Automatic latch-off circuit saves batteries

摘要

Although rechargeable batteries offer many advantages, they can suffer damage and shortened service lives if they're fully drained of their charge. The circuit in Figure 1 shuts off a battery-powered appliance-in this instance, an LED flashlight receiving power from NiMH (nickel-metal-hydride) cells-when the battery voltage falls below a preset limit. Although intended for an LED flashlight, this circuit can apply to any battery-powered application. Without ensuring that the user will remove the batteries for recharging, this circuit latches the flashlight off when the battery voltage falls below the usable limit and thus provides a strong hint that it may be time to recharge.