URGENT - advice needed on dead i3 after 12v battery failure.

[TedStriker]

Hi All,

Apologies for the length of this post but a lot has happened and I'll try to give as much info as I can. Please - dont roast me for doing 'wrong' things - sometimes when an alarm is going off waking all the neighbours at 3am you aren't in the most stable state of mind!

So, I have a 2018 i3 REx, which has given me no significant problems for the 7k miles I've owned it for so far. A few days ago I was woken by the alarm going off at 3am.When parked up, the car had approximately 70% HV battery capacity and the REx tank was completely empty. It kept going off. Couldn't unlock the car with the remote. Used the physical key, got into the car and couldn't wake it up. There were various flashes from the displays but nothing else. My diagnosis - 12v battery had died. First thing I tired was a 12v automatic car battery charger. This didn't seem to help, I think the 12v battery voltage was too low for the automatic charger to start charging. I tried this with the HV both on and disconnected via the breaker in the frunk.

So - my next idea was to use a spare 12v car battery I had in the garage to 'jump' the dead 12v battery. This succeeded in bringing the car to life. I noticed the HV battery was showing --- (ie zero) miles remaining and 1% charge on the idrive. I plugged it into my 'granny' charger and managed to get up to 2%. At this point I disconnected the jump battery and the car stayed alive. I'm assuming the DC-DC converter had now taken over and was keeping the car alive. I then drove a few hundred yeards to a nearby 7kW public charger and charged up to around 5%. I should mention that at this point I had ordered a new 12V battery from a BMW dealer 45 miles away and knew that unless I started driving right away they would be closed (Saturday afternoon) and not reopen until Monday.

So my plan was to drive on battery to a nearby fuel station, fill the REx tank up and use that to get me to/from the dealer. Unfortunately when I stopped to refuel I let the car go off and it wouldn't wake up again after refuelling. Luckily I'd planned ahead for this and had the spare battery and jump leads with me so managed to wake it up again. As soon as it awoke, the REx fired up. I then drove to the dealer and picked up the battery, with the REx keeping the HV battery around 6% charge. Remember, when I parked up the night before the HV battery was around 70% charged. At the dealer I got out of the car via the passenger door and left the keys in the car so it stayed alive. Drove back and briefly stopped close to home. Locked the car, unlocked it a few mins later and lo and behold all looked good - the battery was showing 70% charge and the REx was no longer running.

I then drove home and put the car on charge. I couldn't fit the new battery as I had no tools and planned to fit it later. The charge would have completed around 10pm and at 2.30am - alarm going off again. I had hoped that being plugged in to the charger would have kept the 12v battery topped up but it appears not. Again, I used the jump battery to wake the car up and left it unlocked which kept it quiet. Next morning I had to make an emergency journey as my partner was ill so jumped the 12v battery and drove to a hospital 20 miles away without issue. Parked up and when I came out to the car after half an hour or so the car was dead. No problem I thought, jump it and we'll be fine.

But no. The car woke up but I now had a red drivetrain error and couldn't get from ON to READY. I had an OBD dongle and used Bimmerlink to read the codes. There was a huge number of them and I've attached the pdf of the fault codes to this post (hopefully). Only a few months ago I'd updated the i-step of the car so all codes would have been cleared around then so these are all fairly recent. I tried to clear the codes but some would not clear - those relating to such things as Range extender digital engine electronics, Electrical Digital Motor Electronics amongst many others. Unfortunately I did not keep a copy of the remaining errors after the attempt to clear was made. I noticed that once again the HV battery was showing as 1% charged with ---- in the range display - it should have been around 80%. However this time I had a mostly full REx tank so tried to activate the emissions test mode to see if it would get some charge in. Sadly this didn't work - I did get the 'emissions mode' display but the engine didn't fire up.

So this is where I am now. There are a few complicating factors though. The car is nowhere near a charger or power outlet. It is also in a secure location where it would be virtually impossible to get a tow truck to it. It's stuck in Park. I'll be going to the car tomorrow and and intend to install the new battery. I don't think this will solve my problems though as the 'jump' battery powers the car up just fine so would expect the new battery to do the same, with the same drivetrain error.

My question - I do have a working copy of ISTA 4.39.20, any experts on here that could advise whether there's anything I can do with ISTA that may get the car back to life? I'm sincerely hoping that jumping the battery has not done any damage. In theory it shouldn't as all it's doing it providing 12V to the battery terminals where it should be anyway. Is it possible that the car wont go into READY as there's zero range on the HV battery and all it needs is a (don't know how I'll achieve it) AC charge? Why isn't the REx firing up in emissions mode? I do recall that the REx was one of the modules that couldn't clear all of the codes.

