Searches for POWER PRO typically result in body building supplements and a mains operated VAX carpet cleaner.
You may have the name wrong - perhaps it's Performance Power - a B&Q brand.
Solent Tools 023 8057 8057 sell B&Q spares
As for overloading the charger - probably not - to overload a charger you will need to draw too much current by - for instance - trying to charge two batteries in parallel at the same time - which I doubt.
Good Luck..., August 2016
