[Cascade]

This is last year's rule below (which seems to be missing this year)

<R41> An automatic battery charger rated for a maximum of 6 amperes must be used to charge the supplied batteries. When recharging the KOP batteries, either the charger provided by FIRST or an automatic charger with an equivalent charging current rating may be used.

I don't know if the rule changed this year or just an over site in the rules to date; however, since this is a safety thing, might just stay with last years rule until this is clarified.

Good luck to you