HiLetgo 2pcs 24V Single Bistable Self-Locking Relay Module Push to Start and Stop …

I bought the 24V version. It was a 2-pack. The first one didn't work at all. I tried the second one and the power LED came on! It actually worked properly, both with the onboard switch and the pushbutton. I powered it down for a couple of minutes. When I turned power back on it didn't work. No power LED. Dead as a doornail. The quality control on these is nonexistent, or it's just a terrible design that can't handle the rated voltage.

Contrary to the other negative reviews, these do work. On one side are three terminals. This is where you attach the load you want to switch on and off. In theory this load can consume anything between 0 to 10A, and 0 to 28VDC. As with nearly all relays, you can decide whether you want the load normally powered, or normally unpowered. On the other side are two terminals. This is what powers the relay circuit itself. How much power is needed? The vendor doesn't say. I found that a mere 5V was enough to make the red power LED turn on, and I was able to switch the green LED on and off. However, 5V is not enough to engage the relay. I then tried 9V. Same result. I then tried 12V. Same result. I then tried 13V and voila!—the relay started working. Can I go higher? I tried 24V. No problem. Higher? Probably up to 28VDC, but I didn't try. Where confusion comes in is that both sides of the board (the relay circuit and the load) can be powered from the same DC source. So the same 24V battery (or whatever) used to power the relay circuit can also be used to power the load you're trying to switch on and off. But that doesn't mean power flows from the two-terminal side to the three-terminal side! And in fact that isolation is why we often use relays in the first place, even when the current requirements are modest, and a single switching transistor might suffice. The test button and LEDs are nice features to make sure the module itself is working without having to wire up the external switch. So why four stars instead of five? First, the lack of clear instructions. Also, the module consumes about 100 milliwatts in standby mode, and about 700 milliwatts to energize the relay, which is electrically latched, and must remain energized to stay that way (mechanically latched relays would only consume power to switch state, and are far more efficient).

Bought the 24V version to test suitability in my applications. The boards are marked "HCW-253" (on the photo - FC-73); an unnamed chip marked "FMD" and "B2NTRDE" was used (on the photo - STC 13F104E). Current consumption 19 mA (relay off) and 48 mA (relay on) when powered by 24V DC. One board died after 2 switches. A stationary (laboratory) power supply was used (test voltage 24V +/- 0.01V DC). Most likely, the built-in stabilizer burned out and then the microcontroller, but I have not yet checked for sure. The second board has not been tested yet, but I am more than sure that the quality is the same as the first one. Saving on millicents in production leads to produce garbage.

Build quality is spot on, but that is where it ends. Picture show that it has an STC-15F104E IC but that is not what you get, instead it has FMD-B1K0 IC that you can find nothing on. The only wireing diagram is that which you see with the listing. Says it can handle a base of 12v, the IC on one of mine blew its keaster (lit up and cracked apart) out between 12 and 15v. I'll admit, I wasn't looking at my multimeter at that exact moment, but I know what the exact range was limited to because I was attempting to use it for a mod on the turn signal wiring harness for my motorcycle which has a 12v system.

No matter how I tried on my test bench I could not get this relay to work. Whipped out the multimeter to confirm and it just never actually translated the action to the contact side of the board. No matter how you try you can't get it to work. Junk.

Hooked up to test with all voltages verified and the relay doesn’t change state at all using the test button and the trigger wires. Don’t waste your money or time.

Exploded, 12 V from bench with .5A OCP, shrapnel hit my face. Don't ignore the bad reviews

1out of 4 order actually worked.