There are many sizes of batteries and configurations. To get an idea go to cheapbatteries.com -> battery packs -> custom packs then enter the "cell count" count that you want. 6.0v batteries have 5 cells. Go ahead and select any of the configurations. You'll be presented with 25 - 30 different cell options. Different cell size and weights (same voltages) can be used to construct the pack. Let your imagination roll on ...