Shunt resistor build for testing parasitic draws
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- Опубликовано: 21 окт 2024
- Hey everyone! Just doing a little different video today on how I'm making a shunt resistor for testing parasitic draws as well as making a math channel within pico so that the pico software calculates amperage for us! I hope you all enjoy.
.1 ohm 100 watt resistor:
amzn.to/31FMAiF
Safety Banana jacks:
amzn.to/3kv2LYJ
Alligator clips:
amzn.to/30KnL5Q
Milwaukee Soldering Iron:
amzn.to/3ixOwQS
Questions, comments or concerns. Please reach out to me at yotaguruyt@gmail.com
The views and opinions expressed are in these videos are my own, and have not been reviewed or approved by my employer, and do not necessarily represent the views and opinions on my employer.
You've gone above and beyond the normal tech PJ. This is a great addition to your arsenal of tools.
Thanks Wyatt! But im just a normal tech trying to do the best that I can lol
"Ya'll can bash me in the comments, I have no clue what I am doing here." 😆😆😆
You're breaking all the rules I never follow my damn self when it comes to doing this kinda stuff...ABSOLUTELY LOVE IT!
Whatever inspired you to do this video, keep it up!
😄...you are awesome man!
haha! Thanks man! I posted this waiting to get bashed. So far it has been relatively painless lol.
You have so much to offer, how can someone hate on that!?!?
why would we do that, life is always trial and error
@@bartekmedes8281 yessir
Thank you Patrick. Good job. Have a blessed and safe week to you and your family.
Thanks, you too!
of course you would!!! I bought a couple shunts a while back but never implemented it into a usable test tool. Now I need to find what I did with them.
We have had some issues with newer toyotas draining batteries overnight. But I don't have an amp clamp currently that I trust for 5-6 hour draw tests. SO hopefully these will do for now.
This is a great tool! Got to love DIY scope accessories 👍
Thanks!
The tool idea is great and I have used a very similar one for for years . One suggestion is to change to a 1 ohm resistor and eliminate the math. Simply connect your meter or scope to each side of the resistor as you did and the volt drop across the resistor is the amperage with no math required. As you pointed out ohms law. Great use of ohms law for troubleshooting thank you.
Signalrouter i agree about the 1 ohm resistor. But i figured by adding the wire and clamps that I’d be adding a slight resistance anyhow.
Plus, thought it would be cool to show the math channels.
With that said. A 1 ohm resister is probably more than close enough to not need to do the math.
Signalrouter:
A 1 ohm resistor would be too high. With a 2amp draw 2 volts would be dropped leaving only 10 volts for the car. At 10v you might start causing un-intended issues with your diagnosis. (google burden voltage). Using 0.1 ohm the math is still simple, You just have to multiply your voltage reading by 10 to give amps. In addition a lower resistor would not heat up as much which can affect it's value (throwing off the calculation).
Dave I completely agree with the issue of burden voltage. I only use the resistor for very low (usually less than 300 mA) parasitic draw and when I want to view the draw over a long time period
@@signalrouter3480 Fair enough. It just needed to be pointed out that the chosen resistor value could upset what you're measuring.
Great vid PJ. It's awesome making our own tools. I'm going to make this in the next week or so! Thanks for the tip
Thanks! Let me know how well it works for you!
Great video PJ. You're awesome brother!
Thanks Joe! I appreciate it!
Yo Pat, did you have any issues with your build since you made it? Also, how come you didn't put a fuse on it? Thinking about making one. But will fuse it to see the difference
Can I be honest? I built this for a very specific failure that Toyota was having on a very specific vehicle. After building this, I didn't see another fail. So I never got to actually use it.
Love it bro. Going to build one asap.thanks
hahahaha..... attacked by bugs!! You crack me up Pj! I'm so happy to see a video out by you! Truly interesting tool! I like it!
It got me too! haha Thanks for watching Cuba!
