12V battery and charging problem


I'm getting a "12V battery needs service/replace 12V battery soon" message. I rebooted the dash and restarted the car but still getting it.

This is very strange, I received the car less than two weeks ago, the 12V battery is supposed to work just fine.

Also, I can only charge the car to 385 KM. It stops charging at 385KM and gives me a "charging complete" message. I'm using 110V 12A for charging.

Anyone know what's going on here?



It sounds like you need to replace the 12v battery. Its not the first car with this problem.

1) As MB stated, please call Service Center to take care of the 12V battery service.

2) I assume 385km is "standard" charging right? If you want more, have you "MAX RANGE" charge it (but be warned of premature degradation of battery)?

fairly extensive coverage of this issue on however the "fix" that is posted has not worked for me or others that I have seen. post here if you find a fix - PLEASE?

Yes, I posted on the Tesla club. Waiting for approval.

Thanks for the help people!

This also could be a software bug. Talk to Tesla.

What is the 12v battery for? Similar to an ICE? I just assumed the car battery would solve all electrical needs.

I know the seat heat runs off the 12v and a few other things according tone rep I spoke to yesterday.

I've had mine replaced twice now. I was told there are a few bad batches out there. It takes then about an hour or so to replace it at a service center.

I wonder if this is related to my problem: received the car on 12/23, drove it (a little) for a few days, then plugged it at 110V in in my garage for ten days while we were traveling. When I got back today, it was dead. According the the support person I spoke with, who ran remote diagnostics, the main battery is full of charge, but a few days ago the battery management system stopped being to control the 12V battery and/or the 12V battery died. The car was also apparently upgraded over-the-air from 4.0 to 4.1 over the past few days.

Car is out-of-commission until someone comes to replace or repair the 12V battery and run some diagnostics on the battery management system. :-(

Glad I didn't trade in the eight-year-old Prius when I picked up the Model S.

All the auxiliary stuff, opening doors, etc. Easier than knocking down high DC voltage to standard device levels, which is very wasteful. Main power is just for drivetrain and heating/cooling etc.

FYI - someone in Georgia first had problems with his 12V on Dec 23. Tesla took his car on a flatbed to the Tamp service center (nearest one) to work on it. After replacing his 12V several times they replaced the 85KW pack - apparently there was some problem that involved both batteries. Now it's working but they want to hold onto it for a few days to make sure all is good. Good that they're taking care of it. But sside from the obvious, the bummer hear is they didn't give him any kind of loaner and he's been without his MS for about 2 weeks!

Major Here from Fremont!

I got my car 12/15 and tesla took my car on last week thursday and i had same issue my car won't start and till today they have my car. I just got a call from service today that we are still having problem writing firmware on the car. Engineers are working on it and we will update you today evening. Man i need my car!

How was your car fixed? I've had almost the same situation. My 3week old MS 60 will be towed to Menlo Park service station on Monday.

My Tesla honeymoon is over.

My MS 60kw is 3 weeks old. Ive had no real problems except for a passenger rear door that would not open from the outside when I chose the child lock feature.

Yesterday Friday I received the 4.3 update notice on my screen and opted for a 2 AM update. As soon as I punched it in, I received a yellow warning sign that something was wrong and to bring the vehicle in for service. After a few seconds the screen went dark and the vehicle was not driveable.
I called Tesla and reached the Menlo Park Service Center. I described what happened. Brian told me that I may inadvertently punched in the update now button. I was told to wait two hours.
It's been four hours and the car has not woken up yet. The service center tried coaching me into rebooting by pressing down the two center buttons with no success.

They kept the communication line open and promised to send a Technician Saturday morning.

The technician came promptly at 9am. He immediately hooked up his laptop and diagnosed the problem to be more complicated. He could not wake up the car. He was also concerned that the 12v battery may discharge fully if left in its present condition in my garage.

He promised to call his supervisor to arrange for the car to be brought to a service station. An hour later his supervisor called to arrange a truck to load the car on Monday morning. They asked and I declined a loaner car.
Meanwhile the car is not driveable. The door opens and lights go on.

Still the 4.3 glitch? Seems like all the recent troubles coincide with it.

Seems there were some substandard parts shipped and installed in the DC-DC converter.

I had that problem the first week I had the car. It's fine now.

My 12 V light came on several days ago and I have been driving while trying to dicern what I felt must be a mnor problem. I could not find any information in the manual or Tesla's web site. I finally found this site to learn I am not alone and it's a more serious than I thought. I think Tesla has been coy about this problem. If only they had trouble shooting information we as customers could use our time more productively and interestingly.

@kermitjohnson Tesla has a remarkable troubleshooting protocol in place which is activated when you call ServiceHelp or what used to be called Ownership. It's the first thing you do when you get a warning message. They will analyze the problem and inform you of your next best step.

Call Technical support and they will look at your logs and tell you what you need to do. Very straightforward

@hamer Great idea!

@J.T. Could be the answer to half the questions asked. Or more.

Yes, I know, that's why I said the post just before yours. :-)

Sad it

Sod it?

Sud it

My 2 weeks old Model S 85+ died while I parked next to my storage unit and went to pick up few things. When I returned, door handles were in open position, but doors were locked and car did not respond to its keys or mobile app. I was very happy that baby seat in the car was empty when this happened as I understood from Tesla's technical support that there is not much I could do beyond arranging vehicle transportation to Sweden (closest service centre to me) or they can arrange it themselves (costs €2600+tax to be covered by myself). Tesla's staff was very friendly, but in addition to costly transportation issue, there is a queue and I have to wait about a week before my car can be serviced.

After some googleing, it became quite obvious that car has some kind of 12V battery or DC/DC converter issues. I bought jump starter kit and by removing front panel, got the car main systems working. No error messages. Car is driving without any problems...until I leave the car. Then it has to be jump started again. I do not know what data Tesla has collected about my car problems, but I wish they share it and figure out how simple 12v battery or converter replacements could take place outside Tesla's own service network.

VIN 51862

I just got a 12v battery warning, need to replace 12v battery soon! . I phoned service center and they told me I could keep driving the car. I already had a service apt for other issues scheduled for next week but this will be my 3rd 12v battery in ~20 months.

Perhaps the problem here is the 12 volt battery does not receive any recharging power from the 400 volt main battery when the car is "shut off" by placing it in the park position. Thus, if you turn the climate control, seat heater, headlights and other such accessories while the car is in park, you will be drawing all power from the 12 volt battery and no charging from the 400 volt battery will occur. I have noticed that when sitting in the car with the climate control (AC on)and radio activated on a warm night in the garage with the main charging UMC cable plugged in, but not in the charging mode, the amperage meter showed I was drawing like 12 amps at 240 volts.

I am suggesting that if you leave the car accessories running (off shore power) while the car is in the parked position, you will be draining the 12 volt battery fast. Maybe, if you left the car in the "neutral" position (with the wheels against a curb or block of wood behind the wheel) you would be able to energize the charging system between the 400 volt to the 12 volt batteries and thus avoid discharging the 12 volt and disabling the car.

When Bjorn is running the heater for comfort sleeping in the Model S overnight in Norway, are the accessories getting power from the 400V/thru the 12V?


My Model S was 7 months old when the check 12V indicator came on. Took a couple weeks to get it serviced, but they said you have 2-3 weeks from the warning to get it sorted out as its just indicating a low voltage level. I've heard of several others with short ownership durations needing new 12V batteries. At least they're covered under warranty.