generator. Also the efficency a power plant reaches like 50%.
@@midnightmotors7202 one of the guys testing the Chinese diesel heaters on here used an exhaust heat exchanger to a car radiator inside I think it was, worked pretty well.
One thing that I learned by building these is the gearing for the engine and alternator needs to be about 1:1. That pairs the engine perfectly with the alternator, since it doesn't need to be spinning that fast. The alternator will run significantly cooler and your engine will use less fuel. The reason alternators have electromagnets instead of permanent magnets is because it drastically increases performance at low rpms. Since you are requiring 48v from a 12v alternator, you might still need to spin the alternator faster, but not likely. You should put a small load on the alternator (like 10 amps) and lower the engine rpm until the voltage starts to drop then speed it up just a bit. That will get your alternator at peak efficiency and you can run a gearing calculator to see what gearing you need. You could probably even get away with just running the engine at the speed that you had during the test mentioned above, since the governor will maintain that speed as the load increases. I love your videos and am glad to see you make some of the things that I make for fun too.
if you load it with 10A you'll find the rpm for 10A. on higher load the rpm will sag much more and the dropping rpm will drop output drastically. you'd need a current and voltage sensing circuit and a servo controlled carb that would lower the rpm on slight loads and rise it on high loads.
@@casemodder89 Since this is designed purely for charging a battery bank, the load can be the same all the time. The same rpm will work just fine. No need for the expensive carb. The point above is to find the Amperage you want to feed the battery bank, then figure what rpm to run the engine at to achieve that as efficiently as possible, I believe.
@@Tumbleweed5150 Running ANY internal combustion engine at anything other than full throttle at its peak torque point will always result in big efficiency losses. A piston engine has comparatively very high frictional losses that are largely independent from load. What you want to do is get the maximum amount of energy out of any single piston stroke, because every time the engine makes a stroke you incur those losses. Since energy (work) in physically is defined as force times distance, and we cannot change the length of a stroke (for obvious reasons), all we can do is look at the force. The force acting on every power stroke is linearly correlated with the torque (torque is just force * distance between the connecting rod bearing and the center of the crankshaft). Given all that, in order to get the maximum energy out of the fuel you need to look at the torque curve (not power curve), set the governor at the RPM where said curve peaks, load the engine up to the point where the engine speed is just beginning to sag, and then back off again just a tiny bit. That's the maximum amount of load you can put on the engine while keeping its speed in the highest efficiency band. If you wanted to go further that that you should start looking at optimizing the cam profiles or otherwise changing the combustion characteristics of the engine itself, but that's most likely beyond the scope of an amateur building a diy generator like this. One thing you could do is get rid of the carburettor and run the engine on LPG/propane. With a fixed load it's easy to just pipe a constant stream of gas into the intake without having to come up with complicated gas flow regulators. LPG would mix with the air much better than gasoline, providing cleaner and more efficient combustion. The only issue I see with this is that it would change the combustion characteristics of the fuel and may shift the torque curve slightly, but you could adjust for that by performing a couple test runs with +- 100RPM from the peak curve. If you find that your efficiency goes up, try moving another 100RPM in that direction. If it drops, back off 50RPM. Repeat until you find the new peak. Another possible issue is that LPG burns hotter than petrol, so you'd have to keep an eye on your engine temperature. Edit: also the optimal ignition timing on LPG may be different, even with the same compression and cam profiles. Yeah basically, optimizing combustion engines is complicated, there's a lot of variables at play. There's a reason why car manufacturers spend billions on R&D every year. However, I do believe that in the small engine space there is probably room for a dedicated enough DIYer to do better than the manufacturers themselves. Consumers don't really care that much about the fuel consumption of their little garden tools, so the manufacturers are not heavily incentivized to optimize for it.
Those cheap converters from China are all common ground, in my experience. They will connect the grounds, if you don't. I suggest protecting the field coil with a fuse. Also, the output of the alternator is controlled by limiting the field current. That's what a voltage regulator does. I would try turning down the current limit on the converter until the output power begins to drop. If that's immediate, that explains why you didn't burn up the field coil- you don't have a big enough converter to do it.
Thanks for the videos great content and well made too ! Regarding the diodes fitted to the original alternator that you removed. These diodes are usually "avalanche type diodes" in modern alternators and do 'zenner' and conduct at around 20-24V reversed to help prevent damage when things fail. So if you do not remove them the voltage you can generate will be limited by the diodes reverse zenner action to about 20-24V. Not a well know fact.
IT WAS fun watching you go through all the trouble but it look to me like you tried to reinvent the wheel. lol there are lot of different ways to achieve better results with less costs and risks . but it was very educational and fun for the people with less understanding of electronics and the ohms law.
Great job David! You could also put some solid rubber wheels on it (two fixed and two pivot with locking brakes) and a handle so you can move it around easily if you need to. Also a mesh guard on the belt to stop fingers from getting mangled!
Can you use/build a 48Volt Belt Starter Generator? To Auto-start and auto-throttle the engine too? There is something about these videos on this generator that just glues me to the Screen am I have Engineered huge industrial systems.
Probably. I was trying to keep things simple with this build because I was learning as I went. My next version will probably have an auto start function.
I've been thinking about a 6kW diesel "light tower", plus Signature Solar's 5kW Chargeverter... not only is diesel more efficient than gasoline, but you can run diesel generators on used vegetable oil for that "renewable smell"! ;-)
Indeed! Bio fuels fit much better into the home power narrative, since you can make your own. Source: UA-cam Robert Murray Smith ua-cam.com/video/ZZg6hirk9r0/v-deo.html Also diesel can be used (be careful!) for heating. (beware of Carbon Monoxide)
This is a great video! You could try using a smaller field voltage. This will reduce losses in the field coil. As long as the output voltage from the bridge rectifier is greater than the battery voltage, you should be able to charge the batteries (might need a different charge controller). This may increase the current in the stator winding, so maybe it will not be a net win. I am not sure. It is just something to try. There may be a specific field voltage that produces maximum efficiency is what I am saying. One other thing you could do is attach a motor controller to the three-phase output (instead of the diodes) and operate the controller in regen mode. That should bump up the efficiency a bit. But there is a lot of learning curve with motor controllers.
I have so many junk cars, it would be worth it if I needed it. I could leave the motor in the car with the alternator already installed. Just add the modifications.
i have two 4.2l trailblazers that have oem 150amp alternators. i added a 3.5kw psw inverter to each vehicle. i played around with it using 120feet extension cord from my back parking lot pad to my house. we had some bad storms one weekend and was able to power a small window ac unit in the summer heat plus run some lights and electronics. i let the vehicle run like this for a great deal of the weekend, but i dont remember how much fuel i used but it was more than i thought it would maybe 60% of a full 20gal tank. at the time of doing this i was more interested in whether i could do this or not, now that i know much more about things i suspect it was close to .....1.5kw for 40hours =60kwh @12gallons of fuel. 60kwh/12 approx 5kwh per gal, but this is a very rough guess. in the end i know it worked, and it was quite, unlike most open frame generators
yes my Honda is way more fuel efficient than the CHonda from harbor freight. My big next step in the grand experiment is to harvest the heat from the motor and store the heat in a 275 gallon tote. Then use the hot water for a supplemental heat system. jUst need a way to make a water bath heat exchanger for my genny
Awesome job overall. I think the reason your Honda had more efficiency is it was engineered as a unit. If you have ever seen one in pieces the three phase alternator is directly coupled to the engine on the flywheel side as well as the proprietary components. At first I thought you had an EU7000is and thought it was fuel injected. Your project uses off the shelf components and probably cost far less than the generator did as the EU7000is is close to CA$6000 brand new before taxes.
Really cool setup David! I enjoy watching these projects and the results develop! Props again for all the hard work involved! I was thinking maybe this same setup could be used to harness wind or hydro energy.
Here i am. Im back. You just thought me something that should be something i knew. But have never thought about it. The alternator need power to engage the power to getting produced. I a couple summers ago in my car that i had parked in my driveway with a boat on a trailer behind it came out and the battery was flat. Thinking since i live with a kilometer of downhill all the way down to the lake i just figured out i wouldnt do anything about anything and just took the car with boat and all behind and thought it of course would fire up immideately when i engaged the clutch and had the motor turning. No. Noooooooope. My diesel car running at 3000rpm down that hill didnt even make any power at all because as you showed me, the alternator hadnt even enough power for creating a magnetic effect for it to start making power. Short story later, i called my friend wich came on his scooter and i borrowed it back to my place borrowing the neighbors car and brought my starter cables. wont do that again now. This has always puzzled me the last 2 years why it never started. Now i know. Btw im 49. And i work on motorcycles and all that stuff all the time.. guess i never have had such a voltage dead battery ever happen to me before teaching me this.
