SMAKN&reg; 5v Mobile Power Supply USB Battery Charger 18650 Box-Matte Black Output voltage: 5V Output current: 2.0A Charge voltage: DC 4.5-5.5V,2A (recommended more than 1A ). the center PIN of Charging port is +. Battery protection: full auto stop, protection against overcharge, the battery voltage is below 2.9V start protection, turn off the output, you can perfect or protect the lithium polymer battery 18650! !