@@VoltageDropDiagnostics hey, I hope you do an update. Demonstrate how well they worked out at the job, with all those parasitic drains. We see how to how it all up here, but going over the captures or your findings would be cool.😉😄
Great tool for the toolbox. My comment is related to the super high accuracy you mentioned. You measured the resistance at a different place compared to where you measured the voltage drop, so the resistance will be inaccurate, in turn giving inaccurate current measurement. That said, the tool is great and will give more than enough accuracy to see if excessive current exists or not and how it is changing.
Thank you for another method on checking parasitic draw, I will try to make one like that. 😁
Please do! Let me know if it works for you.
@@VoltageDropDiagnostics hey pj, do you need 100w 1ohm? Can i use 200w 1 ohm? Im in canada and the only available is the 200 one for prime hahah. Thanks hope to see your reply
This is so awesome! Thanks for sharing can’t wait to go build mine !
Nice! Are you still making videos yourself?
Voltage Drop Diagnostics I’m gonna get back on it soon.. we just had our baby so since last nov it’s been nothing but house projects and getting things ready
I love these types of videos. Who wouldn't hold their head high when someone asks "hey, where'd you get that?" when you proudly answer I MADE THIS TOOL, YOUNG MAN! Then you promptly sell it to him for quadruple of what it cost you to make it.
Commercialism at its finest!
We need lots of commercialism when we're married. 😉
hahahaha! Thanks Dave!
I use the screw crimp style banana plugs. I hate solder lol. Plus I'm constantly redesigning my test leads. I don't have connectivity issues like I thought I might. The screws do back out from time to time, but I check to make sure the wire is secure before I use it.
I need to build one of these. I have the same problems with my Amp clamps.
Using 1Ω resistor vs 0.1Ω resistor:
With a 1Ω resistor (which I used) an issue may arise on amp draws >3A leaving insufficient voltage (
the GADGETS playlist have you noticed any issues with heat with yours? When I was building mine, Cody from Cody’s Auto Diagnostics mentioning be careful with them getting hot. And if it does get hot, does it effect your resistance much with them having built in heat syncs?
@@VoltageDropDiagnostics these things can get HOT in certain uses. BUT not doing what we're doing here.
At
Hey PJ! Thanks for the vid. What kind of amperage can the shunt handle? Was thinking would it be better to keep power to the vehicle while connecting the shunt as to not shut down any modules that maybe staying awake after key shut down that would normally go away with a power disconnect? Or can you start the vehicle with the shunt connected (I'm assuming no lol) ?
Hey PJ.. great video as usual - very helpful! I'd love to see this tool in use after you've done an overnight test (or 5, 6 hr sort of thing) just to see how you evaluate the results. I've got one of these shunt resistors in use right now and am pleased with the results but would be super interested to learn your thoughts on a car you're testing. Keep up the great work bro!
I havent had the chance to use this! Shortly after making this video toyota found the cause of the parasitic drains. And it was being caused by a telematics module waking up in the middle of the night looking for a GPS signal. So they came out with a software update for them that fixed them.
I havent had a single parasitic draw since lol
@@VoltageDropDiagnostics as "luck" would have it I had a honda pilot in yesterday with a complaint of dead battery after sitting overnight. I used both my 30a clamp and your shunt resistor in the diag. The car had a 1.1a draw after about 5 minutes of sitting. Turns out it was the switch that pops the hatch glass open as well as the backup camera shorting to ground. The great part was, both the math channel and the amp clamp were in agreement with draw values so I'm confident now that I can put a bunch of time on my screen and will have a reliable capture. In the past on these long captures my amp clamp has turned off or the battery died at just the important time. This shunt resistor is gonna be a great addition!
Gunna have to make this one too thx PJ
Thanks Mark! Let me know how well it works for you.
Tundra in the driveway!!! I just got a brand new 2020 my second
I really like those new models. I recently seen a “sx” trim package that I really liked.
