Voltage measurement range: 0.0V-100V Current test range: 0-999mA, 0-10A, 0-50A, 0-100A (4 ranges are optional) Power supply range: DC4-30. OV Voltage error: ±0.1% Current error: ±1% External shunt specification: 75 milliohms Working current: 20mA Refresh rate: about 300mS-times Display mode: double three-digit 0.28" LED digital tube Display colors: red+red, red+blue. Lead length: 15cm Dimensions: 48x29x22mm, length x width x thickness; Mounting hole: 46x27mm Operating temperature: -10"C *65°C Note: A meter with a range of 50A or 100A must be connected to a shunt to measure whether the measured current is less than 10A. Current! Otherwise it will burn the meter. The voltage shows normal, the current shows 0.00 or 0.0 Make sure the thick black wire is connected to the negative terminal of the battery and the thick red wire is connected to the negative terminal of the load. (Note that the wiring between discharge and charging is not - like, see the concept of load and power at the end). (The meter head uses the original imported C chip, which has been very Strict testing and calibration ensure 100% no quality problems before leaving the factory. When the current shows 0, 99.99% is connected The wiring is wrong, please be patient and carefully check the wiring) Inaccurate current display If it is a direct power supply or an independent power supply and the power supply of the device share the same ground, just disconnect the thin black wire to be accurate. No display when plugged in Any rectified AC power must be filtered by an electrolytic capacitor above 1000uP before powering the meter. Judge whether the header is good or bad (the following are two cases of normal header) Do not connect the shunt, connect the thin red wire and thin black wire to the power supply, the current of the meter with a range of 50A shows 50.059.9, the range is 50.059.9 Display 100 109 for the 100A header; Connect the shunt, connect the thin red wire and the thin black wire to the power supply, the current of the meter with a range of 50A shows 0.00, and the range is 100A The header shows 0.0; Size: about 5*5*3cm Included: ammeter and voltmeter*1