A blue-ultraviolet on-p-GaAs substrate pin Zn1-xMgxSySe1-y photodiode with high quantum efficiency, small dark current, high reliability and a long lifetime. Channel re-estimation is performed by transferring the estimation calculations from the time domain into a channel state domain. The batteries are charged according to a dynamic charging sequence in which batteries are added into the charging sequence in order of increasing state of charge as batteries already in the charging sequence are charged to exceed the state of charge of a battery having the next higher state of charge relative to the state of charge of the batteries already in the charging sequence.