12 V Lead Battery Charger

This charger charges the battery by means of pulse charging. Whenever the voltage drops below 13.2 V the charging begins. It is stopped when the voltage gets above 13.8 V. This means that the battery gets charged with pulses of approximately half a second and then pauses for some ten seconds.

The advantage is that you can judge the condition of the battery from the way the light emitting diode behaves.

	Flat battery: Constant red light.
	Fully charged battery in good condition: Green light interrupted by short red glimpses every second to tenth second (10 AH battery).
	Battery being charged: Constant green light with very short red glimpses, looks like green light with a yellowish tone.

When the battery gets old, it normally lacks water, causing the internal resistance to increase. With this charger this becomes visible by an increase in the blinking frequency. At the end the frequency becomes so fast that the light seems constant, just like constant charging a flat battery. The same effect occurs if the resistance in the wiring/fuse is too high.

The charger is short circuit protected.

It has one disadvantage: If a hurricane passes by, disconnecting the power source, the battery slowly gets discharged.

Diagram

Print

Diagram and print was constructed by the use of Eagle (the freeware version).

Diagram and print in Eagle's format: akkuLader.zip