That was a blast! Thanks David. Man, any scheme based on diesel or gasoline sure costs a boatload more than the utility rates these days. Essentially a $1 a killowatt hour instead of 10~30 cents a kWhr. I guess now you should get that methane digester going? 😀
So many thoughts: I saw so much promise in this project when I started the first video. What you have demonstrated is the amazing efficiency of an alternator, even with all the faux pas you have made. I finally get why you removed the original full bridge rectifier...those buck converters do often adjust the negative, not the positive voltage. You're essentially using your buck converter as a current limiting power supply...and having to remove the original rectifier to do it. Those original rectifiers see any voltages in the original design which you are producing with your mods. Further, you claim that you are making it a closed loop... That's not true. Going back to control systems a closed loop requires that the output be used as an input in controlling the output. A buck converter (supposedly) holds an output voltage without reference to the input voltage. As already noted, you are actually using it as a current limiting power supply, so I'm not really certain what to call what you have produced. I believe it is closer to an alternator with a voltage divider across the output to feed the rotor, running without any real regulation. I hope you realize that you are putting essentially all of the demands for regulation on your charge controller.
alternators are far from amazing efficiency. around 45-60% depending on rpm and load. so 50% is a good guess. that is OK'ish. great would've been 80+%. alternators are build for reliability not efficiency (except for the newer bosch series with one high amp and one high efficiency model)
Hello! I'm really writing to say how much I enjoyed both of your videos on this subject. Thank you! As regards the ultimate limit to the power you might draw from your alternator I suspect you could go very much further using a really large exciter current. Of course all that power has to go into the alternator mechanically, in your rig through the belt: I think the ultimate limit there might lie with the alternator shaft bearings because of the tension you'd have to put on the belt to transmit that level of power! Looking forward to more and all the best meanwhile! Cheers, George Morris
I just ran an efficiency test charging my newly made LiFePo4 48V battery I made. Running a Westinghouse 8.5 kW generator into my Sungold inverter I managed just over 4kWh per gallon which is on par with what you ran here. The inverter could only load the generator to about 2700 watts (50 amps charging). I'd like to try with a smaller generator and see if I could come closer to your Honda results. An automotive alternator just isn't that efficient but like you said was a cool project.
Very cool. I'd love to see some tinkering and see how things it affects the efficiency. Larger or smaller alternator? Maybe some alternators have a different design? Gearing for higher or lower rpm?
lager alternator = thicker wires = less heat = higher efficiency. and 3000 Alt RPM is the sweetspot. alternators can take up to 18K rpm on some models. but energy loss on the fans rises squared with rpm. so low rpm is low amp output and high rpm is a bit higher amp output but at way worse efficiency.
The Honda generator and convertor to charge at 48 Volts DC at 100 amps. Thats why it was more efficient. Try charging a 12 volt DC battery bank at 100 amps. Takes forever. Yes, I'm sure the build was fun. My application is more for fuel savings while camping. I'm doing direct connection. Pos and Neg to battery bank.
Really cool project! The capacitor size should depend at least partially on the frequency of the ripple, different size capacitors will be effective at different frequencies. Eevblog channel has a great video on this, titled something like why multiple filter caps. Maybe scope it and check what frequencies you're dealing with, perhaps it's low enough frequency that the capacitor size becomes insignificant, from a frequency perspective. Also I'm completely impressed that physically small alternator seems to be thermally stable at ~2kW, that's impressive. The only thing that would make this project cooler would be replacing that motor with a diesel, also cheap on Amazon. ;)
Well done. Now, to triple your viewership AND be paid by engineering schools to use your videos, simply do THIS: 1. HAIRCUT and close trim your beard. (University administrators and their growing female staffs and interns will go wild!) 2. LAB COAT (Embroidered it with 🎉 DOCKTA DAVE) 3. Solicit musicians to create your new branding rap song: "🎉 DOCKTA DAVE IT!" Intro/end your vids witit. Get Jiggy Witit! 4. Send me 10% of the gross. 5. Your welcome!
If that I may: you, Sir, definitely have talents that are worthy of the Showalter Brothers building an advertising platform around you. I mean only the greatest respect when I say that; you have the enthused appeal and adept knowledge to be the DIY equivalent of a cross between Bob Vila and Bill Nye with a touch of mr. Wizard.
Im thinking you could get some small lithium pouch cells, a BMS and a momentary switch and hard wire that from the 12 volt from the buck converter to charge through the BMS then up to the alternators poles, thru the momentary switch so you have a push button to induce the magnetic field. Depending on how many amps it needs to kick start a magnetic field. it can get as small as the size of a 9 volt battery. Running out there with a lawn mower battery to kick start it off alligator clips looks like it could get old. If my idea can work it would cost very little. Im thinking a 3S10A as the BMS and I'd say 3 battery 402025. BUT those batteries are supposed to be a dollar. at consumer grade prices its probably cheaper to do 3 18650 since they refuse to mail battery. This thing has an economic efficiency of 65 cents a KWH at current gas prices vs the grids 15 cents. not great unless you can tap a gas field.
These results make perfect sense. What doesn't make sense is the EPA spec for electric vehicles. MPGe. Example F150 says "EPA MPG MPGe:Miles per Gallon Equivalent 1 gallon of gasoline=33.7 kWh About All-Electric Cars" . That has to be wildly inaccurate. Or Intentionally misleading. 33.7kwh per gal?
Nice looking set-up, and it WORKS! I've known several folks who used a similar set-up to charge their 12V systems. We call them "poor boys", short for poor boy generator, because we couldn't afford the real thing. LOL Thanks for doing these two videos. My neighbor and I both run 48V systems for our off-grid homes. So far, we haven't had to run generators because we get a lot of sun, but this might be a good thing for us, in case of a blackout at night, to put in enough sun so that the inverter will start powering our refrigerators asap. I do have a Honda 6500, but it needs to be taken in to adjust it, as the Voltage isn't right coming out. (I think a neighbor screwed in all the adjustment screws as a joke). I could get the Chargeverter from Signature Solar and use that, once I have the generator running properly. Just haven't gotten the cash saved up to take it into the shop. Thanks again. Love your channel!
Comparing efficiency to you r Honda generator, it looks like this motor is a bit larger than it needs to be for the power you can get from one alternator. You could power two alternators at less than the 2100 - 2200W you were able to get out of one, and boost the efficiency. The Honda 2200i has a run output of 1800W, on a 121cc engine. Assuming the engines are close in performance, I'd expect around 3200W out of the 224cc motor. So you could run two alternators at around 1600W each and close the efficiency gap with a setup like this.
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Very nice video. regarding the Fuel efficiency - it is horrible. There is 8,5 kWh per liter of Petrol, so 32,176 kWh per Gallon. You have a fuel efficiency of 13%, Most of the losses are from the Engine of course, since the meximum efficiency is at roughly 35% for gasoline combustion engines.
Good job and idea for solar dependent electricity in remote area The effecieny of invention is required Japanese smart with Honda I red some comments, some people really experts For my additive I mention tips for maximizing effeciency Tips 1. Select japanese gasoline engine or chinese diesel engine like "Kepor"5.5kw diesl engine 2. Select 24 volt alternator "Bosch" 140A that used for buses ,it works continously without hotting , it only warm and it is reliable 3. Connect the engine and the alternator with direct coupling to minimize the energy loss by belt for 50 Amperage load 3300rpm is suffiecient for bosch alternator for higher amperage u need belt to increse the output 4. The goal must reach over 20% fuel energy . 5. Incresing rpm for the engine decrease the effieciency The good effeciency between 1500 and 2500 rpm 6. The use of 24 volt alternator with chnging the charging cicuit for 57 volt is more effecient without use solar mptt charger that consume power Good luck.
14:17 A while back I had to setup my house to run off my truck (a small S10), had my inverter hooked up using maybe about 1KW and it got well over 100C, that had me kinda concerned so every now and then I came out with a spray bottle of water and sprayed it until it stopped vaporizing the water :P - Ran it like that for a few hours, alternator still works fine.
4.2kWh seems about right if we consider that the conversion efficiency of most alternators is around 60-70% and your Honda generator is probably closer to 80-90% conversion for the generator portion of the system. The gas motor is always going to be the biggest loss for efficiency but there is probably some room to gain efficiency by either making improvements to the alternator so it isn't getting as hot or replacing it with a more efficient permanent magnet generator head.
Hi David. Nice experimets. I have new suggestions about the fuel efficiency. First engine is 7,5HP (5,595kW) and your alternator produces at peek 2,2kW. This way a lot of fuel is wasted on engine running at half power. Your test with honda generator and dedicated battery charger (with 100A charger current), as I remeber the values, was not run at same conditions so the result could not be compares. So to run engine at full power, adding second alternator will increase total output and could improve fuel effiecency. Second putting bridge rectifies in series could help Victron MPPT charge controller find better point. Maybe alternator current will not drop, but higher voltage will decrease all losses in wires and electronics. Good job.
