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Intermittent Battery Drain?

So I guess there isn’t much for me to say other than my battery is dropping in volts over night. In two days of sitting it went from 12.7V to around 12.4V. The thing is, I’ve tested everything. Battery, alternator, starter etc. Everything is fine. (BRAND new battery, and old battery was doing this too) I’ve also done a parasitic draw test, with doors open but locks tricked to make car think everything is closed. After a while, i got a 50mA draw (which is about normal) unplugged IBCM 1 fuse, dropped to 10mA, but still, that isn’t a big deal. Im completely lost and wondering if somehow something is turning on in the middle of the night? Brand new battery ground cable. My horn doesn’t work… (If this indicates something) blows a fuse everytime it goes in. So i just pulled both fuse and relay for horn and kept it out

First off, Why are you not troubleshooting and resolving the horn problem? I could be wrong (If that’s possible), but I believe it is the law in every state that a vehicle has an operating horn! Here, in some locations, like Long Boat Key for instance, even bicycles are required to have a functioning horn or a bell (more practical on a bike).

This lack of maintaining the vehicle makes me question the condition of the entire vehicle. Perhaps it shouldn’t be on the road. Why are you not repairing things that are not operating properly, particularly safety items?

What is the model-year of this little beauty?
:palm_tree: :sunglasses: :palm_tree:

edit: Quoted from HG Legal Resources

"However, there are a number of general characteristics that all vehicles must have to be legal in every state in the U.S.:

Horn – It may not seem the most important piece of safety equipment, and many big cities even limit how it can be used, but to be street legal every vehicle must have a horn that is audible for at least 200 feet. The horn can generally be any note or sound (even ones that play musical tunes are usually permitted), so long as the minimum volume requirements are met."


Year, make, model, engine size would be helpful on this one.

Hey, the horn is the only thing i haven’t been too worried about because so far ive done everything on my car myself, but the horn is an electrical short problem and im not very good in electrical. Im replace rear coil springs, rear shocks, battery, front struts, O2 sensors, brake calipers, brake pads, rotors, etc. Ive done a ton. So its definately being maintained. Just not grest with electric. Its a 2004 chevy malibu LT 3.5L V6

If you find an amp meter that does min\max recordings, I wonder if you could leave it hooked up over night just to see if something is turning on. I’ve never tried this, but it’s an idea.

While on the high side of the range, still 50 mA is within the normal range for “everything” off draw. The battery voltage dropping from 12.7 to 12.4 over a couple days is probably normal. Is there a particular symptom you are trying to solve that affects the use of the vehicle, or are you only wondering about the battery voltage dropping over time when the vehicle isn’t being used?

12.7 to 12.4 over several days is absolutely minimal… At that rate your vehicle would probably have to sit several weeks before she cannot start on its own.

You may not be able to ID the problem, because one does not exist.

What problem are we actually trying to solve here and what symptoms does it manifest?

I don’t see a problem here

50 milliamp draw is within acceptable parameters

Why did you even measure the battery voltage in the first place . . . ?!

Did the engine fail to start one cold morning . . . ?!

How old is the battery?

If you are in fact having problems starting the engine, I’d say you need to look some where else besides parasitic draw, because you’re fine in that regard. Might want to check out the charging system

If your battery is pretty old and in marginal shape, just replace it now and consider it preventive maintenance.

:palm_tree: :sunglasses: :palm_tree:

1 Like

I’ve had this problem also. My wife went to start the van but had no crank. It has new battery. I did parasitic draw test. 30 Milla amps. Battery took full charge and alternator tested good. My battery cables were clean but I cleaned them anyways. There was no indication anywhere that anything was wrong. So my diagnosis was: battery failed due to a combination of cold weather. It sat for over 5 days without starting, it has electric sliding passenger doors and lift gate, the daytime running lights are set to stay on 30 seconds after shut down {too long}. So a combination of heavy use of electrical components, cold weather without using it in a long time caused battery failure. She drives 5-15 miles per trip. So short trips between stop and starts could also be a factor. I told my wife there is nothing wrong with the van, we just need to take some preventative measures, especially when letting it set for a while.
All that to say that I think the others may be right on this. There may not be a problem with your vehicle. It may just be reacting to driving habits.