Features: 100% brand new and high quality Made of high quality material, durable 50/100A LED voltmeter dual digital test meter ammeter Product parameters: Type: red + blue two-color digital display LED voltmeter ammeter Style: 50A voltmeter and 50A shunt ammeter, 100A voltmeter and 100A shunt ammeter (optional) Operating voltage of the instrument itself: DC 4-30V Operating current of the instrument itself: 20mA Voltage measurement range: DC 0-100V Current measurement range: DC 0-50A, DC0 -100A (shunt is required for more than 10A!!!) Voltage resolution: 0.1V Current resolution: 0.01A Measurement accuracy: 1% (plusmn; 1 digit) Display: 0.28'' digital tube, blue and red Refresh rate : about 300mS/time Dimensions: about 48x29x26mm Working temperature: -10 ~ +65 Note: only the 50A and 100A voltmeter and ammeter sets have shunts Note: the maximum input voltage cannot exceed 30V. Otherwise the counter will be burned. Note: For the meter oacute;within the range of 50A or 100A, no matter whether the measured current is less than 10A, please connect the shunt to measure the current! Otherwise it will burn out suddenly. Voltage indicator is normal, current display 0.00 or 0.0 Make sure the thick black cable is connected to the negative pole of the battery and the thick red cable is connected to the negative pole of the load. (Please note that the discharge and charge connection methods vary depending on the load and power concept.) (The meter head adopts the original imported chip. After leaving the factory, it has undergone very strict inspection and calibration to make sure there is no quality problem before leaving the factory. The display shows 0 99.99% due to incorrect wiring. Please be patient and check the wiring carefully) The current display is inaccurate: If it is a direct power supply or an independent power supply, and the equipment power supply has the same ground, simply disconnect the thin black wire carefully. No Power Connection Appears: All rectified AC power supplies must be filtered by electrolytic capacitors above 1000uF to power the meter. Judge whether the header is good or bad (below are two cases of normal header) Without a shunt, connect the thin red wire and the thin black wire to the power source. The current of the 50A meter displays 50.0 ~ 59.9 and the 100A meter displays 100 ~ 109. Connect the shunt and connect the thin red wire and the thin black wire to the power source. The current meter with a 50A range displays 0.00, and a meter with a 100A range displays 0.0; Other considerations: Current can only be measured at the negative pole of the power supply and the negative pole of the load. Voltage range: the power supply voltage range of the 5-wire head is 4 ~ 28V, that is, the voltage of the thin red wire cannot exceed 28V. About the concept of load and power When discharging: the battery, switching power supply and transformer are power sources, and resistors, lamps, motors and power devices are loads. When charging: chargers, generators and solar energy are the power sources. Accumulators and batteries are cargo. Package List: 1 * Voltmeter & Ammeter 1 * Shunt Note: 1. The real color of the item may be slightly different from the website images caused by many factors such as brightness of your monitor and light brightness. 2. Please allow slight manual measurement deviation for the data.