I thought this was going to be another useless alternator voltage video, but turned out to be one of the most amazing videos I’ve seen! Never knew this could be done.
@inventions ideas actually as an engineer my approval is needed for tons of stuff daily, but I was just showing some support for a great DIY tool. FWIW no one needs keyboard jocks telling ppl what to do lol.
@inventions ideas I think as a teacher for a few years during school I'm pretty covered for my "random keyboard warrior approval award" for giving back... 😂🤣😂🤣 what a joke
I am going to follow your steps and make a living out of it as i cant afford a clamp meter for my shop. I will appriciate you and pray for you every time i get benefit from this setup
The "Shunt" here, I think, is actually a voltage divider. First, about meters. Internal to the meter, between the "AMP" and "COM" connectections, is a shunt made from a calibrated size of copper. Although copper is considered a "conductor" there is still a resistance to copper that can be measured - although it will be in the milliohm or micro-ohm range (.001 to .000001 ohms). Suppose the internal shunt inside the meter for the amps function has a resistance of 1 milliohm. And now you hook the meter up to the battery while it is drawing 10 amps. Using Ohm's Law were E=IxR. That is, voltage = current x resistance. So, 10 amps x 0.001 ohms = 0.010 volts, or 10 millivolts. The meter is actually internally measuring 10 millivolts across the internal copper shunt (which is actually a precision 1 milliohm resistor) and the meter is actually displaying 10 millivolts... but since the human operator has selected the AMP function, the display scale is re-calibrated to be shown as amps so that the human operator does not have to keep using Ohm's Law to convert the meter reading. The meter's internal shunt has a limit of safely handling 10 amps without damaging the very sensitive voltage measuring circuits. To measure current greater than 10 amps requires the use of an external shunt. Think of his black wire, which has an overall resistance of about .002 milliohms (or 2,000 mico-ohms), as a long string of 2,000 one micro-ohm resisters connected end to end. At the end connected to the battery (at the first of our imaginary resistors) there is no voltage drop. At the 2,000th resistor at the other end there is about an 8 millivolt drop. So, along the length of the shunt, there is a gradient of voltage from 0 to 8 millivolts. By using the pin to probe through the insulation, he is finding the exact spot where the voltage drop is exactly 4.3 millivolts. He picked the spot where number of millivolts would equal the number of amps. He could have picked anywhere - but there would have been more math involved to convert the ratios. This way, we can just read the millivolts reading on the meter and know that it has a one-to-one ratio correspondence to the number of amps. The theory for his shunt / voltage divider is actually covered in the first few days of DC Series Circuits. But, what Carolina Custom has done to turn a chunk of wire into a semi-calibrated meter multiplier is brilliantly clever!!
I learned something tonight. I worked as an electrician for years and did not know this, I always had a clamp meter at work but don't have one now that I'm retired. Very clever and now I'm going to make one so I can use it at home. Thank you for making this video :)
Good speaker teacher very knowldgable very good demo I've worked on car since 10 year agent 73 asof yeasterdaynever seen thing made so simple on 1_10 its a 15 thankyou
Very good video for the home mechanic. Explaining and showing how to fabricate a highly usable measurement tool with simple means. Even how to calibrate it - and that is pretty important - because you want to be sure that you have 1amp, when you are actually reading 1amp on the meter. Great 💚
Just plain and simply AWESOME! Recently purchased high amp alternator. Also DC amp meter. Meter isnt showing anything to speak of. Ive got to insure the price of both articles was worth it. This homeboy shunt will do it. Thanks many times.
Nice. I can now test the actual charging current of our service vehicle to determine if my alternator is still working, without buying that expensive amp clamp. Thank you.
A very good video, thank you.. It shows the general operating principal of a current shunt which are a vital component in many electronic devices. When I build heavy duty power supplies I usually buy premade ones which are solid brass and calibrated, however for the smaller supplies I use a piece of wire of the same length on all of the models, and wire up a stand along milivolt meter which says it measures amperage on the display. It's wired just like you have here except made permanent with soldering.
Your a boss, bro, thanks. Thanks for being so smart and helping us poor folks. I have money and I work, but money is tight and cannot be wasted. Good job, GOD BLESS
Works for big jumps in current draw I found. I had a hard time finding that sweet spot you mentioned. So I just tapped off not far from the on clamp. Basically the greater the distance you spread your volt meter leads for the pick off the higher the millivolt reading you will get. At least that's what I was seeing. I didn't find it was very useful or accurate in the 10's of amps range, but 20's to 200's you will def see a jump and a big change in that millivolt reading if you turn on say an 1600w inverter with a 1600w load like a heat gun, which is just what I have in my company truck since I do avionics work on Helicopters sometimes remote in the field. Thanks for the vid. I found it useful.
