Need some tools to diagnose battery drain on car?

[OilPatch197]

I got a Craftsman multimeter, a test light.

I got a pesky 2 amp battery drain, and I would like to use something like a clamp ammeter to trace down this leak. It would be much easier than hacking up some wires!(for a Isolated continuity/resistance test)

What am I looking for? I noticed a lot of Clamp meters are designed for HVAC technicians, do these meters have resolution down to 2 amp DC current draws?

 

[mentalbreakdown00]

What year vehicle (later models you have to do a little different) how much electronics i.e. dual climate control, fancy radio, cruise, etc. If you have a vehicle with a lot of modules that have to "sleep" you need a couple different things...

 

[97RangerXLT]

hook your ammeter inline with your battery. go to the fuse box. yank a fuse. check ammeter, if it still has the drain, yank the next fuse. rinse repeat, wipe hands on pants until you find the fuse that stops the drain. that will get you the circuit that you need to look at.


AJ

 

[mn_smokeater]

hook your ammeter inline with your battery. go to the fuse box. yank a fuse. check ammeter, if it still has the drain, yank the next fuse. rinse repeat, wipe hands on pants until you find the fuse that stops the drain. that will get you the circuit that you need to look at.


AJ

This

but if its something you caint get to if its hidden away somewhere in the car something like this: http://www.galls.com/style.html?assort=general_catalog&style=VP007

could help im sure theres cheaper but this is the one i know of off hand and works as a good example as i am a customer with them.

 

[mentalbreakdown00]

but that trick does not work with newer vehicle mnsmokeeater, when you disconnect the battery, and hook up the ammeter all the modules try to come awake again.... This is what i'm trying to get at, forgive me though as i am sleepy

 

[97RangerXLT]

but that trick does not work with newer vehicle mnsmokeeater, when you disconnect the battery, and hook up the ammeter all the modules try to come awake again.... This is what i'm trying to get at, forgive me though as i am sleepy

I am assuming it is his 84 or 87 in his info... prolly does not have those fancy modules

AJ

 

[mentalbreakdown00]

well now that you mention that, a test light is all ya need.

 

[adsm08]

I think it's his Bruick, and it's new enough to have issues with modules waking up. He was saying something about this in another thread earlier this week.

You are going to have fun with this because of it being a GM. AJ is right about his process, but the fact that it's a GM makes it a bit harder.

Usually what I do is put one of these :

on the positive terminal, let it sit for an hour, then alligator clamp my meter leads to either end of the disco and undo it. The meter allows enough power to pass through to not disturb the modules, and then you can go about pulling your fuses.

If you can find one and get it hooked to the car in question it will make your job a lot easier.

Also, find out if it has a factory amp. Both Ford and GM had problems in the late 90s with factory amps going bad and causing about a 2 amp parasitic draw.

 

[OilPatch197]

Yeah it IS that '92 Buick.

Great advice guys about the modules. I just bough a Clamp meter that can measure "DC amps" (the only one product in a town of 26,000 people, the rest of the ammeter clamps were AC for those HVAC techs. )

So now I'm going to charge battery hook it up, wait an hour, clamp on the SOB on the positive lead, then pull the interior light fuse, so I don't have to wait for the stupid dash lights to go out every time I open the door.

Start pulling each fuse, I'll check the amp draw(10 amp setting on mutimeter) and record the ammeter reading at battery .

Then pull the relays, record ammeter reading.

If problem is still not found, use the ammeter at the starter solinoid, and check the two fuse block/alternator fuse link wires. This should narrow it down.

I've been doing some "googling" and have found that SOME people install gadgets like "battery brain w/ remotes" and just have that disconnect the battery every time they park, I found this tid bit interesting>>>>>

This was my hacky solution for way-too-many untraceable drains in my truck. Now I just cut power when I park, and the battery reads the same when I come back. It even has provisions to wire up some accessories to continue to receive power and not lose settings, but right now I don't care - I no longer have to charge my battery every week! OK so my usage is not typical for this device - it's meant to shut off automatically at 11.8V as a last resort, but I don't need to wait that long or keep my battery that low - I know it will get there in 4-5 days Anyway, unit works as advertised, drains nothing when off, allows me to shut off the battery

 

[adsm08]

Yeah, I used to see a lot of devices like those. My last job was at a Roush dealer, and so we kept a lot of Mustangs on the lot and sold a lot of them. It wasn't uncommon for customers to come in complaining about the battery being dead every time they went to drive the car, which they only did once or twice a year. We ended up installing a lot of those things.

 

[OilPatch197]

I checked all the courtesy switches...

I check it today and it drains 2.5 amps for the first 20 seconds that the battery gets hooked up, then it drops to zero.

So it looks like no short, just some module powering up, but still how did my battery go totally dead just sitting 7 days?

The battery reads 12.7 volts. Seems healthy, it is five years old though.

 

[Mutant Pony]

The battery is getting old. If you do a load test on the battery, you will find that it has far less CA than it did new. It is probably down to about 400 CA. 400 is fine for that car if you drive it everyday or every other day. It would take closer to 800 CA to last a full week.

 

[kp3ft]

wiggle test

I checked all the courtesy switches...

I check it today and it drains 2.5 amps for the first 20 seconds that the battery gets hooked up, then it drops to zero.

So it looks like no short, just some module powering up, but still how did my battery go totally dead just sitting 7 days?

The battery reads 12.7 volts. Seems healthy, it is five years old though.

Might be an intermittent connector/wire short; try the wiggle test with ignition off, looking for amperage drain on the meter. Had a similar random dead-battery problem with my 94 B2300, found the problem by accident when I was doing work under the hood. Moved some wires near the fuse box on the firewall and the electric fuel pump came on and wouldn't shut off till I moved the wires and fuse box some more. Took the box off and couldn't find anything obvious, and reinstalled it, now it's fine.

 

[97RangerXLT]

another vote for battery. 5 years old is getting up there.

something esle.. do you have a cell phone charger (or ipod or any other charger plugged in to the cig lighter? if so, that might be an issue. those things can be a reall pain in the butt for draining a battery.

AJ

 

[Mutant Pony]

A customer had their car hauled to my shop for a no start, There was a GPS unit plugged into the cig lighter! The guy wasn't dumb, sometimes you just don't think about the relationship of things. He sure did feel dumb when he picked his car up though!