Features:100% brand new and high quality.Thisdischarge tester is used for testing capacity of a 1.2-12V battery.It is easy to operate and powered by microUSB power source.This discharge tester allows you to check the test capacity, voltage, and current of battery.Designed with LEDs that indicate which parameter is showing on display.Specification:Power Source Voltage: DC4.5-6V (micro USB)Working Current: 70mADischarge Voltage: 1.00V-15.00V, resolution 0.01VCutoffVoltage Range: 0.5-11.0VSupported Current: 3.000A, resolution 0.001AVoltage Test Error: <1%+0.02VCurrent Test Error: <1.2%+-0.002ABattery Capacity Range: 9999Ah (1Ah=1000mAh, the decimal point can move when the number is large, e.g. it displays X.XXX when lower than 10Ah, and displays XX.XX when higher than 10Ah... )Weight: 27g / 1oz (approx.)Package list:1 * Battery Capacity Meter2 * Resistors (5W, 7.5R)1 set * FastenersNote:1, The resistor load will heat up severely during discharge process, please be careful.2, In order to improve the voltage measurement accuracy, this circuit is specially designed with a DC bias, and will display a small voltage when not connecting terminal blocks to anything, which does not affect the actual measurement. If you connect input terminals together(0V), it will display 0.Estimating method for collocation resistance:According to Ohm's law, to estimate the resistance value = divide battery voltage by expected discharge current; resistor power choice is more than two times of result that the battery voltage is multiplied by expected discharge current. It is important to note the voltage is higher when battery is fully charged, and to ensure that the current can not be more than 3.0A in the case of full charged battery voltage.For example, if need to use 2A to test 12V battery, then the resistor should be 6 50 W. New 12V battery fully charged voltage is about 13.5V, which is corresponding to the maximum current 13.5/6=2.25A (less than 3A), so it can be used.In addition if you use the lamp bulb to test, then the current can only be less than half (1.5 A) because the light bulb cold resistance is low, the impact current is very big, too big current may burn circuit directly.Instruction:1. The measured battery should be charged in the first place.2. Connect the battery to the input terminals correctly(positive to positive, negative to negative), reverse input may damage the circuit.Connect load to the output positive and negative, then power the meter with micro USB work power (do not use a desktop computer or laptop USB as power supply), it displays the battery voltage at this time.3. Direct start test just need to press the "OK" button, then meter will automatically develop an appropriate cutoff voltage according to the battery fully charged voltage, then begin testing after display flashing 3 times.If need manual setting up for cutoff voltage, you can press "+" or "-" button when ti shows battery voltage. The cutoff voltage is displayed with a initial "P", and the resolution is 0.1 V, press "OK" to start testing after setting.4. The testing data will be displayed in turns among discharge capacity (Ah), real-time discharge current (A) and battery voltage (V). When the battery voltage reaches set cutoff voltage, tester cut off the load control switch, and displays capacity (Ah) and fast flashing indicator light. The capacity now displayed is the actual discharge capacity of the battery. Press the "OK" button to stop flashing, and press the "OK" button again to reset tester for next battery testing.Error code and meaning:Err1:battery voltage is higher than 15VErr2:battery voltage is lower than set cutoff voltageErr3:load discharge current is too big for battery or circuit inner resistance is too bigErr4:current is too big (current is more than 3.1A)Err5:Improper use or burned tester because of incorrect connection (current sampling or control switch MOS is burned)Secondary calibration operation:Press and hold three buttons at the same time and power tester to enter calibration mode. First display calibration record times then enter formal calibration sampling program shows 0u0A; Connect input terminals positive and negative then press the "OK" button, display shows J10u; Connect standard 10.00V DC voltage to input positive and negative then press the "OK" button, display shows J2.0 A; Connect constant 2.0A DC current to output negative and input negative then press the "OK" button to complete the calibration.Tester will pre-check calibration data, if the calibration data is correct, it will show four calibration data in turns then exit; if pre-check of data is unreliable, it discards the data then exit.