Thanks for the video, I'm from a place where its not that easy to source a decent amp clamp (though Multimeters are easily available) and your video has really helped me and several others stuck in a similar situation. Cheers, A.P.
Well damn! That amp clamp is the one thing I wish I left my last job with 🤣 Now I don't feel so bad... I'm gonna make one of these tomorrow, because I think my Alternator is getting tired. Thank you! Subd
Wow, i know a enough to get me by but this is new knowledge to me. Being an entry level tech with limited funds, this seems like a really good technique to get a quick reading on a budget. thanks for the upload!
U saved money; u learned a principle; your value increased; you can pass along for free either a new lesson and or loan this new tool or both with no worries. The plastic " i can buy one at my local Chinese bulk parts distributor" crowd miss this whole opportunity. Right? 👍
Lots of guys commenting on how an alternator's output may be, say 130amps, but the system may only demand 85amps for charging, a/c, lights, or stereo, etc. You may have leaky connections. Where do all those extra amps _go?_ Easiest way to find out is to slide a piece of cardboard under the car when you pull into the driveway. Next day, pull the cardboard out and look for any extra amps that leaked out overnight. They're silvery, shiny, and may leave tiny burn marks.
Nice trick, but instead of using this testing cable and "calibrating" it, it is much simpler to use the procedure you describe by using the car's negative cable that goes from the battery to the chassis and measure mV across this cable directly. Calibration can be done in the same way. By putting a bulb of known current draw across the battery terminals and reading the resulting millivolts on the multimeter. Then, this value is the reference value for every new load measurement, by applying the arithmetic analogy method, that is, for the (say) 21 Watt lamp I used as a reference, I measure (say) 15 millivolts as translated current. Now that my new measurement is (say) 86 mV, how much is my new current? In this way one does not need the external testing cable and its calibration making things easier and simpler, while the general idea remains the same. Anyway, your presentation is correct. Thanks for sharing the idea. Personally I am using it for many years now whenever I suspect something wrong with the electrical system of the car. Moreover, one can detect even the slightest parasitic current drain of the car's system, provided that the multimeter he uses is of a good brand name, with proper measurement properties for that purpose i.e. high accuracy in the millivolt range. In this last case, only the immobiliser current draw (which must be known beforehand) should be measured when the car in in a "key off - motor off" status. Any other indication in excess of the (known) value will represent a failure (i.e. parasitic current draw) of the system needing further investigation...
It's always great to learn something new everyday thank you for sharing that knowledge I'm very thankful and grateful for it I hope you post more videos about things like that
@@NukeNukemson Inflexible business model. Segments of the business lost to Walmart, tire chains, oil change shops. There was a Sear in my area until a few years ago. Their clothing section was small but they sold good men's clothes, I thought.
I like your vid even though I just bought a clamp meter that I can also use as a general function multimeter. I just like the idea of not having to disconnect anything to take measurements. Your video however, taught me a few things and for that, I'll indeed subscribe. Thanks for making this.
Thanks, good video... I used to load-test PC power-supplies and needed a way to measure the load. That's where the shunt would come in, and I could then attach a mili-volt meter across the shunt, instead of a DMM.. It's the same principle, but using analog guages,,,
Good of you too share a thing like that.. as let's be honest if sombody didnt take the time to show how to so do that.... you would never have come up with it...👍👍
If you don't need over 100 amps I recommend the uni-t ut210e it can do dc current up to 100 amps and is pretty accurate even at small currents like under 1 amp if you need that I have one and have been happy with it and it's under $50 but make sure you get the E because they have others but they don't do DC current
Thanks for the video its just that amp meters so cheap these days so I don't think people would go this way to test but I like the way u calibrated the wire i just never kn a wire that gage could have that kind of resistance in such a short distance.
@@bgriffis420 Harbor Freight hand tools are good and the price is right. The rest of it, I'm not so sure. I did get a good floor jack from them though. They have premium lines for some of their products.
The (calibration) was pretty neat but I'd hook your connections on the copper wire not the clamp because those clamps are probably adding a good amount of resistance
What you have done is measured a voltage drop, known as an I.R. drop across a section of the internal resistance of of your wire. By probing the wire while connected to meter, you located the place where the milli volt reading matches your amperage or current for the light (4.3 amps) . For (4.3 mV) drop to appear on DVM screen matching (4.3 amps), you have located a place where the remaining resistance of wire length is (0.001 Ohm) or 1 milli-Ohm. A current flow of 4.3 amps pushing through a resistance of 0.001 Ohm will drop 0.0034 volts or 3.4 mV. to agree with the amperage drawn by light bulb. At a nominal DC voltage of 12V pushing 4.3 amps (12x4.3) the power or Wattage at the light= 51.6 Watts. The hot resistance of the light is R=E/I = 12.0/4.3 R=2.79 Ohm when energized.