Using the lower heating value of gasoline, it produces 36kWh per US gal. Your setup got 11.6% efficiency. A thermal power plant and grid get between 25% and 40%. A stationary diesel generator about 30%.
Should be running multiple alternators to maximize the engine power to electricity ratio. The engine is far overpowered for just a single alternator, and so the overhead for the engine to run is eating up a significant portion of the fuel consumption. Increase the load does not impact the overhead, so it can be split up between the loads(i.e. alternators) with no decrease in the output of each.
You can make it through the winter with no generator. We did, barely. You just might need 30-40kWp. My LP Generac 10kW produces about 5kWh into battery per gallon when I have used it,
Great video, a galon of gas have aprox. 33,7Kw/h of energy, your conversion has 12,5% eficiency. Pretty good for modied alternator predator powered generator set! Thanks for Share!!
I found 42.9kWh in 1 gallon it's aprox 10.2% efficiency.
That method doesn't do any justice be cause its an equivalency in raw power to compare to electric vehicles. ICE are roughly 20% efficient. Typically when generating power from a gallon of gas you get between 4 and 7 kwh. for a small generator this is actually not to bad. The fact its put together a garage is also outstanding.
This has to be my favourite series of DIY on UA-cam currently. You've done such a great job for all us hobbyists explaining all the little tid bits so that we can all have a crack at it. Thank you so much for all the effort!
Your welcome. Thanks for watching.
I really like all the detailed info. If you're only taking 2.2kw from the alternator, you should get a smaller pulley for the alternator or a bigger one for the engine, then you can turn the throttle down and still spin the alternator at the same speed. You have more engine than you need, so it doesn't need to run at full speed. A smaller engine could make better fuel efficiency also...something like a 160cc would be good for 2.2kw.
You should try playing with the voltage to the rotor, between that and RPMs you may be able to adjust it to run cooler or at a different speed with different voltages.
There is a governor on the engine.
that a good point dose it need to run so fast. if it was slowed by the ues of a bigger pully it as a possibility to save fuel by running it slower. been equal to the Honda generator by mens of . efficiency. their is serval different ways to carol of rotter sculpt with a Verica in the siystom. grat thinking son .
I would go the other way. Run the alternator at 50+ A and direct air cool it with 12V fans. That way, you can run the current motor at a higher efficiency level. He said the motor had over 6 horse power, so a bigger or even two alternators, could also work better.
Different approach same result.
My home made 48 vdc generator/charger contains a 80's, 10 horse Hatz diesel engine and a permanent magnet hubmotor of an electric scooter/moped.
I run the diesel at a slow 1400 rpm driving the hubmotor at about 650 rpm with a belt, put the 3 phases directly through a rectifier and like you did, the DC + and - through capacitors to smooth it out.
I can make 2200 watts without stuff overheating, the hubmotor gets about 50C but I'm limited by the bridge rectifier that needs forced cooling at this point, but i can get a whopping 2.7 kwh out off 1 liter of diesel which is about 27% efficiency
(One liter is 10kwh) and i was blown away by that result as it is an old NA diesel and some hubmotor i had laying around.
With some duty free diesel i can charge my batteries for about 0,45 euro per kWh, which is not bad concidering that gasoline cost me at least double that per kWh....in Europe i might add where gasoline is liquid gold.
It would be nice to make a gasoline genny with the same hubmotor setup, i would be curious how efficient that would be, the system would be much simpler, no need for a buck converter to generate an output, the amount of RPM decides how much current is flowing as the engine and hubmotor are loaded up once you hit battery voltage.
I like it!
I can't decide what's better, actually building out this Idea and testing it, or the quality of the video. Both are outstanding.
Thank you.
it would also be interesting if you altered the buck converter voltage and see the resulting watt output
Great videos, just a few comments from an old engineer. Small engine carburetors only provide optimal mix for a single RPM, load, air temperature, air density, and fuel variant. Fuel injection (like newer Hondas) would substantively improve fuel efficiency. You might be able to get an FI kit, or set one operating rpm/load for battery charging and jet/set the carb optimally for your RPM/load point and altitude, and adjust seasonally.
wish i lived closer, I'd loan the channel my eu7000 for testing. basically the same as his EU6500 but fuel injected.
He should just use a Honda engine from a used generator.
I thought about that also. This HF engine is only 2/3 the efficiency of the Honda engine
The alternator is 3 phase. The way that the phases overlap greatly reduces the output ripple . Even if you don’t use any smoothing cap at all, the ripple in the output is low enough that it probably could go to the charge controller as is.
Maybe, but why risk damaging a pricey charge controller when capacitors are so cheap? If nothing else, the internal monitoring software will not be expecting pulsing input voltage and may become inaccurate with some noise. Even with external measuring devices, the system is easier to measure with less ripple. I don't see why anyone would go through all this trouble just to save a few bucks on a capacitor.
@@kellyj1464 The 1000uF capacitor feeding 25A to the load is a 25V/ms slew rate when the 85VDC system already has only about 10V of peak-to-peak ripple at 500-600Hz which is 1.5-2ms. If you put an oscilloscope on this or simulated it in something like LTSpice, you would find that it makes no meaningful difference on voltage waveforms. What the capacitor does do though is wreck stator and diode current waveforms.
Ford states these alternators as a 6 phase. You have 2 3 phase outputs.
One note David: If your gas stays cold, the motor is more efficient. Especially if it has a fuel injection CDI ignition instead of carburetor. But nice project. And practice
@@teardowndan5364 Dude 10V of peak-to-peak ripple is pretty bad, that's 10% of the output voltage. If it means a little bit of current spikes that's fine, with the high ESR of a big electrolytic like that a little 100A current spike for half a millisecond won't do anything anyways. Those bridge rectifier packs are usually good for 1500A spikes, 200-300A continuous.
But yeah, really he should've made a resonant LC network to perfectly cancel the ripple without causing huge current spikes.
It would be interesting to see how a permanent magnet alternator would perform in efficiency and temperature.
The output control depends on control of the rotor excitation. With permanent magnets you would need to figure out some other means of control. Or oversize the charge controller to potentially handle hundreds of volts.
Permanent magnets could give you a better efficiency, as used in wind turbines, no waste of energy in having to input current to get the thing going. Your controller of course needs to be able to handle the voltage output and could be more costly depending on the specifics.
It would be more efficient, but probably not by much. The rotor electromagnet is using 60 watts. At 2.2kw that's only 2.7% of the output.
12v @ 5a loss, so 60 Watts lost energy - as compared to a permanent magnet alternator.
Have you tried reducing the Stator feed voltage? High stator power is typically only needed at low RPM conditions, and will cause more magnetic drag and energy loss at normal RPM conditions. That DC to DC converter is probably adjustable, most are.
You are also wasting power by using passive silicon bridge rectifiers... about 120 Watts lost, since each diode loses about 1.5 Volt during conduction, and you always have 2 of them in full conduction. 40 Amps x 1.5v x 2 diodes is 120 Watts. Using synchronous rectification would reduce that to about 10-15 Watts, but would be expensive.
using a controller you get a flat output vs speed where as using a permanent magnet you get a means(bell curve) output. if you are trying to figure this out then look for car dynamo outputs for autos pre 1978
Your fuel economy result answers the largest question that I've long had. I seems that my 90-120 hours of winter battery charging by an AC generator is not such a inefficient solution compared to a possible DC charging option. Many thanks for all your work and sharing with us.
Your welcome. I'm glad I could help. I had the same question for years and finally got around to testing it.
We have a remote cabin and have been using a Honda 2000 to charge the batteries when the sun isn’t good for over 20 years. With the eco throttle I don’t think any other generator will charge the batteries as efficiently because as the battery charge tapers off the generator runs slower. I set the charger in the inverter to 10amps AC max to keep from overloading the generator because you should never run a generator more than 75% of its rated output continuously.
@@Chris_at_Home sounds like your using lead acid batteries?
Your charging solution *is* a DC charging setup, you just have the rectification and capacitor in the charger box, with a step down transformer.
Commented on last video. A lot of effort and expense here for a 48 volt charger. What i did was take a 'broken' inverter generator, where the inverter wasn't making power anymore. Used a bridge rectifier right off the AC windings to convert the direct output of the AC into 250 volt DC. Then Wired up MC4 plugs to go to my charge controller. To the charge controller, it just looks like a solar array. Generator was $200 broken, $50 for the bridge rectifier or so. So for a 48 volt charger, cheaper to reuse a 'broken' genny and use a rectifier than to completely build one
When you mostly need this setup in winter, it would be nice to gain the heat, too. Even when you only can gain half the heat and the other half is lost, it would double the efficency.
