Abstract: A protection circuit for a primary battery pack provides the battery pack with reverse charge protection. The protection circuit features a metal oxide semiconductor field effect transistor (MOSFET) with a steady state source to drain voltage. The source to drain voltage is controlled through a feedback loop that includes an operational amplifier. The MOSFET is configured in series with one or more battery cells allowing current to flow from the cells and preventing current from flowing to the cells. The MOSFET provides reverse charge protection with a small forward voltage drop and a small reverse charge leakage current.

Abstract: A battery having a complete discharge mechanism includes a spring-biased switch with an element spring-biased from the switch and acts to close the switch when in a fully extended position. A block is position above the element with a passageway aligned with the element. A flexible positioned between the element and the passage prevents the element from extending into the passage. The tab extends through the battery casing. When pulled the tab allows the element to extend into the passage thereby closing the spring-biased switch and completing the discharge circuit.