Total loss of Electrical power

[danlo]

Hello all, I bought a 2010 x28i a few months ago. It has been perfect but a week ago I was parked in the snow at -17c all day and when I got back to the car it started without hesitation, drove 20m and then just totally shutdown. Road service came and tried to jump it but nothing. Finally got it towed back home after a week (long story) and will start diagnosing it in the coming days. The only thing I have done is put a multimeter on the battery and it is reading under 3v. I will be trying to connect another battery just see to if I get power back but I don't get how it started normally and then just shut down. Unfortunately I don't know what voltage it was just after the shutdown.

Is it possible that it just a bad battery? Previous owner said it was changed 2yrs ago and it is an original BMW battery.

First challenge will be to get off all the stuff connected to the +terminal and pull it out! Looking for details instructions but no luck yet.

After looking at the battery, next will be to have a look at the power cable going to the fuse box which some cars from that period had a recall issued. Not sure if the e84 was one of them.

Any other theories or information would be much appreciated!

Thanks.

[Gamb1t]

Well 3V means dead battery.

Maybe your BST kicked in for whatever reason and blew the +ve connector. It's a BMW safety thing. It's annoying. Happened on my Z4 when I went over a bump. Fortunately it occurred at a Home Depot parking lot.

Changing battery videos abound. You can look up e90 one or 1-series if you cannot find X1 e84.

[danlo]

Thanks for the e90 tip! Plenty of videos on battery removal.

I connected an old battery from another car that only has 74Ah and 750A just to see if I could get dash lights up. All I got was the hazard button and START/STOP button lights flashing/Flickering really fast. There was a lot of clicking from under the dash and then the dash came up and the flashing stopped. I Then put my foot on the brake and the flashing started again.

The battery was 12.6v when I connected it but was quickly down to 5v after just 30 seconds or so. I put a multimeter on it while the flickering was happening and it was jumping between 5v and 7v and dropping. Everything now disconnected and the test battery is sitting at 5v.

My hopes of a simple fix have now evaporated. Anyone have any idea what could cause a battery to behave like this?

[danlo]

Finally got ISTA+ installed and a new battery delivered today which did the trick. When I bought the car 7 months ago, the seller told me he had a new battery installed by bmw 2 years previously. I mistakenly took him for his word and it made me think there was a serious issue as what could kill a 2 year old battery.

The car production date is May 2010 and the date stamped on the -neg terminal was 17/10 which I learnt means the 17th week of 2010. ISTA+ had no record of a battery change at all, which I assume it would read from one of the modules? Or could it be that it would only show me if I was actually connected to the BMW network in Munich? Either way, the old battery was produced in 2010 so it has had a long life. Nearly 13yrs and 145,000km is pretty good going I'd say. It took a day at -17deg to finally put it to rest. RIP.

[danlo]

Back to the drawing board. 24hrs later and the new battery is flat. Measures 12.3v and once again, key went in, dashboard lights came on then everything went off and the key is stuck in the ignition. Battery now on the charger and I need to find possible causes. No signs of water anywhere in the cabin or around electronics (that I can see). Any thoughts?

[Gamb1t]

Well you can put on your Sherlock Holmes hat & pipe.... remove one accessory fuse at a time to see where the draw is. On a Bimmer, this will take a while. Perhaps start with the high powered accessories first.

[danlo]

I'm reading conflicting things about the battery. This second shutdown happened 24hrs after a new battery was installed. I measure the voltage at the terminals immediately after and it was 12.3v. I charged it and now it is a constant 12.6-7v but still no power to anything. At 12.3v it might not crank but would it be totally no power to anything? Do the car electronics have a minimum threshold that it shuts everything down if not met? When I installed the new battery it was 12.6v, then I had the car on for some time whilst in ISTA (first time using it so probably took longer than it should) to check errors and register the battery change, so that would of dropped it down some. Then I only took it for a short drive so I didn't really give the car a chance to charge it much. I should of checked the voltage before I left the car thinking it was done.

My symptoms lead a lot of people to think my B+ cable to the fuse box is the culprit. If that was the case, whilst the battery is connected, if I measured the voltage across any of the fuses it should be zero right? in the cars current dead state that is. If the B+ cable has burnt of become disconnected there should be no power at the box?

I am quite new to this so please bare with me. I'm trying, and I apologise if my logic is flawed!

[danlo]

Final update incase someone experiences similar symptoms and finds this.

It was indeed the B+ battery cable to the fuse box.

I confirmed this by removing the bottom trim panel in the passenger footwell (2 screws). Found the red battery cable coming up from under the carpet, gave it a tug and the power came back up.

Bought the REP.WIRE FOR B+ part number:61129312133 from a BMW dealer for 17chf (less than $20us).

Multiple guides online on how to change it. The only special tool i needed for this was the Hydraulic Crimper (pretty cheap on amazon). The right-angled connector did indeed show signs of melted plastic but the fuse box itself was fine.

In most countries this is a factory recall so check in yours whether you can get it done for free. In Switzerland it is not a recall for an X1 e84 mid 2010 just FYI. It should be as it shares all the same parts as those with a recall.

Hope this helps someone down the line.

Thanks.

[Gamb1t]

Well done! Isn't it satisfying to perform the diagnosis, methodical analysis and finally able to fix it?


Wish BMW would not complicate things.