I would use insulated color coded alligator clips - splurge a little for safety. You short out your "shunt" and lets see: blown diode bridge on alternator, battery blows up, roasted electronics/computers, fire, slagged copper and what ever Murphy can think of extra. You might have gotten away with those things thirty years ago, but not today.
Great video I would just like to add that a good volt meter that reads acurate MV's aint that cheap either . AND the price for a fair clamp meterThat reads AMPs DC can be round same price as a good volt meter that reads acurate MV"s. So with that I have to say this video is by far the most clever I have seen thus far on youtube KEEP EM COMING BRO cool accent too lol 10 thumbs up for YOU! Check cheaper clamp meters on Amazon that read amperage I picked one up for $27
I am going to be testing a vehicle with 2 batteries. What difference's should I take for hooking up shunt, multimeter, etc,etc. Do I isolate to one battery or does it matter. Thank you in advance. And thank you for a very clear and valuable presentation.
I am reminded that I don't know as much about alternators as I thought. Thanks. Back to finding out why my alternator won't charge at idle with the headlights on and heater full blast with a 130 amp gen 3 mustang alternator. I am thinking its the grounds?
I have a clamp meter but found it almost impossible to actually clamp it round the battery/alternator cables, the only access would be from underneath with the car on a ramp. But if anyone is interested you can buy from Amazon and other outlets an adaptor for your multimeter to convert it into a clamp meter quite cheaply.
you are wright,you are my kind man, i love math and the real thing's , i was electrician and electronic's technician for more than 40 years ( the real one )
Interesting video. But my question is, do you need to make a new wire for each new car you test? I dont think this wire will work on all cars, because there is different voltage drop.
He made a 0.001 Ohm resistor so any time you read Voltage v= i x R y x 0.001 = 0.00y or as he said y mV. same number just move the decimal over. which the meter does for you.
Actually has nothing to do with theory other than the fact that any current carrying wire has internal resistance to it. Very ingenious of this man to figure to correlate the actual current to the millivolt reading at a certain spot along the wire.
A shunt (the wire in this case) is basically a resistor with a known, very low resistance. Placing it in series with a circuit allows you to measure the current indirectly by measuring the voltage drop. Because the resistance is so low, the shunt has negligible effect on the current and voltage supplied to the of the rest of the circuit. It lets you measure high currents without having to put a meter in series with the circuit. Ohm's law says V = IR (voltage = current x resistance, or volts = amps x ohms). Solving for current gives I = V/R. If you have a piece of wire with a resistance of 1 milliohm (1/1000 of an ohm), then the voltage drop across the wire when measured in millivolts will be numerically the same as the current through the wire in amps (0.001 V / 0.001 ohm = 1 A). The trial-and-error in the video was to find what length of wire provides the desired 1 milliohm resistance. This will vary a bit with temperature.
@@thromboid Thanks for the explanation, at first I did not get how the mV readings are the same as the amps. The trick with the shunt by-itself is cool, but the thing that you can find the sweet-spot with 0.001Ω of resistance and you can get the result without any additional calculation is so clever.
make your own diagram on paper with basic instructions. I did and it will be easier than trying to deal with a phone or going back inside to revue vid.
My 2018 Promater City van's OEM alternator is 160a has gone bad and only putting out 12.5v. There is a lot of power demand on my van. I run a giant battery 155ah AGM starter battery and 2000 watt inverter + 12v fans and LED lights and other appliances overnight. I want to put in a 320a after market high amp alternator, but worry about the computer and affecting gas mileage. Should worry the battery fuse to my alternator is only 150a. Any pully or adapter changes if manuf claims it will fit?
very good could be improved for your interest my 67 Ford Cortina 1500 GT had a built-in current clamp meter you can make a current clamp meter using a multimeter
Hi - Do you sing? There was someone famous, very funny, and had a lovely voice, not too long, ago. I'm guessing folks have told you way before me. :-) Thank you for the video. Excellent. Even though I can afford the nice tool, using yours is more fun (as long as we add some shorting protection - see @10:54 !) , because it focuses us to the principles we take for granted/fun. Thumbs up.
So to be clear, you started off with a long thick(ish) cable with crocodile clips connected to both ends which you then cut off, shortened the cable and bodged two more clips onto?
