Hi 944,
I recommend that you restore your Tamiya tiger as close to original as possible. Some of these tanks are worth a bunch of money to model collectors, and just the original box that it came in is worth money. Consider getting a cheap battery pack and charger for testing the Tiger out, and if all is OK, try to get a Tamiya batt/charger so as to stay as original as possible. Search the net for a Tamiya owners manual and instructions. These models are only going up in value as time goes by.