Digital Voltage Current Meter DC 0-300V 0-100A Ammeter Voltmeter Red Green LED Dual Display with Shunt Two-Wires

Worked fine 1st try easy install doesn't include dash for neg values it will just change direction and values. If calibrations are required two small dials are inside after you remove plastic cover as noted in photos.

The display is nice, Nice colors. Can read it just fine from a distance.I did a test using a precision reading power supply and load which produced the following results which I verified with additional precision meters;Test values:Voltage input: 15vdcCurrent given the load: 3.33 AmpsDisplay: 14.1 Vdc, 3.5 AmpsThis test demonstrates an accuracy of ~ 5-6%. High on amperage reading, low on voltage reading.According to the diagram this unit should allow you to connect it into the circuit without the supplied shunt. I've found this not to be true at all. If you read the resistance of the current path in the meter, there is no internal shunt and there would have to be in order for it to work without the external shunt. Perhaps a different model has an internal shunt. It's not a problem for me, I can use the external shunt even though I will not be using it with more than 10 amps at 120 vdc.I opened the case and there are current and voltage calibration potentiometers on the circuit board, so it's possible a person could calibrate the unit to read more precisely than it does out of the package. I may look at doing that when I put it in service. The shunt is rated at 100A - 75mv.

Just what I needed for my new DC power supply.

I like that the meter could measure up to 300v DC. I was only needing to measure 10 amps and the description said under 20 amps there was no need for a shunt. It didn't sound correct, so I asked the seller if it was correct. They told me maybe 15 amps at the most. I connected it up to test and tried 10v @ 1 amp. The meter showed an error I believe. I do not think it will actually work. The 100 amp shunt is a 75mv. So when 100 amp flows through the meter, there will be a 75mv drop across the shunt. When 20 amps would flow through the meter, there would have to be a 15mv drop across the meter. There is no way for that to happen unless there's a shunt built into the meter itself.

I put this in my homemade power supply to keep an eye on the voltage and currantwhen testing circuit boards. The unit does need a separate power low voltage DCpower source to operate. But it looks and works great.