[sunnygs6]

I have a BMW i8 2014 and less than 40k miles but last week after i came back from event, I left the trunk open which might have caused an issue with the low voltage battery and now car won't start. I got jump start and when i plugged in high voltage charger for high voltage battery i was able to start the car and let the engine run. But the moment i unplugged, car doesn't turn on and i got bunch of error messages like, " Hybrid System Malfunction", "High Voltage System Fault" "Check Engine light is also On" ... but it looks like high voltage battery is not charging, bec after that one time start now i get msg, "Unable to charge" ... any suggestions? I might have just ran out of warranty. Plz advise to text asap.

[billy.gif]

Have you let it to sit and charge fully? Meaning leave it charging for like 36 hours and LOCKED. The car charges hybrid battery pack and then it charges 12V battery. If latter is dead or near dead it will throw all sorts of errors.

But if the "Unable to charge" -message keeps coming then google "BMW KLE UNIT". Its known issue at early 330e/530e/740e models.

Some say that i8 does NOT have a regular alternator so you cant recharge 12V battery by idling the car or driving it with ICE.

[sunnygs6]

When AAA came and i asked to chk battery health of 12v battery he said it has 40% capacity/life left. I have had this car from 2019 and while i only drove for like 15k miles, u think i should possibly first try to replace low volt battery also?

[YWGT3]

Time to replace the 12-V Battery.

[Flasher]

the HV battery gets a permanent 12v supply from the 12v battery to enable cell balancing during standstill.
When a crash is detected a pyrofuse in the + connection of the low voltage battery blows and disconnects the 12 v supply to the HV battery causing a immediate emergency shutdown.
When your 12V battery gets depleted or faulty this has the same effect, your HV battery will detect this as a crash situation and disconnects.
I would suggest to disconnect your service disconnect connector before you install your new 12v battery- when you switch on your ignition you will see the red flash symbol with a diagonal line indicating your HV system is switched off.
Then switch off the ignition and wait for the car to go in sleep mode ( may take some time ! keep the hood or trunk open to access the service disconnect connector) -when the car is in sleep mode reconnect the service disconnect connector.
now you can switch your ignition on - this might reset your HV problem otherwise it might be nessesary to reset all stored faults.
You also have to register your new 12v battery with a suitable tester.
Good luck !

[sunnygs6]

Wow !! Your level of understanding of this is impressive. Thanks soo much. Car is saying "Unable to Charge" and wont start at all now - so i guess i need to tow it or get it replaced at home itself. Is there a video on how to disconnect service connector - i dont even know what that is.

i found this video to deactivate - is this what u are referring to? Also how do you put car in Sleep mode?

[Spss]

Hello, I am having same problem with my i8. When I plug the charger, unable to charge and main battery too low message. Did you resolve in your end?

Originally Posted by sunnygs6

I have a BMW i8 2014 and less than 40k miles but last week after i came back from event, I left the trunk open which might have caused an issue with the low voltage battery and now car won't start. I got jump start and when i plugged in high voltage charger for high voltage battery i was able to start the car and let the engine run. But the moment i unplugged, car doesn't turn on and i got bunch of error messages like, " Hybrid System Malfunction", "High Voltage System Fault" "Check Engine light is also On" ... but it looks like high voltage battery is not charging, bec after that one time start now i get msg, "Unable to charge" ... any suggestions? I might have just ran out of warranty. Plz advise to text asap.

[sunnygs6]

I'm going to try the suggestion of installing New battery. How old is your 12 v battery? Have u tested that to see if it needs replacement?

[billy.gif]

Unfortunately the dreaded "unable to charge / main battery too low" -message refers to the "KLE unit". Google it, "BMW KLE unit problems" or such.

Before I got my i8 I had 7-series and it throw exactly that message when the KLE unit finally broke. At first car randomly threw all sorts of error messages so I replaced the 12V battery. Sometimes it charged from home charger or charger stations, sometimes not.

But culprit was the "KLE unit". Its know issue with many different BMWs from i3 to 330e, 530e, 740e from ... 2015 onwards.


And BTW, the i8 HV batterypack does NOT keep the 12V battery charged if car is let to sit w/o it being "plugged in". HV battery only does mantain 12V battery IF car is connected to a power outlet / home charger.

I personally tested this... I let my car sat at my garage for one month, then went to drive it - it threw all sorts of codes related to a weak 12V battery. Which was replaced like 3 months prior during a service. After that I've kept car "plugged in" 24/7 when I'm not using it -> no problems what so ever.

[Flasher]

Originally Posted by sunnygs6

Wow !! Your level of understanding of this is impressive. Thanks soo much. Car is saying "Unable to Charge" and wont start at all now - so i guess i need to tow it or get it replaced at home itself. Is there a video on how to disconnect service connector - i dont even know what that is.

i found this video to deactivate - is this what u are referring to? Also how do you put car in Sleep mode?

no this video is for emergency rescue purposes , the orange ( or green in newer EV/hybrid vehicles) HV disconnect connector is near the 12v battery in the i8 but it is very important to wait until the car is in sleep mode before disconnecting it - otherwise it will do damage to the contactors inside the HV battery because of the charged capacitors in the EME unit , these will cause severe arching of the contacts when they are not discharged first like when you shut down your car in the normal way.
so you have to open the hood/bonnet first, wait for sleep mode (wait for 20 min. to be sure) then disconnect the connector and lock it to the safe position by putting a padlock through the hole in the connector. ( a m6 bolt and nut will do fine also) to prevent accidental activation of the HV system.
Now you check if the HV disconnected message is shown on your instrument panel after key-on, when the lightning sign and disconnected message is shown you can turn your car off and disconnect the 12v. battery.
Before reconnecting the 12v battery first remove the padlock or safety bolt and reconnect the safety connector - this way the HV battery will be activated right after connecting the 12v. battery.
When you connect the 12v battery before closing the safety disconnect connector the HV battery will interpret the missing 12v signal as as crash signal - the + connection of the 12v battery has a built-in pyro device which disconnects the 12v battery after a crash signal from the SRS unit which in turn immediately disconnects the contactors in the HV battery ( which damages the contacts due to the improper shutdown procedure so this has to be prevented if possible !)
the hv disconnect connector has 2 seperate connections - 1x 12v to the contactors inside the HV battery and the other 12v line is used for the safety loop through all HV components , when this loop is interrupted anywhere the HV system is shut down immediately , this is what rescue workers use to be able to work safely on a EV/hybrid car....

[sunnygs6]

Thanks for the detail reply - really appreciate it.

[sunnygs6]

So update on where our unsuccessfull effort have led to soo far -

1) WHen i replaced battery and had a technician clear as many error codes as possible - car wont even start.

2) But before replacing old battery - i did try to jump start with high voltage charger plugged in - i was able to get car started.

3) Unable to charge msg still comes though HV battery is showing progress bar and being fully charged.

So i dont understand the connection. But we will try again by chargin HV battery and try to start but it's not looking promising yet. Any suggestions?