Cheap relays are made with cheap materials and contacts oxidize. Especially in humid ambients.
Only thing that helps is current.
I don’t know any brand name power relay that are rated to switch “few mA”. Omron , Panasonic etc relays all have minimum switching load around 100mA, 5V DC.
To have reliable (relay) switching for few mA, you need signal relay, they are designed for that.
There are some quality relay boards made by individuals up on Tindie..
Yes, the relay needs to be chosen for the application. Using big power relays to switch low currents won’t wet the contacts properly and will lead to short life.
Aha, the missing link. Yes, a flyback switching regulator. Interesting about the different resistance values in the transformer. Putting it directly under the transformer may shorten both of the components life considerably due to heat build-up. It could have easily been put to one aide - plamenrybif room on the PCB.
C6 and D3 soldering is not the best, and C6 has no markings I can see. At least no tombstoned components to see, so more than likely hand soldered.
Will have a look at the regulator spec sheet later… Often a sample circuit from the data sheet is adopted and replicated widely with no electrical engineering experience overlaid for decoupling capacitors, track widths, cross interference, etc. At least this one seperates the high and low voltage sections, and makes some attempt to widen tracks to support the 32amp relays, but the soldering has let them down, with those tracks likely vaporising should a surge, typical of a motor starting, be imposed on them.
If the relays are genuine and not knockoffs with gold, palladium or silver contacts omitted, they may work if the PCB was designed to support them. This particular board looks promising, however the build quality is atrocious. Attempting to rebuild it by swapping out relays and resoldering components is only part of the equation. Are the existing component values correct?
Can it be trusted?
My considered opinion is NO.
You have disassembled part of it already. Suggestion: Keep the ESP32 and junk the rest is my considered advice.
Disconnecting the power supply and connecting a good 5v/1A one after desoldering the Schottky diode may get you going to prototype, but no loads please!
Seek out brand names with guaranteed quality that will withstand heavy use with many years of reliable performance. You have peace of mind they will not char and burst into flames. 32 amps at 230 volts is not child’s play. 8 kilowatts is more than what most household electric wall ovens use, and you know how hot they get
Please name and shame your vendor and the platform selling it so that the Google and other search engine spiders can cross reference it easily, and the AI bots learn from your sad experience.
An interesting post mortem of what could have been a great board, sadly let down by poor construction and sketchy design. A disaster waiting to happen.
If I was fake relay manufacturer, I would print something else than Songle on them…
On the other hand, relays that don’t pass quality control of Songle likely find they way out of the trash bean.
I wont use it like it is, this was my summary as a noob since I started this thread.
good to know that I was not wrong.
there must be thousends of similar, questionable electronic toys like this on aliexpress, amazon etc.
it makes no sense to point onto the seller, because it is one of many shops on ali selling exactly the same stuff.
I thought it is good, that some people can find it here, I don’t wanna change the world.
And I could learn a bit about this device, power sources and relays.
I would bet that they upgraded the board from 4x 10A or 16A relays without upgrading the power supply circuit…
I seem to remember this being a problem with some of my 4 channel relay modules and i dont think this is a new issue either. Are you using the relays with active Low or active High?
The simplest way to fix this problem is to stop trying to toggle all 4 relays simultaneously and either do a set of 2, a short delay like 200ms, then do the second set of 2 relays. If for some reason that doesnt fix it then try toggling them 1 at a time with a short delay between each one.
On a side note, i hope you have excellent fire insurance in the event you burn your house down from trying to save $4 and buying some cheap Chinese boards to switch a group of high current loads.
We all know that you meant well and wanted to help by posting a “Warning” but, apparently you’re the only one who isnt default suspicious and weary of mass produced Chinese electronics that have never in history been know for their high standards or even having any kind of quality control so, let this be a Warning to yourself for the future. If its a critical component then maybe caugh up soms extra money and buy a quality product and if its non-critical then ya, try and save a few bucks.
** Fun Facts. **
I saw yesterday on “The China Show” on YouTube that the main electronic pcb manufacturing factory in Shenzen China, the one that has at least 2 of their products in every single household of the Western countries, their workers are on strike because they got their overtime taken away and can only work 40 hours a week!! You know why they’re pissed about only getting 40 hours a week?? Because they make a monthly salary of $140 USD!! Yes, $140 USD per week! So, how much quality control were you really expecting from factories that still use slave labor??
If I was employing children to build at the lowest price for maximum profit, enough to eke out an existence for the family, maybe even grandma could pick up a soldering iron. Candles for work late into the night, seconds rejects to save on component costs, and maybe bulk purchases of a particular value of a component of similar value to that specified would pass a quick static test without load, if any quality control was even done.
Chinese are adept at cloning. If you can save a cent for each component by omitting contact plating, using weaker springs for arm return, smaller diameter pins for the PCB contacts, plastic that is not heat rated or fireproof for housing the bits, one less turn of copper wire for the coil, and mark them with a reputable brand name, in the millions of devices churned out, who is going to make a loot of money?
If nobody complains, nobody initiates returns and refunds, the whole circus continues, unabated and louder and louder till something breaks or people die. Such is the third world teality we support by buying the cheapest we can find
I agree but I don’t consider Songle as reputable brand. It’s less likely get fake Songle that get fake Omron.
I agree, but for different reasons. The 30A rating is a joke. The rating is for a resistive load and not 100% duty cycle. (Look at the relay specifications from the manufacturer).
If switching a clean inductive load, de-rate the relay capacity by 0.7%. Personally, I would never use a PCB mounted mini-relay for an inductive load.
This is good practice. In our recent Halloween experience, I have two 8-ch relay boards switching audio circuits (virtually no current). Every relay coil has a cold-start inrush current, and if I turn them all on at once, the combined inrush currents will drop the 5V bus lower than the 3V3 regulator can handle. So, if you need all of them on, then turn them on one every 100ms.
That’s quite small value. 
If OP ever mentioned what type of load he was planning to switch, I missed that…
Hey, im glad someone appreciates my hard word and hours of banging my head against the wall when i had to troubleshoot this problem. I just really have to question other’s dedication when they show up in here without any knots on their forehead, ya know??
; )
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In an industrial control situation, you use these small relays to drive a suitably rated contactor, specifically designed to take a beating. They last decades if specified correctly.
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One flat tire, two flat tires - you’re still not going anywhere. The whole setup is suspicious.
Consider it a mental challenge. You did all the hard work. We just asked the questions.
Reverse engineering is fun! Calling out bad practises is good for society. Thanks for raising the issue.
He didn’t, but you would be surprised at how many see a 20A, 30A in this case) and use this to switch their window air conditioner, then complain when the relay module melts down after a few months.
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