Self-powered digital voltmeter/ampermeter ?

Thread Starter

Externet

Joined Nov 29, 2005
1,609
Greetings...
Maaaany years ago there was a discussion somewhere, why a multimeter was unable to power itself from the voltage being measured. Or was it able to ?
Can anyone refresh the subject ?
Am after one of these to permanently display the DC generated by a solar panel array, up to 600VDC / 20A full scale. If turns off at night as there is no generation, fine. If turns on again at dawn, perfect.
1620694971602.png
 

dendad

Joined Feb 20, 2016
3,835
600V20A_meter.png
If your meter is one of these, you will need to add a power supply as the max input for that is 30VDC.
One way may be to use another small solar panel to run the meter.

What is your actual expected DC output from the main solar panels?
If it is under 350VDC, a universal plug pack, like a phone charger could be used as they will run fine on DC input.
Or you could add a charger and rechargeable battery to keep the meter running.
 

Thread Starter

Externet

Joined Nov 29, 2005
1,609
Undecided yet to run on 240VDC or 480VDC. Am in the installation process. A dedicated small panel sounds good for the meter I still have to choose. Thanks.
 

Bernard

Joined Aug 7, 2008
5,788
My 5.5 kW system displays DC V, I, kWH, so should be dooable but for home brew T'd go for a small panel as a low power HV DC to DC, isolated inverter might be hard to come by.
 

MisterBill2

Joined Jan 23, 2018
8,781
A meter that requires power to operate and measure should not affect the circuit being measured. So for lower powered circuits it must have a separate power source. For higher powered circuits it may not affect the circuit by drawing power from it. So there are two very different classes of operation.
 
Top