How long can a ZHP sit? Or.....how do I track down a drain on the battery?

[redwagon]

I'm more of a mechanical guy......this one has me stumped on where to start.
My ZHP sat undriven for 2.5 weeks in the garage due to biz travel, crap weather, etc. This morning the battery was totally dead. Battery is less than 6 months old......I had bought it when it went dead after the car sat for a week in October.

So either I have really bad luck with batteries.....or I have an ongoing significant drain on the battery even with everything turned off. How does one isolate the drain?

Hopefully the new battery will recover, but I bet its damaged goods at this point.

Tim

[danewilson77]

We have a pretty long parasitic drain thread somewhere. Will find.

HTC Thunderbolt+TT

[danewilson77]

Couldn't find the one I was looking for.

http://forum.e46fanatics.com/showthread.php?t=847871

I swear someone here did a lot of work... Regarding this.

HTC Thunderbolt+TT

[az3579]

I'd still like to answer the first part if the question in the thread title. ZHPs do not like to sit at all. They need to be driven.


Mine will run rough when not driven for a week or two, and will throw a check engine light, which eventually goes away. When I'm away, I have to have someone start it every couple of days otherwise it'll run rough. Always started fine though, so the battery never drained. My battery is only a touch over a year old.


Sent from my iPhone 4S from Tapatalk

[redwagon]

I've done some searches and havent found the thread....yet. Most newer cars have a significant parasitic drain, but it should be able to sit a month I'd think.
Tim

[telijah]

To find a drain, I thought one way was to stick a meter on the car, and car pulling fuses one at a time, looking to see a change in the voltage. If the fuses don't shed any light, then relays next...

[aurelius]

Go get a Battery Tender and charge the battery with that, preferably with the negative cable disconnected and the BT plugged into a surge suppressor. It may take quite a while, like 48 hours or more.

If you do this in a garage with trunk lid raised, the lights in the trunk will turn off after a while.

Then if it charges up ok, use the OBC to monitor voltage. If it's low, which it probably will be given how quickly your new batt died, I'd suspect voltage regulator.

Beware situations where you're swapping out batteries and alternators. Start with the VR.

[johnrando]

My parasitic drain was the FSR, final stage resistor. Apparently they are known to go bad and therefore the car doesn't "sleep", and the battery drains. The dealer found this one for me when it was under CPO.

[redwagon]

Thanks all, lets keep the ideas coming.
It charged up fine and started OK today. I think I will need to hook up a meter and watch the drain as I pull fuses.....cant think of any other way to help isolate.

John- re the FSR- if thats a problem doesnt that mean the fan isnt turning off? in my previous E46 I replaced the FSR when I had the mysterious fan speed changes......that was really wierd....wondering if you were experiencing that or if the fan was running low after shutdown.

Tim

[johnrando]

No, it wasn't the fan not turning off. You actually couldn't tell anything was still "on". As described to me, figuratively the BMW sleeps, and the FSR going bad was keeping some systems on, therefore draining the battery.