Some pieces of equipment will complain about "low battery" long before the cells which power them are fully discharged.
One use for these "tired" cells is in remote controls or clocks, where they can often give some months of useful further service.
But eventually even these low-duty-cycle low-power
devices start to operate intermittently.
Yet the cell is not yet completely discharged; some energy remains.
At last, away of getting those last few picojoules of energy !
We offer the BorgCo electron harvester. It consists of a silver battery clamp with gold-flashed contacts, connected to the electronics, which consist of a high valuue low leakage capacitor connected through a CMOS switch.
An ultra high impedance differential electrometer senses the voltage on the cell terminals, and if it is above the capacitor voltage, opens the CMOS switch and allows energy to flow to the capacitor. When enough energy has accumulated, a second CMOS switch opens and dumps the charge through a pulse transformer and thence into a larger capacitor wich is also ultra low leakage and with a very low ESR.
From this capacitor, some energy is diverted to to power the device itself, and the rest is pulse charged into an alkaline cell to recharge it.
The Harvester only gives up when the input cell is completely and totally dead.
The DeLuxe version has multiple input cell bays which are polled in succession.