Mystery Battery/Alternator issue?

[LBMF30]

I’ve been having an intermittent battery/alternator issue that I’ve been chasing down. I replaced my battery today because last night every single light came up on the dash and the car started sputtering until it just shut off. With the new battery it started right up and everything was back to normal. A few hours later on the SAME DAY, my clock/trip odo resets and I get the same discharge warning. Anyone know what the deal is?

[spammysammich]

What is the battery voltage with the car running? Get the alternator tested.

[NiBe]

When you charge the battery does it discharge itself while the car is off? This would suggest parasitic draw.

As already suggested get a voltmeter and provide numbers to us

[Redd]

Originally Posted by LBMF30

I’ve been having an intermittent battery/alternator issue that I’ve been chasing down. I replaced my battery today because last night every single light came up on the dash and the car started sputtering until it just shut off. With the new battery it started right up and everything was back to normal. A few hours later on the SAME DAY, my clock/trip odo resets and I get the same discharge warning. Anyone know what the deal is?

You put in a new batt and few hours later you get the same problem. High chance it's the alternator. If your current alt is over 80k kms it's an even higher chance it's due for replacement.

[Fooksdaddy]

Very sure it’s the alternator, random electrical gremlins while driving is a tell tale sign.

[DrFerry]

On the off chance the alternator turns out to be good, don't rule out a bad IBS (Intelligent Battery Stabilizer). When it goes bad the alternator may not produce enough current to charge the battery *even if* the alternator is good. See this post at the link below for more information.
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https://www.m3post.com/forums/showpo...20&postcount=7

[Theodore2]

The most common parasitic drain for the E9X M3 is the EDC module if your car is equipped with EDC struts/shocks. Check out this discussion here.