I had a 5V One Channel Relay Module Relay Switch that broke after repeated usage (e.g., 3-4 months). I am wondering if there are any ways to prolong the life of a relay module switch or are there any better 5V Relay Module Relay Switches that could last for a longer period of time (e.g, 1-2 years). I have heard of industrial relay switches but I am not sure if they can be paired with Arduino, or if there are any viable options.
Lastly, are there ways to install a 'fail-safe'? For instance, in the event one relay breaks another relay could take over?
You get what you pay for. If you buy industrial quality relays you will pay more and get longer life. No problem using with an Arduino but you will need something to drive it, most probably a logic level N channel MOSFET, and don't forget a diode across the coil. I think you can buy industrial relays with built-in drivers, do some searching.
However, the problem might be your circuit is damaging the relay, if you want an opinion on that post a schematic and list of parts. Also, do make an effort to quantify how many operations your relay makes, there might be ways to reduce it.
Do you have a way to determine when a relay breaks? Does it fail to make contact? Does it fail to open? You can certainly put relays in parallel and operate them simultaneously.
you say that the relay failed. you do not specify how it failed. smoke out of the coil? melted contacts welded together? oxidation on contacts preventing current flow?
the most common relay failure, in my experience: big fat blue sparks across the relay contacts when they open, which oxidizes the contacts, turning the relay switch into a resistor.
cause:
relay energizes
NO contacts close
load draws current
contacts open
magnetic field created by motor under load collapses in microseconds
inward collapse of magnetic field is a magnetic field in motion. a magnetic field moving past a wire induces a current. the collapsing field is in inverse polarity to the current that created it, so it generates an opposite voltage. this voltage is not determined by the voltage that created the magnetic field. it is determined by the rate of collapse, and the strength of the magnetic field. a 6 volt coil that collapses instantly can generate a -321 VDC surge when it collapses. this is the source of the fat blue spark when you unplug a running DC motor.
the solution is a commutating diode, which is well documented on the internet. basically a diode with a high PIV - peak inverse voltage rating - connected from the side of the relay contacts that feed the motor, to ground. it is installed in reverse polarity - the cathode connects to the positive side of the motor, anode to ground. it shunts the fat blue inverse polarity surge to ground. no fat blue spark, no oxidated contacts
The top review of the solenoid valve is very informative, highly suggest reviewing it.
The common part number for the relay component used in the 5V single relay module is SRD-05VDC-SL-C. From the datasheet, I've highlighted the contact rating when used with your solenoid ...
Mechanical relays are very poor at switching a DC load. In your case, the load is close to the relay's max rating. Additionally, the fiyback diode across the relay coil (on the relay module) has a side effect of giving the relay a slower release time, which further depreciates life expectancy of the relay module when switching a large DC load.
Post #2@Idahowalker has my vote as a suggested replacement.
In my experience relays are generally very reliable (when used within-spec and not over-stressed).
I've only seen a few relay failures in my life...
I had a horn relay in a car go bad once. And in the old days the turn signals were controlled by a "flasher" which was a little module with a relay and a timer and occasionally they would fail. There are LOTS of relays in a car and failures are rare... I've now got a 20-year old car and a 30-year car and neither of those has ever had a relay failure.
I've never had a relay failure any anything I've built.
There are also solid state relays that will "last forever" like any solid state electronics, if not over-stressed. Electro mechanical relays are actually a bit more "rugged" when it comes to voltage spikes and current surges. Those things can fry solid state electronics instantly.
Note that AC & DC solid state relays are not interchangeable so you have to be more careful selecting one. But, you can find solid state relays that can be directly driven by the Arduino without a driver circuit.
I agree. I've also seen them being poorly used and turning on and off every few seconds, leading to the "designer" being surprised that they die so quickly.
