DROK DC8-63V 12V/24V/36V/48V LCD Lead-acid Battery Capacity Tester Gauge Panel Battery Statue Indicator Monitor Electric Quantity Detector Reader Wide working Voltage range: DC 8-63v (conventional); DC 5-12v(low) Low working power consumption(5ma max) and Standby power consumption(120a max) There is two white button(kup and kdn) behind the meter for choosing suitable parameters for your battery, such as the Voltage, quantity of batteries Simple installation: red wire: positive; black wire: negative Note: there is a Brown protective film on the surface, please remove before installation