Better Battery Modding with your DIYed Meter
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- Опубліковано 27 жов 2020
- If only I had done this sooner! Every time I test batteries, or inverter, or charge controller, etc. I'm always spending too much time setting up the meters. I have finally had enough. Now I'm building myself a dedicated test rig. This has a DC watt meter, with shunt, fully enclosed, and most importantly, it records wh!
Why do we care? Because I'm building myself an off grid solar system and I need to know the total capacity of my batteries. I like to do full discharge tests on my battery builds. This capacity meter will save me a ton of time, and I will be more accurate in the end. Now I can test every battery for its full capacity with ease.
Video building 12v LiFePO4 battery: • Save $500/day when you...
The 12v battery in the video is one I built previously. Here is the link to that video: • Save $500/day when you... I used cells from batteryhookup.com/ If you purchase anything from Battery Hookup please use my coupon code DAVIDPOZ for 10% off. It tracks affiliate which helps out this channel.
Amazon affiliate links:
DC Watt Meter: amzn.to/35US1fR
Electrical Box: amzn.to/37Qdlp8
Cable Connectors: amzn.to/3801LrR
Heat Shrink: amzn.to/37Qzyng
Large Soldering Iron: amzn.to/35I2Otl
Flux Pen: amzn.to/31Md16U
Solder: amzn.to/2Ts6jyC
Ring Terminals: amzn.to/3e2lZC4
Crimp Tool: amzn.to/3oGm6bB
Wire 4 AWG: amzn.to/35HFoV4
(Alternative to the EV wire I had in video)
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My videos are in no way intended to be instructional "how-to" lessons. I am simply documenting my project for informational purposes. Property damage, personal injury, or death may result, even when following manufacturer's instructions. I cannot be held liable for such damage or injury. It is YOUR OBLIGATION to ensure that you are complying with any local and federal laws as well as code and permit requirements. - Навчання та стиль
Very cool idea! You could probably just cross the negative wires so they go out opposite sides to eliminate the bend radius issue, but you'll loose length and they're already short the way it is...
To get the most accurate battery voltage reading you should ideally have the thin voltage sense wires running right to the battery end of the thick wires so that you are not including any voltage drop in the wire (see 4 wire voltage measurement for more info.)
With wires that thick it probably doesn't make a lot of difference but might be interesting to test this. While it is running you can use your multi-meter between the mid point of a thick wire and the battery end to see if there is any measurable voltage drop in it.
Yeah
Yeah. Not sure what gauge wire he's using, but assuming it's ~4 gauge, and it's about a foot to the battery from the box, you're off by about ~1watt @ 45 amps.
now, if you include the terminal resistance (which I assume is going to be much higher -- 5-10 milliohm per terminal?), that adds another 10-20 watts.
His comparison showed ~38 watts offset, which is probably an exaggeration (I'm sure the BMS is itself not super accurate), but I think the conclusion is he's probably off by about 3-4% due to not using the 4-wire measurement.
The easy solution would be to just run the wire up next to the main lead, and heat-shrink it on, then right at the connector solder it down to the ring terminal.
The shunt should be calibrated to measure the voltage drop across the shunt.
Great idea David. If you're going to be load testing high capacity batteries with it, I'd suggest adding some ventilation like a muffin fan to the box as the shunt will get hot with extended use on larger loads.
Might want to put Anderson connectors on both ends. This way you can have multiple leads and add it anywhere quickly. Great vid!
Also a circuit breaker on the power meter so you can connect to any battery without having a spark from the inverter capacitor charging
@@ryan543213cant that be achieved with a resistor?
Thanks David for another great and informative video, you break it down so much that i am very confident to tackle diy battery projects ,keep up the great work
Appreciate your tips for future builds. Thanks!
Good idea and great videos. I enjoy watching them while learning at the same time. Thank you David.
Great project completion!! Thanks for clearly making a beneficial piece of functional equipment from scratch!!!
Thank you for all the links! I am going to build one!
I love your builds. Keep up the great work. Your soldering iron is ridiculous! I don't think I have ever seen an iron that big! I was thinking it might be a good idea to put a fuse in this testing box for extra safety.
Great little project. I like how you state things you'd do different to improve.
