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Yes. The 12v is used for all the safety systems and allows the car to disconnect the HV pack if it detects problems. Without the 12v there would be nothing to activate the air bags, help with the power brakes, etc.I never understand why Tesla couldn't engineer the big 75 kwh to charge up the 12v battery when low voltage is detected. Or just drop the 12v battery altogether, and only use the 75 kwh battery. Is it really that hard?
No, no vents to open. There is a vent tube though.
yeah, the good ol' days, when every gas station had a pitcher/spout of water for you to top off your battery water level -- supposedly distilled water, but prolly tap for many stationed that skimped...In the old days, all lead acid batteries had vents and we’re supposed to check the water. Then they made the water capacity a bit larger and covered the vents with a sticker. Instant maintenance free battery.
1. What normally charges this battery?
(They main battery pack apparently can not so I have to assume it only charges when car is plugged in.)
2. I assume this is a sealed lead acid battery the does not require maintenance?
3. How long is the OEM battery expected to last?
(I have read that some have failed within the first 2 years.)
4. Does switching battery to an OHMMU lithium void any type of warranty?
5. Why did a software change create issues with the OHMMU battery and what would prevent that from happening again?
6. What is the best way to monitor the health of your 12v?
We had no warning, just a stranded wife.Just one more, did you get any kind of early warning when the 12v is going bad or does it just die on you?
well, compared with ICE, the difference is that one rarely gets stranded... in 40yrs I've never been really stranded. At most, I get a jump within 15mins or so, often faster if a friend is around. I then drive home or whatever. ICE batteries rarely are truly dead, dead and invariably I can limp along for another week or two, sometimes bringing along a jump battery just in case, so I can replace the battery at my convenience. I have never not been able to drive the ICE cars because of a dead battery.We had no warning, just a stranded wife.
... the car was ready by noon the next day.
Of course it sucked being stranded, late to picking up kid at after school activity, finding a ride home that night and a ride to Tesla the next day.
This kind of thing happens to all my cars. I typically just get a lift to the nearest auto parts place, replace it, and move on.
well, compared with ICE, the difference is that one rarely gets stranded... in 40yrs I've never been really stranded. At most, I get a jump within 15mins or so, often faster if a friend is around. I then drive home or whatever. ICE batteries rarely are truly dead, dead and invariably I can limp along for another week or two, sometimes bringing along a jump battery just in case, so I can replace the battery at my convenience. I have never not been able to drive the ICE cars because of a dead battery.
It would be good for Tesla to figure out how to minimize stranding its customers, keeping the car driveable in the face of a "dead" 12V battery.
So they gave you credit based on the battery warranty even though you had it changed out before any problem?Well I just now went and pulled the paperwork from the glove box and you are correct the 12V battery replacement was not $199, it was $124! Maybe I was given some credit for the battery still being under warranty? Anyway I would have been happy to pay $199 just for the peace of mind of not being stuck somewhere. I'll replace it again when it gets closer to two years on the new battery.
Oh my god, there's so much misinformation about the 12v in Tesla, I'm almost legitimately crying while I read this thread, thinking people are going about their lives thinking these things about the car... not your post in particular - just quoting it as it's asking all the right questions - but just... so many things. 14 pages, and so much has gone on (I wish we could use emoji here)Reading thru the thread just had some questions about the 12V battery.
1. What normally charges this battery?
(They main battery pack apparently can not so I have to assume it only charges when car is plugged in.)
2. I assume this is a sealed lead acid battery the does not require maintenance?
3. How long is the OEM battery expected to last?
(I have read that some have failed within the first 2 years.)
4. Does switching battery to an OHMMU lithium void any type of warranty?
5. Why did a software change create issues with the OHMMU battery and what would prevent that from happening again?
6. What is the best way to monitor the health of your 12v?
Teslas put more cycles on the 12V than any other car. The power used while “sleeping” is significant. It is true that if you were to drive the car 24/7 the battery would probably last a decade.But honestly, I'd expect them to last forever with how they're treated. I suspect that failure cases are caused by firmware bugs, e.g. a system failing to go to sleep and bleeding the battery dry, not due to routine use cases. As explained with #1, normal operation of the car doesn't touch the 12v battery at all.
well, compared with ICE, the difference is that one rarely gets stranded... in 40yrs I've never been really stranded. At most, I get a jump within 15mins or so, often faster if a friend is around. I then drive home or whatever. ICE batteries rarely are truly dead, dead and invariably I can limp along for another week or two, sometimes bringing along a jump battery just in case, so I can replace the battery at my convenience. I have never not been able to drive the ICE cars because of a dead battery.
It would be good for Tesla to figure out how to minimize stranding its customers, keeping the car driveable in the face of a "dead" 12V battery.
No idea if I was given credit or not. All I know is what I paid after examining the paperwork that I keep in my glove compartment. I can't speak for others on this thread but I have also replaced the 12V battery in all of my ice cars, usually after about 2 & 1/2 years.So they gave you credit based on the battery warranty even though you had it changed out before any problem?
The difference is AAA won't replace them and while auto parts stores do sell batteries that fit (Group 51R) if you call and ask for a Tesla battery they'll say they don't sell them. I agree that someone reading through this 14 page thread should have no problem finding all the information needed to change their battery.Hate to repeat myself, but after jumping back into this thread it seems worth it. There is no reason a dead 12V should strand a Tesla owner either. It’s really no different than an ICE. When mine died (after 80k miles) I jumped in my wife’s Volvo and headed to O’Reilly. After educating the kid who worked there (had never heard of Tesla) I bought the battery needed and returned home. Installed new battery and BAZINGA, not stranded. Entire process took maybe 90 minutes soup to nuts. This is really a non-issue unless you are unwilling or unable to perform a simple maintenance item on the vehicle. Some people are and that’s fine, to each his own. But those people probably wouldn’t change the 12V on an ICE either so again, no difference.
The difference is AAA won't replace them and while auto parts stores do sell batteries that fit (Group 51R) if you call and ask for a Tesla battery they'll say they don't sell them. I agree that someone reading through this 14 page thread should have no problem finding all the information needed to change their battery.
I am waiting for my purchase to arrive of a 12v battery tester, I think this one
I'd like to hear your opinion
What is the best way to monitor the health of your 12v?
We had no warning, just a stranded wife.
Thus, for the overwhelming majority of the car's active existence, it's running on the HV battery, not the 12v battery. The 12v battery is just standing-by
I am honestly dumbfounded by how 12v batteries in Teslas fail, because of how lightly they're used.
when does the car charge the 12v battery?
Any time it's not fully sleeping,
You put a tester on it and you'll be testing the car... not the battery. So it has to be tested while disconnected from the car completely. Not terribly easy to pull off...