It has made quite a lot of space in my PSP Phat collection. In each Driveless mod I do I usually put a Memory stick storage spring into, That way you can switch from Memory Stick A to B easier than getting out some kind of case or your wallet all the time to swap them. The Drive is almost big enough for a 9 volt battery, Try taking one apart and making a Flat 9 Volt, it may help you make the PSP last 2-3 hours more, but you must put in a switch and wire that to the charging circuit.
NEVER CHARGE THE PSP WHILE THE 9V SWITCH IS ACTIVE!!!!
That way you won't have leaky leaky in the PSP.
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Remember, Battery and charging mods are liable to Frying the Backlight Fuse in the PSP. Be careful about it.
If you fry that, you have to bridge the fuse with a drop of solder. from then on you can not remove your screen once it is installed or else it's backlight will be killed upon removal.