Annoying Battery Drain

[llll1l1ll]

Hey Mafia,

I've been having this annoying battery drain problem for a while now. I just got a new battery because the original one died. No worries, that's not a big deal. However, I've noticed that after a day or two of sitting, it was weak to start. Strange. Just this weekend, it sat from Thursday evening until Sunday morning, and I had to get a jump. There wasn't enough juice in the battery to turn the starter.

I don't think it's the alternator, because once running, the car doesn't stop. A bad alternator would not keep the battery charged, and eventually the car would run out of voltage and not have enough to keep running.

Based on some basic internet research, I think the culprit might be the final stage resistor. Although I haven't experienced any erratic fan speeds, it seems to be the only thing I've noticed that causes this issue.

Does anyone else have any similar issues or any other suggestions?

Many thanks,
Pete

[Ryans323i]

To help narrow it down, can you eliminate definitely some less likely causes: Your lights aren't left on, all doors and trunk are completely closed, and there's nothing left plugged in the cigarette lighter for a power source? (this would be during the "sitting" period)

[llll1l1ll]

Yeah all the doors are shut, trunk is closed, and I don't have a GPS or in-car charger or anything. Sometimes, I forget I have a cig lighter. Plus, I would know if the doors/trunk weren't shut properly since the lights would stay on.

[johnrando]

Had the same thing, it was my FSR (no erratic fan speeds either btw).

[BavarianZHP]

More like a FYI: Doesn't the car shut off all of the lights (interior and trunk's) if it's on for more than 15 mins? It's a safety feature built to avoid draining the battery. I figured this out while I was working on the door last night.

[brettbimmer]

Is the car "going to sleep" as it should after about a minute or two once you turn it off? Never had a problem with this myself, but it would make the case for fairly rapid battery drain if it wasn't shutting off completely.

[Dave1027]

Does the car have an aftermarket alarm? Sometimes those induce parasitic loss. You can check for a leak of battery power by disconnecting the positive terminal and hooking an amp meter between it and battery positive.

[johnrando]

A faulty FSR can keep the car from going to sleep.

[brettbimmer]

^ Great to know John! I was wondering if that may be one of the causes. Thanks for the clarification.

[llll1l1ll]

Does the car have an aftermarket alarm? Sometimes those induce parasitic loss. You can check for a leak of battery power by disconnecting the positive terminal and hooking an amp meter between it and battery positive.

Nah no alarm on my car!

Had the same thing, it was my FSR (no erratic fan speeds either btw).

This is what I'm thinking. I found an FSR for like 50 bucks or so on bavauto. I'll probably order it today or tomorrow.