Maybe a generator with water cooling and putting the heat in the house water heating system? Maybe an enclosure with a air/water heat exchanger and another heat exchanger in the shop?
for kick-starting the alternator i think there's a couple of things you can do.
The less obvious is to find a way to embed a perminent magnet in to the rotor somewhere so that when it spins it seeds the magnetic flux in the stater before the buck converter comes on and the closed loop takes over feeding the winding.
A second and less invasive approach would be a small kickstart battery and a latching relay circuit
Use a relay with a minimum closing voltage of 12v and tie it to the rotor winding circuit.
Connect the buck converter output via the relay's 'normally open' side and the relay coil.
Connect the battery to the normally closed side
Connect the center contacts to the rotor windings.
When there's enough voltage on the output to pull that relay closed it will disconnect the battery from the circuit and switch over to the buck converter, allowing the closed loop to take over feeding current to the rotor.
As a bonus, You can cut the battery off when not in use with any kind of switch that serves as the 'ignition' switch for the generator so it doesn't go flat when not in use. as a small bonus, why not add a small trickle charger in there somewhere to keep the battery topped up =)
Please please continue optimizing this project as a series to get the maximum output... I'm enjoying the journey. Don't stop here
Oh, boy. There are so many more projects to keep working on. This one will have to take a back-seat right now.
I think most efficiency would come by getting rid of that belt.
@@bumbarabun: Not really. I think in the first video he said that the engine is 6 horsepower. If that’s true, that means the engine can do 4.41kW of power; and his tests showed getting about 4.2. Is worth chasing 210 watts of power? Probably not.
@@jacobcarlson4010 Did the engine run for an hour? 4.2 kWh per gallon but how long did that take?
@jacob seria kW/gal, não kWh a comparação. Que análises excelentes, parabéns pelo vídeo!! 👏👏👏👏 Eu planejo fazer um com automações de partida, desligamento e sensores para um gerenciamento na manutenção do motor.
Thanks David! Very interesting and informative test. In Alaska connected the exhaust of air and water cooled generators to a coil stainless steel and copper tubing, and immersed the coil as crude stack robber and estimated I was able to recover up to about 20% of the thermal heat energy from the engine. I mounted the generators above the heat exchanger coil inlet and plumbed the outlet out the bottom of a spray-foam insulated fiberglass or steel tanks so the exhaust condensate would drain out.
On water cooled generators from 7kw to 600kw we installed coolant heat exchangers to the engine coolant system, removed the engine thermostats and used AMOT valves (Thermostats) in the heat exchanger loop to maximize heat recovery. Combing engine heat recovery with commercial exhaust to water stack robbers recovered up to 60% of the engine heat, so basically the fuel cost of our electric load provided heat most of our space heating.
I was thinking a heat recovery might project might be interesting for viewers, and I would be happy to provide insights from my experience if needed.
That is very cool.
Do you have any websites, books, or videos you could link to? I'd like to learn more about the plumbing and try it.
@@DavidPozEnergy That was back in the 90's so I don't have a website or videos. Heat generator heat recovery hydronic heating in Alaska was somewhat common. I worked with a variety of hydronic heating and recover systems from what might be used to heat a small trailer from 2kw to large oilfield camps of several hundred men and megawatts of power generation, and depending on the scale of application you would be interested in I can provide information as the design depends varies greatly depending on the size of the system.
The smallest system I did that might apply to a home system used a pair of 2800w air-cooled Honda generators. Basically, I welded threaded fittings to the exhaust outlets of the generators. As I recall the exhaust outlet of the Honda was about 3/4" diameter, and used 3ft of of 1.5" dia. flexible stainless steel tubing to reduce the vibrational stresses on the generator exhaust, insulated it with fiberglass high temp and connected the other end of the flex to, two coils of about 20' of 1.25 copper tubing immersed in a 350 gal steel tank that was about 3ft tall by 3ft. wide and 5 ft. long filled about 2.5ft. full ,and insulated with spray foam. I mounted the generators on a platform just above the top of the tank, and routed the flexible stainless tubing through a sleeve below the water level and connected it to the threaded fitting to one end of the copper tubing coil, and the other end of the tubing to a outlet in the bottom of the tank, so any condensate would drain out the end and into a drip pan.
In the Alaskan arctic, in sub-zero temps there was little humidity so little condensate was produced, but in above zero temps you could see a gallon in a day that had had some soot. We used a locally produced gasoline that was more like white-gas / naphtha mix that had few additives and burned pretty clean. so the condensate was likely not too hazardous.
The tank was open to the air and I used a small Grundfos pump (UPS15-58FC 1/25 HP 115-Volt 3-Speed Circulator Pump) on a thermostat at the bottom of the tank to pump hot water to baseboard heating element lengths with a fan to heat a small mobile trailer office, the generator delivered about 2000w of power for lights, a microwave, fridge, radios and a couple of 1500w electric heaters, and a few other things.
The office was a well insulated ATCO trailer about 28ft long by 10ft wide that had about 3" of spray foam added to on the outside. The generators ran pretty much 24hours, and the system was pretty much self balancing down to about -25f, as the more electrical heating load produced more hot water. The grundfos pump was set to turn off when the tank temp got below 135f. below -30F we typically needed to use a 12V webasto gasoline heater to keep the trailer comfy
We used glycol water mix but in warmer some applications water might be ok if you don't have to worry about freezing your coils or tank.
I would estimate that the system recovered a about 2000 watts of heat from the combined generator exhausts when they were running at about 50% load. In warmer temps we only ran one generator.
I'm thinking that you might be able to recover 1000 watt-hours or more of heat from the from a 4kwh run of your portable generator, and that would be pretty easy to calculate by measuring temp rise in a water tank. it might also be possible to plumb up some iron or steel water pipe for a direct exhaust heat exchange if you were sure to prevent exhaust leaks.
If you want to chat about recovery systems and how to use AMOT water cooled generator recovery let me know.
Yes a part two!! I literally built the same thing with a few of the same parts. It works pretty good at higher throttle I can pull about 2,800 Watts found a little constant current adjustable regulator where I can adjust the current going to the field windings so it doesn't bog down The motor too much. Works great. I found about 2.1 amps to be a good output for my alternator. It's literally just an alternator from an '87 mustang
Loved it and great for learning now get a small diesel engine and do it all again with 2 alternators
How you got cookie monster?
With regards to the flexing that we see of the motor plate with the mounted alternator, it seems that a piece of angle iron going perpendicular to the angle iron alternator mount may reduce that flex. Adding some more angle iron to make an "X" or a cross of angle iron in approximately the middle of your plate. I'd bet that would stiffen things up so you wouldn't see that flexing we see in the video due to the harmonics. All in all a GREAT project, one that I think many of us (myself included) have thought of "what if I built this?" and you did! Even though it's not as efficient on a gallon of gas when compared to the Honda inverter generator, not everyone can afford to put down the funds needed for a big Honda inverter generator like that. As you said, folks may have a spare engine and alternator lying around in their stash. Thank you, David!
Thanks for the nice comment. I appreciate you watching to the end. After each version, there are more modifications to be made. I wish I had the time for all of it.
Was going to mention the Angle iron Fix..👍
@DavidPoz hello, any plans on testing some Chinese lithium ion storage battery brands. Like Bslbatt, narada, gsl, bluesun.
Looking forward 👌
It would be cool to see you make modifications to this to meet or beat the Honda's performance.
For almost all buck/boost converters, the two negative connections are actually untouched/commoned. This is because these circuits modulate voltage on the positive side in reference to this common negative rail. To double check, just check for continuity between -IN and -OUT on your converter. Hope this helps!
Given the voltage ratio, I expect a two active switch buck with a transformer.
@@liam3284 even if there is a transformer, in- and out- may well be connected internally to simplify voltage sensing etc.
You can probably get more power by increasing the RPM of the alternator. 8000 RPM is not really optimal.
Alternators can normally go to 15000RPM. in the vehicle, the ratio is like 1:3 or 1:4, so 6000*3.
But nice setup, congratulations.
Needs a smaller motor. You're getting only ~3 hp of output from a ~7 hp engine. You could probably use a more fuel efficient 160 cc engine with proper pulleys. Also increase motor pulley size or decrease generator pulley size to increase voltage output while lowering amperage or increasing generator's output while maintaining same heat levels. You have a lot more efficiency available in this DC setup. It just requires more experimentation to find the proper balance. Honda beats yours currently because they've done the performance to output testing in their design.
Thank you very much for the follow up video, and thank you in general for making video's, here in South Africa we have multiple times of power outage per day, thanks to loadshedding from 2 hours to 16 hours a day. So doing stuff diy really helps especially when solar pannels is always out of stock and inverter generators is quite scares aswell, but thanks again for the follow up video.
