car doesn't start question

[derpimpkar]

i parked my car tuesday night and it wouldn't start friday morning. the start button flickers, speedo lcd is good, headlights flicker, clicking sound from behind passenger dash.

the car wouldn't jump and the bmw roadside person said the battery was fine. same symptoms when they tried to jump. i measured 12.6V across jumping terminals.

are these symptoms of a dead battery or something else?

[MaynardZed]

Dead battery. Roadside assistance is wrong. It’s a bitch to jump start, could try from trunk terminals but you’ll likely need to tow to dealer. 12.6V is too low, mine wouldn’t jump at 13.3V. Besides that’s just volts, doesn’t mean amperage is fine what is what’s needed to crank the starter.

[derpimpkar]

ugh and thank you.

what drained your battery? the dealer said some connection can stay open if you don't lock your car and that's what may have done it. mine was in the garage so i don't lock it. i've had the same routine for three years with no issue. it seems odd it suddenly decided to drain itself.

[MaynardZed]

Originally Posted by derpimpkar

ugh and thank you.

what drained your battery? the dealer said some connection can stay open if you don't lock your car and that's what may have done it. mine was in the garage so i don't lock it. i've had the same routine for three years with no issue. it seems odd it suddenly decided to drain itself.

I didn't drive it for a few months, should've had it on a tender. It will drain faster if you keep it unlocked like you were doing though. Mine's a 2015, could just be the lifespan of the battery. Normal batteries only last about 2 years here in AZ.

Luckily got mine replaced at dealer under warranty. Would've sucked to cough up $1250 for a new battery. I have a Lithium battery tender now, so will get that hooked up.

[derpimpkar]

thanks for the info.

[michaelalex17]

Originally Posted by MaynardZed

I didn't drive it for a few months, should've had it on a tender. It will drain faster if you keep it unlocked like you were doing though. Mine's a 2015, could just be the lifespan of the battery. Normal batteries only last about 2 years here in AZ.

Luckily got mine replaced at dealer under warranty. Would've sucked to cough up $1250 for a new battery. I have a Lithium battery tender now, so will get that hooked up.

I didn't realize our batteries were under warranty?

[derpimpkar]

i think they won't say authoritatively so they can look at each case individually. car constantly checked for let seems like a bug, it better be under warranty. someone wired up a dashcam badly, you're on the hook.

follow up with this one, it was a computer issue. lessons learned:
- lock your car even in the garage.
- out a string from the trunk manual release to the cabin.

[aboulfad]

So much wrong information in here, sorry. If your battery drained in few days, it is NOT because your car was unlocked. Dealers give all stupid reasons when they don't know the cause. Granted it could be some very weird electrical problem where something didn't shutdown, but if that was the case, the dealer can run a test procedure *Energy diagnosis* that will tell tons of things. Read my old thread for details http://f80.bimmerpost.com/forums/sho....php?t=1217987 i always leave my car unlocked in my garage for days... (ok now don't come and steal it)

The fact that your car couldn't be jump started points to a serious problem with the battery and/or something else (how did roadside assistance jump start it, w what?). LifePO4 batteries have a lot of protection and to wake them up , requires jump starting using a jump starter, suitable trickle charger or another vehicle.

LifePO4 batt voltage of 12.6 is essentially < 10%, dead empty. Our batteries are supposed to last twice if not longer that regular lead acid, but time will show...

So what happened with your case, did they replace the battery? And for them to do that they have to show Fault with the battery.

[derpimpkar]

roadside didn't jump it, we had to tow it. the issue was a computer. i don't think they replaced the battery.

[aboulfad]

So mysterious electric gremlins again, Do you know which ECU they replaced?

[derpimpkar]

i'm picking up my car on monday. i'll check the order and reply.

[derpimpkar]

the dealer called it the front engine module, the work order listed it as the front control unit.

[aboulfad]

Most likely FEM, Front Electronic Module, what's the part nb? That's crazy...but glad all it sorted out for you,

[derpimpkar]

61358707674

yeah, i have zero mods and it was a surprise. car ran fine when i drove it home. chalk it up to bad luck. warranty covered, no worries.

[aboulfad]

Yep, FEM, http://www.realoem.com/bmw/enUS/partxref?q=61358707674 this is one critical unit in our car's electrical/electronic systems and let's hope failure rate is just one in a million during warranty period