VooGenzek 2 PCS 0.28" LED Voltmeter Ammeter, Red and Blue Detector Voltage Current Meter Panel Amp Volt Gauge, DC 0-100V 10A for 12V / 24V Multimeter Amperage Meter Volt Amp Gauge Panel

Displays amps and volts from my small scale solar array. Been working ok for12months so far.

good thing: it works great. bad thing: it uses the negative rail.

There are no instructions beyond the Amazon page. Thin red and black wire are the meter power. 5V is best, as higher will make the on-board regulator hot. Then the yellow wire measures the voltage maybe up to 99.9V. The Voltage decimal point doesn't move for less than 1V or at all. The current meter is actually a 1V approximately max voltmeter for 50.0 A on display. Thus the shut drops 0.2V at 10A, which is 2W. I expect the shunt, which is a surface mount resistor gets a bit two hot at 10A. Being experienced at electonics I removed the shunt. Then suitable external resistor can be used, A 20 ohm shunt will thus measure 0 to 50 mA, with the decimal point shifting one to the left for less than 1.0 on the display (was 1A, now 1mA), thus 0.99 down to 0.01. I'd not use the built in shunt for more than 2.5A. The adjusters are to calibrate voltage and current.

Buy it good

Worked as expected. The shunt bar is close to 1.5 milliohms, making it useful for other projects.

Series shunt resistance much bigger than competitor versions so useless for higher currents. Unable to calibrate V and A independently. Waste of money

I use 2 off these to measure voltage and current and these match my DVM readings. Fitting in a cut out hole works best if you first take the unit out of the bezel. Then fit the bezel, then put the unit back in the bezel. Else the unit blocks the locking pushy things and you may break something. With before procedure it locks very easily in the cut hole.

The voltmeter bit seems to work fine. But the connections for the ammeter - two thin brushes onto metal pegs - just aren't designed to take the full 10 amps, and particularly not without adding significant resistance - which no ammeter should ever have. You can bodge this up by soldering your own wires onto the pegs, as recommended in another review. But be sure to get these wires the right way round - if current is flowing the 'wrong' way through this ammeter, the display reads a steady 0.00 A. Small, accurate, digital, cheap - for 10A fsd ammeters , choose any 3, at most.