You can even try with external lipo charger, or with one power regulator: just set a voltage limit to 4.20V and charge with maximum 1C (that means if the battery has 500 mAh capacity, the max. charge current is 500 mA)
You can even try with external lipo charger, or with one power regulator: just set a voltage limit to 4.20V and charge with maximum 1C (that means if the battery has 500 mAh capacity, the max. charge current is 500 mA)