TP 4056 is a Constant voltage – Constant current Chip used for charging a single 3.6 V Lithium Ion battery from 5 volt power source including USB port. It sources constant 4.6 volts for charging. An external Programming resistor can be used to provide constant current for charging. The Chip can handle up to 1 Ampere current. It has internal protection circuitry for polarity reversal, so external diode is not necessary.
The chip senses both charging and full charge status of the battery and two LEDs can be used for visual indication. Red LED lights during charging and Green LED lights when the battery is fully charged. R Prog is the resistor that controls the charging current . An NTC Thermister can be added in series with the R Prog resistor to control current based on temperature. In the circuit, a 10 Ohm NTC Thermister is added in series with the R Prog resistor( 47 Ohm ). The Chip provides 4.6 V constant voltage for charging. So in the cold condition, total resistance of NTC and R Prog will be 57 Ohm . So current will be 80 mA ( 4.6 / 57 = 80.70 mA ). NTC should be fixed close to the battery.