Temperature dependent current and pulse controlled charging method for a battery charger
A pulse controlled charging method for higher temperature charging in addition to the current-reducing operation at ambient temperature. A specific software control strategy for these purposes is proposed, which can be divided into two parts, (a) two-stage charging current control at ambient temperature, which sets different current-limiting transient points for chargers with different outputs; (b) high-temperature pulse charging, which utilizes an internal NTC (Negative temperature coefficient) thermistor inside the charger to detect the internal temperature of the charger, if the temperature exceeds a pre-determined value, the charging process will be stopped for a period of time to avoid the temperature of the charger becoming too high.
1. A method for charging a battery comprising:
providing a charger circuit;
measuring temperature of interior component of the charger;
measuring the output voltage of the charger;
measuring the output current of the charger;
checking whether the temperature of the interior of the charger is greater than or equal to a preset temperature value and lasts for a first period of time, if the temperature of the interior of the charger is greater than or equal to the preset temperature value and lasts for the first period of time then stop charging the battery for a second period of time;
checking whether the output voltage of the charger is less than a first threshold voltage and lasts for a third period of time, if the output voltage of the charger is less than the first threshold voltage and lasts for the third period of time then charge the battery by a constant current charging mode with a first fixed current value;
checking whether the output voltage of the charger is between the first and a second voltage threshold for a fourth period of time, if the output voltage of the charger is between the first and the second threshold voltages for the fourth period of time then charge the battery by the constant current charging mode with a second fixed current value;
checking whether the output voltage of the charger is greater than or equal to the second threshold voltage, if the output voltage of the charger is greater than or equal to the second threshold voltage then charge the battery in a constant voltage charging mode with the second threshold voltage; and
checking whether the output current of the charger is less than a first preset current value and lasts for a fifth period of time, if the output current of the charger is less than the first preset current value and lasts for the fifth period of time then the charger enters into a floating charging detection process.
2. The method of claim 1 , wherein the floating charging detection process comprising:
checking whether the output current of the charger is less than a second preset current value and lasts for a sixth period of time, if the output current of the charger is less than a second predetermined current value and lasts for the sixth period of time then the charger switches into a floating charging mode from the constant voltage charging mode through operating the charger's circuit; and
checking whether the output current of the charger is less than a third preset current value and lasts for a seventh period of time, if the output current of the charger is less than the third preset current value and lasts for the seventh period of time, the charger switches to operate at stopping charging mode from the constant voltage charging mode, and then ends the charging procedure, otherwise the charger goes back to perform the floating charging detection process.
3. The method of claim 1 , wherein the charger circuit comprising:
a power conversion unit; and
a charging control circuit electrically coupled to the power conversion unit, wherein the charging control circuit includes:
a switching circuit;
a microcontroller unit electrically connected to the switching circuit; and
a constant current/constant voltage loop electrically connected to the microcontroller unit, wherein the charging control circuit is arranged for providing a battery electrically connected to it and utilizes the power conversion unit to manage a charging control for the battery; and
wherein the microcontroller unit can detect the charger's output voltage, output current, and temperature of its internal component for adjusting its charging procedure.
4. The method of claim 1 , wherein the preset temperature value is 100° C.
5. The method of claim 1 , wherein the first period of time is 3 seconds, the second period of time is 1 minute, the third period of time is 1 second, the fourth period of time is 1 second, and the fifth period of time is 1 minutes.
6. The method of claim 2 , wherein the sixth period of time is 1 second, and the seventh period of time is 300 microseconds.
7. The method of claim 1 , wherein the first threshold voltage is 25 volts, and the second threshold voltage is 29.6 volts.
8. The method of claim 1 , wherein the first fixed current value is 2.5 A, the second fixed current value is 2 A, and the first preset current value is 800 mA.
9. The method of claim 2 , wherein the second preset current value is 550 mA, and the third preset current value is 60 mA.