Ya thats what I was going to get but got sold. Went with a trd off road led lights sunroof is what I wanted. Shortage of tundra s around north America
Looks like a great idea but what happens when you crank the starter and draw 90-100+ amps ... I’m thinking those thin wires will melt. Incidentally you can make your own .1 ohm resistance with less than an inch of nichrome wire. Probably what’s inside the one you bought.
I’m truly not sure why you’d be cranking the engine during a parasitic draw test. Can you elaborate on that?
Think I would put the whole works in a plastic project box and better quality alligator clips and a type that can be soldered directly to the resistor vs using a plug/jack. Gold plated etc
I agree! If i build another, that’s the route I’ll go! Thanks for watching!
Have you set up a math channel with Pico 7 yet? How different is the process?
Super vid! What if u accidentally hit it with a big draw? Would it smoke the resistor? That would b my worry.
Bill Rimmer so it’s a 100 watt resistor. The amperage would need to be over 8 amps to smoke this.
If you’re looking for an 8 amp draw this isn’t the tool for the job.
I recommend only using this for small draws. Below 2 amps
Hi all, checking for a parasitic draw on the battery cable shows us there is a parasitic draw, however it doesn't show us which circuit ii responsible, a far better method is to put a miliamp meter across each fuse in the fuse box, all fuses have a slight resistance therefore if there is current being drawn on a particular circuit you will be able to find which one is at fault.
Regards from Ray in North Wales (UK)
I agree with you about finding which circuit is causing the draw. I made this because there have been a couple issues that i recently seen where a car doesn’t show a draw until after it has been sitting for a long amount of time, and i wanted something that could verify that i did have a draw, or not. I’d hate to let a car go to sleep for 4-5 hours and test all of the fuses when there wasn’t a draw actually present at the time of me testing the fuses.
i use both methods together.
so i got mine working. i was playing around with the volt scale and noticed that it changed the amp reading substantially when going past the 2v scale. why is that?
very interesting. i'm gunna inject a few thoughts.1) is that a wire wound or a doped composite resister? the amount of change from heat is different as with the tolerance spec. an immediate reading will be real close but after a while it will be off. 2) since you are puting that in series you are now changing the entire circuit. therefore the resister value chosen may or may not affect the amount the circuit would normally flow(i hate the misnomer current draw as it is never a draw) so in escence one may need multiple values on hand to match the circuit as close as possible. when trying to get that precise a measurement even the length of your meter or scope leads make a difference. with that said PJ i applaud your thinking and ingeniuty to create a low cost solution for people that dont have a scope and can use this with a voltmeter. a very practicable way to demonstrate ohms law and a good use of ones imagination!!
Hey, do you have Facebook? I was also worried about heat changing the resistance. So i ran some tests this morning with it. I want to send you the pictures.
@@VoltageDropDiagnostics no too much drama i give it up years ago. maybe under your "community " tab? im pretty sure i know what you found. my remarks were meant as much if not more for others as i have personally ran into wide ranging outcomes when testing resistors some good some bad. unless its military spec you always have to test. thees a reason some resistors are cheap and for a military spec expect on spending up to 5X or more for the same thing
richard cranium email me. My email address is pwalter0810@gmail.com.
I want to bounce some things off of you.
Voltage Drop Diagnostics can you build in temperature correction in the math of the oscilloscope or a cheet sheet if your chasing true numbers.
allan mitchell so i left this hooked to my truck for about 20 minutes with the door open with 2 amps going through the circuit. I know that 20 minutes isn’t an extremely long amount of time but i didn’t want to drain my battery.
After 20 minutes my resistance measurement went from .1192 to .1189 ohms.
That barely makes a dent in my calculated amperage. Does it make a difference? Yes. But I’m not truly looking for extreme accuracy.
I just want something that will tell me that “at 3 hours, amperage went from 13ma to 220ma
I hope that makes sense.
