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Tam
Well-Known Member
Good question! It is silent on that subject.
Majority of owners do not have 12V battery problem but there are quite a few of the rest of the population do.
Thus, it might be too costly for Tesla just to uniformly and preemptively change it every 12,500 miles so you might just have wait for the error message to tell you that it's time to change it!
I'm sure the Freemont Engineers are researching failure rates of 12v batteries and trying to figure out the root cause. They'll be more qualified than you or me. Once they figure it out, I'm sure they'll either design a more robust solution or provide guidance to customers. My bet is on the former since Tesla tries to keep things simple for the customer.
FlyingCookie
Member
Near annual replacements of the 12V battery are not unusual.
If you leave your car parked a lot, this can become even more frequent. When the car is sitting it cycles the 12V battery from fully charged to 80% discharged about once every 3 hours. This can be reduced with the power saving features, but even then you're still in the five hour neighborhood for a cycle of the 12V battery, until the car enters deep sleep. I think this usually happens after 48-72 hours, but i'm not sure on that.
When driving, the car charges the battery and then runs all the 12V electronics off the DC-DC converter. When parked, the car discharges the 12V battery (computers still awake, etc) and then has to power up the DC-DC converter to charge the battery. The High voltage rail can't be left online all the time due to safety issues, so this is the only solution.
I did read somewhere that a 12V DC-DC converter now exists within the traction-battery itself, which is there to prevent a car from being stuck due to a dead 12V battery, but I'm not sure this has the ability to charge the battery, or that it's left on all the time. (Or that i entirely understood it correctly)
If you leave your car parked a lot, this can become even more frequent. When the car is sitting it cycles the 12V battery from fully charged to 80% discharged about once every 3 hours. This can be reduced with the power saving features, but even then you're still in the five hour neighborhood for a cycle of the 12V battery, until the car enters deep sleep. I think this usually happens after 48-72 hours, but i'm not sure on that.
When driving, the car charges the battery and then runs all the 12V electronics off the DC-DC converter. When parked, the car discharges the 12V battery (computers still awake, etc) and then has to power up the DC-DC converter to charge the battery. The High voltage rail can't be left online all the time due to safety issues, so this is the only solution.
I did read somewhere that a 12V DC-DC converter now exists within the traction-battery itself, which is there to prevent a car from being stuck due to a dead 12V battery, but I'm not sure this has the ability to charge the battery, or that it's left on all the time. (Or that i entirely understood it correctly)
According to WK057, model S has had a small dc - dc board in the main battery since the 2016 refresh.he posted a picture of it. It probably takes care of the very small drains and keeps the 12 volt from cycling as much. A friend of mine had the 12 volt in his Prius go flat, even though it has an ice to charge it and is much larger. He found out about vampire drain the hard way.
Xenoilphobe
Well-Known Member
You may be cranking the starter too long
They will send the Quick Reaction Ranger Team. I guess I was fortunate I have owned 3 Model S's and none have ever done this. I did get this Lithium battery recently when it did throw a code after 3.5 years of use.
EV-lutioin
Active Member
You may be cranking the starter too long
Jeez, you would think Tesla would use a lithium 12V battery to start with! Saves weight too.
JimVandegriff
Member
We just had the 12 volt battery warning show up today at 20 months and 26,000 miles. We had its maintenance done at 25,000 miles but I guess they didn't catch any warnings. A Tesla ranger is scheduled to come up here to replace it next week under warranty. We are about 300 miles from a service center.
First-rate battery geekery in this blog post
Syonyk's Project Blog: Tesla Model S 12V Battery Analysis
That was a good read. Thanks.
I did notice a strange smell in my garage early in the morning around the time my battery failed. In fact, I called the gas company out to check for gas leaks, which had dissipated by the time the gas tech arrived. Now I know it was probably due to outgassing from the lead battery. New battery - no gas smell since.
I did notice a strange smell in my garage early in the morning around the time my battery failed. In fact, I called the gas company out to check for gas leaks, which had dissipated by the time the gas tech arrived. Now I know it was probably due to outgassing from the lead battery. New battery - no gas smell since.
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