Not sure if it is intentional or not, but I believe I can keep raiding indefinitely while I'm online by using this item. With a powerful fleet I nearly always come out of a battle with more energy than when I went in.
when you join big battle like fortress, you need a lot of energy since you can't recover right the way. battle of fortress is very long which you need microcomputer to recover energy. so that item is fine.
also when big fleet attack it will consume your energy a lot.