That doesn't account for manufacturing tolerances and variances. It's really best to verify the individual parts being used and work with those readings if you hope to have an accurate and well engineered system.
A link to those clamps would have been nice. I did an internet search for them. I saw every type of clamp except those and then tried a parts house. nada.... darn.
This is a cool homemade amperage tester. What is the physics behind this volts to amps test? Simply finding the sweet spot along the cable which correlates numerically to amperage? Wow, thanks for the learning of something new!
Hi, can you help me with something? I have a positive and negative wire going to the back of my van. This wire was used to power a wheelchair lift. I gave the lift away and now I have the cut wires. How can I figure out how many amps it can provide? I know hoe to test volts but how do I test those two wires, positive and negative, to know how many watts are coming out? Thank you.
I don't know. It goes towards the engine but than its covered. It looks like DC wire and a high gauge/skinny wire set. But maybe its AC. These are two important factors.
Just found your channel & I have to say that is a GREAT WAY IF YOU DON'T HAVE AN AMP. CLAMP. One question, What size ALT. was in that vehicle as in AMPS. ? I just bought a 1 month old Denso ALT. 56027931 on Cragslist for $5, ( LOOKS BRAND NEW ) he took it out of his 5.2 98 Grand that rusted to HE** & I'm going to put in my 4.0 97 Grand. for an upgrade ? GREAT VID. & I AM A SUBSCRIBER NOW, THANK YOU SIR.
I thought this was going to be another useless alternator voltage video, but turned out to be one of the most amazing videos I’ve seen! Never knew this could be done.
I'm an Electrical Engineer and I approve of this video. Amazing DIY tool!!
Wht is he poking on the cable que made , setting at millivolts range ? and checking for 4.3
@@daaudiome I think a T shape needle available craft stores
@inventions ideas actually as an engineer my approval is needed for tons of stuff daily, but I was just showing some support for a great DIY tool. FWIW no one needs keyboard jocks telling ppl what to do lol.
@inventions ideas I think as a teacher for a few years during school I'm pretty covered for my "random keyboard warrior approval award" for giving back... 😂🤣😂🤣 what a joke
@inventions ideas lol I am American!
I am going to follow your steps and make a living out of it as i cant afford a clamp meter for my shop. I will appriciate you and pray for you every time i get benefit from this setup
The "Shunt" here, I think, is actually a voltage divider.
First, about meters. Internal to the meter, between the "AMP" and "COM" connectections, is a shunt made from a calibrated size of copper. Although copper is considered a "conductor" there is still a resistance to copper that can be measured - although it will be in the milliohm or micro-ohm range (.001 to .000001 ohms). Suppose the internal shunt inside the meter for the amps function has a resistance of 1 milliohm. And now you hook the meter up to the battery while it is drawing 10 amps. Using Ohm's Law were E=IxR. That is, voltage = current x resistance. So, 10 amps x 0.001 ohms = 0.010 volts, or 10 millivolts. The meter is actually internally measuring 10 millivolts across the internal copper shunt (which is actually a precision 1 milliohm resistor) and the meter is actually displaying 10 millivolts... but since the human operator has selected the AMP function, the display scale is re-calibrated to be shown as amps so that the human operator does not have to keep using Ohm's Law to convert the meter reading.
The meter's internal shunt has a limit of safely handling 10 amps without damaging the very sensitive voltage measuring circuits. To measure current greater than 10 amps requires the use of an external shunt.
Think of his black wire, which has an overall resistance of about .002 milliohms (or 2,000 mico-ohms), as a long string of 2,000 one micro-ohm resisters connected end to end. At the end connected to the battery (at the first of our imaginary resistors) there is no voltage drop. At the 2,000th resistor at the other end there is about an 8 millivolt drop. So, along the length of the shunt, there is a gradient of voltage from 0 to 8 millivolts. By using the pin to probe through the insulation, he is finding the exact spot where the voltage drop is exactly 4.3 millivolts. He picked the spot where number of millivolts would equal the number of amps. He could have picked anywhere - but there would have been more math involved to convert the ratios. This way, we can just read the millivolts reading on the meter and know that it has a one-to-one ratio correspondence to the number of amps.
The theory for his shunt / voltage divider is actually covered in the first few days of DC Series Circuits. But, what Carolina Custom has done to turn a chunk of wire into a semi-calibrated meter multiplier is brilliantly clever!!
I have an amp clamp. It's nice because you don't need to disconnect anything but your shunt is a clever way to measure high amps. Good video.
