Deep Discharge Protection for Rechargeable Cells

With this circuit built into the power supply of a battery powered device, it will prevent the rechargeable cells from being completely drained when you forget to turn the equipment off. When the battery voltage drops below a pre-set limit (9.5 V in this example) the circuit will automatically disconnect the battery. Power is re-connected when the voltage rises above an upper threshold level (10.5 V here), this will typically occur after the equipment has been plugged into its recharging station. The circuit is designed to use as little power as possible.

www.irf.com/product-info/datasheets/data/irlml6402.pdf