Lead Acid Battery Charger Circuit

To charge lead-acid batteries we can use this circuit that consist of a current-limited power supply and a flyback converter topology. Here is the schematic diagram of the circuit :


Isolation and voltage input range flexibility are provided by the flyback transformer, even at the battery voltage higher than supply voltage. MAX471 current sense amplifier is used to monitor the charging current by sensing the output. To detect if the value falls below the predetermined threshold or not, this circuit uses the output current monitor’s result that gives a feedback to a threshold detector. When a lower voltage is applied for lower charging current, this circuit will switch the charger into trickle mode using the detection. [Circuit schematic source: Maxim Integrated Products Application Notes]