One small improvement: add a rocker on/off switch to the +ve power lead that powers shunt. That way to can easily reset the meters figures without having to disconnect/reconnect from the battery source (obviously in this case you could just turn your batteries breaker on/off to have the same effect but assuming not all your future test batteries will have a built in breaker :)
There is a tiny button on the front of the display. When you press and hold you can reset to zero.
Ah brilliant, sorry I didn't know :)
Nice one :D
Neat way to make a 12V test method for your battery. Wish I could find a way to check my 64.8V batteries that simply. Anxiously awaiting your next video on your new batteries and racking system.
What a coincidence, I was thinking of doing the same thing. Now I know what not to do. Thanks for the demo. Love your videos as always.
I like everything except leaving w wires with stripped ends tapped in the box. If that electrical tape lets go, you run the risk of a short circuit. I guess there may not be a lot of places for it to short out, but given the power involved - Murphy will find a way.
That’s a nice box. It’s a great starter project too
Your BMS is likely accurate as well as your meter box. The reason they are slightly different is because you have a circuit breaker in between them. Circuit breakers use a resistance heater to heat a bi-metal trigger inside the breaker. They voltage drop across the breaker will depend on the amp rating of the breaker and the amps flowing through it. I have found many blowing breaker issues to be faulty breakers or bad connections to the bus-bar by measuring the voltage drop while under load. There is also the voltage drop associated with the main conducting wire to consider which you intercepted for your meter mid wire.
As always...Outstanding!
If they die isn't small enough, I turn one of the dies over with just the flat part.
Great idea for the build. I'm using 4 of them with a 12x12 box, and thanks for the link to the metter gauge thingy.
Also safer to avoid 'wires' running all over the place. Great Job! Great Video!
Nice job David,
Gonna make one for the my shop in the Bahamas
Nice work!
This is awesome. One improvement that could be added, (in my opinion) an external power supply so that if the battery (for whatever reason) dies or whatever mishap may occur the meter then retains the information collected.
I use this particular meter for some things and I use a separate 12 bus just to power them as I find them more accurate that way.
Nice build.
Suggestion: Instead of having the wires come out from the box to the load/battery, have heavy terminal lugs/bolts sticking out of the box for each wire. This way you could have different length wires if need be. Also allows for storing a lot easier as you won't have pigtails.
For the Amp reading on those digital meters, there's "usually" a trim-pot inside to calibrate them. But not all of them have those. Worth a look, though.
Love all his videos. So many good ideas
Very cool video! Thanks.
Good job 💪
I Expect some voltages difference as you show. Because each meter have a 1-2% tolerance and also they are pulling data from different points in the circuit. I believe they are very accurate. And you doing a great job in your channel.
nice build!
I think subtle music in the background was a good touch on your vids bro.
Anyone else notice?
Thanks for the feedback, you are first to comment on that.
Yeah and very soft too so it wasn’t distracting
@@DavidPozEnergy wondering can I use the same multimeter for a 48 volt lithium ion LG from battery hookup
Keep it up Mr pots!👍 Thumbs up and subscribed!
Love it brother. Thanks so much for sharing with us. God Bless brother
Great project ... way better than the way you did it before.
I would consider putting some tape on the ends of the extra wires also since they could short a circuit out if the tape holding them to not came loose. Good Project.
heya lol I selected all of your vlog's to watch and it seem I'm going back in time because I first saw the upgrade and now I'm watching the biblt of this DIY meter lol
Great job! I have a few suggestions for your next build: Rather than running wires through the box, install passthrough studs, like the battery, that way if you need a LONG cable, you simply have to bolt it on. I would also consider adding a disconnect switch on the load (or even also the battery) side that way you can connect/disconnect test equipment without having to isolate the battery. If you had a disconnect wired in, you would also be able to run a separate set of test studs to test inline amp measurements rather than relying on the clamp on meter. This could all be done to make the unit fairly weather resistant as well. Having built some enclosures in the past... its much easier to plan it than to execute. Looks like your unit will do what you need it to do.
Great video!
looks good
Thank you. Good video!
This is a great idea!!
I don't personally much like the idea of using an inverter and an ac load.
I would visit a junk yard and collect 50w 12v bulbs then you can switch them in series/parallel for a variety of loads.
