The mafia have shared charges, so we could also use that to trick them into lying.
First, we could all claim the number of charges we have, and then claim who we targeted for charge transfer. If someone targeted one of the mafia, they would gain a charge, but wouldn't know who got that charge, so there's a 50/50 chance that they'll make a mistake (Since they'd have to lie at first about each having 2 charges, one of them would have to claim 3 charges while the other claims 2).
But, one problem is that the rechargebot has no defined charges, and I don't know how to get around that we might lynch the rechargebot instead... so this plan needs some more work.