Battery Drain

[Steve Corbett]

I have an issue with my 1989 325I, The battery drains down after a day of not using it. With car off battery reads 12.5 volts, Engine running reads 13.5 volts. With battery disconnected at positive terminal, Radio disconnected and trunk light bulb removed, volt meter between terminal and battery it reads 12.5 volts. I removed each fuse and relays one at a time and got no noticeable drop. I figured I would see something?? Am i doing this wrong?

[TimeMachinE30]

13.5 seems low while running.

Try a battery.. Free load tests at AAP or AZ.

Then of course alternator.

[MINIz guy]

When you have the multimeter between the terminal and battery, you should be reading current. When the car is in sleep mode, you shouldn't draw more than xx(?) milliamps. Any more and you have a drain.

You shouldn't be measuring voltage in series anyway. You measure voltage in parallel.

[Steve Corbett]

Using an ammeter it shows 0.00 no matter what scale I use.

[AndrewBird]

I think you are using the meter wrong. Set the meter to the highest setting for amperage that it has. If there is a draw higher than what the meter is set to, it will fry the meter or at best, blow a fuse if it has one. Then you need to disconnect one of the battery cables and then connect one lead of the meter to the cable and the other to the battery terminal. Make sure you set the meter BEFORE you connect it, otherwise you might move through a lower setting while hooked up and fry it.

If you touched both battery terminals with the leads of the meter, you fried it, no question.

[AndrewBird]

Here is a good video explain how to do the test:

[Steve Corbett]

Thanks for the video!! After watching it I realized I did not move the red lead to the Ampere side of the meter. Oops.

Found 56 milliampere draw at fuse 21. Not much but something to run down.

[AndrewBird]

56ma is nothing. A single led is more than that. No way it would drain your battery over night, or even in a month of sitting.

Are you sure it wasn't 5.6 amp, or maybe 560ma?

[Steve Corbett]

Yes, I have meter set to 200 miliohms and it reads 56.9. I am grasping at straws trying figure this out. My boy needs this car for school and I am getting flustrated. I agree it is nothing but it is all I can find at the moment. Going to check the engine running voltage again, but yesterday both my 89's were 13.5-13.8 and the 84 325E was 14.5 if anything the 84 seemed high.

[TimeMachinE30]

Have you had the battery tested?

Are you running the car at all, giving it a chance to charge? Has it been sitting as you troubleshoot? Can you put it on a charger? Something to get the battery full?

Is the charging system working?

When was the last time you replace or serviced the battery?

Any other weird things going on? Lights misbehaving, stuttering, slow to start, dim headlights?

Have you done anything with the vehicle that predicated this issue?

[Steve Corbett]

Have you had the battery tested? I checked with my meter, 12.56V Will get load tested tonight. I also did swap in a known good battery.

Are you running the car at all, giving it a chance to charge? Has it been sitting as you troubleshoot? Can you put it on a charger? Something to get the battery full? I have had it on atrickle charger overnight. He is afraid of driving to work or school and getting stranded with it.

Is the charging system working? Shows 13.43V running.

When was the last time you replace or serviced the battery? Swapped in a known good one.

Any other weird things going on? Lights misbehaving, stuttering, slow to start, dim headlights? No other issues.

Have you done anything with the vehicle that predicated this issue?

Not recently.

[JinormusJ]

I've had battery drain problems before

The first time it was a battery with a bad cell (got a warranty replacement)

The second time I suspected it was a bad battery (again), but I had it tested and it was good. What I found was 500mohms running through my ABS system that was starting at a short in the ABS relay.

Now, how this applies to you? Getting the battery tested is the first place I would start, then check the ABS if the car has it: there is no fuse for it and it's fairly easy for the metal casing to touch the inner workings of the relay and cause a slow draining short if it doesn't have the paper strip inside. If all else fails; I would then check the alternator

[StereoInstaller1]

Yes, I have meter set to 200 miliohms and it reads 56.9. I am grasping at straws trying figure this out. My boy needs this car for school and I am getting flustrated. I agree it is nothing but it is all I can find at the moment. Going to check the engine running voltage again, but yesterday both my 89's were 13.5-13.8 and the 84 325E was 14.5 if anything the 84 seemed high.

Excuse me, you sure about that setting?

[Steve Corbett]

Took battery to advanced auto parts to get tested. Said it read twelve volts but only 200 CCA. It is a 700CCA battery. Put new battery in and will see how it works.

[beta14ok]

Just in case you haven't checked it......remove the battery lead wires, clean the posts and clamps,....reinstall and snug it down well. Your battery won't last if the connection is even slightly loose.