Battery died

[///M KID]

So my battery died and I had my car towed to the dealership because I figured my battery should not just die on a 3 month old car. They are saying I left my car 'on' for 3 hours and my battery died and are telling me that I may have to buy a new battery. Correct me if I am wrong, but doesn't the car shut off automatically if you leave it on? I told them I am not paying for a new battery. Should I be paying for a new battery?!

Sorry for the vent, just frustrated!

[PatrickC23]

Man im finally back after a long hiatus - I think the only way you leave the car on draining the battery is if you only hit the Start/Stop button once on shut off and dont lock the doors. Locking the doors does the same as hitting it a second time?

I would hope that they gave me a new battery in this case out of goodwill. But ultimately depends on your dealer.

[///M KID]

I never lock my car when it is in the garage at home. I will be pissed if they make me buy a new battery!

[mwlmd]

I had a similar issue with my E90 M3. Except they claimed I wasn't driving the car enough.

After several threatening emails to the service manager they "did me a favor" and replaced the battery free.

My guess is that unless you have a fantastic relationship with your dealer they won't warranty it unless you make a stink.

The batteries are $400ish. I think it is worth a small stink.

[///M KID]

There is no way I am paying for a new battery! I was yelling at them in front of everyone telling them no way I am paying for a new battery on a 3 month old car that is over 100k. They just said 'ok'. We will see what they actually do... They are trying to revive my battery now.

IMO BMW should have a fail safe so this does not happen...

[savela]

I'm pretty sure that if you drain a battery by leaving accessories on, it should take a charge and function just fine. Why do you have to buy a new one? Does a complete drain ruin it somehow?

Also. 3 hours? Not that long unless you're running the AC or the headlights....I guess the DRL's could do it.

[CFisher]

400 smackers!?!?!! You joking? Holy smokes that seems worse than steep, doesn't it??

Anyway - Savela - armchair mechanic talking here - automotive batteries main purpose is to provide a blast of current in a short amount of time for starting purposes - they really don't like slowly draining at all...and they REALLY don't like being discharged* at all - a battery discharged isn't "ruined" - you'll be able to charge it plenty of times, but don't expect full performance out of it. Something about crystals forming on the lead plates at the microscopic level (?)

*I want to say something like a reasonable sounding 11.5V reading on a 12V battery is considered really discharged btw. A fully charged 12V battery probably reads somewhere in the 13.8 - 14.7 volts.

[Spinny02]

Sorry to hear this BS. I have taken my cars in for all sorts of issues trim, seats leather showing excess wear, batts ect never once did I get question on these high dollar cars. Sounds like a shitty service rep.

[avlnch]

What's up Ryan

I know if you shut down the car with one press of start/stop while in Neutral, it will keep the ignition on.

If you shut down the car with one press of start/stop while in gear, it will turn off the ignition.

If you attempt to lock the car while the ignition is on, it will honk the horn at you. The same thing happens if you leave your key in the car and try to lock it.

Since you don't lock your car when you park it in your garage, it's possible that the ignition was left on and the car drained it's self.

I know that with our M5's, if you leave a light on, or an accessory is left plugged in, the car can intervene and stop the battery from draining itself by temporarily switching off a fuse until the car is started again. Next time you get back into the car you get a warning message that says something like:
"Battery discharging while stopped. Electrical devices were temporarily switched off".

I don't think the M5 can turn its ignition off by its self. The most it will do is warn you when you attempt to lock it. I could be wrong, but this is what I think because why else would it honk the horn at you? Instead of just turning the ignition off automatically for you.

I think that once a battery is fully depleted, it will never be able to fully charge again or it losses it's charge faster than normal.
You might be better off paying the $400 instead of having to worry about a recharged battery that could fail again in the future.

I think you can get them to warranty or goodwill the battery. I would expect that from my service center.

[Road racin]

This happened to me. My detailer parked it in the garage and left the ignition on. I didn't drive her for a few days and when I tried it was dead. Called service, jumped it. It's been fine for 10mo.

Yes killing a battery is bad for it and it typically won't be "as good" as before however in my case it's posed 0 issue. I wouldn't spend 400 unless this is a recurring problem. Meaning don't fix what ain't broke yet

[JOHNBMWM5]

My M5 shuts it's self down "Ignition on or off" after 10/15 mins, so they should renew if required under warrantee not give a load of bollocks to paying customers, my dealerhip would change out the battery without question
Change the dealership if it's not replaced /offered free.