I learned something tonight. I worked as an electrician for years and did not know this, I always had a clamp meter at work but don't have one now that I'm retired. Very clever and now I'm going to make one so I can use it at home. Thank you for making this video :)
Good speaker teacher very knowldgable very good demo I've worked on car since 10 year agent 73 asof yeasterdaynever seen thing made so simple on 1_10 its a 15 thankyou
Very good video for the home mechanic.
Explaining and showing how to fabricate a highly usable measurement tool with simple means.
Even how to calibrate it - and that is pretty important - because you want to be sure that you have 1amp, when you are actually reading 1amp on the meter.
Great 💚
Just plain and simply AWESOME! Recently purchased high amp alternator. Also DC amp meter. Meter isnt showing anything to speak of. Ive got to insure the price of both articles was worth it. This homeboy shunt will do it. Thanks many times.
Wow, I have never seen something so ingenious!
You have opened up a lot of room with this video again thank you
Yeah, I'm a 12V shop owner and I too like this video...well presented, sir.
One of the most helpful car electrical tips I have ever seen. Thank You for the amazing post!
Nice. I can now test the actual charging current of our service vehicle to determine if my alternator is still working, without buying that expensive amp clamp. Thank you.
A very good video, thank you.. It shows the general operating principal of a current shunt which are a vital component in many electronic devices. When I build heavy duty power supplies I usually buy premade ones which are solid brass and calibrated, however for the smaller supplies I use a piece of wire of the same length on all of the models, and wire up a stand along milivolt meter which says it measures amperage on the display. It's wired just like you have here except made permanent with soldering.
Just take off the positive battery cable while the car is running. If engine stays running, the alt. is good.
Larry Zoch a
@@larryzoch4344But this isn't true on older models pre sensors and fuel injection is it?
That was fun! I'd probably be more neurotic about insulating those clamps, myself, but, your point was clearly made ( no pun intended) THANK you ☺
I was thinking the same thing about insulation. I have insulated clamps similar to those. You can always throw some heat shrink around them.
Going to make one right now. Pricing amp clamps yesterday for a single use. Brilliant!
Your a boss, bro, thanks. Thanks for being so smart and helping us poor folks. I have money and I work, but money is tight and cannot be wasted. Good job, GOD BLESS
You are awesome! I knew there was a way to do this I just couldn't figure it out myself. Thanks man
Works for big jumps in current draw I found. I had a hard time finding that sweet spot you mentioned. So I just tapped off not far from the on clamp. Basically the greater the distance you spread your volt meter leads for the pick off the higher the millivolt reading you will get. At least that's what I was seeing. I didn't find it was very useful or accurate in the 10's of amps range, but 20's to 200's you will def see a jump and a big change in that millivolt reading if you turn on say an 1600w inverter with a 1600w load like a heat gun, which is just what I have in my company truck since I do avionics work on Helicopters sometimes remote in the field. Thanks for the vid. I found it useful.
this is a good video to teaching 99.0000000000000000000000000%the electrician's and 99.000000000% the technician's what is OHMS LAW
Thanks for the video, I'm from a place where its not that easy to source a decent amp clamp (though Multimeters are easily available) and your video has really helped me and several others stuck in a similar situation.
Cheers,
A.P.
Well damn! That amp clamp is the one thing I wish I left my last job with 🤣
Now I don't feel so bad... I'm gonna make one of these tomorrow, because I think my Alternator is getting tired.
Thank you!
Subd
Nowadays, ampclamps are nowhere near as expensive as they used to be and the purchase of an ampclamp is a good investment for any homeowner.
Wow, i know a enough to get me by but this is new knowledge to me. Being an entry level tech with limited funds, this seems like a really good technique to get a quick reading on a budget. thanks for the upload!
This is genius. You just saved me $50. Thanks!
Anytime bro.
U saved money; u learned a principle; your value increased; you can pass along for free either a new lesson and or loan this new tool or both with no worries. The plastic " i can buy one at my local Chinese bulk parts distributor" crowd miss this whole opportunity. Right? 👍
Lots of guys commenting on how an alternator's output may be, say 130amps, but the system may only demand 85amps for charging, a/c, lights, or stereo, etc. You may have leaky connections. Where do all those extra amps _go?_
Easiest way to find out is to slide a piece of cardboard under the car when you pull into the driveway. Next day, pull the cardboard out and look for any extra amps that leaked out overnight. They're silvery, shiny, and may leave tiny burn marks.
Awesome Video! Thanks for the education. So cool to see this alternative method/how to measure amps indirectly
This helped me go back to sleep after taking a leak at 0200 hrs.
SOLID VALUE in a video...
