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rusteee

E39 Battery drain guru's

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Yea just to update. I could not find anything that was draining the battery. Much to my skepticism, went and forked out for a new 850cca battery on Sunday. The new battery still sits at around 12.1volt, and up to 13.7v when car is running. Will check it again tommorow as it will have been sitting for a couple of days, and see what its down to.

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New battery at 12.1v - that's only partly charged. 11.8v is technically flat & 12.8v is fully charged.

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Back to the drawing board... I F***en hate this car sometimes. New $400 battery sitting at 10.6v today, so obviously still something draining it? Anything I could pick up on the meter was very negligible, maybe something intermittent? running out of ideas

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Its not the hedgehog. I have no issues at all with the aircon/fan/heating, and pulling the fuse makes no difference nor could I get trace current while car is asleep. I'm guessing it could be something to do with the radio/phone as I noticed this time that the in car phone had not turned off. Will try again in the weekend

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Bugger! I wasn't suspicious of the previous battery - just throwing out the variables / possibilities.

What is the current draw when the car is asleep?

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I tested it a couple of times and it sat from 0.2 to 0.08 amps which really should not drain an 850cca battery in a couple of days. It must have something intermitent as the battery was still fine when I checked it yesterday, but this afternoon was flat.

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Ok, .2 is way too high, even .08 is getting up there. Should be up to about .05 & constant at that.

That said - even .2 won't flatten the battery in a couple of days from a charged state. You did say though - it was at 12.1 from memory. this is well down on charge to start with so will hasten the discharge.

Try disconnecting the FSR (regardless of you saying the system works ok) and recheck.

Then, if that is ok, try disconnecting the phone. Does your car have a monitor or the radio in the dash?

Had a S Class Benz at work a few years ago that drove me in sane trying to find a random intermittent current draw that was flattening the same size battery every few weeks.

Could never catch it out. After pulling half the car apart, and disconnecting the seat modules (previous Benz experience of current draw) I walked past it in the workshop one afternoon & noticed the dash cluster illuminated & stayed on for about 5 mins then turned off again. Finally traced it to the keyless start module in the boot that had gone awol. Owner wasn't using it anyway so just disconnected the module.

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Set the AC to defrost then shut down the car, and put a single layer of tissue paper (a single ply from a tissue) on the dash vents.

see if it's blown them away during it's "rest".

They commonly work perfectly when in use, but turn on and off randomly duirng off times.

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I seem to have a similar problem with my wife's e46.

Where is the best place to buy a replacement battery from, and should I be getting the bmw one?

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Do the trouble shooting first as they are not cheap, mind you your car might have a smaller battery.

Yea cheers for the suggestions, I'm doing them one by one, currently have the Fuse 56 pulled to see if that makes any difference. If not, will try the heater. Yea that current was a bit high, but as you say, I'm not going to worry about that as thats no where near enough to flatten a battery in a few days and the car usually gets used once a week atleast. Will update with findings.

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So, many fuses pulled and it is still draining, went from 12.8V to 11.5v in a day and a half. I've eliminated the phone, radio system (all of it), after market amp, heater fan, any lights.. I'm really not too sure what else to check. Anyone have any out of the box ideas?

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Disconnect the alternator & recheck.

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Not sure how much its worth but figure id put it out there

I fixed a battery drain issue on my old's E46, turned out to be the climate control panel. Everything worked fine but must of had an excessive draw once the car was shut off. They used to have to manually turn off the HVAC system before turning off the car otherwise the battery would drain overnight.

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Was it the panel itself or the the fan running on? I've had the big fuse pulled out to the fan, but have not left it with the panel disconnected yet.

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The panel itself.

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Onto it, that seems to be the issue. If I shut it off before turning the car off, its fine... trap for young players. Have purchased another car now so will be selling my one, and just take the panel off the price. Thanks heaps for the help! was doing my head in

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