Hey guys,
I am trying to charge a single cell lithium ion battery with a five volts phone charge power supply. The problem is 5 volts is too high to charge the battery and I am trying to make a simple switched mode circuit to reduce to voltage to get a desired amperage (in this case 200mA). I am using an arduino to PWM to a logic level mosfet to control current through the cell with the 5 volts. Is this something that is workable and safe? My battery seems to be charging fine and is not seeing any degradation. Using voltage measurement and a current sense resistor, the microcontroller PWM is varied until the battery reaches 4.2 volts (the maximum voltage of a lithium-ion cell) while maintaining the desired 200mA. Am I missing something to make this a safe circuit? I know every time the mosfet is switched on, 5 volts is technically going through the cell but the average voltage and amperage are at safe values. Is this okay/safe?
-Khan
I am trying to charge a single cell lithium ion battery with a five volts phone charge power supply. The problem is 5 volts is too high to charge the battery and I am trying to make a simple switched mode circuit to reduce to voltage to get a desired amperage (in this case 200mA). I am using an arduino to PWM to a logic level mosfet to control current through the cell with the 5 volts. Is this something that is workable and safe? My battery seems to be charging fine and is not seeing any degradation. Using voltage measurement and a current sense resistor, the microcontroller PWM is varied until the battery reaches 4.2 volts (the maximum voltage of a lithium-ion cell) while maintaining the desired 200mA. Am I missing something to make this a safe circuit? I know every time the mosfet is switched on, 5 volts is technically going through the cell but the average voltage and amperage are at safe values. Is this okay/safe?
-Khan