What used PSP model should I get that can still be softmodded?

[bonemanager]

Why doesn't my PSP seem to charge, or seems to charge erratically? For some reason the VSH by default disables charging when USB is connected. I enabled it.

When I first got it I could see that it was charging, but now the battery on the upper-right corner just stays still no matter what (wall charger and USB connect).

But sometimes I end up with 2 bars instead of 1, so it does charge at some point.

And no, I haven't been playing it the whole time. I've let it sit for hours connected to the PC and the wall, it doesn't charge (usually, and never to 3 bars).

And it's the same whether I'm in CFW or OFW or have the system off.

edit: I unplugged and plugged into a different USB port and I magically got another bar of power. But it still didn't have the charging animation. So am I basically driving without a speedometer?