The generator with battery is powered by a lithium battery that can be charged. When the battery is under voltage, the under voltage lights are on. Please turn off the generator and recharge the battery in time. If the generator is not used for a long time, charge it at least every 2 months to avoid damaging the battery. MICRO USB powered and charged. Current output: the output encoder current is turned right, the output is increased; and it is turned to the left, the output is decreased. You can change the position of the slider using the encoder knob to change the different output increments and decreases (0.01mA, 0.1mA, 1mA, 10mA).Features:Name:Signal GeneratorActive Current Output : 0-22 mA (minimum output is approximately 0.06 mA), load: 0-550 Passive current output: 0-22 mA (minimum output is approximately 0.06 mA), external supply at 30 V, load: 0 -550Output voltage: 0V-12V (minimum output is about 0.05V)24V output voltage: drive current: 35mA (not to exceed 35mA)Operating environment: 0C-50C non-condensing item: 90 * 70 * 28mm / 3.54 * 2.76 * 1.10inPacking size: 150 * 100 * 80mm / 5.91 * 3.94 * 3.15inPackage weight: 120g / 4.23ounce