My Model 3 LR 12V is about 2.5 years old, and I know from monitoring the voltage that less than a day passes when the car is sitting at home before the battery drops to ~ 12.6v, which leads to a charging session. I suspect that my relatively high vampire drain is related to these 12v battery charging sessions.
I don't feel like swapping out the 12v battery blindly so I've been thinking about a way to check its capacity. The method follows. I have not tried it yet, so this thread is meant to elicit comment and advice.
Tools
Scan my Tesla (SMT) App. It reports current flow into or out of the 12v
Battery Monitor. 12v voltage monitor, logged every 2 minutes
Method
Catch the 12v when it approaches 12.6v
Use SMT to log current during the charging session
Read Battery Monitor to know how long it took to reach 13.1volts
Calculate Wh added to go from 12.6 to 13.1v, which I presume is ~ 50% of total capacity
I'm OK with +/- 5% inaccuracy. Will it work ?
I don't feel like swapping out the 12v battery blindly so I've been thinking about a way to check its capacity. The method follows. I have not tried it yet, so this thread is meant to elicit comment and advice.
Tools
Scan my Tesla (SMT) App. It reports current flow into or out of the 12v
Battery Monitor. 12v voltage monitor, logged every 2 minutes
Method
Catch the 12v when it approaches 12.6v
Use SMT to log current during the charging session
Read Battery Monitor to know how long it took to reach 13.1volts
Calculate Wh added to go from 12.6 to 13.1v, which I presume is ~ 50% of total capacity
I'm OK with +/- 5% inaccuracy. Will it work ?