10PCS Mini DC Voltmeter 3-Wire DC 0-100V Voltage Tester 0.28 inch LED Panel 5 Colors Combined

I do a lot of projects, often I use a Raspberry Pi and/or I am working with stepper motors that take 12v. I want to get a visual idea of how my circuits are doing. I 3D printed a faceplate and installed several... now I can monitor the status of the project with ease. I will note that they are often NOT ACCURATE... you will likely need to make an adjustment on the back. Measure your circuit with a DMM, then use a small screwdriver to adjust the potentiometer on the back to get an accurate reading. After that wey work well. I also like that they have an independent power wire. Other units only have two wires... so anything below 3v can't be measured... with these I can go down to 0.02 volts with ease... connect the power line to 5v for a nice bright display.

Sumklin Mini DC Voltmeter 3-Wire DC 0-100V Voltage meters. Hooked some up to my solar panels and others up to batteries and battery chargers. They are accurate to +/- .1 volts. There is a 1 turn pot on the back that can be used adjust the accuracy. It takes several tries to get the voltage reading adjusted to a known calibrated source. I compared these meters to my 6 digit multi-meter for adjustment .

These work exactly as described, tested only on 12 volt systems but reads great, hit or miss on accuracy out of the box, some pretty far off, green one in the picture was straight out of the box untouched and almost right on the nose.Haven’t tested power draw, hopefully it doesn’t run down the battery, I’d be surprised if it did. It is pretty darn bright too.

The power voltage to +red will work fine at 5 volts and achieve full function and brightness. I think it was at about 20 volts and the magic smoke came out and killed a few. I don’t know if it will last long at 12 volts. It seems to work fine for 100 volts to yellow sense wire. The listed 40 volts to power (red) is probably a bad idea, I don’t think that its regulator can handle it. The wires can break or short so use a tiny dab of Shoe Goop (not silicone) as a strain relief. Other wise, yes they are a good deal. Only four stars because of bad documentation.

You get what you pay for. No more, no less. Don't expect great accuracy from these. Also don't bother trying to calibrate it with the adjustment pot on the back. It's finicky and odds are you'll never get it any closer to accurate than it ships, and if anything you'll make it worse.Maximum resolution is around 0.07 volts.Still the cheapest functional voltmeter you'll find, and also probably the cheapest 3 digit 7 segment display. Scavenge for parts if you want.Solder joints on the wire leads are trash. They can get crossed/ shorted as they are. Recommend desoldering and replacing the wires.

Will buy more

great for rower banks / solar / auto . great for experimenting

Added these to some of my equipment to monitor battery just find a good spot like a old toggle switch and glue using two part epoxy after drying coat with nail polish make it rain proof so far only lost one using super glue?