These meters are good when you want to measure current and voltage at the same time. A feature that usual multimeters lack. For example, you can use it to measure the output of a solar panel. They are inexpensive and easy to connect.it is all in one solution for monitoring voltage and current. External shunt included for the 100A model.
These meters calculate current flow by the voltage drop across the shunt resistor. They have built-in shunts that should withstand measuring as much as 10 amperes. You must see shunt behind your volt- and ammeter. That small bridge bent from a thick wire on PCB.
Built-in shunt on volt- and ammeter-100V / 10A / DSN-VC288
They are basically the same. There is a connector with thick wires and connectors with thin wires. But the coloring of wires varies. Amperage measurement is done by passing power through thick wires. Power to the meter itself is fed through thin wires.
They all can be wired in such a way that you don’t need a separate power supply for the electronics part. You can use the same power supply where your measured load gets electricity. But then you can only use a maximum of 30V since it’s the maximum operating voltage for the meter itself. Also, you can’t measure voltages below 4.5V. If using the same power supply you even can leave thin black wire un-connected since they have common ground/GND.
You can’t reverse polarity on these meters when measuring amperages (voltage also)
Also important! You CAN’T read current in the reverse direction with these ammeters.
Wiring DSN-vc288 makes the most sense to me and seems to be most popular also. It also has clearly marked model name on the PCB which makes it easier to identify.
HOW TO Wire a DSN-VC288 volt- and ammeter
Important! The voltage sense line is also a thick wire and it’s not yellow. It’s a red one instead!
10A / 100V volt- and ammeter wiring with thick red, black and yellow wires and thin black and red