You made a current shant reading meter, You are genius
Nice trick, but instead of using this testing cable and "calibrating" it, it is much simpler to use the procedure you describe by using the car's negative cable that goes from the battery to the chassis and measure mV across this cable directly. Calibration can be done in the same way. By putting a bulb of known current draw across the battery terminals and reading the resulting millivolts on the multimeter. Then, this value is the reference value for every new load measurement, by applying the arithmetic analogy method, that is, for the (say) 21 Watt lamp I used as a reference, I measure (say) 15 millivolts as translated current. Now that my new measurement is (say) 86 mV, how much is my new current? In this way one does not need the external testing cable and its calibration making things easier and simpler, while the general idea remains the same. Anyway, your presentation is correct. Thanks for sharing the idea. Personally I am using it for many years now whenever I suspect something wrong with the electrical system of the car. Moreover, one can detect even the slightest parasitic current drain of the car's system, provided that the multimeter he uses is of a good brand name, with proper measurement properties for that purpose i.e. high accuracy in the millivolt range. In this last case, only the immobiliser current draw (which must be known beforehand) should be measured when the car in in a "key off - motor off" status. Any other indication in excess of the (known) value will represent a failure (i.e. parasitic current draw) of the system needing further investigation...
It's always great to learn something new everyday thank you for sharing that knowledge I'm very thankful and grateful for it I hope you post more videos about things like that
I am happy with the explanation. At last someone talking about amperage when testing the car alternator.
Very good. I'll go out into the garage and do it. Just installed amplifiers for new radio system.
Sears sells their amp clamp for about $60. It measure AC/DC amps, voltage, resistance, freq., and continuity (with sound).
joe r what is a sears?
Sears, Roebuck, and Company.
joe r I’ve heard of them...it’s a shame they aren’t around any more, poor mgmt probably ran them into the ground I’m guessing.
They ARE still around though few and far between. I still believe you can order that meter.
@@NukeNukemson Inflexible business model. Segments of the business lost to Walmart, tire chains, oil change shops. There was a Sear in my area until a few years ago. Their clothing section was small but they sold good men's clothes, I thought.
I like your vid even though I just bought a clamp meter that I can also use as a general function multimeter. I just like the idea of not having to disconnect anything to take measurements.
Your video however, taught me a few things and for that, I'll indeed subscribe. Thanks for making this.
As my brother would say, while holding his arms out wide, you have brains out to here!
Thank you sir. Hope you enjoyed!!
Lol that’s EXACTLY who gifts you those cheap jumper cables. And she’s damn proud of it too!!
Well done i have never herd it put so concise and pertinent thank you
You can connect each clamp to one battery post, and use it as a nice heater. Life hack ;)
U can get claim meter for $50 you have everything what you need right in one tool. AC & DC reading, Continuity, ohm and even temperature
This is an ode to the death of overthinking.
Thanks, good video...
I used to load-test PC power-supplies and needed a way to measure the load. That's where the shunt would come in, and I could then attach a mili-volt meter across the shunt, instead of a DMM..
It's the same principle, but using analog guages,,,
Hey thanks for this. I really appreciate you taking the time to share this.
Good of you too share a thing like that.. as let's be honest if sombody didnt take the time to show how to so do that.... you would never have come up with it...👍👍
Nice channel-locks. I have the same pair that I carry on my person a majority of the time. Almost feel kinda naked without them.
Great video as well!
I believe those are knipex and not channel lock tho right?
They are very useful and can loosen many bolts that pliers just won't touch
Another tool is always handy. Iwill defo make this, I have all the bits in garage inc multimeter.
If you don't need over 100 amps I recommend the uni-t ut210e it can do dc current up to 100 amps and is pretty accurate even at small currents like under 1 amp if you need that I have one and have been happy with it and it's under $50 but make sure you get the E because they have others but they don't do DC current
Very nifty trick ~ The way you did that wire !
Thanks for the video its just that amp meters so cheap these days so I don't think people would go this way to test but I like the way u calibrated the wire i just never kn a wire that gage could have that kind of resistance in such a short distance.
D.C. Amp meters, not so cheap. especially clamp meters.
22.99 harbor freight
@@bgriffis420 Harbor Freight hand tools are good and the price is right. The rest of it, I'm not so sure. I did get a good floor jack from them though. They have premium lines for some of their products.
Great video...simple n straight to the point..thnks very helpfull
Great video. New you could make a shunt but did not no how to calibrate it.😀
You sound like and have a lot of the mannerisms of The History Guy.