Any idea on the amperage that resistor would be able to handle? Love this idea, I hate the low amp clamp drift and the fact that my DVOM can't record the amperage over time like a scope. Also, would it be more efficient to setup a custom probe instead of a math channel. Then you wouldn't have 2 waveforms on the screen. Thanks for the great content!
I didn’t think about the custom probe idea. But this is a 100 watt resistor. So somewhere around 8 amps it should be able to handle. With that said I’m sure the heat created with that amperage would throw off the resistance. So I’d keep the amperage below 2 amps to be safe.
@@VoltageDropDiagnostics Yeah I was just thinking for cases where arming the system, all doors lock, lights flash and horn honks etc. Just ordered one from amazon, won't be here for a month according to the estimated shipping though. :(
Family Nause oh wow. I had mine delivered in 3 days lol. I hope that it shows up sooner!
@@VoltageDropDiagnostics That's the problem with living in Canada. Amazon.ca doesn't have all the same products as Amazon.com. I can order from .com but then shipping and exchange brings up the price.
That's neat 👍
Thanks buddy!
Do you have settings recommendations for capturing over night? We tried to set one up, but it erased the previous recording after hitting 32 pages.
Using PicoLog rather than PicoScope software should work for this. The default capture interval is only 1/sec, but that should be fine for identifying an intermittent draw that is enough to drain the battery. At least I hope so - getting ready to try this on my brother's car...
@@Sidecar-pk3cg we figured out a way. I think it was 5000s per division
Old school I like it
Thanks Mason!
People get bent out of shape over everything these days. I try to use my heat gun on heat shrink whenever I can but a lighter works just fine too as long as you don’t over do it. I’ve made some great wire repairs over the years with no issues using a lighter on heat shrink.
haha You have no idea some of the comments and private messages I have received lol. Some are over the top!
Just curious will that resistance change due to heat?
Yes. So i tested those resistor to see how much after filming the video. And after running 2 amps through the resistor for 20 minutes. It changed my resistance .0003 ohms. So it will have a very small effect on the amperage measurement. And i believe a lot of that is due to the metal housing being a heat sync.
This is actually how multimeters measure amperage. But obviously they’re using far better quality resistors.
@@VoltageDropDiagnostics Do you think it would be a good idea to warm up the resistor for ten minutes and then zero the channel?
why I don't understand, why not just use a 1 ohm resistor. their also available in Amazon, they also come in different wattage range and different quality, you can even get a 1 ohm 500 watt load [shunt] resistor,
If you use a 1 ohm load [shunt] resistor you get a direct amperage reading, this is because using 1 ohm makes the math easy. Moreover, anytime you multiply by 1 you get the same value , this is why you get a direct reading in you scope or dvom no math conversion .
One thing to add, we are taught in trade school that amperage causes heat, not true, what's true, is that amperage is used as a guide, as long that voltage is consistent. If you measure amperage in bought sides of the circuit [ positive & negative] you will notice the current is equal in bought sides. It's the product of
volts times amps that makes heat in a circuit measured in watts.
Formula : Watts = (volts)(amps)
The positive side of the circuit is the hot side of the circuit, the reason the Fuse is always found in the positive side of the circuit, if you measure for voltage at the negative side of the load [when] switched on you will get a mV reading. You a multiply the mV by amps [current] and you get the wattage on the ground side of the circuit, [ watts = (mV)(amps) ].
It will be a small value compared to is you apply this same mathematical calculating on the hot side of the circuit, this is the main reason ground side control switching is used in computer controls, due to the tiny transistors can only handle low amount of watts [heat].
Did you ever compare the pico reading to a dmm reading in series?
I've built a 0.1ohm 100w shunt, worked out the resistance of the shunt and my two readings are massively different, like 100mA different.
I know my Mac Tools DMM is very accurate when measuring amps in series, the more I use my pico the more I'm not trusting it.
What kind of truck is that
Jeremy Anthony ‘07 tundra
Awesome video