Question: how many joules of energy in car battery?
Answer: In summary, the energy (measured in "Joules") stored in a 36 V, 15 Ah (15,000 mAh) battery is 36x15= 540 "Volt-Amp-hours" or Watt - hours. Where a Volt-Amp-hour (Wh) is 3600 Joules (J). So our battery has stored 1,944,000 Joules of energy!