Product Description: 100% Brand new and high quality 18650 Li-ion Lithium Battery Level Indicator Li-ion Battery Level Display Parameter: (2% error should be acceptable) Battery voltage > N*3.2V, 1 LED lights up (note:N = battery cell number) Battery voltage > N*3.4V, 2 LED lights up Battery voltage > N*3.6V, 3 LED lights up Battery voltage > N*3.8V, 4 LED lights up 3.7V lithium battery,full charge 4.2V 2S lithium 7.4V battery , full charge 8.4V 3S lithium 12V battery , full charge 12.6V 4S lithium battery , full charge 16.8V 5S lithium battery, full charge 21V 6S Lithium battery ,full charge 25.2V 7S Lithium battery , full charge 29.4V 12V lead acid storage battery , 12V car battery Size: 40x 15x 2.5mm (L*W*H) Cable Length: 150MM Ultra thin power display, 5 LED indicators, display more intuitive, more beautiful. More widely used, lithium battery, lead-acid battery, lithium iron phosphate, electric vehicle battery, electric equipment can be used Installation: 1. Connect the positive and negative terminals of the display board to the positive and negative ends of the tested battery, pre the red button gently with your finger, and the IED lamp lights up to display the real-time battery power 2. Release the finger, the LED lights will go out after 3-10 seconds delay, and there is no power consumption in static state. 3. With reverse connection function, even if the positive and negative connection is reversed, it can be adjusted Package includes:1Pc 18650 Li-ion Lithium Battery Level Indicator