Tesla 12V Battery Health Check

Описание: All Teslas have a lead-acid 12V battery, which is used to start up the vehicle electronics. The vehicle will not function without a working 12V battery, and these batteries have a finite lifetime. Nominally, the vehicle will show a warning message that the 12V battery is dying and needs replacement, but there have been cases where no warning appeared, and the vehicle subsequently became immobile.


This video shows how to assess the health of the 12V battery by measuring its voltage level. This was a bit of a voyage of discovery for me, as I have measured my 12V battery voltage recently after the vehicle sat idle for a week, and I expected to find the same reading at the start of this video. I was wrong, and I learned something about how the vehicle manages the battery to keep it charged.

I’d recommend other Tesla owners do the following to check your 12V battery:

1. Run your vehicle drive battery down to below 50%
2. Measure the battery voltage as shown.
3. Let the vehicle sit overnight and re-measure the battery voltage without recharging the vehicle.
4. If the battery voltage remains at or above 12.6V, it’s OK
5. If the battery voltage falls below 12.4V, especially after sitting overnight, consider replacing the 12V battery.

This is not a comprehensive test of 12V battery health. The battery should be tested under some load condition to get the best sense of its health. However, given that the 12V battery is relatively inaccessible, this is a good alternative for assessing the battery’s condition.

I will point out that I charge my vehicle every night to 80% for routine use. This apparently means that the vehicle is actively maintaining the 12V battery most of every day.