[necropsyblade]

My BMW i8 LCI was manufactured in late 2018 and sold in early 2019. I bought it in the UK. However, I shipped the car to Trinidad.
The car worked well for a year and then a month ago I get the error ' Drivetrain. No restart'. When this happens the engine light is on and the car will not power on. The OBD scan of errors at this time usually include ‘ Power management, battery: Faulty charge by high voltage battery’. Also sometime i get ' Cell supervision circuit 2: Temperature measurement of cell block, measure value implausible'

However, there are times when the car starts normally and when it does, it drives well with no errors occurring. The car also charges the HV battery normally at this time and the dash displays a normally functioning HV battery.

The error usually occurs after the car has been switched off for about 4 -5 hours. It may restart spontaneously after pushing the start / stop button multiple times or sometimes if the 12v battery is disconnected then reconnected ( not all the times though)

I have tested the 12v and it has a good state of health. When the error is active the voltage is about 12.76 V. When the car works the voltage is about 14.5 V ( I assume that the HV is charging it ).

I have updated the software of the car from 2018 to Aug 2020. This has not made any difference to the error.

Does anyone have any thoughts on how I can solve this. BMW UK has basically said they refuse to have anything to do with the car anymore! So i'm looking for any help I can get!

[CaboM4]

get you hands on a copy of ista-d & a BMW ENET Cable and use the OEM BMW Shop diagnostics software to do a thorough scan and test workplan for resolving the issue next time you have the problem occur.

do a google search ... you will find the software readily available for download on MEGA or torrents, etc.

[Chickenmusket]

Hi ,
I have a 2015 that had this issue last year, same error, and sometimes it would start and run fine. The car was at the dealer for 87 days, waiting for 4 of the 6 high voltage battery packs. Once those were replace, I never saw the problem again. Just my experience.

Thanks,
JP

[avdept]

Has anyone ever resolved this ? I have same issue when car wont start after being idle for ~8hrs. It takes 10-15 mins clicking start stop until it starts and then drives with no issues.
I took a screenshot of errors at the moment of occurrence https://monosnap.com/file/iX76NjvUe8...et3seTosOYMyCZ

Was wondering if anyone had similar and got it resolved?

[Tazzie]

Just had this for the second time. Says No regenerative braking. Unable to restart car. Left it for 30 minutes and it has started again. But will have to book it in. I know reading all the reports it literally could be anything. It’s a 2015 65 uk car.

[billy.gif]

Are you guys by any chance one of those owners whom does not charge their cars from home socket / charging stations but only by driving in SPORT-mode?


















-Above is what happened to me after my car was at the BMW Main Dealer in order to perform official "BMW High Voltage battery test". The test was left incomplete as their time run out (service department was closing).

When I picked the car up, everything was fine expect I could feel that the regenerate braking (slowing down) when letting off the gas was inoperative. Even the SPORT-mode was not charging the High Voltage battery.

As I got near my home, after like 35km of driving the HV-battery showed literally 0 bars, usually there's always some "blue bar" (EV range) left there. Then all these faults came on the dashboard and after I parked the car, it would not restart.

I plugged the car into my home charger and it would not begin to charge. I left it over night and at the next morning it started. Also eventually it had charged itself up and the HV battery was at 100%. No errors at the dash, nothing. The regenerative braking was working and I drove the car back to the same Main Dealer.

Their EV-tech inspected the car / ECU / HV-battery (etc.) and gave "clean health". After this I've had zero problems with the car (*knock on wood*). This happened at 75k km mark exactly one year ago May 2023 and now car is at 89k km.

I have no clue what really happened but the I presume that the HV-battery and the 12V battery (which was new BTW) both were under stress while the BMW battery health test was performed and then it was just stopped middle of the test (as the service department closing time came): ECU or something didn't like it and some kilobytes decided to go haywire.


So it may be that your car(s) just need a long wall charge session? I mean like 12-24 hours w/o any usage of the car. And after that Main dealer inspection?


EDIT: And the tech claimed that usually "charging the car only via SPORT-mode" is more consuming to the HV-battery compared to the charging the car via charging station / your portable home charger.

As the battery will never be charged to the 100% (SPORT only charges up to like 70%) and when SPORT-mode is charging it usually users also drive aggressively so the SPORT mode is demanding adding demanding adding huge amounts of electrical power from the HV battery while its charging up. Compared to the charging from home charger / wall charger where car is just sitting unused and minding her own business while she is being charged up

So for longevity of the HV battery system of any "plug in hybrid" vehicle I would and I will always plug it into a home / 3-pin / etc. charger.

[Tazzie]

That’s great it was all sorted in the end. I do charge the car from the mains but don’t do it every day. I don’t use the car daily. Iv had it 5 years and always done the same. When the message first appeared I left it for an hour and it restarted and drove perfectly. A week later it popped up again. It’s still on its original 12v battery to my knowledge. So maybe it’s that starting to go. Will be booking it in and hopefully they will find what’s wrong. The dealer has been very good.

[avdept]

I ordered new 12v battery, should arrive tomorrow so will see if that help or not.
For now, I don't see any other real reasons why would my car not start up on first attempt

[Tazzie]

Did you get the new 12v battery and did it make a difference?

[avdept]

Originally Posted by Tazzie

Did you get the new 12v battery and did it make a difference?

No, not really.

I found real reason - faulty temp sensor inside HV battery. It was reporting -2C while others were around 25C.

By default i8 will not switch on contactors(and hence HV system wont be available) when difference between high/low more than 5C.

In my case sensor eventually starts to work in about 10-15 minutes and then car drives and charges with no problems.

[Tazzie]

Finally found the problem seems to be a wiring harness that is the culprit of the car throwing up the error message RBS regenerative braking not available. They haven’t said it’s been chewed so will find out when they replace it. Going to cost £657 which I find quite reasonable. I will be paying for it myself as Warranty wise has said it doesn’t cover this particular wiring harness for some reason??