If you Disassemble a powered RM13 combat armor (5 plutonium for 2500 charge), you receive the remaining charge in plutonium cells, multiplying it by 500.
While you have to be extraordinarily foolish to do this on your only advanced powered armor, if you are as lucky as me you’ll find a spare and have enough plutonium to power it forever…
Assuming you can carry 440 lbs of plutonium cells away, that is.