First an issue with the 12V battery. Got it fixed, then two days later a problem with the HV battery? Service request opened, but has anyone ever seen this?
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BMS_a079 - Unable to charge - Maximum charge level reached
- Thread starter TBrownTX
- Start date
See that search bar in the upper right.... Try typing BMS_a079 into it and pressing Enter.
TLDS: You almost definitely will be getting a replacement HV battery. I sure hope the car is still in warranty.
TLDS: You almost definitely will be getting a replacement HV battery. I sure hope the car is still in warranty.
Did that, several threads but many left without the outcome, or related to older cars. I have a ‘21 M3P with 13K miles.
Very first result:
2021 MYP error BMS_a079 2021 model Y with 19k miles "I took it to the SC and was told they have to replace my main battery unit. "
Thank you for that. Any chance you can teach me how to use generative AI while you are at it?
Soul Surfer
Cancervivor, tech geek & musician
From what I have read in the past about replacement HV batteries, is that they are often “refurbished” and have less full charge in them. Just sayin’.
Teslas battery warranty specifically calls out that they may use refurbished batteries, and their obligation is to provide a battery with the same charge level as before the failure (not new capacity).
OP, Perhaps the HV battery issue caused your LV battery issue? I dont know that, just speculating. In any case, please let us know what the SC ends up saying. The only feedback I have seen here on that error is "new battery" but more data is always better for something like this.
I was thinking the same thing about the LV battery failure, and I will for sure provide as much information as I can once the SC gets a look and diagnoses.
Earliest appointment I could get is two weeks out, so just hoping the respond via the app before then. So far, crickets.
Im not sure how far you are from your local SC, but I think this is one of those errors where, after you make an appointment, you could drive down there to the SC (like today) and say something like:
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"I am really sorry to drive down here, but the earliest appointment is in 2 weeks and I have this error that I cant charge the car. I need a car to <get to work> / <Take kids to school / Practice> / <Take family member to doctors appointments / <insert critical transportation need>". Can you get me in sooner, and could I have a loaner vehicle?
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Thank you for the suggestion. If I don’t hear from them by tomorrow, I’ll do just that when I return from my trip.
Did have someone with the same errors post this on another forum, so it’s not always 100% pack replacement guaranteed.
The Tesla battery warranty states you'll receive a battery with "equal or greater capacity" even if refurbished. I'm not worried about it, so long as that's the case.
Update... dropped the car of Monday 11/6 and was given a M3LR loaner. Test drove a Model S while I waited for the loaner (more on that later).
During drop off the Service Center fellow told me a battery had already been "allocated" and was on its way to the service center via freight.
On Tuesday (appointment day) they drained the battery and did a "shipping screen retrieval" whatever that is. Technician notes only say "Diagnosed".
Car sat in the back lot all day yesterday with the battery hovering around 20% which I assume is the discharge level they like ahead of replacement.
During drop off the Service Center fellow told me a battery had already been "allocated" and was on its way to the service center via freight.
On Tuesday (appointment day) they drained the battery and did a "shipping screen retrieval" whatever that is. Technician notes only say "Diagnosed".
Car sat in the back lot all day yesterday with the battery hovering around 20% which I assume is the discharge level they like ahead of replacement.
Picked up my car yesterday. Final invoice shows HV battery replaced with this part number: HV BATTERY,E3,AWD,1-PHASE (1234422-10-A).
Charged up to 80% and checked the range. The new pack has yielded around 15 miles of additional capacity at 80%.
Looked the car over carefully and there's no signs of any work having been done, glad there was no damage with the interior removal, etc.
One change is the car charged several times overnight (just 1-2kW) whilst sitting I'm my garage.
I must imagine the BMS is calibrating, will see if it settles down over the next couple of weeks as it relearns my patterns.
Only gripe was the car was returned with 25% charge, which was enough to get me home, but I opted to hit up a supercharger along the way.
Charged up to 80% and checked the range. The new pack has yielded around 15 miles of additional capacity at 80%.
Looked the car over carefully and there's no signs of any work having been done, glad there was no damage with the interior removal, etc.
One change is the car charged several times overnight (just 1-2kW) whilst sitting I'm my garage.
I must imagine the BMS is calibrating, will see if it settles down over the next couple of weeks as it relearns my patterns.
Only gripe was the car was returned with 25% charge, which was enough to get me home, but I opted to hit up a supercharger along the way.
Well maybe all is not well after all. Car is home and I've noticed my charger has been running every few hours to top off the car. I noticed this behavior started on October 28th after a LV battery replacement, but before the HV battery was replaced. This AM I have a PCS_a022 error - unable to charge, service is required. Le Sigh.
Let us know how it goes (posting to let you know that someone is following along and still interested in the outcome).
Thanks! Here’s the Service code behind the alert - PCS_a022_bmsMia: “Charger does not receive all expected CAN messages from battery management system”
I’d assume all that was just replaced along with the HV battery, assuming the BMS is in the tent, but maybe not. Could be a simple timeout with a busy BMS?
Does anyone know if the BMS board would have been replaced with the pack?
Can’t seem to figure out where in the Model 3 it lives based on searches.
Can’t seem to figure out where in the Model 3 it lives based on searches.
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