This is a circuit for battery charger circuit. In this circuit, the battery is charged with a constant current that is generally one-tenth of the battery capacity in ampere-hours. This constant-current battery charger circuit is divided into three sections: constant current source, overcharge protection and deep-discharge protection sections. This is the figure of the circuit;
R2 and T1 limit the charging current if something fails or battery terminals get short-circuited accidentally. To set a charging current, while a multi meter is connected in series with the battery and source supply is present, adjust potentiometer VR1 slowly until the charging current reaches its required value.
Adjust VR2 when the battery is fully charged (say, 13.5V in case of a 12V battery) so that VGS of T5 is set to zero and hence charging current stops flowing to the battery. LED1 glows to indicate that the battery is fully charged. When LED1 glows, the internal LED of the opto coupler also glows and the internal transistor conducts. As a result, gate-source voltage (VGS) of MOSFET T5 becomes zero and charging stops. If the battery terminal voltage drops to, say, 11V in case of a 12V battery, adjust potentiometer VR3 such that transistor T3 is cut-off and T4 conducts. LED2 will glow to indicate that the battery voltage is low. Values of zener diodes ZD1 and ZD2 will be the same for 6V, 9V and 12V batteries. For other voltages, you need to suitably change the values of ZD1 and ZD2. Charging current provided by this circuit is 1 mA to 1 A, and no heat-sink is required for T5. If the maximum charging current required is 5A, put another LM236-5 in series with diode D2, change the value of R11 to 1 kilo-ohm, replace D1 with two SB560 devices in parallel and provide a good heat-sink for MOSFET T1. TO-220 package of IRF540 can handle up to 50W.
0 comments:
Post a Comment