Great idea!
Nice info
This is a great video thanks! You have motivated me to build a test box!
At 45Amps you will have a detectable Voltage drop across your wires and contacts. This drop will cause the BMS to read a different voltage than the external power meter. I use a fluke 289 to get really good milliVolt measurements so I can measure losses in wires and connections. Im sure there is a cheaper meter that is similar. You should be able to measure a volt drop across your connects by probing the base of the battery post (or from the inside of the battery) and probing the copper in the wire next to the lug. I estimate you are losing 35mV from the negative 5 awg wire alone. You can move the negative power wire for the meter closer to the battery lug connection to get better accuracy in the power meter. Im not sure where the positive meter power wire connected but it wouldn't hurt to move it close to the battery lug as well. The battery internal wiring and lugs will create a drop that the BMS wont see but there isnt much you can do about this.
I would love to see a video of all the measurements to show the losses in the system.
Great ideas for a follow up. Thank you.
Nice job David. I have a very similar one I built a few years back and I still use it all the time.
Why not add a 150A DC breaker for around $10? This will protect your outputs from short circuit and extreme over-current. Over-sizing the breaker a bit minimizes internal voltage drops. In your configuration, the shunt which is likely just painted steel is your largest power drop. Probably slightly more than the cables themselves. Having a breaker gives you the added advantage of being able to disconnect the power without having to remove cable terminals. ~Cheers
It's a good suggestion, thanks. In my head I was thinking of this particular build, and I already have a breaker. But it would be useful for other batteries that don't have a breaker.
The voltage reading of the bms is little bit high because it's directly reading at the battery. But the wattmeter and the multimeter is reading the terminal voltage of the battery - which is little low because of the drops on the powerMOSFETs, connectors etc....
Nyc work 👍
Suggestion is a 120A circuit breaker in the box. There is room and not all batteries will have their own breaker.
Add an extra switch, with a 9V (or something rechargeable with a USB input) in the case so all you have to do is flip that switch for lower voltage, OR for testing packs with low voltage cutoffs (so you don't loose your data when the BMS kicks in).
very good
you could put a double pole double throw switch on the sensing wires that go to your shunt and be able to monitor current in both directions like if you were charging from a solar panel
I used to buy a lot of enclosures like that but now with the cost of 3D printing so low I find it's cheaper to print the panels and design the top panel in cad rather than having to cut and punch the metal. It's a little more time consuming but it gets faster and easier with every project.
Good Idea David if you do a lot of power testing. Should perhaps have a Breaker ON/OFF Switch on the input of the DIY Meter when the input Battery being tested does not have a Breaker ON/OFF switch.
BTW... I zero my same Amp meter after I hook it to the wire... then turn on the power for a reading. That Amp meter uses a Hall sensor and the wire could skew the Zero reading after clamping.
The BMS sits right on top of the battery so it almost doesn't sees any voltage drop. There is a voltage drop in the wires so the meter sees a smaller voltage than the BMS.
The difference you are measuring from the battery bms to the shunt is likely wire resistance. At lower amp readings it should be closer
Petition to write on the side of the case "My Shunt In A Box" xD
David, with your UNI-T clamp meter, have you noticed that it measures a different value depending on the current direction? I found it only measures correctly when the direction is correct, so the current flows in the way it shows on the clamp. Have you noticed something like this too or is this just mine?
Thanks for the great video and built.
David, this looks very handy and easy to understand and use. What do you figure you have in this build for parts cost? Good luck.
Nice project, but I'd like to suggest two more improvements if you do it again:
1. Put a fuse on the supply line for the meter. I don't like the idea of running a high current source into cheap electronics without protection. If the meter develops a fault the results could be exciting.
2. Maybe use different cable clamps for the wires. It's probably not an issue but it looks like the edges of the clamps are biting into the wire. With these big wires you might want to have two clamps on each side, one for each wire.
you should put some Anderson power poles on the end and then you can also make different adapter that can plugin for different configurations.
I thought about doing that (SB50). But most of the time I'm using ring terminals.
