Power tool battery interchangeability

[Eugene]

Anyone mess with power tool batteries a lot? I have some black and decker 18v tools that are yard tools, weed whacker, blower, etc and the charger is a simple trickle charger and after a year now the batteries are not holding very long. Also have a new Porter Cable set which is basically a rebadged Black and Decker but has a charged that shuts off when charged. I'd like to be able to use the PC charger but the batteries have tabs preventing swapping, I'm wondering if anyone else is familiar with either and knows if its safe to file off the plastic tabs to the B&D batteries will work in the PC charger.