The (calibration) was pretty neat but I'd hook your connections on the copper wire not the clamp because those clamps are probably adding a good amount of resistance
What you have done is measured a voltage drop, known as an I.R. drop across a section of the internal resistance of of your wire. By probing the wire while connected to meter, you located the place where the milli volt reading matches your amperage or current for the light (4.3 amps) . For (4.3 mV) drop to appear on DVM screen matching (4.3 amps), you have located a place where the remaining resistance of wire length is (0.001 Ohm) or 1 milli-Ohm. A current flow of 4.3 amps pushing through a resistance of 0.001 Ohm will drop 0.0034 volts or 3.4 mV. to agree with the amperage drawn by light bulb. At a nominal DC voltage of 12V pushing 4.3 amps (12x4.3) the power or Wattage at the light= 51.6 Watts. The hot resistance of the light is R=E/I = 12.0/4.3 R=2.79 Ohm when energized.
I would use insulated color coded alligator clips - splurge a little for safety. You short out your "shunt" and lets see: blown diode bridge on alternator, battery blows up, roasted electronics/computers, fire, slagged copper and what ever Murphy can think of extra. You might have gotten away with those things thirty years ago, but not today.
Great video I would just like to add that a good volt meter that reads acurate MV's aint that cheap either . AND the price for a fair clamp meterThat reads AMPs DC can be round same price as a good volt meter that reads acurate MV"s. So with that I have to say this video is by far the most clever I have seen thus far on youtube KEEP EM COMING BRO cool accent too lol 10 thumbs up for YOU! Check cheaper clamp meters on Amazon that read amperage I picked one up for $27
Tell us something on the small jump-start how they work how they produce the power thank you indeed
I am going to be testing a vehicle with 2 batteries. What difference's should I take for hooking up shunt, multimeter, etc,etc. Do I isolate to one battery or does it matter. Thank you in advance. And thank you for a very clear and valuable presentation.
Well done, sir - well done indeed.
I should have shuntin knew this.
Awsome video.
I learned way more than what I needed, very useful info! thank you!
You've just learned how to make a high-current, 1-milliohm resistor.
Brilliant, very impressive. Thanks for sharing!
Very nice, it would be a nice teaching aid
I bought an amp clamp on Amazon for $29. True RMS also
RMS is not applicable in DC circuits.
29 bucks ...don't bet your life on it...
Great idea, it was very useful. Thank you so much.
I am reminded that I don't know as much about alternators as I thought. Thanks. Back to finding out why my alternator won't charge at idle with the headlights on and heater full blast with a 130 amp gen 3 mustang alternator. I am thinking its the grounds?
to prevent accidents be smart to tape up bare clamps
I understood strictly NOTHING and I am straight going to buy meself a clamp ampmeter....... But thank for the video nonetheless..
I have a clamp meter but found it almost impossible to actually clamp it round the battery/alternator cables, the only access would be from underneath with the car on a ramp. But if anyone is interested you can buy from Amazon and other outlets an adaptor for your multimeter to convert it into a clamp meter quite cheaply.
Very Good
Please Iwant diagram for your method of cheak charg
Ohm’s law doesn’t lie!
Brilliant!
Thank you.
you are wright,you are my kind man, i love math and the real thing's , i was electrician and electronic's technician for more than 40 years ( the real one )
Very clever idea
Interesting video. But my question is, do you need to make a new wire for each new car you test? I dont think this wire will work on all cars, because there is different voltage drop.
No because you tested the drop of the cable you're using so you're good.
Correct.
Pretty neat! if to complicated Advance Auto will load test your alternator for free.
Yeah...they tested mine today. I love Advance Auto!
I've never trusted parts stores to diagnose vehicles and components.
Much smarter than before I watched the video. This is so awesome! Anyone wanna share the math behind this?
@@Happymacer Why would the alternator fry? I've ran them with open leads for decades without problems.
@@Happymacer I always figured the voltage regulator would keep the voltage in check.
@@Happymacer no clue. Been doing it for nearly 40 years with no problems thus far lol
ohms law that's it
He made a 0.001 Ohm resistor so any time you read Voltage v= i x R y x 0.001 = 0.00y or as he said y mV. same number just move the decimal over. which the meter does for you.
I love your videos very helpful and no bs.
Hi
Thank you for your information. Im just curious about theory and formula behind this current meter that you made?!
Actually has nothing to do with theory other than the fact that any current carrying wire has internal resistance to it. Very ingenious of this man to figure to correlate the actual current to the millivolt reading at a certain spot along the wire.
A shunt (the wire in this case) is basically a resistor with a known, very low resistance. Placing it in series with a circuit allows you to measure the current indirectly by measuring the voltage drop. Because the resistance is so low, the shunt has negligible effect on the current and voltage supplied to the of the rest of the circuit. It lets you measure high currents without having to put a meter in series with the circuit.
