You've gone above and beyond the normal tech PJ. This is a great addition to your arsenal of tools.

"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!

Thank you Patrick. Good job. Have a blessed and safe week to you and your family.

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

This is a great tool! Got to love DIY scope accessories 👍

This is so awesome! Thanks for sharing can’t wait to go build mine !

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.

Love it bro. Going to build one asap.thanks

Great video PJ. You're awesome brother!

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. 😁

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!

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.

Gunna have to make this one too thx PJ

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. 😉

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 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.

Tundra in the driveway!!! I just got a brand new 2020 my second

That's neat 👍

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) ?

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 (

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?

Old school I like it

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

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

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)

Super vid! What if u accidentally hit it with a big draw? Would it smoke the resistor? That would b my worry.

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!!

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.

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.

Have you set up a math channel with Pico 7 yet? How different is the process?

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!

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.

Just curious will that resistance change due to heat?

What kind of truck is that

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.