[Al Skierkiewicz]

Sanddrag,
This has been answered before but I will try again. The rules specify the 4 amp or 6 amp smart chargers for several reasons. First and foremost, the battery manufacturer specifies that charging be no more that 6 amps. By using a smart charger you get maximum charge in the minimum time. All of the battery chargers supplied by FiRST over the years have been smart chargers so they know what to expect in terms of safety, speed, damage to batteries and humans, etc. when these devices are used at competition venues.
You might hear of teams that fast charge batteries at high currents but that is strictly illegal and must not be done at competition.