Hi Darius. Im also in South Africa and these rolling blackouts that get called loadshedding is the exact reason I'm here!
Another south African here! I knew some Saffas would check this out. It is a kak spul there.
Mom is still left there, she refused to leave. I packed up in 2019 and came to USA. Mom is off grid with 7kw lithium and 5kw inverter and 1800l JoJo. Just sponsored her with some ecoflow goodies and solar panels for the caravan trip to Scottburgh. I am off grid too, my yacht is on solar power and only needed to run the generator once in last 20 days due to a 5 days of rain. I have a 100amp alternator on my 55hp Diesel engine, and a 20amp and 40 amp DC to DC charge controller for my 6kw of lithium on my sailboat. I can charge all 6kw with 3.5 liter of petrol in the Honda generator in 8 hours. In conclusion of this video, Not worth the effort and cost to go directly DC charging on another engine, although a single cylinder diesel Lister would be lots of fun to play with
I built a generator like this probably 15 years ago, I used a 5HP B&S engine with a spare alternator from my Suburban. I kept it 12V because thats what the solar system at the cabin was set up for. One thing I found really helped was dropping the engine RPM, it allowed me to still pull about 40A at 12V, but I could run it at just above idle, it did a good job of juicing the batteries without blowing my eardrums out. I still have it, I'm going to rebuild it this summer, I really like the modifications you made as far as reducing vibration and I'm going to incorporate many of those features.
Good series, liked it a lot, learned a few things.
Cool. Maybe I'll run another fuel test at a lower idle.
How many hours would you say you got out of the block?
@@DavidPozEnergy would you consider providing more details maybe by a series of video/s at a beginner level on the secondary components or electronic components that you have on this unit? Thank you!
@@DavidPozEnergy Great suggestion Drew, and great video, David. Most of the store-bought generators seem to rate their run times at half-load. The trade-off seems to be the slower you go, the higher the effiency. Of course this only works if you have the time - most people don't drive down the freeway at 35 MPH, even though we'd save on gas. Choices are good, though. Appreciate the work giving us the information to make better decisions. 🙂
I also built similar only using a 8hp B&S and a GM alternater charging 3 semi batterys running 3 2500 watt inverters barely above an idle ran my fridge heat lights ect and would only burn 5 gallons of gas at almost 51 hrs of runtime still have this setup for my backup Peace
I have no intention to heart anyone’s feelings.
But this is a terrible terrible terrible idea!!. Why are you trying to reinvent the wheel? You can’t. you just can’t!! You can’t reinvent something that is already invented. I have seen way too many video’s connecting a trimmer engine (two strokes) or mower engine (4 stroke) connected to either a car alternator (like yours, brushed motor bad on ware and tare, using a 12V stater waste of energy) or to a brushless electric generator (like wind turbines generators. Fixed stater, rotating permanent magnets. No brushes ware and tear). None of these projects were cheaper than just a standard Gas or propane electric generators that you can buy from any store including harbor fright. The off the shelf generators have an “Automatic RPM adjustments”, has belt in circuit breakers and other safeties that being ignored in these projects in general (including yours).
First of all, you are thinking doing this will get you of the grid. You are lying to yourself. You will be off “the electric grid” but now you are connected to “the Gas Grid” (that’s 4 times more expensive) or “the propane Grid” (about 2 to 3 times expensive). The only time you are truly off the grid only if you are doing solar or wind (which u do have solar). But then how much do you save that depends on where you are and the weather and how reliable the equipment’s you are using (equipment life expectancy). This is an open debate for the past 10 years or so. And still going…
Let me explain the “Automatic” RPM systems. In any electric generators you need to run it at 3600RPM (60 hz per sec * 60 sec). there are two types “Mechanical” and that’s a spring-loaded arm in front of the cooling air blower of the Engine. When you start without load the throttle will be at idle and when you add load, the load will cause the generator to slow down to let’s say 3200RPM, that will slow the air from the blower and the spring will bring the arm closer to the engine and the arm connected to the Carb and it open ‘s it up. By adding more throttle, it adds more torque, adds more RPM and it goes back to 3600RM. The more load the less RPM, the arm opens more throttle, more torque until the RPM goes back to 3600 RPM. When you remove the load the RPM increases pushing the arm further way from the engine reducing the throttle until the RPM goes down to 3600 RPM. This happens so fast in milliseconds and in every second keeping the engine running at 3600 RPM regardless of the load.
The “electronic automatic” type uses an electronic TACO meter to control the throttle. It’s more efficient than the mechanical and more accurate and faster to reach the target RPM.
Now, if you still keen on your idea, you should have tried this. Buy off the shelf Gas or propane Electric generator. Get a 120V AC to 120VDC full rectifier (I get them from any broken computer or TV power supplies. Or you can buy them online). Use couple of 200V capacitors for the ripples, then connect that directly to your solar charger. That’s it!! Done. You don’t even need to add circuit breakers because you will have them on the generator anyway.
Again, I have no intention to heart anyone’s feelings.
I would not have ever imagined the efficiency with either setup could be that bad!
A US Gallon is 3.8L. A litre of petrol contains close enough to 10 KWH of energy. You therefore burned 38 KWH of energy to get 4.2 and 5. whatever KWH out of that. I knew there were losses but I never imagined that much! The fact the Honda did not do that much better just shows how poor all the conversions are.
I am making a Small Diesel Driven setup and going to make it co-gen or combined heat and power to supplement my solar system in winter. Looks like using the waste heat will have potential for huge efficiency gains due to what must be at least 10 Kwh of waste heat.
Car alternators with their base electronic controls I knew were inefficient even though the design itself being claw pole is capable of good efficiency. I would have thought the setup you did would be much better but obviously not. The Honda is direct drive and inverter so not going to get much better than that.
Where I am, electricity is .30C KWH. Fuel is currently $6.85 a Gallon. To get say 4 KWH out of a gallon of fuel makes the cost of the electricity here a Whopping $1.71 Kwh! Glad I will be running the engine on free waste veg oil!
Thanks for the very informative vid. A real eye opener! Really shows me doing the heat capture side of the setup will be worth while far more than I thought!
Glad to help. I agree that co-gen will be great. I have plans to convert my water-cooled diesel genset (MEP-802A) into a co-gen as well. It's just going to take awhile to get there.
@@DavidPozEnergy it's a simple principal but when you start going through all the sub systems it needs, it's quite involved.
I think the payoff will be worth it though in reclaimed energy.
Back in 1965, I modified the 55 amp alternator on a 55 Dodge station wagon. I setup 12 to 14 volts on the stator field and got out 150 volts at 4000 engine rpm, gauging pulley ratios from 1955 memory, likely 3 to 1 so 12000 rpm. The 1/4 hp variable speed universal brush motor on the drill worked fine except that it wouldn't turn off. Had to unplug it. What did I know, I was just a kid. Anyway, for short term use, 50 amps times 150 volts would be 7500 watts possible or about ten horsepower off that car engine. Half that 7500 or 3750 would be going into the load and the other half would be lost into the field windings. I'm fairly sure your setup was much more stable than mine was.
That phone measuring and adjusting the power rating was really cool. Not available back in 1965. Anyway, your alternator was prepared to operate at full capacity in a much overheated engine compartment, with safety margins on their capacities as well. You said yours was a 215 amp alternator, and you ran it at 50 amps and the field ran up to 100 deg Centigrade, but the field rating was 160 deg C, my guess might be linear relationship so 50 amps times 160 deg divided by 100 deg might ask ya to test long term monitoring at 80 amps, certainly within the 215 amp device capacity. I'm also thinking Amperage squared times resistance would suggest 1.6 squared or 2.5 times as much heating, but at higher temperature you have more dissipation. Maybe change motor pulley size to get it up towards 12000 rpm as rated and get more alternator internal fan cooling. (also you'd have more max voltage, not needing as much current for the same power rating. You could certainly draw more power out of that gas motor with your system) Looks like great fun, thanks for letting us watch your exploration!
Makes you wonder how the Chinese diesel would do?
Next steps.. Super caps to charge field windingings on startup and Remote start lol
Thanks for the fuel economy part it cost you $.80 approx per KWH much more than the grid at $.14 per KWH in my area. you are over cap on filtering for two reasons one it is 3 phases the other it is higher than 60 hz more like 400 hz +. You did right on the 12 vdc rotor voltage if you had driven it with the stator voltage you would have got way over voltage on everything.
