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12-volt Battery Capacity

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ATPMSD

Active Member
Mar 12, 2021
3,211
3,333
Atlanta, GA
One of the things I love about my Tesla is learning new things, and so a question for you 12-battery gurus!

  1. My car has a 12V 30A (20HR) battery. I think this means the battery capacity is 600 amps (30 * 20), which can also be stated as 7,200 watts (600 * 12). Is this correct?
  2. Assuming the above is correct, if my car draws 1 kWh / day when sleeping, and the BMS tops off the battery when it reaches 50% capacity, this means the car will charge the 12-volt battery roughly once every 3.5 days.
  3. And if the above still holds, if I arrive at a location with a fully charged 12-volt battery and stay for just two days, the HV battery will remain at the same SOC as when I arrived (except perhaps a minor drain due to natural discharge.)
Thanks!