[mountaineersti]

2020 X3 M40: I came home last night and locked my car (on the 8th floor parking garage). I just went to get in my car and the door did not unlock via comfort access or clicking the key fob button. So I took out the little metal key and unlocked the driver door manually.

Nothing happens when I click the Start button...

The security alarm light is flashing in the mirror. The hazard light (triangle) button is illuminated and the Start/Stop button is illuminated.

I have no idea why the battery would suddenly be dead overnight. Nothing strange prior to this. I can't open the rear hatch door to access the battery.

Being in a parking garage, I can't hook up a battery charger (no outlet), so my brother is going to bring his marine battery and jumper cables to give a try. Anyways, just thought I would post here while I'm waiting in case there is anything else I should look for....

[exE36M3]

Yep. It happens. When the battery starts dying or dies there really isn't much warning.
My E36 M3... fine one day, then dead battery. My wife's 2021 X3... bought 2 weeks ago, drove fine 1st week. Then the digital cluster went dead. Came back on with plug/unplug battery. Then 3 days later dead again. Left parked for 2 days. Car is DEAD. No electronic anything. Measured battery with voltmeter... 5v. Tried a CTEK charger... 12 hours later... 11.95v. Won't even crack 12v.

Went to dealer this week. 77 fault codes. 6 of them electronics related. The other 71? voltage.

Battery is bad per the dealer.
They did suggest to either lock the car or press the radio button to completely turn off the car.

Thinking BMW got some bad batches of batteries.

NOTE: Make sure you jump your car from under your car hood. But thinking since you can't open the rear hatch, you probably already did that!

[Coi]

Are you sure your car battery is dead and not just the key battery? Our X3s are known for going through key batteries really frequently. If it's the key then there's a spot on the right side of the steering column where you can hold it to start the engine.

That said I once had a 12V battery suddenly go bad on a new car and it was replaced under warranty. Just randomly wouldn't start one day when I was out shopping. With almost any part a certain number of defective units will escape the factory, and car batteries are no exception.

[mountaineersti]

Thanks guys.

Yes, I tried placing the fob next to the steering column just in case, but it's not a dead fob.

We jumped it (under the hood) and I was driving it around to get the charge back and there is a lot of weird stuff going on now. The radio does not work. The buttons around the gear shift (menu, etc) do not work. And then I got a CEL about possible drivetrain issue

So I suppose it will be a trip to the dealer to see what is the root of all of this.

I also notice that the backlights around the headlamp knob (to turn on auto, parking, etc) stay illuminated even after the car is off and locked....I can't recall if that is normal.

And I always lock my car.

Thanks for your help!

[morekimchi]

Why not jump from the trunk? My x3 wouldn’t start (everything was dead). Jump from the hood didn’t work but allowed us to open the tailgate. Finally got it started from the trunk. Is that bad for the car?

[freshxdough]

Originally Posted by morekimchi

Why not jump from the trunk? My x3 wouldn't start (everything was dead). Jump from the hood didn't work but allowed us to open the tailgate. Finally got it started from the trunk. Is that bad for the car?

You should generally not jump from the trunk. First off, it's rare you can ever even get a good bite from the jump clamps at the battery because the battery terminal connection is surrounded by protective plastic. That is why there are jump points in the front of the vehicle. If you have a good jumper jumping from the front won't give you problems.

[morekimchi]

Got it. Thanks, freshxdough!

[keithguido]

My x3 wouldn’t start (everything was dead). Jump from the hood didn’t work but allowed us to open the tailgate. Finally got it started from the trunk with BMW assist. Dealer replaced battery as there was a service advisory on this.

[Coi]

Originally Posted by mountaineersti

We jumped it (under the hood) and I was driving it around to get the charge back and there is a lot of weird stuff going on now. The radio does not work. The buttons around the gear shift (menu, etc) do not work. And then I got a CEL about possible drivetrain issue

So I suppose it will be a trip to the dealer to see what is the root of all of this.

Low voltage can cause a lot of weird errors in modern cars. Would be fairly expected for a bad battery to do all of that.

[mountaineersti]

When I went to try to start it this morning, it would not start, but did have enough juice to show me an error on the screen:

"Battery Management. Start Engine. Malfunction while shutting down the vehicle electronics when vehicle is stationary. If the problem recurs, have it checked by your service center."

So it sounds like it isnt shutting down properly and is draining the battery.

I jumped it and dropped it off at the dealer...

[KingM40i]

Originally Posted by mountaineersti

When I went to try to start it this morning, it would not start, but did have enough juice to show me an error on the screen:

"Battery Management. Start Engine. Malfunction while shutting down the vehicle electronics when vehicle is stationary. If the problem recurs, have it checked by your service center."

So it sounds like it isnt shutting down properly and is draining the battery.

I jumped it and dropped it off at the dealer...

I know this is an old post but curious if you were able to get this resolved and what was the issue/solution?

[jwong77]

Originally Posted by KingM40i

I know this is an old post but curious if you were able to get this resolved and what was the issue/solution?

I recently ran into this issue, I couldn’t even raise the trunk lid to access the battery. I had to call AAA to give me a jump. I bought my own battery and replaced it myself. Used ISTA to code the car to the new battery and called it a day.