Dominik W

So we have this problem where the battery will drain overnight. The lights are off, everything is off, but it doesn't start in the morning. Our alternator is not broken, since it recharges the battery once the car starts, and we replaced it a couple months ago. Every night, we unplug the battery, and when we plug it in, the cars starts, so that's why we suspect something might be draining it. One thing we were thinking about was the alarm. Could that drain the battery overnight? What else can drain it?
Any help is appreciated.

IgottaTLyousomething

iTrader: (1)

Is the alarm system aftermarket? The first thing I would do is unplug the HFL unit and let it sit overnight with the battery still connected. Those units are usually the first item that comes to mind when talking about a parasitic draw.

Dominik W

The alarm is the one built-in by Acura. Will try unplugging the HFL Unit, we'll see what happens.

Dominik W

The HFL Unit doesn't seem to be the problem. We tested it overnight and the battery still drained. What else could be the problem?

Altair

When I got my car used chose to replace relays, search for A.C. relay, radiator fan relay.

After a year started losing the battery over long weekends with no driving. Had to disconnect the HFL module mine and would still struggle, tested battery and was bad, shortly afterwards found the starter malfunctioning and replaced it with an used one, no problems since.

alternatively google look for phantom battery draw and DIY tests with a good multimeter.

hth

CSmoney28

Check the battery to make sure it is holding a charge when you charge it, which it seems like it isn’t able to do so you might need a new one. Then check the alternator to make sure it is actually charging the battery completely. Then you could check the starter to make sure it isn’t going bad. As always make sure all connections are clean and tight with no corrosion. Check all fuses and relays and let us know the findings...