How Does a Battery Float Charger Work?

You hate to get in your car and find that the battery is dead.

There is nothing worse than going out on a cold winter day to start your car and finding that the battery is dead. You can keep that battery charged with a float charger. You never have to worry about overcharging.

Trickle Versus Float

There are two ways to keep your car battery charged: a trickle charge or using a float charger. The problem with the trickle charge is that you can overcharge your battery, burning it out or even causing an explosion. The float charger senses when your battery is completely charged and shuts off.

The Float Charger

A float charger constantly charges your battery. As the charger approaches the maximum battery charge (about 13.8 volts for a car or marine battery), it then reduces the current to keep the battery charged. A good charger quickly gets the battery to about a 75 percent charge, then reduces the current for the last 25 percent.

Charger Controls

The simplest way to control the charge is with a magnetic sensor. This can be bulky. Linear chargers use simple transistors to control the circuit. These chargers can overheat. The best option is a switched mode charger using high frequency AC current and a sophisticated control circuit to charge and protect your battery.

References

• Operating Technical Electronics, Inc.

Resources

• Battery Tender:Float Charging