Any and all thoughts/suggestions would be greatly appreciated.

Cheers,
Ted

 

[Mondomensch]

Others have posted that it’s important to fully charge the new 12 V battery before installing it. I think they’re typically sold maybe half full. Good luck!

 

[TedStriker]

Others have posted that it’s important to fully charge the new 12 V battery before installing it. I think they’re typically sold maybe half full. Good luck!

Unfortunately I won't get a chance to do that as it's in the back of the car which I won't be near until ready to do the job tomorrow.

 

[EvanstonI3]

"jumping" the 12v does not work as it does with an ICE vehicle. The only time the 12v dies in this car is when it has FAILED. The car will not "charge" the battery once it starts.
You've already discovered that with a proper 12v source, the car will turn on and possibly drive, so it should do the same thing with a new 12v battery.

One of the problems with a failed 12v battery is that the dash will no longer display the proper HV levels. You could have 70% but the dash may show 0%, even after installing a new 12v battery. There will be all sorts of electronic weirdness until those modules have a proper and consistent voltage and have time to clear themselves unless you can do it yourself with ISTA or BimmerLINK. Stop looking at error codes and trying to figure out what is wrong when you have a failed 12v battery.

 

[TedStriker]

"jumping" the 12v does not work as it does with an ICE vehicle. The only time the 12v dies in this car is when it has FAILED. The car will not "charge" the battery once it starts.
You've already discovered that with a proper 12v source, the car will turn on and possibly drive, so it should do the same thing with a new 12v battery.

One of the problems with a failed 12v battery is that the dash will no longer display the proper HV levels. You could have 70% but the dash may show 0%, even after installing a new 12v battery. There will be all sorts of electronic weirdness until those modules have a proper and consistent voltage and have time to clear themselves unless you can do it yourself with ISTA or BimmerLINK. Stop looking at error codes and trying to figure out what is wrong when you have a failed 12v battery.

Thanks for that.

Yep, I'm aware it's not like an ICE vehicle, looks like 'jumping' it did enough to kick the DC/DC convertor into life so it maintaned the 12V even with a dead battery. My problem now is that it wakes up but I get drivetrain error and it doesn't go READY like it did a number of times when I jumped it. I did try clearing the code with Bimmerlink but it couldn't clear them all. I'm hoping that armed with ISTA I can run through some processes to clear the remaining errors.

Yes, I have the issue that it shows the HV battery as completely dead - I'm reallly hoping that's why I'm getting the drivetrain error and so if I can fire up the REx with the aid of ISTA then it should be able to put enough charge in to get the car moving. Fingers crossed!

I'm no expert with ISTA but I have seen for error codes that there's generally a scripted process to run through to eliminate them. Hopefully some kind of reinitialisation will get things going again.

My last thought is maybe hire a portable generator and see if I can get some charge in via the granny charger - at 240V (UK), I should be able to get around 2kW of power into it, which won't take long to put a few percent into the battery. My worry here is that there was definitely a 'Unable to charge' warning last time I woke the car up with the jump battery. Again, hopefully ISTA can help there.

If the car was at my house I'd be trying all sorts, but unfortunately it's not so I don't have access to local power etc.

Thanks for the info. I hear what you say about not chasing error codes, but surely with a external 12v battery connected to the 12v battery terminals, that's functionally the same as having a good 12v battery installed?

Worst case scenario I've fried a very expensive hard to access module...

 

[alohart]

My last thought is maybe hire a portable generator and see if I can get some charge in via the granny charger - at 240V (UK),

Charging with a portable generator isn't always successful. The EVSE ("granny charger") isn't always happy with the generator output not being a pure sine wave or not having a true earth ground.

 

[EvanstonI3]

Thanks for the info. I hear what you say about not chasing error codes, but surely with a external 12v battery connected to the 12v battery terminals, that's functionally the same as having a good 12v battery installed?

The error codes and issues do not instantly go away with a good battery.
The car was basically bricked and just because you Frankensteined it back to life briefly does not mean all your problems are gone. There have been owners who have experienced EXACTLY what you are going through and even after having it towed to a Dealer who cleared as many errors as they could, the car STILL had to sit, plugged in, for 24hrs before it was "fine".

And don't call me Shirley.

 

[Dutchi3]

Charging with a portable generator isn't always successful. The EVSE ("granny charger") isn't always happy with the generator output not being a pure sine wave or not having a true earth ground.

It is perfectly possible to charge the car with a portable generator. If you take an inverter model that puts out pure sine waves and enough power you will possibly manage. I know because I have such a generator and used it to charge a few times, just to find out if it works. Driving on gas lol.