A battery output disable when unconnected is described. In an implementation, a battery comprises: a conductive terminal configured to electrically connect to a battery-powered device; wherein the conductive terminal is disconnected from battery connector terminals; and a controller configured to detect whether the conductive terminal is grounded, and to enable the battery connector terminals if the conductive terminal is grounded and disable the battery connector terminals if the conductive terminal is not grounded. In other implementations, a battery protection circuit and a method are discussed.