Brother you should try wind generator
Best regards from Philippines 🇵🇭 and thank you very much for your informative videos
I love the Ingenuity man and just getting to do Hands-On projects like this are so fun it's easy for anybody to go out and just buy something to do the job and that's totally fine I'm not against that if you are not comfortable trying to build something like this by all means don't there's nothing wrong with that but it's so much more fun to try and build it and make it work yourself the end result is always much more satisfying sure you might not use that DIY unit you built all the time or maybe you will but the point is you had a lot of fun building it you learn you discover through trial and error and it just makes it all so worth it great job love the videos on this!
Well said!
@@DavidPozEnergy This was a REALLY cool project man! Kudos!
I know I'm late to the party, but I have a question.
When you were measuring the capacitor current, were you measuring AC amps, or DC amps?
Potentially, especially if you took the measurement in DC, it's probably nowhere near accurate?
Also, depending on the frequency of the ripple, and whether or not that meter reads in RMS, that 180-190 mA may also be anywhere near accurate?
If I were anywhere near you, I'd offer to bring one of my Oscilloscopes over to have a look at the output waveform, just for shoots and giggles.
Either way man, very cool project, loved it!
So what if you use the permanent magnet alternator from a inverter generator. Without using the 120v inverter. You can hook the 3 phase stator to a rectifier and capacitor then to the pv input of your chage controller. It will remove one power inverter out the picture and should increase 10%-15% efficiency.
Nice demonstration David!!
If you wanted to measure the conversion efficiency of the alternator + charge controller, you could replace the petrol motor with an electric motor, measure the power required to drive the electric motor and then see how much power you get out of the alternator (before the charge controller). I think the 100oC on the alternator amounts to a substantial amount lost energy going to heat. You will need to factor in the efficiency of the electric motor, but I suspect that will be greater than 90%. Mayby part 3?
an electric motor is NOT 90% efficient
Please wear "eye protection" always, when working on stuff like this !
how well would the setup work if you used the treadmill dc motor ? last time the engine you used was under powered, that 212cc should do much better.
You can install a charging system on the engine that would be able to excite the parts.
How about using two alternators connected in parallel in order to get more amps/ kWh Per gallon?
That is quite interesting. The total heat output potential of 1 US gallon (As opposed to an Imperial gallon) of "gas" is 35.96 KwH. That makes this setup 11.68% efficient.
Would you share the maths behind this please? I'm running an inverter generator to charge 48v lifepo4, and wondering if a 48v alternator on my diesel engine will be more cost effective.....
One more suggestion: The belt -will- stretch with use. Why don't you add any typical alternator idler puller/belt tensioner that will always maintain the optimum belt tension ? This will also act as a shock absorber of sorts and reduce vibration.
You need a fan on the alternator. Many alternator just use a small fan behind the pulley for forced air cooling. This would allow you to extract more amps and run cooler which should be more efficient. Also, as you stated before, direct drive rather than a belt.
Check out 12:15
@@DavidPozEnergy Missed that... Thanks.
Have you considered testing the affect of raising or lowering the stator voltage? I know you're already gauging 40A as the max safe output by temperature, but it would be interesting to see if 15v for example could provide 40A at a lower RPM. Given the fan would be spinning more slowly, it would get hotter even if the same amount of heat is created. Since the heat created is based on current, I was thinking increasing the voltage may allow it run more efficiently, with the same amount of power delivered in higher voltage and lower current. Alternatively (pun intended), lowering the stator voltage may allow you to run the engine at higher RPM for the same current output and allow the motor to operate at a more efficient part of its power curve.
I would take off the rubber mounts and bolt them to the plate.
Also you could run it on propane and get no bad fumes.
Put a bigger pully on the engine it will spin the alternator faster but spin the engine at a slower rpm saving gas and keeping the engine temps down.
Connect a bicycle to the alternator and not a gas engine. Wanna see if its viable for a 2 years after the fall situation sort of electricity generation when all the gas is bad. Can a normal guy do it or do you need to be Lance Armstrong.
Hmmm I would just build three or four wind generators from alternators. no fumes, less noise
Stock alternators are about 40-50% efficient on average due to their 12 volt rectifiers. It will be interesting to see how external 48v rectifiers change that.
The fact that they don't use regular magnets and instead electromagnets also makes them take a blow to their efficiency
I think an ohms check will confirm that the buck converter's input and output negative terminals are tied together so that other experimenters may indeed be able to use the internal diodes. Great follow up video.
But in your case external diodes are still a good call. Newer alternators use diodes that avalanche around 20 to 40 volts. Finding this spec on an unknown alternator can be tough so external diodes remove any doubt.
@@craignels A safety feature I suspect
Thanks so much. I have to say you could see your worry about Heat. LOL. Amazing and completely understandable. You answered all my questions. Once again Thank You.
Between the two generators what’s the cost difference? 4.2kw vs. 5.8kw but at what added cost for the 5.8kw? Sub’d and thanks a bunch for all your videos.
I built my alternator-generator for $400. The Honda generator is about $5,000.
Thanks for this learning experience !
It would be neat to capture the heat from running it and use it for heating. Since you only plan on running it in the winter months, you need heat anyways. For 4kWh of electricity you should have about 29kWh of heat produced. If you can capture this then you're using it as a heater as well as a power generator
I often wonder why we burn natural gas at atmospheric pressures to heat our homes... it would make more sense to generate electricity for heat and capture the heat
the exhaust running through a water heat exchanger would do that
I've wondered about this, although obviously CO poisoning is the reason people don't do it. I suppose connecting an exhaust line to the engine would help - but in practice these Harbor Freight engines' mufflers do not have an easily-accessible pipe to hook onto. I suppose if you built an adapter it might work, but removing the muffler and running indoors might be a nightmare on the ears. Also, what would you realisticly heat? Water going through a heat exchanger into the house? I'm actually curious if you have some thoughts on this. It seems difficult in practice.
@@benniethejew Do to economy of scale. It is much much much cheaper to run a big powerplant, than a bunch of tiny generator.
Also the efficency a power plant reaches like 50%.
@@midnightmotors7202 one of the guys testing the Chinese diesel heaters on here used an exhaust heat exchanger to a car radiator inside I think it was, worked pretty well.
One thing that I learned by building these is the gearing for the engine and alternator needs to be about 1:1. That pairs the engine perfectly with the alternator, since it doesn't need to be spinning that fast. The alternator will run significantly cooler and your engine will use less fuel. The reason alternators have electromagnets instead of permanent magnets is because it drastically increases performance at low rpms. Since you are requiring 48v from a 12v alternator, you might still need to spin the alternator faster, but not likely. You should put a small load on the alternator (like 10 amps) and lower the engine rpm until the voltage starts to drop then speed it up just a bit. That will get your alternator at peak efficiency and you can run a gearing calculator to see what gearing you need. You could probably even get away with just running the engine at the speed that you had during the test mentioned above, since the governor will maintain that speed as the load increases.
I love your videos and am glad to see you make some of the things that I make for fun too.
if you load it with 10A you'll find the rpm for 10A.
on higher load the rpm will sag much more and the dropping rpm will drop output drastically.
you'd need a current and voltage sensing circuit and a servo controlled carb that would lower the rpm on slight loads and rise it on high loads.
@@casemodder89 Since this is designed purely for charging a battery bank, the load can be the same all the time. The same rpm will work just fine. No need for the expensive carb. The point above is to find the Amperage you want to feed the battery bank, then figure what rpm to run the engine at to achieve that as efficiently as possible, I believe.
Alternators use electromagnets so they can adjust the output current based on the varying load rather than having to change the rotor speed
@@Tumbleweed5150 Running ANY internal combustion engine at anything other than full throttle at its peak torque point will always result in big efficiency losses.
A piston engine has comparatively very high frictional losses that are largely independent from load. What you want to do is get the maximum amount of energy out of any single piston stroke, because every time the engine makes a stroke you incur those losses. Since energy (work) in physically is defined as force times distance, and we cannot change the length of a stroke (for obvious reasons), all we can do is look at the force.
The force acting on every power stroke is linearly correlated with the torque (torque is just force * distance between the connecting rod bearing and the center of the crankshaft).
Given all that, in order to get the maximum energy out of the fuel you need to look at the torque curve (not power curve), set the governor at the RPM where said curve peaks, load the engine up to the point where the engine speed is just beginning to sag, and then back off again just a tiny bit. That's the maximum amount of load you can put on the engine while keeping its speed in the highest efficiency band.
If you wanted to go further that that you should start looking at optimizing the cam profiles or otherwise changing the combustion characteristics of the engine itself, but that's most likely beyond the scope of an amateur building a diy generator like this.
One thing you could do is get rid of the carburettor and run the engine on LPG/propane. With a fixed load it's easy to just pipe a constant stream of gas into the intake without having to come up with complicated gas flow regulators. LPG would mix with the air much better than gasoline, providing cleaner and more efficient combustion.
