There is an easy way to gain unlimited jetpacks energy by buying a fuel efficiency ix book from the shop and applying it to any jetpack. It grants a negative fuel cost and allows you to fly for free and also use it as a capacitor for other machines.
Probably best to change the book to a Max of 5.

I've found this can also cause a max integer drain on your power system when using this enchant and hover mode. Effectively draining all your stored power if using wireless charging.

Fixed in new update v1.4.9