What is Cut off Automatic || How to protect battery from over charging

The cut off automatic is the name of a circuit, which used in battery charger for automatic charging off, when battery fully charged.

The automatic charger is most important things for battery, because if battery fully charged and charge will continuously running, then battery's life can be reduce, for this we use cut off automatic circuit for off to charging.

So now we will see that "How we can make cutoff automatic Circuit".


This is the diagram of this circuit.

How to use it?

The basically this circuit we can use different ways, such as Transformer charger, Solar charger etc.

The 12v will apply at "+12v" and "GND" so when 12v will applied at circuit then circuit will be ON, and Red LED will indicate that circuit has ON, then we set "cut off" voltages will set by variable, the cut off voltage means when battery will be full charged, and typically battery will be full at 14.5v voltage.

How we can set cutoff voltage?

First of all circuit connect with 12v power source such as battery or variable power supply, then voltage increase up to 14.5v, if you used variable power supply than you can easily increase voltage up to 14.5v, but if you not have any variable power supply then you can set it by battery. If you are using battery then battery charges up to 14.5v.

So if you have increase voltage now rotate the variable like clock wise, when you rotate the variable then relay will “ON” and when Relay will “ON” then Green LED will glow and indicate that relay has “ON”.

So you need to rotate the variable in slowly, remember the Voltage should at 14.5v, then variable rotate clock wise and Relay the “ON”, so if you keep relay on minimum at 14.5v then when voltage will be decrease  then Relay be ”OFF”, and aging when voltage will reach at 14.5v then Relay be “ON”.

This remember that much variable will back, such as much it rotated anti clock wise then relay will “ON” at high voltage, and much variable rotated clock wise then relay need low voltage.

So we will cutoff setting by this thing, that much voltage will “ON” or “OFF” to relay.