@BvU @Rive sorry I'm relatively new to this topic, but why would Battery B not be depleted if they have the same charge capacity of 3Ah. Doesn't battery store energy by storing charge in electrodes. If they are both rated as 3Ah, don't they have the same total charge capacity and when charging...
Let's say both battery have the same charge capacity of 3Ah
Battery A has voltage of 3V and B has voltage of 6V. Battery A is completely discharged while B is completely charged.
If I charge battery A with battery B, wouldn't B be completely drained because they hold the same amount of charge...