What is the Wh of a "12V" 1000 AH car battery with internal resistance of 20 milli-ohm? Try that for starter engines that draw 50A, 100A or 200A One may think

What is the Wh of a "12V" 1000 AH car battery with internal resistance of 20 milli-ohm? Try that for starter engines that draw 50A, 100A or 200A One may think that at 100A, the starter engine will be able to consume 1200W However, if you pull 100A, the internal voltage used to overcome the internal resistance is 2V, so you really only generate 1000W, or 5/6 of the raw energy stored in the battery. At 50A, the voltage loss is only 1V, so the start engine gets 550W, or 11/12 of the energy tapped from the battery. Finally, at 200A, the voltage loss is 4V, meaning that the starter engine only gets 1600W, or 2/3 of the energy stored in the battery. And this is under relatively good conditions. If the battery is freezing cold, the internal resistance can become much higher. In all cases, the internal resistance leads to heat inside the battery. Hopefully, it should be clear that for low resistance / high wattage loads, the Wh metric is not very accurate.