The only issue I see with this is that it would change the combustion characteristics of the fuel and may shift the torque curve slightly, but you could adjust for that by performing a couple test runs with +- 100RPM from the peak curve. If you find that your efficiency goes up, try moving another 100RPM in that direction. If it drops, back off 50RPM.
Repeat until you find the new peak.
Another possible issue is that LPG burns hotter than petrol, so you'd have to keep an eye on your engine temperature.
Edit: also the optimal ignition timing on LPG may be different, even with the same compression and cam profiles.
Yeah basically, optimizing combustion engines is complicated, there's a lot of variables at play. There's a reason why car manufacturers spend billions on R&D every year.
However, I do believe that in the small engine space there is probably room for a dedicated enough DIYer to do better than the manufacturers themselves. Consumers don't really care that much about the fuel consumption of their little garden tools, so the manufacturers are not heavily incentivized to optimize for it.
Those cheap converters from China are all common ground, in my experience. They will connect the grounds, if you don't. I suggest protecting the field coil with a fuse. Also, the output of the alternator is controlled by limiting the field current. That's what a voltage regulator does. I would try turning down the current limit on the converter until the output power begins to drop. If that's immediate, that explains why you didn't burn up the field coil- you don't have a big enough converter to do it.
Thanks for the videos great content and well made too !
Regarding the diodes fitted to the original alternator that you removed. These diodes are usually "avalanche type diodes" in modern alternators and do 'zenner' and conduct at around 20-24V reversed to help prevent damage when things fail. So if you do not remove them the voltage you can generate will be limited by the diodes reverse zenner action to about 20-24V. Not a well know fact.
Thank you. I didn't know that.
IT WAS fun watching you go through all the trouble but it look to me like you tried to reinvent the wheel. lol there are lot of different ways to achieve better results with less costs and risks . but it was very educational and fun for the people with less understanding of electronics and the ohms law.
Great job David! You could also put some solid rubber wheels on it (two fixed and two pivot with locking brakes) and a handle so you can move it around easily if you need to. Also a mesh guard on the belt to stop fingers from getting mangled!
Can you use/build a 48Volt Belt Starter Generator? To Auto-start and auto-throttle the engine too? There is something about these videos on this generator that just glues me to the Screen am I have Engineered huge industrial systems.
Probably. I was trying to keep things simple with this build because I was learning as I went. My next version will probably have an auto start function.
Great project and video. Maybe fab up some small fan and mount to the alternator to pass more air over it and keep it cooler.
I've been thinking about a 6kW diesel "light tower", plus Signature Solar's 5kW Chargeverter... not only is diesel more efficient than gasoline, but you can run diesel generators on used vegetable oil for that "renewable smell"! ;-)
Indeed! Bio fuels fit much better into the home power narrative, since you can make your own. Source: UA-cam Robert Murray Smith ua-cam.com/video/ZZg6hirk9r0/v-deo.html Also diesel can be used (be careful!) for heating. (beware of Carbon Monoxide)
This is a great video! You could try using a smaller field voltage. This will reduce losses in the field coil. As long as the output voltage from the bridge rectifier is greater than the battery voltage, you should be able to charge the batteries (might need a different charge controller). This may increase the current in the stator winding, so maybe it will not be a net win. I am not sure. It is just something to try. There may be a specific field voltage that produces maximum efficiency is what I am saying.
One other thing you could do is attach a motor controller to the three-phase output (instead of the diodes) and operate the controller in regen mode. That should bump up the efficiency a bit. But there is a lot of learning curve with motor controllers.
Its not as good as your generator, but way cheaper, and still does a decent job. Also its easy to work on and cheap to buy parts.
When you say a gallon do you mean 3.785L...or do you mean a real gallon 4.546L...?
US Liquid Gallon. The first one, 3.785L.
Hi David, what about increasing the rotor voltage from 12v to 16v? Great video, by the way.
I have so many junk cars, it would be worth it if I needed it. I could leave the motor in the car with the alternator already installed. Just add the modifications.
i have two 4.2l trailblazers that have oem 150amp alternators. i added a 3.5kw psw inverter to each vehicle. i played around with it using 120feet extension cord from my back parking lot pad to my house.
we had some bad storms one weekend and was able to power a small window ac unit in the summer heat plus run some lights and electronics.
i let the vehicle run like this for a great deal of the weekend, but i dont remember how much fuel i used but it was more than i thought it would maybe 60% of a full 20gal tank.
at the time of doing this i was more interested in whether i could do this or not, now that i know much more about things i suspect it was close to .....1.5kw for 40hours =60kwh @12gallons of fuel. 60kwh/12 approx 5kwh per gal, but this is a very rough guess.
in the end i know it worked, and it was quite, unlike most open frame generators
Really fun video. Thanks.
yes my Honda is way more fuel efficient than the CHonda from harbor freight. My big next step in the grand experiment is to harvest the heat from the motor and store the heat in a 275 gallon tote. Then use the hot water for a supplemental heat system. jUst need a way to make a water bath heat exchanger for my genny
A water cooled engine is a great start het I suppose. If you live off grid, that makes a lot of sense - especially if you use it in winter.
David, Thank you for sharing the outcome of the mods. I'm glad the input was helpful and worked. Take care, Tony
I honestly with a more efficient engine your setup could be more efficient than generator and a charge controller
Maybe. I have a few more experiments planned. We'll see.
Awesome job overall. I think the reason your Honda had more efficiency is it was engineered as a unit. If you have ever seen one in pieces the three phase alternator is directly coupled to the engine on the flywheel side as well as the proprietary components. At first I thought you had an EU7000is and thought it was fuel injected. Your project uses off the shelf components and probably cost far less than the generator did as the EU7000is is close to CA$6000 brand new before taxes.
HOWdy D-P, ...
Thanks
COOP
the WiSeNhEiMeR from Richmond, INDIANA
...
Really cool setup David! I enjoy watching these projects and the results develop! Props again for all the hard work involved! I was thinking maybe this same setup could be used to harness wind or hydro energy.
I would double up the alternators
Here i am. Im back. You just thought me something that should be something i knew. But have never thought about it. The alternator need power to engage the power to getting produced. I a couple summers ago in my car that i had parked in my driveway with a boat on a trailer behind it came out and the battery was flat. Thinking since i live with a kilometer of downhill all the way down to the lake i just figured out i wouldnt do anything about anything and just took the car with boat and all behind and thought it of course would fire up immideately when i engaged the clutch and had the motor turning. No. Noooooooope. My diesel car running at 3000rpm down that hill didnt even make any power at all because as you showed me, the alternator hadnt even enough power for creating a magnetic effect for it to start making power. Short story later, i called my friend wich came on his scooter and i borrowed it back to my place borrowing the neighbors car and brought my starter cables. wont do that again now. This has always puzzled me the last 2 years why it never started. Now i know. Btw im 49. And i work on motorcycles and all that stuff all the time.. guess i never have had such a voltage dead battery ever happen to me before teaching me this.
Excellent video, with plenty of details and VOLUME LEVELS to avoid blowing out eardrums. Liked and Subscribed!
Thank you for noticing the sound levels. It takes a lot of time to adjust them.
That was a blast! Thanks David. Man, any scheme based on diesel or gasoline sure costs a boatload more than the utility rates these days. Essentially a $1 a killowatt hour instead of 10~30 cents a kWhr. I guess now you should get that methane digester going? 😀
or a big hamster wheel and put the kids in it for an hour a day :)
So many thoughts: I saw so much promise in this project when I started the first video. What you have demonstrated is the amazing efficiency of an alternator, even with all the faux pas you have made.
I finally get why you removed the original full bridge rectifier...those buck converters do often adjust the negative, not the positive voltage.
You're essentially using your buck converter as a current limiting power supply...and having to remove the original rectifier to do it. Those original rectifiers see any voltages in the original design which you are producing with your mods.
Further, you claim that you are making it a closed loop... That's not true. Going back to control systems a closed loop requires that the output be used as an input in controlling the output. A buck converter (supposedly) holds an output voltage without reference to the input voltage. As already noted, you are actually using it as a current limiting power supply, so I'm not really certain what to call what you have produced. I believe it is closer to an alternator with a voltage divider across the output to feed the rotor, running without any real regulation.
I hope you realize that you are putting essentially all of the demands for regulation on your charge controller.
