Review on ⚡ Waterproof Battery Monitor DC 4.5-150V Voltmeter Tester for Automative Electric Cars, Golf Cart, E-Bike, Bicycle & Motorcycle - Small Digital Gauge with 0.56'' LED (Blue) by Brian Page

Ultra small meter. This is the second one I've bought. The first one still works perfectly after 3 years. Someone asked how much current does this meter draw? I measured with two different gauges. digital and analogue. Here is the answer. At 48 volts it draws 5 milliamps. We do math (Ohm's law). Voltage = Current x Resistance. So 48 volts / 5 mA = 9.6 kΩ resistance or impedance. Assuming this resistance. 12 volts / 9.6k = 1.25mA. So for a 48 volt source you are drawing 5 mA. For a 12 volt source you will draw 1.25 mA. This means that for every 12 volt increase in voltage, current draw increases by 1.25 milliamps. The mounting cutout should be 43mm x 26mm.