is there a way to recharge old power tool batteries after they won't seem to take a charge?
Answers:
nickel based batteries do crystalize over time. one way to break up this crystalization is to run it using 0.5 volts or less over a period of time. A small LED or reistor could be your load. After the battery is run "dry" let it sit for a couple of days and do it again. You might have to do this a couple of times. Then charge it, let it sit a day then charge it again. To prevent batteries from premature failure, don't let them sit in the charger and use them periodically.
Other answers:
Buy a new battery
Buy a new battery
Run them completely dead then try to charge them. If they won't charge then it is time for the trash can.
no
Nope, just replace the battery.