WH-DL1-7S State-of-Charge SOC Indicator for Single Cell Li-Po Batteries DIY

Features : 

Instantly displays battery state of charge (SOC) in five levels (0%/25%/50%/75%/100%)

Dedicated power status indicator

Press button to display state of charge

Works with single cell lithium ion (LI-ION) batteries between 2V and 4.4V

For 2s 18650 or 2s Li-Po battery

Status vs battery voltage range :
4-LED: 100% / 4.1V-4.4V
3-LED: 75% / 3.9V-4.0V
2-LED: 50% /3.7V-3.8V
1-LED: 25% / 3.3V-3.6V
0-LED (all off): < 3.3V

Power & Batteries
Battery Max Voltage 4.35V
Battery Min Voltage 2.5V

Dimensions
Depth 40 mm
Height 3 mm
Width 13 mm