back to PZEM-031 power display

operating the meter's menus:


This meter has a single multi-purpose push-button on the front that is used to change the backlight, configure
the shunt, set the min/max voltage, and to calibrate the voltage/current measurements.

To turn the backlight on/off, just briefly press the button. The backlight will always turn on when the meter
starts up, but it should remember its setting and turn off automatically if it had bene off before. There is
no "inactivity timer" function for turning the backlight off automatically.

To reset Wh to zero, hold the button down for several seconds. You will first see the power indicator show
"SET". Continue to hold the button down. SET will change to CLR. Release the button, and you should see the
power indicator return to normal and the current energy (Wh) value will start to blink. Briefly press the
button again to zero the Wh and return to normal operation. If you change your mind and don't want to reset
the Wh, do nothing for five seconds and the meter will return to normal operation with no changes made.

To change the min/max voltage, hold the button down for several seconds. When you see the energy indicator
change to SET, release the button. SET will continue to be displayed, energy will be hidden, and you will see
two voltages above. The voltage on the left is the max (which defaults to 90.0) and the voltage on the right
is the min (and defaults to 06.0) These are not the min/max the meter operates at, these are the points at
which the meter will try to alert you of an over/under voltage condition by flashing the backlight. Every 3
seconds a different digit will flash. Briefly press the button to increment the digit. To save changes, hold
the button down for 7 seconds, and "PASS PASS" will be displayed below for a few seconds before the meter
returns to normal operation. To cancel changes, you will need to briefly unplug the meter from power for it to
reset.

To change the shunt value, hold the button down for several seconds. Continue to hold the button as it
displays PASS and SET. Release the button when you see CUR. The current shunt value will be displayed in
the Amps position, either 50 or 100. To change the value, briefly press the button. Changes will be saved
automatically after a few seconds of no button pressing. You should probably recalibrate the current reading
after changing shunts.

Recalibrating the meter does not involve the button. Instead, you will need to obtain an electronic load that
can be set to maintain a 1 amp current draw, a power supply that can provide a precision adjustable voltage of
at least 25 volts, and a precision volt-meter. You will also need a short bit of #20 or so solid wire.
When you are ready, proceed:
- configure the electronic load to 1.00 amps, and leave it turned off for now
- configure the power supply to 20 volts and leave it off for now.
- connect the power supply to the SOURCE on the meter, using reasonably heavy, short wire. 3ft of #10 is good.
- connect the volt meter to the SOURCE, AT THE METER.
  Do not connect to the power supply or in the middle of the power line
  It's fine to just hold the meter probes on the top screwdriver heads on the green connector
- turn on the electronic load
- turn on the power supply
- adjust the voltage on the supply so that your PRECISION VOLTMETER (not the PZEM or power supply) reads
  20.00v. Don't take too long to do this, wires warm up and resistance will start to change, causing the voltage
  to drift.
- turn off the power supply. give the wires a minute to fully cool back down
- locate the two pads on the meter's circuit board labeled "W". One terminal is square and one is round.
- bend the short wire into a U shape and insert it into the W contacts to short them together
- turn on the power supply (the electronic load should still be on)

The meter display will start up showing "CAL CAL", and then change to "PASS PASS" when done. If you see this,
the meter should be properly calibrated for both voltage and current. You can verify voltage reads whatever
your power supply is currently set to (with the load turned off), and then turn the load on to verify current.

If it displays something other than "PASS PASS". review the above steps and try again.

Don't forget to remove the wire from the "W" contacts after you're done calibrating the meter.

Also keep in mind that the voltage reading is going to be lower than expected when there's any significant
current passing through, especially when using thinner power wires. Wire resistance and higher current will
combine to create a voltage drop across the wires. Voltage should be pretty accurate when current is zero.


calibration procedure (at Drok.Blog)



last updated 02/04/2025 at 10:20:22 by make_www_index.command version 2025.01.29.A