Natedogg tried to charge a 510 battery with a Blu PPC and it killed the battery. I would imagine it has something to do with the little chip in the battery that is incompatible.
I believe + and - are reversed for the 510 and blu batteries and chargers, but I haven't tested it myself. If that's true, though, a mod should be possible, at least electrically-- the size is a whole other matter, because the 510 batteries are a lot larger.