2007 M coupe battery issues

[mineo77]

My battery keeps going dead if i leave my car for 1-2 days without driving. I typically drive 40-60 miles during the week getting to work. The dealer told me that i need to purchase an external charger to keep the battery alive..seems odd to me. any suggestions?

[chickdr]

Originally Posted by mineo77

My battery keeps going dead if i leave my car for 1-2 days without driving. I typically drive 40-60 miles during the week getting to work. The dealer told me that i need to purchase an external charger to keep the battery alive..seems odd to me. any suggestions?

Get them to look at the battery and make sure it is holding a charge. Mine was not charging properly and I had it checked out. They found corrosion on the terminals which was affecting the charge rate, but the battery checked out good. Mine is not driven that often either(~2,500 miles/yr), but they still did the check and terminal cleaning for free. I use a charger (https://www.shopatron.com/products/p....23205.0.0.0.0) once a month to keep it topped off/conditioned. It will have issues with so few miles being driven if you don;t maintain it. The battery is very $$$ too.

[Starscream]

While I do use a battery tender on my car yours seems to be a little strange,
I have to leave mine a few weeks to a month for it to be dead,
But after a charge its fine again and holds,

(this was before I bought the battery tender)

Now I always have a charged battery and never had any problems,

[trsbmw]

Yes, that does seem odd. I too have a 2007 M coupe. I average probably 100 miles per month. I have never had a dead battery, though for the winter I do hook up the battery tender.

Did the dealer actually test the battery? I would start there.

[skim]

One day I started my car and I noticed everything was reset, like clock, speed limit beep thing, etc. I think somehow the power was cut off for some period of time. It happened once and I will keep an eye for this..

[Incompatible]

Originally Posted by skim

One day I started my car and I noticed everything was reset, like clock, speed limit beep thing, etc. I think somehow the power was cut off for some period of time. It happened once and I will keep an eye for this..

I also had something similar occur about a year ago and since then there has been no repeats. Other then driving, nothing had been done to the car.

[AWM3]

Originally Posted by mineo77

My battery keeps going dead if i leave my car for 1-2 days without driving. I typically drive 40-60 miles during the week getting to work. The dealer told me that i need to purchase an external charger to keep the battery alive..seems odd to me. any suggestions?

Obviously your battery should not go dead after a few days of not being driven. Either you have a bad battery, or you have a current drain on the battery that is running it down. You can have the battery tested; if it is bad replace it. If the battery is OK, try disconnecting the battery while the car is sitting. If it doesn't go dead, you know you have a current drain. This could be as simple as something like a courtesy light, or as complex as one of the main systems not going into "sleep mode".

[VitaminT]

I drive about 50 miles a day. From time to time would let it sit over a weekend and it sounded saggy when starting. Finally one weekend I got ready to go somewhere, again after it had sat, and it wouldn't start. A jump and everything seemed fine unless I left it parked for a while. The terminal was a tad corroded but not real bad. Dealer ran a check, printed out some little receipt with a code and replaced it free under warranty. No issues since.