Abstract: An increased capacity battery holder, which allows a device to be used for a longer time duration than can be achieved from solely internally contained batteries, capable of providing additional energy to the device, beyond internal space and volume limitations of the device, having additional battery holding capacity external to the device, with the additional battery holding capacity self contained within the battery holder. The battery holder provides maximum energy output, a portion of the battery holder being matingly removably attachable and optionally removably lockable to the device. The battery holder is safe, of simple construction, easy to install and remove therefrom the device, acts as an additional means for holding and/or handling the device, and is capable of forming an integral assembly with the device. The battery holder has means for preventing inadvertent shorting and/or reversing polarity of the batteries, and optionally recharging means for recharging the batteries.