It sometimes won't charge as the current supplied is too low (0.5A at most). Switching off the LCD screen would ensure that the power level does go up instead of going down.
Originally Posted by kite
And if the battery is already flat, you can't even try charging it through the USB port.
If you can find another port from another device that fits in the PSP (And it's AC adaptor) and are rather proficient at soldering, you can replace it.
I've never had a PSP before, but my friend has one he'll sell to me for twenty bucks, which is a great deal, but it has a broken AC port on it, so it can't charge. I don't know how I'd be able to fix something like that, so I'm not thinking I should get it, right? Or is a busted AC port fixable, or there's another way to charge it?
Otherwise your only other option is to get another port and plug it in (The port has got a plug on the other end).
Unmodified SCPH-77006 with SM 3.6
SCPH-39006 with M-chip modchip, SCPH-10281 NA and refurb Seagate 80GB HDD
SCPH-10000 v1.00 with SCPH-10190 PCMCIA NA and SCPH-20400 HDD unit