MH-CD42 4in1 DC 5V 2.1A Mobile Power Diy Board LiPo Charger 3.7V 2A IN 5V + LED Level

When charging, the four level battery indicator (fuel gauge) starts with one flashing LED, meaning the battery is less then 25% full. After some time, 2 LED will lit up and the first one would stop flashing. That means your battery is 25% to 49% full. Your battery is fully charged when all 4 LEDs are lit and not flashing. In discharge mode, same definition applies but in reverse.

• Charging Voltage: DC 4.5V-5.5V
• Charging Current: 0-2.1A
• Charging Quiescent Current: 100uA
• Full Voltage: 4.2V+-1%.
• Discharge Current: 0-3.5A
• Discharge Quiescent Current: 50uA
• Discharge Efficiency: 96%
• Maximum Output Voltage: 5V
• Output Current: 0-2.1A
• Ambient Temperature: -20°C to +85°C
• Battery Protection Function
• Over Current Protection (OCP)
• Over-Voltage Protection (OVP)
• Short Circuit Protection (SCP)
• Over Temperature Protection (OTP)
• Charge and discharge power level 4 interval indication
• Weight: 4g