Feature: LED lead acid battery BMS capacity indicator voltage meter. Can display the battery voltage, battery power, you can also plug directly into the phone or the 5V equipment charging. Suitable for all kinds of outdoor power, mobile power, instrumentation and other equipment additional battery power voltage display and additional USB to charge the phone and other functions. Uses synchronous rectification step-down chip scheme, with little heat, energy saving and environmental for protection. Small size and light weight. Fine workmanship and good performance. Easy to read, Easy to use, Durable in use Specification: Opening Size: approx. 45*26*18mm USB Output 5V/2A(max), two USB port total is 2A The accuracy of the voltmeter is about 2% Working Temperature: -10~+65 Working Humidity: 10-80% (no condensation) 12V lead acid voltage range: (4 series of lithium iron phosphate batteries can be used) Battery voltage is greater than 10.3V + -2%, showing 10% power Battery voltage is greater than 10.6V + -2%, showing 20% power Battery voltage is greater than 10.8V + -2%, showing 30% power Battery voltage is greater than 11.3V + -2%, showing 40% power Battery voltage is greater than 11.6V + -2%, showing 50% power Battery voltage is greater than 12.1V + -2%, showing 60% power Battery voltage is greater than 12.3V + -2%, showing 70% power Battery voltage is greater than 12.6V + -2%, showing 80% power Battery voltage is greater than 12.9V + -2%, showing 90% power Battery voltage is greater than 13.2V + -2%, showing power Package included: 1 * 12V Lead Acid Battery Capacity Indicator