Thanks Jack - Yes, everything he said. And you dont have to hardmod - if you screw it up, you'll hose the battery, this alternative is much safer, several of us here at pspmod can vouche for it and love it.
But it will cost you 20 bux plus shipping.
Battery Tool & Demo
PSP Battery Service Tool - Codejunkies US YouTube - Datel Battery Service Tool - PSP (Pandora)