Have A 55 T bird with 6 volt system. Always used a 6 volt battery but don’t drive it much and battery goes dead. Used the battery charger and kept a automatic battery charger on it but lately battery is dead and can’t revive battery. 6 volt batteries hard to find and Don’t know the price of them now. What happens if you put a 12 V battery in a 6 V system. Will it damage the system after using it for a while. I don’t want to convert it to a 12 V system.