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Got back from out of town yesterday and tried to start up my '07 E63 but no luck. Battery reads less than 2V with a multimeter.

About 7 or 8 months ago I had the original battery replaced as it was 5+ years old by then.

The car sat without running for roughly 15 days. The last time I drove it I noticed no error lights or warning signs that the battery may be having trouble (as it shouldn't with a battery this new).

I tried to jump start it twice since yesterday but no dice. What would cause the battery to read that low in just two weeks - and also not be able to jump start the car?


Any advice here would be greatly appreciated.

Thanks,
 

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At this point, I would either 1) pull the battery and get it to a shop to have it analyzed for condition. Have it fully charged, if able; or 2) leave it in the car and hook up a tender/maintainer to the terminals under the hood and leave it connected until it shows fully charged. This could take a full day or longer. Once you have a fully charged, healthy battery, then I would attempt to restart. As for what happened to drain it the last 15 days, since you had no warnings before, have to assume the battery level was okay. Maybe the battery was defective and you should be covered by warranty; or, there is some drain that brought down a healthy battery. Did you replace with the correct spec battery 7/8 months ago? To match the OEM? AGM, 110Ah? Had the car ever sat this long before on that new battery? Had the car ever sat this long on the original battery (with no problems, evidently)?
 

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Did you replace with the correct spec battery 7/8 months ago? To match the OEM? AGM, 110Ah?
Yes.


Had the car ever sat this long before on that new battery? Had the car ever sat this long on the original battery (with no problems, evidently)?
With this new battery I've had it sit up to 7 days or so, never longer than 10 that I can remember. This is the first time I was gone 2+ weeks. Roughly the same schedule on the old battery. No issues there.


or, there is some drain that brought down a healthy battery.
I'm thinking most likely this. I've just been kicking myself trying to think of what I could have left on. Last drove it during daylight, light switch was left in auto, no phone, etc, left in the charger. I couldn't sleep last night with my mind trying to think so hard. :kaffe:

pull the battery and get it to a shop to have it analyzed for condition. Have it fully charged
This is what I'll be doing today. Will monitor for recurrence. I'm already dreading having to research grounding issues or having to search for electrical ghosts. :crying2:


Thanks for the advice!
 

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I travel at least 4-5 times a year with the car sitting for 13-18 days and never an issue. I have (on another car) gone through 3 batteries till I got a good one.
 

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...I'm thinking most likely this. I've just been kicking myself trying to think of what I could have left on. Last drove it during daylight, light switch was left in auto, no phone, etc, left in the charger. I couldn't sleep last night with my mind trying to think so hard. :kaffe:
There is a "kill battery" feature ouich
BMW calls the feature "roadside parking lights" :nono:
You might have accidentally hit the turnsignal lever while exiting the car, but since it was still daylight you did not notice the parking lights were on :crying:
 

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