I had finally got my hands on a decent PS3 controller a few weeks ago, a standard black Dualshock3. But like most of the stuff I post here about, it had a problem... It refused to charge the battery. I had changed the battery twice, the first was a brand new one from DealExtreme, but it still didn't charge. The second was a known working one from my crappy Sixaxis, the DS3 worked fine until the battery died, and the thing still wouldn't charge >_>
Well, I decided it had to be the board since that was the one constant thing that never changed during my tests, so I checked it out. The part of the board under the battery plug had some kind of black goo all over it, and since it was so close to the battery plug I'm guessing it was the charging circuit... I cleaned it up as best I could and hoped for the best, and it did charge after I reassembled it :D
I tried to get on my PS3 last night using said controller, and the battery was dead. I didn't think it was a big deal, so I turned the PS3 on manually and hooked up the USB and let it sit for a while (I can't use wired PS3 controllers in my setup). I came back to it after 10 minutes and unplugged the USB... nothing. It once again refused to charge ~_~ I disassembled it and set it aside for tomorrow.
The next day (today), I did a few tests to see if I could bring it back, but I couldn't. So I set about my last resort option. I had a few PSP Slim batteries laying around doing nothing, and a standalone PSP battery charger. The voltage was close enough (DS3 batt=3.7v, PSP batt=3.6v) so I decided to mod the DS3 to use a PSP Slim battery.
The plan was simple enough, attach wires to the battery port on the DS3 board and route them thru the place the USB port was, then attach the battery to the underside of the DS3 using sticky tack. And I did just that.
After attaching the wires, I tried it out and it worked fine :D I reassembled it and sticky tacked the battery to the controller, and here's what I got:
This mod does have some restrictions. I can't use the controller while charging the battery since I have to take the battery off to charge it, and the USB can't really be used while the PSP battery is connected (the wires are blocking it, and I wouldn't want it to magically start charging and damage something). But the first one doesn't bother me since I have 2 spare 1200mAh batts, and the second one doesn't matter as long as the DS3 stays paired with my PS3 :P I also should get more playtime with this battery as it's 2x the capacity of a standard Sixaxis battery :D