Nice. Maybe install another braker inside the box for Safety.
pro tip: when making high amperage leads, if you offset the connections for + (pos) and - (neg) by a few inches in length you greatly reduce the chance of an inadvertent short.
great build! I have the same watt meter (but in 300A ) that will be part of my high amp LiFePO4 4s 12v pack.
thanks for all your great content
I agree. That is built into this because the shunt added 3 inches to the negative lead. If I stretch it out on the table it's pretty obvious, sorry I didn't say it in the video.
Nice
Muito bom,seus vídeos parabéns
I agree with Scott Hibbs
The reason you have to run separate wires to the battery to measure the voltage is because if you don't, your meter will be reading the battery voltage minus the series resistance. This doesn't appear to be an issue in your application but I have seen this cause some serious problems in some situations.
Suggest you look at adding a separate battery to power the meter so it doesn't switch off when the BMS cuts off, it could potentially be a small Lion cell with a buck charger from the incoming 12V. Also your Voltage comparisons are going to be skewed as you have a high current running through the cables, and the test points are at different locations, you need switch off the load (or reduce it as low a possible) when comparing the voltage accuracy between each device
Whoa!
I subbed as I like your interesting videos. So....is the BMS reading high, or is your watt meter reading low? Is the clamp meter more accurate than the watt meter, or less? The age old question! I would expect your wattmeter to read slightly lower than the BMS as it's got voltage drop across nearly half a metre (ish) of cables to deal with (not just the main batt cables but the thin ammeter cables too). Either way it's not far out so no real concern! :)
It is the question. I recorded myself joking about how I'm checking one cheap meter with another cheap meter, but edited it out due to time, and sarcasm doesn't always come across well.
I was thinking about adding one of those to our big battery charger that has a like 200 amp start function it has some analog gauges but they don't really work well anymore but I was going to go with an inductive current transformer
Just an FYI current transformers can only measure AC current so aren't very useful with batteries. If you look you can find DC-capable sensors which are used in a similar manner, though. I believe they're less accurate than a shunt but should be good enough to replace an analog meter.
I bought several of the basic Drok meters a few years ago. I put connectors on them and taped up the shunt with the wiring. I put the head on 4 ebikes because they are a great battery monitor. They work in one direction Everything I have is wired with an XT60. I must have three hundred. Anyway if I monitor a battery I can hook the meter to the bike and motor with one set of connectors. Those meters are labeled 'discharge'. I have charge meters. I can hook the discharge meter to a battery and a charger by using gender changers, basically a male to male and fem to fem adapter. The Hall meters that are showing up on Amazon (cheap) show flow in and out, and the accumulated flow. They are less accurate. For ebike batteries where cycles and charge % are an issue, this is pretty precise. Your project is great but. My only gripe is that the nice box is kind of worthless for mounting on a bike. It really pays to have everything set up with the same connectors. The XT60 handles my loads. The battery monitor that SOK Battery sells (everyone in China) quite cheap does a great job, just connected to a big lith. In and out flow and %, very low draw.
nice
I like it David, easier and safer than the spaghetti method. When I was watching you put the ring terminals on, I thought that some solder would make the connection solid and cleaner over time. Do you think I am overthinking it? Would this not be recommended for some reason?
The lugs I'm using can be soldered OR crimped. Either is fine, but not both. I find crimping to be faster, and I'm not that good at soldering.
👍this vid was way over due
the bms voltage is reading higher likely because of calibration but also very likely because you tapped the voltage from the load line. There's a reason it's supposed to connect to the battery in parallel. I bet if you took the load off they would get closer in sync.
Great Video! By any chance would you have any use for an a/c compressor out of a chevy bolt? Reason it was replaced was due to rodent damage, they chewed the orange wire half way up and apparently you can only get that wire with the compressor. They also chewed the main "engine harness" was a insurance job, but pretty simple and paid pretty well for the amount of time it actually took.
Is the compressor self-contained with it's own 12v motor, or does it need a belt-drive?
@@DavidPozEnergy It is self contained, but it is a 300 volt compressor. Also uses 1234yf refrigerant. but i honestly don't see why 134a couldn't be used as long as poe oil was used.
Can I meter battery current output to a grid tie inverter to stop excess KWH from over draining battery. Current limit?
You should zero the clamp on meter next to where you will clamp on to. That way you zero out the interference that are close to where you're measuring.
