Might have wrong digital voltmeter?

[ChibbMD]

Hey folks. I recently picked up a 3-wire digital voltmeter off Amazon. I was careful to pick one that said it handled up to 100V. I thought this was all I needed. It arrived this morning and I went out to the garage to test it before installing. The three wire colors were red, black, and yellow. I was running leads off the positive and negative terminals of a 48v battery pack and assumed I would connect the black to the negative terminal lead, red to positive lead, and yellow to positive lead to get the correct reading. When I connected red and black wires the meter would come on and read 0.0. When I connected the yellow wire it just stayed the same. I then proceeded to switch the wires around to see if I could get a configuration that would work. No dice. Best I could get was zeros.

So I took a closer look at the decals on the meter and noticed that it said DC 3.3-30v despite having another reference to 100v. That's got me thinking this meter isn't going to be able to handle 48v. Am I right?

And lastly, If I buy a simple two-wire meter, and I want it to be switched to the key, do I simply connect the black to the negative terminal and the positive to the key switch power?

[Sergio]

The 2-wire meters are definitely more convenient to connect.

Hopefully You have not burned that one yet, but the 3-wire meters require two different voltage levels, one to operate and one to measure.

Black: Pack negative.
Red: ( +12v output if You have a reducer or from a battery post that provides +12v or +16v).
Yellow: Pack positive.

And lastly, If I buy a simple two-wire meter, and I want it to be switched to the key, do I simply connect the black to the negative terminal and the positive to the key switch power?

Yes

[ChibbMD]

Thanks Sergio. I don't have a reducer yet (it's on its way), so I was hoping this meter could handle 48v to operate the meter. It looks like it can only handle up to 30v for the meter power. This one is going back and I just ordered a replacement from Scotty B, so I'm sure it will be exactly what I need.