Alpina B7 F01 : Brand new battery, dead after one short drive

AtomicPlayboy · 11-08-2023, 05:24 PM

I was getting a "charge battery message" recently, but had used a battery tender so I thought I was OK. After driving about 100 miles earlier this week, I parked the car and came back a couple of days later to a completely dead battery.

I then replaced the battery with a new one from Advance Auto Parts with proper fitment, and everything worked perfectly - car started right up, all electronics good, etc. - for another 100 mile drive home. A day later, I just tried to start the car and it's completely dead again. No electronics, won't start, completely dead.

Any ideas on what is causing this and how I can resolve it? I suspect some grounding issue, since even if my alternator was shot a new battery shouldn't discharge completely in 36 hours when the car was only driven for 2 hours. There were no indicator lights or anything. The only thing that seems to be working is a flashing green light on the N position on the shifter (which is odd since everything else electronic on the car seems to be completely DOA)

I recently purchased an OBD ethernet cable so I'd be able to run my own diagnostics, but haven't set that up yet. But I'm pretty technical, so if any suggestions require diagnostics, I can probably run them soon.

Car is a 2012 Alpina B7 w/80k miles. Thanks in advance.

Qsilver7 · 11-10-2023, 03:22 PM

Is it stock...or do you have any aftermarket electronics that may not be shutting off after the engine is shut down?

A "flashing" green light may indicate something is not shutting down. There is a 15-16 minute period that the car stays awake...then shuts down if no calls are made on the communication bus. During those 15-16 minutes...the hazard light usually stays illuminated, and if you have ambient lighting...that may stay on a minute or so after shut down...but again, after 15-16 minutes if the door handles haven't been lifted or no other calls made on the communication bus (like the car picking up the remote fob signal)...the car should shut down.

M_Bimmer · 11-10-2023, 06:06 PM

What's the voltage with the engine running? (An inexpensive DMM will suffice)

If 12.x'ish Volts, you need a new voltage regulator, which is mounted on the rear of the alternator. The brushes eventually wear down.

11-08-2023, 05:24 PM	#1
AtomicPlayboy Registered 0 Rep 1 Posts Drives: 2012 Alpina B7 Join Date: Nov 2023 Location: St Augustine, FL iTrader: (0)	Alpina B7 F01 : Brand new battery, dead after one short drive I was getting a "charge battery message" recently, but had used a battery tender so I thought I was OK. After driving about 100 miles earlier this week, I parked the car and came back a couple of days later to a completely dead battery. I then replaced the battery with a new one from Advance Auto Parts with proper fitment, and everything worked perfectly - car started right up, all electronics good, etc. - for another 100 mile drive home. A day later, I just tried to start the car and it's completely dead again. No electronics, won't start, completely dead. Any ideas on what is causing this and how I can resolve it? I suspect some grounding issue, since even if my alternator was shot a new battery shouldn't discharge completely in 36 hours when the car was only driven for 2 hours. There were no indicator lights or anything. The only thing that seems to be working is a flashing green light on the N position on the shifter (which is odd since everything else electronic on the car seems to be completely DOA) I recently purchased an OBD ethernet cable so I'd be able to run my own diagnostics, but haven't set that up yet. But I'm pretty technical, so if any suggestions require diagnostics, I can probably run them soon. Car is a 2012 Alpina B7 w/80k miles. Thanks in advance.
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11-10-2023, 03:22 PM	#2
Qsilver7 Major General 4442 Rep 7,484 Posts Drives: F06 650ix GC / F15 X5 50i Join Date: Oct 2016 Location: Indiana, USA iTrader: (0)	Is it stock...or do you have any aftermarket electronics that may not be shutting off after the engine is shut down? A "flashing" green light may indicate something is not shutting down. There is a 15-16 minute period that the car stays awake...then shuts down if no calls are made on the communication bus. During those 15-16 minutes...the hazard light usually stays illuminated, and if you have ambient lighting...that may stay on a minute or so after shut down...but again, after 15-16 minutes if the door handles haven't been lifted or no other calls made on the communication bus (like the car picking up the remote fob signal)...the car should shut down. __________________ 2015 F06 650ix Gran Coupe`(Moonstone/Cohiba Brown)\| 2014 F15 X5 50i MSport (Space Gray/Mocha) Become a BMW CCA member! Click HERE to join and feel free to use my BMW CCA member #191509 as a referral.
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11-10-2023, 06:06 PM	#3
M_Bimmer Captain 583 Rep 829 Posts Drives: G12 B7, G07 XB7, F02 B7, 991.1 Join Date: May 2020 Location: Left Coast iTrader: (0)	What's the voltage with the engine running? (An inexpensive DMM will suffice) If 12.x'ish Volts, you need a new voltage regulator, which is mounted on the rear of the alternator. The brushes eventually wear down. Attached Images Last edited by M_Bimmer; 11-10-2023 at 06:14 PM..
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