Is that any worse than leaving it in the device, though?
With all the PSPs I had, it's a bit absurd how quickly the PSP discharges the battery when the system is completely powered off. But leaving a PSP abandoned with a battery in it for months has never killed any of the batteries I had.
Meanwhile the original battery in my GBA SP still has enough charge to turn on with a red LED after at least a decade sitting in a box. Batteries are weird
With all the PSPs I had, it's a bit absurd how quickly the PSP discharges the battery when the system is completely powered off. But leaving a PSP abandoned with a battery in it for months has never killed any of the batteries I had.