A really amazing control loop would lower rpm of the motor to produce a set voltage with your alternator...
alternators are far from amazing efficiency. around 45-60% depending on rpm and load. so 50% is a good guess.
that is OK'ish. great would've been 80+%.
alternators are build for reliability not efficiency (except for the newer bosch series with one high amp and one high efficiency model)
Hello! I'm really writing to say how much I enjoyed both of your videos on this subject. Thank you! As regards the ultimate limit to the power you might draw from your alternator I suspect you could go very much further using a really large exciter current. Of course all that power has to go into the alternator mechanically, in your rig through the belt: I think the ultimate limit there might lie with the alternator shaft bearings because of the tension you'd have to put on the belt to transmit that level of power! Looking forward to more and all the best meanwhile! Cheers, George Morris
I just ran an efficiency test charging my newly made LiFePo4 48V battery I made. Running a Westinghouse 8.5 kW generator into my Sungold inverter I managed just over 4kWh per gallon which is on par with what you ran here. The inverter could only load the generator to about 2700 watts (50 amps charging). I'd like to try with a smaller generator and see if I could come closer to your Honda results. An automotive alternator just isn't that efficient but like you said was a cool project.
That was a really well done experiment! Thanks for the tutorial video I'm sure many people could use it to build their own generator.
Very cool. I'd love to see some tinkering and see how things it affects the efficiency. Larger or smaller alternator? Maybe some alternators have a different design? Gearing for higher or lower rpm?
lager alternator = thicker wires = less heat = higher efficiency.
and 3000 Alt RPM is the sweetspot. alternators can take up to 18K rpm on some models. but energy loss on the fans rises squared with rpm.
so low rpm is low amp output and high rpm is a bit higher amp output but at way worse efficiency.
Was wondering the same thing about messing with gearing to figure out the peak efficiency
That gives you 175 watts for 24 hours so for about $4 worth of Gasoline, your electric bill would be $120 per month to maybe run a Fridge lol.
The Honda generator and convertor to charge at 48 Volts DC at 100 amps. Thats why it was more efficient.
Try charging a 12 volt DC battery bank at 100 amps. Takes forever.
Yes, I'm sure the build was fun. My application is more for fuel savings while camping.
I'm doing direct connection. Pos and Neg to battery bank.
Really cool project! The capacitor size should depend at least partially on the frequency of the ripple, different size capacitors will be effective at different frequencies. Eevblog channel has a great video on this, titled something like why multiple filter caps. Maybe scope it and check what frequencies you're dealing with, perhaps it's low enough frequency that the capacitor size becomes insignificant, from a frequency perspective. Also I'm completely impressed that physically small alternator seems to be thermally stable at ~2kW, that's impressive. The only thing that would make this project cooler would be replacing that motor with a diesel, also cheap on Amazon. ;)
Well done.
Now, to triple your viewership AND be paid by engineering schools to use your videos, simply do THIS:
1. HAIRCUT and close trim your beard. (University administrators and their growing female staffs and interns will go wild!)
2. LAB COAT
(Embroidered it with
🎉 DOCKTA DAVE)
3. Solicit musicians to create your new branding rap song:
"🎉 DOCKTA DAVE IT!"
Intro/end your vids witit. Get Jiggy Witit!
4. Send me 10% of the gross.
5. Your welcome!
If that I may: you, Sir, definitely have talents that are worthy of the Showalter Brothers building an advertising platform around you. I mean only the greatest respect when I say that; you have the enthused appeal and adept knowledge to be the DIY equivalent of a cross between Bob Vila and Bill Nye with a touch of mr. Wizard.
Thank you. Those are some of the greats.
Im thinking you could get some small lithium pouch cells, a BMS and a momentary switch and hard wire that from the 12 volt from the buck converter to charge through the BMS then up to the alternators poles, thru the momentary switch so you have a push button to induce the magnetic field. Depending on how many amps it needs to kick start a magnetic field. it can get as small as the size of a 9 volt battery. Running out there with a lawn mower battery to kick start it off alligator clips looks like it could get old. If my idea can work it would cost very little. Im thinking a 3S10A as the BMS and I'd say 3 battery 402025. BUT those batteries are supposed to be a dollar. at consumer grade prices its probably cheaper to do 3 18650 since they refuse to mail battery.
This thing has an economic efficiency of 65 cents a KWH at current gas prices vs the grids 15 cents. not great unless you can tap a gas field.
These results make perfect sense. What doesn't make sense is the EPA spec for electric vehicles. MPGe. Example F150 says "EPA MPG MPGe:Miles per Gallon Equivalent 1 gallon of gasoline=33.7 kWh About All-Electric Cars" . That has to be wildly inaccurate. Or Intentionally misleading. 33.7kwh per gal?
Nice looking set-up, and it WORKS! I've known several folks who used a similar set-up to charge their 12V systems. We call them "poor boys", short for poor boy generator, because we couldn't afford the real thing. LOL Thanks for doing these two videos. My neighbor and I both run 48V systems for our off-grid homes. So far, we haven't had to run generators because we get a lot of sun, but this might be a good thing for us, in case of a blackout at night, to put in enough sun so that the inverter will start powering our refrigerators asap. I do have a Honda 6500, but it needs to be taken in to adjust it, as the Voltage isn't right coming out. (I think a neighbor screwed in all the adjustment screws as a joke). I could get the Chargeverter from Signature Solar and use that, once I have the generator running properly. Just haven't gotten the cash saved up to take it into the shop.
Thanks again. Love your channel!
Some of the Westinghouse generators like the iGen4200 has a spec sheet of over 12KWH per gallon consumed while operating at 50% load.
Comparing efficiency to you r Honda generator, it looks like this motor is a bit larger than it needs to be for the power you can get from one alternator. You could power two alternators at less than the 2100 - 2200W you were able to get out of one, and boost the efficiency. The Honda 2200i has a run output of 1800W, on a 121cc engine. Assuming the engines are close in performance, I'd expect around 3200W out of the 224cc motor. So you could run two alternators at around 1600W each and close the efficiency gap with a setup like this.
Very nice video. regarding the Fuel efficiency - it is horrible. There is 8,5 kWh per liter of Petrol, so 32,176 kWh per Gallon. You have a fuel efficiency of 13%, Most of the losses are from the Engine of course, since the meximum efficiency is at roughly 35% for gasoline combustion engines.
Good job and idea for solar dependent electricity in remote area
The effecieny of invention is required
Japanese smart with Honda
I red some comments, some people really experts
For my additive I mention tips for maximizing effeciency
Tips
1. Select japanese gasoline engine or chinese diesel engine like "Kepor"5.5kw diesl engine
2. Select 24 volt alternator "Bosch" 140A that used for buses ,it works continously without hotting , it only warm and it is reliable
3. Connect the engine and the alternator with direct coupling to minimize the energy loss by belt for 50 Amperage load 3300rpm is suffiecient for bosch alternator for higher amperage u need belt to increse the output
4. The goal must reach over 20% fuel energy .
5. Incresing rpm for the engine decrease the effieciency
The good effeciency between 1500 and 2500 rpm
6. The use of 24 volt alternator with chnging the charging cicuit for 57 volt is more effecient without use solar mptt charger that consume power
Good luck.
14:17 A while back I had to setup my house to run off my truck (a small S10), had my inverter hooked up using maybe about 1KW and it got well over 100C, that had me kinda concerned so every now and then I came out with a spray bottle of water and sprayed it until it stopped vaporizing the water :P - Ran it like that for a few hours, alternator still works fine.
4.2kWh seems about right if we consider that the conversion efficiency of most alternators is around 60-70% and your Honda generator is probably closer to 80-90% conversion for the generator portion of the system. The gas motor is always going to be the biggest loss for efficiency but there is probably some room to gain efficiency by either making improvements to the alternator so it isn't getting as hot or replacing it with a more efficient permanent magnet generator head.
Hi David. Nice experimets. I have new suggestions about the fuel efficiency. First engine is 7,5HP (5,595kW) and your alternator produces at peek 2,2kW. This way a lot of fuel is wasted on engine running at half power. Your test with honda generator and dedicated battery charger (with 100A charger current), as I remeber the values, was not run at same conditions so the result could not be compares. So to run engine at full power, adding second alternator will increase total output and could improve fuel effiecency. Second putting bridge rectifies in series could help Victron MPPT charge controller find better point. Maybe alternator current will not drop, but higher voltage will decrease all losses in wires and electronics. Good job.
Using the lower heating value of gasoline, it produces 36kWh per US gal. Your setup got 11.6% efficiency. A thermal power plant and grid get between 25% and 40%. A stationary diesel generator about 30%.
Should be running multiple alternators to maximize the engine power to electricity ratio. The engine is far overpowered for just a single alternator, and so the overhead for the engine to run is eating up a significant portion of the fuel consumption. Increase the load does not impact the overhead, so it can be split up between the loads(i.e. alternators) with no decrease in the output of each.
David 1 litre of 91 is 9.8KWh . The engine’s efficiency is not good. However this is great project.😊
You can make it through the winter with no generator. We did, barely. You just might need 30-40kWp. My LP Generac 10kW produces about 5kWh into battery per gallon when I have used it,