@hek I am seeing a lot of st=fail on my nodes. I have added a 4.7uF capacitor between ground and VCC but that did not help. What should I try next? a bigger capacitor? I am using an iphone wall charger as power source.

Thanks!

YES!!! That was it! I got both relays powered from the external power supply now and everything seems to be working fine.
Thank you all very much!

@Nuubi
This is how I have my connections:

Is there anything wrong with it?
Thanks!

Thanks for the heads up. But I tried 9v and 12v and no luck! They only click when powered directly from the Arduino and they stop working after a few hours.

@ServiceXp
What kind of power supply do you use to power the relays? I've tried several different options (iPhone charger, iPad charger, and various other 5v power supplies) but no luck. The LEDs on the relay turn on, but it doesn't click. Would you have a picture of one of your relays so I can see your setup?

I also tried following the advice from @BulldogLowell and powered the relays from the VIN pin instead of the Arduino 5v output, but I had the same problem. The relay worked for a few hours, then stopped working.

FYI: I am using a relay with optocoupler just like the one posted in the link above. Maybe I just got a batch of bad Arduinos from China?

Thanks!

So my problem is definitely that the Arduino is not strong enough to power the relays. When the relays are not powered by the Arduino, my sensor communicates with the gateway just fine. It's been on for more than 24 hours now and still communicating fine.

I found this somewhere else, and I think it's exactly what was happening:
"if you draw too much power from the +5V, the thermal protection circuit on the voltage regulator will trip and the whole Arduino will shut down"

So I just need to find a way to power the relays from an external power source. Has anyone done that?
I've tried several different power sources, and with all of them the relay LEDs turn on but it won't click when turn it on/off. I even tried powering the relay from another Arduino just to make sure the voltage was right, but still no luck.

Thanks!

@sundberg84
Mine says SRD-05VDC-SL-C on top. Im pretty sure this is a 5v because it works fine when powered from the Arduino 5v output. I just wanted to connect it to an external power source because I have two relays connected to my Arduino now and that might bee too much for it to handle.

@BulldogLowell

I tried the ipad charger and still no luck. I also tried another power supply with output 2.5A @5V and it didnt work. Now I'm just curious, if I need a bigger power supply to power the relay, how come the Arduino is able to power it from it's 5V output?

Thanks for the help!

@hek said:

Also try feeding the realys directly from the 5V input from the charger.

I tried doing that, but when I feed the relay with the external 5v supply they wont work. The power light turns on and looks good, but when I click on/off in the UI the relay wont switch. Do I need to do anything special to power the relays directly from the charger?

Thanks!

@BulldogLowell
That is a good idea. But if I do so, can I choose which relay I want to turn on/off from the UI? The water pressure here is not very strong, so I need to turn on only one irrigation channel at a time. But I will give that a try anyways!

Thanks!