Voltage Monitor Module, A30-U1 DC 0-99.9V Delay Relay Controller Board for Overvoltage Undervoltage Control Voltage Detection

Review from Electrical Engineer: There are quite a few advantages over the similar but lower cost "walfront" device. This device comes with a cover which includes a window to view the LEDs. This device has screw terminals that take ring terminals instead of push in and tighten type terminals. This would provide better security against wires pulling out. However, attaching wires large enough to handle the larger relay spec of 230V at 30A is questionable since the rings must be quite small to fit in the terminal block. This device also allows fine tuning of the voltage reading in .1V increments. You can also swap the on/off state of the relay. In addition, the display is in a socket so you can remove it to save power but there is also a setting to turn the display off after n seconds after power on. Otherwise, the function is similar. My use case is Residential Supplemental solar, and the requirement is to perform automatic load shedding when the battery gets low. This is achieved by connecting AC grid power to my inverter (with transfer switch built in). The AC power switching done by controlling a solid state AC relay instead of attempting to drive the AC load directly. This should extend the life of the relay. In addition, a second unit will be used to power up the battery charger when the battery voltage gets even lower. As a matter of convenience, I rotated the board in the enclosure so that the slotted mount point is at the top making it easier to mount since it is difficult if not impossible to get a screwdriver to that mount point with many wires attached to the device. The voltage reading is relatively accurate. I wish the board would allow setting thresholds to the second decimal point instead of just one. A way to zero-in the voltage reading would be a plus. Search around on amazon, there is another company selling the same thing for 8 bucks less.

I got this for implementing a "dump load" in my R.V. It's a way to automatically dump excess electricity into a load, Such as a hot water heater. When my battery reaches a full charge, My solar panels sit idle. I can dump excess power into the hot water heater so that the solar panels can continue generating power for the rest of the day. This device allows me to detect when the battery reaches a full state of charge, and then run the dump load. There is a double throw relay with normally open and normally closed contacts. This can be used to implement any solution. I used it to trigger a separate timer relay device, Which turns the water heater on for 5 minutes. Solar charging continues until full again, and the dump load runs repeatedly as long as the battery reaches full. I find this to be a well built reliable device that easily handles 20 amps.

When display off draw only 5mA

Very good design and quality module. Very nice packaging. Has very useful setup functions to create high and low compare points. Input voltage of 99.9V and supply voltage up to 80V are excellent. Display of measured input voltage can be offset for calibration up to +-0.5v. Isolated relay for interface is HD 30A. Only issue is the operating instructions which are not clearly written. I have rewritten and attached here.

Fit my requirements

Fast delivery and works as it should

I works well for certain projects like battery management. It has a low input impedance so it places too much load on more sensitive electronic circuitry.

Measures and powers relay with DC. Relay described to relay DC, the switch itself has printed on it 120/240 AC for the relay. Very useful since it is being used to power AC space heater and dehumidifier. Directions were not included. Found excellent directions posted by a previous reviewer tho. Thanks to them it is up and running!!!

Prodotto buono ed efficiente

Ich habe mittlerweile 3 Stück von den Reglern. Sie funktionieren hervorragend zur Spannungsüberwachung der Batterien. Wenn die Spannung zu niedrig ist schaltet er das Ladegerät zu. Alles in bester Ordnung. Klare Kaufempfehlung.

Preiswert und gut habe es an der Solaranlagen um mittels Relais den Wechselrichtet bei 11,8V abzuschalten, funktioniert perfekt 👍🏻

Utilizzato per accensione automatica di un inverter di un impianto fotovoltaico, fa egregiamente il suo lavoro. La lettura della tensione è precisa (anche se non lo fosse esiste la possibilità di aggiustarla con una taratura). È possibile scegliere quando il relè deve scattare, cioè se la tensione è in salita oppure in discesa. In ultimo c'è un delay per lo spegnimento del display per evitare di consumare troppa batteria. Attenzione a restare nel range di corrente del relè interno (molto meglio tenersi piuttosto bassi rispetto al massimo dichiarato). Il prezzo alla fine però è piuttosto alto per i componenti che ci sono, ma la sua utilità e la sua versatilità ne fanno un componente utilissimo.

Ok