Qwiic Quad Relay - Bad Relay?

Qwiic System
1

Hi,

I recently purchased two “Qwiic Quad Relay” boards, and started using one of them.

For the circuit I am using a Adafurit feather ESP32 Huzzah in combination with “Qwiic Shield for Thing Plus” and I have no problem controlling the relays. The I2C bus is working fine with no problems. The issue that I have is when I connect a load to relay 1, I find that the relay contacts do not reliability close. If I exercise the relay by turning it on and off I find that about 35% of the time it does not make good contact closure. When the bad contact closure occurs there is little to no current going to the load. When the problem does occur I find that if I tap the relay hard with my finger the contact will close.

For the circuit hook-up I have closed the “5V Wall Adapter Jumper” and have a laboratory power supply connected via barrel connector that is set for 5 volts, current capacity of the supply (Instek GPR-1810HD) is rated at 10 amps. The load that is connected to the relay is a SparkFun heating pad (COM-11289) that is powered from the 5 volt supply and draws about 600 ma. I am using the “normally opened” position. When the problem occurs the power supply is “not” in current limit. Spec sheet for the relay (JZC-11F) on the SparkFun web page indicates that Min. Switching Load is 10 ma at 5V, which the circuit easily meets (i.e., 600 ma at 5V).

After finding the issue with relay 1, I changed the circuit to use relay 2 which is reliably working. I have not had time to test relays 3 and 4 or the 2nd Quad Relay Board that I purchased.

Because of the bad relay, is there anyway to get a few replacement relays or should I return the board for a new one? Note, I do have solder rework equipment and it would not be too difficult to unsolder the bad relay and replace it with a good one. It would be great to get a few spares just in case I find an issue with another relay.

Any help that you can provide is appreciated.

Thanks

2

Hi rsavage.

Can you try increasing your power supply voltage to the barrel jack on the Qwiic Quad relay board to about 7.5 volts and see if that makes things run reliably? (With the 5 volt jumper on the back of the board still closed.)

3

I increased the power supply from 5 V to 7.5 V and toggled “relay 1” on and off 100 times (5 seconds on and 5 seconds off). Result was that the contact closure worked 100% of the time. Click sound from the relay was also louder and more solid. I used the same load (heating pad) and current draw through the relay at 7.5 V is about 860 ma, as compared to 600 ma when the supply was set to 5 V. … Let me know if you want me to try anything else?

4

We’re working on a long term solution for this, but it sounds like the extra voltage is doing the trick for you and I think that might be where you want to leave things. The only potential drawback to the extra voltage is that the relay board runs slightly warmer than it would otherwise. (But this won’t hurt the board)

It sounds like you’re using the same power source for your heating pad and the relay board. The only other side effect is that your heating pad will get slightly warmer as well, but you’re well within the safe voltage limit for the heating pad. You do use a little bit more current this way and the heating pad is a bit warmer, but since the goal is to produce heat anyway, you’re just doing that better. :wink:

5

Running at 7.5 V is ok with me and also helps me get up to temperature faster. For future reference, what would you consider the max safe input voltage to be with the 5 volt jumper closed?

6

My testing indicates 8 volts as a max.

You might be fine down to 6.5 volts as a minimum voltage but don’t exceed 8 volts with the jumper on the bottom of the board closed.