2pcs 12V-36V DC Voltage Protection Module Digital Low Voltage Protector Disconnect Switch Over Discharge Protection Module

Voltage is there, accuracy, build is good, ease of use is not there, you will need to look on YouTube. No instructions

The built in voltmeter is within a few hundredths of a volt to my Fluke meter.The disconnect was within 0.1v of the disconnect setting. Perfectly acceptable for a $5 part.Some have complained that the disconnect continues to drain the battery after disconnecting the load.In my application, I have a 12V SLA battery, an AC to DC power supply set at 13.5V (float voltage) and a load.I connected the power supply and load to the VIN terminals, and the battery to the VOUT terminals.This is opposite to the published diagram.When the AC voltage drops out, the load stays on until the battery voltage drops below disconnect (12v), then the relay opens and the battery is disconnected and has no parasitic load.When AC power is restored the relay closes and the battery gets charged.

This is a very simple but ideal unit for Battery systems. I have configured one with a Battery Charger Plugged into a IOT Relay to turn the charger on when the battery is 25% low and then turn the charger off when battery is fully charged. The other Voltage Protection Module I will use to disconnect the battery complex if the voltage gets too low.The one little funny issue I had set (left button 11.5V) then you set a different voltage (right button to .5) this is wired until you understand if the full voltage is 12V and the charge voltage is 11v the different voltage is .5V. Yea I know a little wired, once you figure this out its easy to work with. On one of my units the voltage read .1V off no problem if you want true 12v you set it to 11.6v. These are very inexpensive units that do just what I needed them to do even more expensive Voltage Protection Module can't do what these little guys can do.

1st one lasted about 4 months on a solar configuration, now its not accurately reading voltage ( low by about 1-2 volts) but did the job. On the second one now, for cheap price still worth using to tinker with, I would spend more if you need something reliable long term.

Another seller of this same item has excellent directions on the amazon page. This seller doesn't. I took off one star for directions. It looks to me like several sellers are selling the same item. The first one I got, from another seller, did not work at all. I opened the first one from this seller and it worked like a champ. And I have a spare. Every feature worked fine. When I lowered the voltage below the cutoff, it cut off great. When I raised it 2V over the cutoff, it came back on. I did not have to adjust the voltage, it was spot on to my meter out of the package. Perfect. I have a 24V LIFEPO4 battery, and it is nominally at about 26V. By 24V, there is almost nothing left in the battery, but my circuit doesn't like low voltage, so the cutoff at 24V makes a clean off, so if I forget to turn it off (yes, I did that once, with bad results), the circuit is protected. This is even higher cutoff than the battery pack bms (2.5V/cell=20V) .

I don't understand why they didn't put a switch on the board to shut off the led readout. The whole point is to protect a battery from discharging too far but it will literally keep discharging your battery by itself.

Came exactly as shown. Will purchase again in the future.

Great product, Awsome price.