these 5 questions in a very short but detailed manner :) 1. I wonder if batteries are not perfectly ideal. I assume some potential energy could be loss to heat, and hence the battery would not have a perfectly constant potential difference, but I am unsure. Does anyone know if this might be the case? 2. So a battery over time does loose its power, but is not the reason it stops working as efficient. The reason they stop distributing less power is because over time the internal resistors become stronger and don't let the current flow as it should. Is this why there is some corrosive material coming out of old batteries? 3. Now that they're mentioning a car battery following the important point they make here, I am curious about one example I thought of. Do they test car batteries by measuring the resistance in the battery? If so, with a high resistance batteries would be less efficient and with low readings the battery's would be newer and more efficient. 4. Why is the electric field doing work if the potential difference is Vab=Va-Vb, thus the charge should be going from high to low potential? Would this still be considered work? 5. So how is work being done if the charge goes from high to low potential