Ohm's law says V = IR (voltage = current x resistance, or volts = amps x ohms). Solving for current gives I = V/R. If you have a piece of wire with a resistance of 1 milliohm (1/1000 of an ohm), then the voltage drop across the wire when measured in millivolts will be numerically the same as the current through the wire in amps (0.001 V / 0.001 ohm = 1 A). The trial-and-error in the video was to find what length of wire provides the desired 1 milliohm resistance. This will vary a bit with temperature.
@@thromboid thanks for the detailed and clear explanation
@@thromboid Thanks for the explanation, at first I did not get how the mV readings are the same as the amps. The trick with the shunt by-itself is cool, but the thing that you can find the sweet-spot with 0.001Ω of resistance and you can get the result without any additional calculation is so clever.
Excellent; I'll have to watch it a few times, but thank you. A wee diagram would be fab...Thanks mate.
make your own diagram on paper with basic instructions. I did and it will be easier than trying to deal with a phone or going back inside to revue vid.
Thanks mate:-)
the factory alternator in my 94 gm 6.5 k3500 is either a 240 or 250amp lol it also has at least 40 factory exterior lights tho lol
Wow that a lot!!
My 2018 Promater City van's OEM alternator is 160a has gone bad and only putting out 12.5v. There is a lot of power demand on my van. I run a giant battery 155ah AGM starter battery and 2000 watt inverter + 12v fans and LED lights and other appliances overnight. I want to put in a 320a after market high amp alternator, but worry about the computer and affecting gas mileage. Should worry the battery fuse to my alternator is only 150a. Any pully or adapter changes if manuf claims it will fit?
very good could be improved for your interest my 67 Ford Cortina 1500 GT had a built-in current clamp meter you can make a current clamp meter using a multimeter
Nice approach. Thank you.
Hi - Do you sing? There was someone famous, very funny, and had a lovely voice, not too long, ago. I'm guessing folks have told you way before me. :-) Thank you for the video. Excellent. Even though I can afford the nice tool, using yours is more fun (as long as we add some shorting protection - see @10:54 !) , because it focuses us to the principles we take for granted/fun. Thumbs up.
So to be clear, you started off with a long thick(ish) cable with crocodile clips connected to both ends which you then cut off, shortened the cable and bodged two more clips onto?
Thanks.thats what i needed to know.to upgrade my wiring and alt.on 79 chevy
That is AWESOME. ...!!!!.....SHUNT LIFE!!!!!
Wattage divided by voltage equals amperage.So once the wattage of the bulb is known then the amperage can be calculated.
That doesn't account for manufacturing tolerances and variances. It's really best to verify the individual parts being used and work with those readings if you hope to have an accurate and well engineered system.
A link to those clamps would have been nice. I did an internet search for them. I saw every type of clamp except those and then tried a parts house. nada.... darn.
This is a cool homemade amperage tester. What is the physics behind this volts to amps test? Simply finding the sweet spot along the cable which correlates numerically to amperage? Wow, thanks for the learning of something new!
Mach 1 its voltage drop, look it up
Ohms law is what you want to study. One of the key parts of Ohms Law for learning how a shunt works, as Airman mentioned, is voltage drop.
So, the amp clamp we can put over the red Alternator wire and check?????? 😊 Or????
Is the 4.3 readinf for all cars???
Thanks for the info awesome video thanks guys!!!
Awesome brother!! Thank you
really nice video, keep up the fantastic work
Harbor freight amp clamp it is!
Well done.
Thank you.
Hi, can you help me with something? I have a positive and negative wire going to the back of my van. This wire was used to power a wheelchair lift. I gave the lift away and now I have the cut wires. How can I figure out how many amps it can provide? I know hoe to test volts but how do I test those two wires, positive and negative, to know how many watts are coming out? Thank you.
What gauge are the wires and what is the power source?
I don't know. It goes towards the engine but than its covered. It looks like DC wire and a high gauge/skinny wire set. But maybe its AC. These are two important factors.
Yes it is. Can you put a volt meter on it?
Just found your channel & I have to say that is a GREAT WAY IF YOU DON'T HAVE AN AMP. CLAMP. One question, What size ALT. was in that vehicle as in AMPS. ? I just bought a 1 month old Denso ALT. 56027931 on Cragslist for $5, ( LOOKS BRAND NEW ) he took it out of his 5.2 98 Grand that rusted to HE** & I'm going to put in my 4.0 97 Grand. for an upgrade ? GREAT VID. & I AM A SUBSCRIBER NOW, THANK YOU SIR.