Answer:
3. They stop producing because they eventually run out of the anode metal so the reaction can not go on.
4. They reverse the flow of electrons when the voltage is above what it needs to go normally.
Step-by-step explanation:
3. as the reaction occurs the cathode is gaining electrodes as the anode loses them so it gets to a point where the anode and shrunk down so much that it can't give off anymore electrons and that is when the battery stops.
4. lets say you have a cell with a voltage of 1.05 then you would need a voltage higher than that to make it go in reverse and recharge itself.