How To Test Parasitic Draw on a Car Battery

In this Steves Garage video I test for parasitic draw test on a car battery. Provided you have a multimeter with an amp setting, it's an easy check to perform.

If your car battery is draining too quickly - overnight, during the work day, or even over a couple days, you could have a parasitic draw condition. This is when something is running in the background that is draining your battery. While there are many things that can cause a parasitic draw, the first thing to look at is any aftermarket component you might have installed. Aftermarket lights, radios, remote start or alarm systems can all be a point of draw if something is wired incorrectly and not shutting off with the key.

If you'd like to purchase the multimeter I'm using in the video, check out my Amazon Affiliate link! It won't cost you any extra and I'll earn a small commission from your purchase

If you have any questions leave them below, I try to help everyone. As always, please be careful working on your car! Any damage to you or the car is not my responsibility.

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Chapters:
0:00 - Intro
0:29 - Preparation Before Testing Parasitic Draw
1:10 - Testing for Parasitic Draw
2:03 - Problems with your Multimeter?
2:18 - Negative Parasitic Draw?
2:26 - Diagnosing Parasitic Draw
3:17 - Outro

[zachlenning]

Had an intermittent drain on a 2000 Bravada few years back. Finally found it. The vanity light switch was failing and the light for the vanity mirror on the sun visor would, sometimes, come on. Couldn’t see it because the flap was closed. Took forever to find.

[Ideal-Setup]

You just taught me so much in so little! Great video. Straight to the point and very detailed as always. Those multimeters are very useful. I need to snag me one for sure.

[mfitzpatrick]

Great video but hard to see how you connect then leads. Are both black and red connected to negative post?

[Snowdog]

Good info, thanks. I would not suggest a BM 15D multimeter. I think they are sold under different names. Just a pain in the azzz all around. You have to press a button to toggle to the setting you need. The instructions are worthless, and to change the fuse you have to take off the plastic protective cover and need to use two paint can openers, look like bottle openers to pry it off.
And the fuse was dead as you mentioned. Which is probably not the multimeter fault, but mine. And they do not list the size of fuse in the instructions. ugh.

[TomKnox-fk]

Dont forget to check water levels in battery. If its low the battery may not be able to sustain even a common 20mA draw.

[elementn]

What about the memory saver before disconnecting the battery

[Progressive.G]

Would it be a good idea to replace the fuse or just permanently keep it empty?

[TomKnox-fk]

Use distilled water or water made for the battery only. Never straight water.

[erichernandez]

Hi, I have a toyota corolla 2017 manual transmission. It draws 140mA with the alarm activated all doors and lights closed. It is the dome fuse that draws 60mA out of the 140mA. It then turns to 10mA when a relay clicks after 20 mins. Is this normal? I hope I get noticed..

[aakudev]

Thanks, my multimeter shows 11.0 draw, don't know what just happened, will check my radio, it just makes a pop sound every time I turn it on😢

[Fingamyaz]

i did a draw test and i get 40ma with the remote starter. (new battery in 2022). 2-3 days not driving the car. the batter would get drain. i removed power to the remote starter and it draws only 20ma. the car would sit for 3-4 weeks and still be able to start fine. so you saying under 50ma is okay.. makes me confuse af.

[football-qkbq]

Mine is at 0.00 what can I do now I don't understand

[RacecarsAndRicefish]

"anything that's not stock-- check those things first"
😭