7. A charger for the 7.2V or 8.4V battery pack. An adjustable DC power supply can be used to charge the battery if it is properly adjusted and timed so that the battery is not overcharged. Overcharged batteries will get hot and will have a shorter life. Automatic peak-detection quick chargers are the easiest and most foolproof to use. These chargers shut off automatically when the battery is charged. One quick charger can be used for several robots as a full charge is achieved in less than 30 minutes with around 5 Amps maximum charge current. Inexpensive trickle battery chargers deliver only around 75 mA of charge current, and they will require several hours charge the battery.