Does this meter count charging as negative on the capacity so you can use it to check the charge state of the battery? Heard from another comment that it doesnt which would be a bummer.
Can you use a cheap grid tied inverter instead so you're not wasting the power during your test to the heaters?
Great job but i would use silicon cable because manipulation
So once the batteries bms disconnects power the watt hour meter will shut down as well ? Perhaps you can power it with a external power source. I would certainly like to build one to test battery capacity for larger cells !
I would have put a Big resistor 1%, a fan and an USB power bank inside the box. Than I would have drill holes on sides of the box. This would give you the best capital rates and than you add 2% to your Amp hour amount.
This meter needs to be calibrated specific to the battery voltage and few other parameters. Without doing that the numbers will be out.
Good job
What’s the best BMS you recommend to use building the 48V LG Chem battery you built. It was a 14s configuration
I’m putting 10 for a 70kW with SMA SI 6048
That's great. If you are doing a few smaller packs (for redundancy) and each will be less than 100 amp, then Battery Hookup has them (10% off coupon DAVIDPOZ ). batteryhookup.com/collections/accessories/products/12v-lifepo4-smart-bms-w-low-temp-cutoff?variant=36287975522466 But if you need larger amps, then Daly brand, I buy through Aliexpress.
Or, some people are very happy using Batrium brand BMS with that type of huge build, but I have not personally used Batrium so I can't vouch for it one way or the other.
I building 10 packs identical to the one you built and hooking them up to SI6048
Do I use one bms per pack or do you know of a bms that can handle multiple packs
Do you like the chargery bms
Use one BMS per battery. So if you have 10 batteries you are building, use one BMS on each. A 100 amp BMS on each would be fine for the battery, but it would give you 1,000 amps available, and one 6kw inverter is only going to pull 125 amps. So you could save some money and buy smaller amp BMSs from Daly or whomever. Or keep to 100 amp each and you will be ready for any future expansion.
I have a 10kW solar array (24 395W Q-Cell) connected to 2 SMA Sunny Boy 240V 5000W inverters feeding the loads and the 2 SMA Sunny Island charging batteries or feeding the houses load at 125A max per SI6048
Max draw will be 250 amps from 10 battery banks, meaning no more than 25 amps per bank
Battery bank consists of LG Chem N2.1 120A 3.7V in a 14s10p configuration
What is the smallest bms size you recommend and is Chargery any good
@@DavidPozEnergy
I’m completely off grid by the way in sunny
Doesn't the BMS have a setting to adjust the voltage range?
Do you still differentiate between +&- with red and black in North America? I like your posts. Really cool. In the U.K. and Europe we’ve moved to brown and and blue. If you’re colour blind, they can’t be confused. Yellow and green stripes are always earth/ground.
Yes, red and black for +/- is common. Thanks for letting me know the difference in UK.
In Diyer straits eh! Ha.. I have two meters like this, one counts in/out watts volts, amps, and has programmable outputs, to set low voltage, high voltage, over current, and who knows what else, maybe even a timer, with a 500-600amp shunt, I think, it's the biggest shunt I could get with it, I'm thinking about using one this one with the batt bank, for protection, wiring the BMS in with, so if the cells go out of balance, it will thut off also, this way its like having a fully programmable BMS, then use the other, simpler one with the solar, 4.4kw plus, to measure either the power from pv, or from the charge controllers, I have about 6! And if I don't get some 100amp controllers, I'll have about 10-12! Anyway, measure the combine output from the controllers, that way it can be measured, and the difference I'd what one inverter used!
