Constant-Current Battery Charger

There are many ways of battery charging but constant-current charging, in particular, is a popular method for lead-acid and Ni-Cd batteries. In this circuit, the battery is charged with a constant current that is generally one-tenth of the battery capacity in ampere-hours. So for a 4.5Ah battery, constant charging current would be 450 mA. You can also Subscribe to FINAL YEAR PROJECT'S by Email for more such Projects and Seminar.

In the above circuit, D1 is a low-forward-drop schottky diode having peak reverse voltage (PRV) of 60V at 5A or a 1N5822 diode having 40V PRV at 3A. Normally, the minimum DC source voltage should be ‘D1 drop+Full charged battery voltage+V DSS + R2 drop,’ which is approximately ‘Full charged battery voltage+5V.’

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This project also has Overcharge and deep-discharge protection. For overcharge protection Zener diode is used as shown in above circuit and for deep-discharge protection there is one more zener diode which drives the transistor connected to it. This circuit and product is from Electronics4u.com which is a good name in Electronics industry and provide good electronic resource too. Use this project only for your reference and study work.

Source: Electronics4u.com

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