Led voltmeters - input range

I bought some led voltmeters to monitor the voltage of some Li-Ion batteries.

However, they will not measure anything less than 4.5 volts.

I found some others with these specs.

• Measuring range: DC 0V--30V
• Input range: DC 2.7V-30V

Does this mean that the lowest voltage it can read accurately is 2.7 volts?

2.7V is the minimum supply voltage it needs to operate.

The display range is 0 - 30V.

Some of the LED voltmeter modules are powered by the voltage they are measuring. That's probably the one you have that measures only down to 4.5 volts. This type of module will only have 2 wires.

Other LED voltmeter modules use a separate power supply - they are not powered from the voltage you're trying to measure. The "measurement range" is the voltage you are measuring. The "input range" is (probably) the supply voltage to operate the meter. This type of module should have a pair of wires for the measured voltage and a pair for the supply voltage.

That may explain why the voltage show on the led meter is not very accurate compared to the readings of my multimeter.

I can not find any meters with 4 wires that will measure from 1.5 volts to around 12 volts.

I found this.


But I bet dollars to donuts that it has no instructions as to which wires are for supply current for the meter and which are for reading the voltage.

And since it measures such a wide range, 0 - 200 volts, would it display a value of say 4.3 volts?