Loss of Power / Battery Issue

[flawless]

Hello Everyone,

I have been having an electrical issue on my e92 M3 recently. After about 20 mins of driving the car I suddenly get all sorts of error messages (brake malfunctions/tpms/etc) the info screen shuts off, my windshield wipers activate on their own, and then the car shuts off. Then the car wont start back up as if the battery went bad... Then after about 20 mins or so the car turns back on but weak as if the battery was low.

The car has a new battery, I took the car to the dealer for the recall of the battery cable thinking this may be the issue but it is still happening after.

It feels like something is draining the power from the battery.. Has anyone experienced this issue??

Thanks ahead, Jose

[Merlin_83]

Have you run an OBD scanner to read the codes? That is the fastest way to try and narrow down what is going on. I would ask the dealer to run ISTA or really any good OBD scan tool and see what codes are being coughed up by the ECU.

Cheers,
Merlin

[PACarGuy]

Sounds like a potential alternator failure, but definitely pull the codes.

[RedScytheM3]

Originally Posted by flawless

Hello Everyone,

I have been having an electrical issue on my e92 M3 recently. After about 20 mins of driving the car I suddenly get all sorts of error messages (brake malfunctions/tpms/etc) the info screen shuts off, my windshield wipers activate on their own, and then the car shuts off. Then the car wont start back up as if the battery went bad... Then after about 20 mins or so the car turns back on but weak as if the battery was low.

The car has a new battery, I took the car to the dealer for the recall of the battery cable thinking this may be the issue but it is still happening after.

It feels like something is draining the power from the battery.. Has anyone experienced this issue??

Thanks ahead, Jose

Replace your alternator don't worry about the codes. When your car dies from loss of electrical power, you're going to get a ton of codes that are unrelated. What you described is exactly what alternator failure looks like. This exact same thing happened to a bunch of us and has been discussed. Pick up a new alternator (with voltage regulator already installed) and swap it it in. You're car will be good as new after.

[msan]

Originally Posted by RedScytheM3

Replace your alternator don't worry about the codes. When your car dies from loss of electrical power, you're going to get a ton of codes that are unrelated. What you described is exactly what alternator failure looks like. This exact same thing happened to a bunch of us and has been discussed. Pick up a new alternator (with voltage regulator already installed) and swap it it in. You're car will be good as new after.

Does the car give any dash light warning when the alternator stops working? Like a battery symbol or anything?

[NoHedge]

Originally Posted by msan

Does the car give any dash light warning when the alternator stops working? Like a battery symbol or anything?

Curious as well.

I have similar symptoms and pulled a "BSD alternator: Missing" code - pretty sure it is the alternator failing. No dash light warning / battery symbol were shown on dash.

[New2Roundel]

I would check the battery charge before doing anything. Also, did you get the battery coded when you replaced it?

[nrubenstein]

Let's start really, really basic: Have you made sure that the battery terminal clamps are tight?

[RedScytheM3]

Originally Posted by msan

Does the car give any dash light warning when the alternator stops working? Like a battery symbol or anything?

No. You can use the onboard computer system to monitor your voltage while driving and see that your battery is not charging. After you start your car up your voltage should jump from ~12V to ~14V within 15 seconds. That's one way to see that your alternator is working fine. If the alternator is not working, your battery drains while you drive. When there's no longer enough battery power to run your car you basically get a systemic shutdown of the car after about 10 min of driving. You will start getting all kinds of dash lights popping up, then your car dies and coasts to a stop. This is extremely dangerous because like what happened to me, it can happen while your driving on a busy freeway with traffic. After about 20 min you can restart the car and begin driving again, but it will repeat after another 10 min of driving.

[pjk380]

Originally Posted by nrubenstein

Let's start really, really basic: Have you made sure that the battery terminal clamps are tight?

Great point!

A couple months ago I had the battery recall done by the Dealer who I've always trusted. When I got home I opened up the battery compartment to reconnect a couple aux. wires that I run directly to the battery. While I was in there my trunk light began to flicker. I checked all the battery connections. WTF, the positive cable going to the power distribution box was loose. The tech who performed the recall obviously forgot to tighten everything up.

Its always a good idea to double check the battery connections.

[flawless]

Just checked the voltage on the battery with the car on and it shows under 12Volts. Must be the alternator.

What is weird is that when it first happened I checked the voltage on the battery and it was showing close to 14V, so I discarded the possibility that it was the alternator..

Going to replace the alternator, hope that is it! thanks everyone for their input.

[PACarGuy]

Yup, I had an alternator failure on my daughter's car (2008 Infiniti EX) back in January and the dealership missed it on their first attempt. Car basically just died while driving on the highway, and even after being jumped, it would die soon after. Threw all kinds of engine, trasmission and stability system codes. Dealer was stumped at first because the alternator didn't throw a code and "passed" the alternator test, but after it died again and I brought it back, they figured out that the circuit inside the alternator was bad and replaced the alternator. That fixed the issue.

[MisterClutch888]

is the battery coded?