Trying to find the electrical draw that drains the battery...

[Ernie ingling]

Mike67 is right phantom drain test. Remove neg. term. Place DVM set on dc ma scale in series. So bulb is car in illustration. All stuff off doors closed ect. If you read .05 mA then drain is ok higher do as mike67 says start pulling fuses or unhooking added elect devices till it drops. That will id circuit.
Go to 2carpros to see a tutorial

 

[toolmanmike]

Kern if you have a DMM that will read DC amps , all you have to do is put your meter in series with the circuit.
Remove the fuse put one lead on one side of the fuse holder and the other on the other side. If you see a reading its on that circuit, & thats your culprit.

View attachment 925242

Watch yourself with that. Most multi meters are internally fused for 10 or 15 amps and you don't know how much the draw is when you hook the meter up. A inductive pick up amp clamp is a better idea.

 

[Mike67]

Watch yourself with that. Most multi meters are internally fused for 10 or 15 amps and you don't know how much the draw is when you hook the meter up. A inductive pick up amp clamp is a better idea.

Yep to protect the meter, but anything pulling 10-15 amps would be kind of obvious I would think. Electric fan, fuel pump ect.

 

[Derwud]

I start with a test light, if it is Bright, start pulling fuses till it goes out and trace from there. If it is dim or to do the test to verify you found the draw. Hook up your DVOM and check for smaller draws and fix going back through the circuits..

Be careful, finding a old Fluke fuse can be hard..

 

[toolmanmike]

I start with a test light, if it is Bright, start pulling fuses till it goes out and trace from there. If it is dim or to do the test to verify you found the draw. Hook up your DVOM and check for smaller draws and fix going back through the circuits..

Be careful, finding a old Fluke fuse can be hard..

With 28 years on the tool truck I sold a lot of multimeters. I sold a lot of replacements and fuses because of tech's checking amps and shorting them out. Good idea to test with a test light first. It let's you know if it's safe to hook up your multimeter.

 

[JimKueneman]

Yup, map light, trunk light, dome light (door jamb switch broken) are what I found 90% of the time when I worked as a GM mechanic. One that took forever to find was a kid put a dime in the rear seat lighter but that was a random fuse blow (saw old gum wrappers too but they were easy to see).

 

[Don Frelier]

The horn relay is another culprit, particularly if the horn itself does not work.

 

[Derwud]

With 28 years on the tool truck I sold a lot of multimeters. I sold a lot of replacements and fuses because of tech's checking amps and shorting them out. Good idea to test with a test light first. It let's you know if it's safe to hook up your multimeter.

You only make that mistake ONCE..

 

[kiwigtx]

Yep to protect the meter, but anything pulling 10-15 amps would be kind of obvious I would think. Electric fan, fuel pump ect.

Connecting the ammeter across the battery terminals would be a decent draw also.

 

[Derwud]

I love Electrical..

 

[Kern Dog]

How old is that picture? You have a big block now, right ?

 

[kiwigtx]

@Kern Dog ...listen to the guys here and do not follow advice from random You-Tuber's...like this moron...

 

[Derwud]

How old is that picture? You have a big block now, right ?

That is my Wagon...

 

[Builderguy]

Don't forget that if your vehicle has a dash clock it will draw in the key off position. If I remember right it is around 50 milliamp or so but it will show up on your DMM. So for perspective if you do have a 50 milliamp draw 24 hours a day (while in storage) you will discharge your battery at (.050 x 24 hours) 1.2 amps per day. If your battery has a 50Ah reserve capacity you will have a dead battery (50/1.2) in 41.6 days

 

[Photon440]

Don't forget that if your vehicle has a dash clock it will draw in the key off position. If I remember right it is around 50 milliamp or so but it will show up on your DMM. So for perspective if you do have a 50 milliamp draw 24 hours a day (while in storage) you will discharge your battery at (.050 x 24 hours) 1.2 amps per day. If your battery has a 50Ah reserve capacity you will have a dead battery (50/1.2) in 41.6 days

The factory clock doesn't continually draw power. It's runs off spring power, the winding/reset for the spring only clicks on every couple of minutes and only for a fraction of a second. You can hear it click when it resets. I think the draw on these averaged out to about 15-16 ma draw.

 

[Kern Dog]

@Kern Dog ...listen to the guys here [/MEDIA]

I have a buddy that lives in a tee pee....
No, he is NOT American Indian, he is a cheap ***.
When he does electrical work, he rarely turns off the power. I'm sure that he has shocked himself a few times.

 

[Kern Dog]

Don't forget that if your vehicle has a dash clock it will draw in the key off position.

Thanks. I have an aftermarket gauge cluster in the car with a digital clock.

 

[JimKueneman]

Thanks. I have an aftermarket gauge cluster in the car with a digital clock.

View attachment 925541 View attachment 925542 View attachment 925543

Ok now you need an ammeter and start pulling fuses if you see more than a couple of milliamperes.

 

[Kern Dog]

Well, I think that I did find the problem last night. The map light was switched on.

 

[JimKueneman]

Well, I think that I did find the problem last night. The map light was switched on.

That will do it.