Or I may use the not quite advanced meter, on the 12v lighting, and backup bank! I'm thinking about getting a 800w MPP inverter 'pip'. Along with a 1200w to 1500w inverter, with a round 400ah LiFePo 12v bank, and a 1500 ups, with 500ah lead acid, ( I have a couple 450w ups's on the 12v bank, I'd like about a 2,kw to 2.5kw pure sine ups, or a pip, 2.4kw12v, but I don't think anyone makes a 12v that big! I just need a 12v inverter that will run a fridge, a 1kw microwave, and start a 7amp well pump, not at once. I have a sort of easy, slow start for the pump,.. But I have plans to build a water tower, for gravity feed, or a smaller 12v or 24v pump! I thought about building a 5-10ah lithium battery, for the 12v pump, put it at the tower, and run a small wire, with a DC to DC, to slow charge set it to 14v, cc CV, and charge at about 500-700ma maybe 1amp, and it shouldn't use much power when fully charged, maybe use a voltage controlled SSR, to disconnect when the battery is at 14-14.2v it should last forever, maybe put it in a insulated box, with a tail light bulb, to come on when its below 35° American, something that pulls less than the battery charger! To allow atleast 250ma charge with it on, it should be kept between 35° and 45°F
I think the 12v pump pulls about 3-5amps. I may use a pwm controller to slow it down, maybe a soft start kinda, start slow, and ramp up the pressure.. I figure 45-55psi running max, being the well does 70-80 psi running pressure. Sorry to be rambling!!
the meters are off due to the loss in the wire from one end to the other ... and the BMS in the batt its correct because it is inside the batt ...... just something you need to know as far as how it drops from one meter to the next
Hi Dave, Do you have a preference to CALB batteries or 18650?
No, I don't.
Where can I get one of those wire gauge boards you have. I looked online and didn't see anything like it.
It was a drill gauge, I just use it for mystery wires: amzn.to/3ntZrjD
Is there a way to calibrate the voltage on this meter? I have the exact same meter. However it is 2/10th of a volt higher than my other calibration voltmeters.
No, or at least I don't see any way to.
The dies in the crimp are metric - 25mm2, 16mm2 not sure what that is in AWG
I new to learning all this battery inverter stuff...i see you have a jupiter inverter...im really confused about inverters because one side says dont use modified wave in your rv, then the other side says its totally fine...smh what is the scoop?
Modified sine wave is fine for some loads, but very harsh for others. For example, heaters (baseboards, water heaters, stoves, ovens, all run fine on modified sine wave. But electronics like LED lights, CFL lights, TV, and some types of motors will not run right on modified sine wave and need pure sine wave. I suggest sticking to pure sine wave most of the time. I bought this cheap inverter (jupiter) just to test loads with heaters, so it's fine in this application. If you want to see the sine wave check out this video: ua-cam.com/video/gx_q0h7YCJU/v-deo.html
muito bom ...
Is that temco heat shrink tubing? I have/had alot of it I love the stuff, i think everything temco sells is great stuffs! it's all good stuff a ith next to the lowest possible price, you can get it cheaper, but the quality is less also, but temco is a great price with great quality!!
This is the link to the heat shrink I used in this video. It says XHF in the listing, so I assume that's the brand. amzn.to/37Qzyng
@@DavidPozEnergy yeah that's good stuff also, I think it may be from the same manufacturer, shrink tubing, is soooo much bet tgan tape, i usedto not bother with it, then tried it. Now I look for an excuse to use it, great stuff, especially the glue lined, 3:1, I'd say the 4:1 stuff is awesome also, but it's spendy, and not as common, I even got some clear 3:1 I'm thinking of putting led tape inside, with the wire, to look like the power if flowing, for a ebike/Ecycle project, keep at it
Does the shunt gets very hot inside the plastic box?
Not at all. At least not at 48 amps. It's rated for 100 amps. Maybe it would get hot up there.
Used your battery hookup code
i think you should get a bigger soldering iron.
Smart job!!! By the way anybody with idea on solar charge controller for my 6v 420ah bat? Using a 500w panel.
Adding the battery voltage sense wires in the box is convenient, but you're losing accuracy. Now you are measuring the voltage after the drop in the wires, instead of the actual battery voltage.
When you tested the voltage reading, there was no load, so no extra voltage drop on the wires, but in actual usage there will be. You have to compare the voltage measurement while there is a large current draw.
You could connect the voltage sense wires to the ring terminals that mount directly on the battery, and then use some cable sheathing to hold the large power wire and small sense wire together. That has the same convenient, but less measurement inaccuracy. Only loosing the voltage drop through the ring connector at high loads.
You are 100% right. I should go back and measure the voltage drop at 50 amps. And I like your idea of an extra wire going back to the ring terminals with a sheathing. Thank you. Now I'll have to make version 2.