Re: cordless tools/rechargeable batteries
Cost and time versus the cost of buying a replacement is a personal decision specific to the value and expected use for the tool. As far a rigging with off the shelf rechargeables, I dont know. Never tried it. I did convert a 12-v makita drill to work on a cord for use aboard my power boat --mostly as a polisher, since I'm at a dock without power. But that was worth the time and effort for me versus hand-waxing.
There are two kinds of boaters: those who have run aground, and those who lie about it.