VCFRONT_a180 Electrical System Power Reduced

[Flybyglass]

Noticed after an overnight charge (to 100% for a long drive the next day) that the charging had been interrupted a couple of times for some reason. Looking at the notifications screen for any clues and found the above message twice. The sub warning is "Vehicle may shut down unexpectedly". But I wasn't driving and it was asleep in the garage connected to the charger. The Manual basically states "the electrical system cannot maintain voltage to support all features". It recommends reducing use of non-essential features to prevent vehicle shutdown. Except I wasn't driving. The manual states "If this alert remains active, schedule service immediately". I have a message in to service and an appointment but the message is no longer currently active. Any ideas what is taking place? There was no 12 volt battery warning and I'm not sure this is related to a failing 12 volt battery anyway. Software 2021.4.21.3.

 

[cybergates]

Noticed after an overnight charge (to 100% for a long drive the next day) that the charging had been interrupted a couple of times for some reason. Looking at the notifications screen for any clues and found the above message twice. The sub warning is "Vehicle may shut down unexpectedly". But I wasn't driving and it was asleep in the garage connected to the charger. The Manual basically states "the electrical system cannot maintain voltage to support all features". It recommends reducing use of non-essential features to prevent vehicle shutdown. Except I wasn't driving. The manual states "If this alert remains active, schedule service immediately". I have a message in to service and an appointment but the message is no longer currently active. Any ideas what is taking place? There was no 12 volt battery warning and I'm not sure this is related to a failing 12 volt battery anyway. Software 2021.4.21.3.

did you get a resolution for this? I think mine is a 12 v battery issue as I have 12v battery must be replaced and a dozen of other error messages including the one you posted. 2019 LR AWD M3

 

[Flybyglass]

I never got the 12 volt battery replacement message but I swapped out to an AGM no messages after multiple charges up to including 100%. Swapped out and put the Ohmmu back in also no messages. Only one time DURING the disconnect of the AGM which I would expect but never returned. Also, these messages started occurring after 2021.4.18.2 and while the AGM was in I updated to 2021.12.25.7. I am guessing wither a terminal was lose on the battery (which I did not notice during removal) or possible the Ohmmu built in BMC was doing cell balancing once the car was fully charged and the Tesla may have interpreted the Ohmmu cell balancing as a voltage drop and put out the message. This is just a guess air this point but since nothing has returned I'm sticking with the Ohmmu.

 

[miketerrill]

I have seen this recently as well on 2021.4.21 and now 2021.24.3 on my 2019 M3P. It only happens in early morning hours and has never happened while driving the car. I would have totally missed it, but I try to check the notifications since these kind of notifications do not show up in the app. I booked a service appointment (but earliest was Sep 21), but once they ran diagnostics they wanted me to take it in as soon as possible. They also said the repair could take awhile and that they do not have loaner cars (but uber vouchers instead). After seeing this post, I am wondering if this is an actual issue or a false positive. I told them I would take it over immediately if it happens while driving. I am wondering if 2021.24.3 (or later) will correct the issue.

 

[Flybyglass]

I have seen this recently as well on 2021.4.21 and now 2021.24.3 on my 2019 M3P. It only happens in early morning hours and has never happened while driving the car. I would have totally missed it, but I try to check the notifications since these kind of notifications do not show up in the app. I booked a service appointment (but earliest was Sep 21), but once they ran diagnostics they wanted me to take it in as soon as possible. They also said the repair could take awhile and that they do not have loaner cars (but uber vouchers instead). After seeing this post, I am wondering if this is an actual issue or a false positive. I told them I would take it over immediately if it happens while driving. I am wondering if 2021.24.3 (or later) will correct the issue.

Currently I have 2021.12.25.7 and the message has not returned. I check every time I drive and no history. Do you have an Ohmmu battery or factory AGM? I asked Sean at Ohmmu and he states the Ohmmu batteries BMC balances the Lithium cells at the end of charging. So one of the possibilities is a slight battery line voltage drop during balance was picked up by the Tesla's BMC as a low battery. The 12 volt replace message never has appeared. If the message returns, I will reinstall the AGM prior to service as in another post that was the first thing done by SC but it had no affect on the message of that individual. Ultimately, several components were replaced own that case. Sean did state if this issue persists and it is traced to Ohmmu, he could reprogram the Ohmmu BMC to balance prior to full charge and Tesla BMC would never then detect a drop. But so far that step has not been needed nor has it been reported to Ohmmu by anyone else. As you noted, unless looking for the message one would not see it as it happens while car asleep and charging. Like yours, mine also occurred in the early hours.

 

[miketerrill]

Yes - I did have the Ohmmu in at the time of these alerts. I had passed that other thread (I think you are referring to) and this one to Sean. I put the OEM back in and haven't had an alert for this since.

 

[cybergates]

UPDATE: it was just a 12v battery issue - replaced under warranty by tesla no charge - fixed in 10 minutes - just wish it could have been sooner by mobile rather than 5 days downtime