How to Make 12V Battery Charger Circuit | Using SCR BT151 | Auto cut off 12v Battery Charger

A basic home battery charger incorporates a transformer and rectifier to change the mains 110/220 volt alternating current to 12 volt direct current and allow the mains supply to provide a charging current at a rate determined by the state of the battery (12 volts).

A simple charger works by supplying a constant DC or pulsed DC power source to the battery being charged. A simple charger typically does not alter its output based on charging time or the charge on the battery control. This simplicity means that a simple charger is inexpensive, but there are trade-offs system.

Check the polarity with a D.C. voltmeter connected to the clamps with the charger on but not connected to the battery. The meter positive is the battery charger output positive termiter. A small spark may be caused by the current drawn by the polarity protector.

At 12.4 volts, the battery is considered 75% charged and can still ignite your engine car. When the battery voltage drops to 12.2 volts without the engine running, it is considered a bad battery that may start your engine but is no longer capable of holding a charge.

When a deep-cycle battery is fully charged, it typically reaches a voltage of around 12.6 to 12.8 volts. However, the voltage can temporarily rise to around 13.2 volts during the charging process. As long as the voltage doesn't consistently exceed 13.8 volts.