Button batteries or coin cell batteries charger circuit is simple to build, must be powered up from a 9V power supply circuit and can charge up to 5 button cell batteries.

D1 is a protection diode while R1 and C1 decouple the power live of the IC1 U2401B. D3 is for protecting the batteries in case we mount them wrong. R4 limits the current at 5 mA. After we connect the adapter to the main line, the button batteries will start to charge at maximum current for a period of time, after this it will start to charge in impulses. The impulse charging it is always made at 1/10 of the maximum charging current.

Use this NiMH battery discharger or NiCad discharger circuit when you need to discharge a battery fast and safe. This circuit is suitable for NiMH or NiCad batteries and is cheap and easy to build but the elements must be corelated with the number of battery elements.

This battery disconnect switch or cut-off (breaker circuit) is designed to automatically turn off any battery operated device when its user has forgotten to switch it off within a preset period of time and so it will preserve the battery’s life.