2014 S - 1 year old 12v battery dead - Possible causes?

[kirkhilles]

Model S, December 2014 Build, 135k miles, API1.

My son was driving my Tesla yesterday and got the voltage too low errors and basically the 12 volt battery was completely drained. Got it jumped and towed home and I charged the 12 volt battery overnight . It seemed to be taking the charge and by morning my charger showed it was complete. I come back a couple of hours later and still the same errors and it looks like the 12v is low on power again. Not completely, but on the charger (12v) again and seems to be charging.

My nearest SC is about 2 hrs away and I'd really rather not have to tow it there and deal with all of that until I absolutely have to.

My 12 volt battery 1 year old (replaced by Tesla). Any chance that could be it? Doesn't seem likely to me. Should I check fuses related to the DC-DC charging? Are there other tests I can do or have mobile service do?

 

[Tam]

Model S, December 2014 Build, 135k miles, API1.

My son was driving my Tesla yesterday and got the voltage too low errors and basically the 12 volt battery was completely drained. Got it jumped and towed home and I charged the 12 volt battery overnight . It seemed to be taking the charge and by morning my charger showed it was complete. I come back a couple of hours later and still the same errors and it looks like the 12v is low on power again. Not completely, but on the charger (12v) again and seems to be charging.

My nearest SC is about 2 hrs away and I'd really rather not have to tow it there and deal with all of that until I absolutely have to.

My 12 volt battery 1 year old (replaced by Tesla). Any chance that could be it? Doesn't seem likely to me. Should I check fuses related to the DC-DC charging? Are there other tests I can do or have mobile service do?

It's a process of elimination. Replace the 12V first. If that doesn't do, then Service Center.

 

[maximizese]

I had a similar issue as well on our 11/13 built S85. I've had a 12V battery last 4 years/60K miles, had it replaced preemptively by Tesla when they replaced my drive unit and HV battery contactors, and then the new battery started throwing the low 12V battery warning message less than 14 months and 20K miles. I measured the voltage from the jumper posts behind the nosecone and it never read below 12.8V and I kept driving it for about a year. I had a mobile tech replace the battery right before I left for a road-trip but I was never clear on what the actual issue was.

It's been discussed that Tesla's 12V systems had a tendency to overcharge the 12V battery thereby shortening its lifecycle. There have been others who have proposed that the 12V battery supplier does not make quality products, and others have had failing charging components. I would contact your local Tesla Service Center to see if there is any warranty or goodwill they could lend you since the battery alert triggered in just a year. Then I would ask if a mobile tech could diagnose the 12V and charging system.