# Do you REALLY want to place a charger on your 12v battery?



## RMann (Jul 8, 2018)

Interesting discussion (warning) came up regarding charging your 12V battery in the car if the battery is weak or failing. Given that the Tesla normally charges the 12v battery periodically when awake, what happens when you have a charger attached, the 12V is proceeding to charge up, then suddenly the car comes back alive and attempts to simultaneously charge it? Thoughts on the outcome?


----------



## JasonF (Oct 26, 2018)

RMann said:


> Interesting discussion (warning) came up regarding charging your 12V battery in the car if the battery is weak or failing. Given that the Tesla normally charges the 12v battery periodically when awake, what happens when you have a charger attached, the 12V is proceeding to charge up, then suddenly the car comes back alive and attempts to simultaneously charge it? Thoughts on the outcome?


I don't think the car would attempt to charge it in that case, because it would detect that the 12V bus voltage is high. If it didn't have that safety built in, the 12V battery would explode in a very short time.


----------



## webe3owners (Nov 18, 2018)

Even in the unlikely case of it happening nothing bad would happen. Back biasing at that level wouldn’t hurt anything.


----------



## JWardell (May 9, 2016)

It's not going to hurt anything per se, both will be targeting ~14.5V. But regularly using the charger will probably start causing errors as the car tracks all energy in and out of the 12v battery and this will throw it off. More for emergency use when you are already having 12v battery errors and issues.


----------

