There is provided an apparatus for battery life estimation comprising an energy harvester; an energy storage apparatus, connected to the energy harvester, the energy storage apparatus representative of a unit of measure; a battery for receiving energy from the storage apparatus; and a processor for monitoring the energy provided by the storage apparatus, monitoring energy provided to the battery by other charging apparatus and monitoring the energy being delivered by the battery; wherein the processor calculates the remaining life of the battery based on the number of energy storage apparatus units that are provided to and delivered from the battery.