Relay sensors stop communicating with gateway after a few minutes

[rafael.brasilia]

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!

[BulldogLowell]

@rafael.brasilia

Reference this you should be powering the relays from Vin which is directly powered (5V) from your USB cable and is not regulated by the Arduino. in other words, the power at Vin is regulated by your power adaptor.

The 5V (AKA Vcc) pin is using the Arduino's on-board regulator, and indeed the current is limited by that device. If you power your arduino with the Raw pin, using a 9V battery for example, the Arduino's on-board regulator will drop that voltage to 5V, thus its marking.

I hope that's clear.

[TD22057]

Perhaps someone w/ more electronics knowledge can comment more but in my limited research, you can reduce power consumption to the relay by getting one w/ an optocoupler. There is a good write up here: https://arduino-info.wikispaces.com/RelayIsolation

Most x2, x4, and x8 relays on aliexpress that I have seen have optocouplers. Here are some single relay boards with them: http://www.aliexpress.com/item/Free-shipping-5Pcs-Lot-Level-Triger-Optocoupler-Relay-1-Channel-H-LModule-for-Arduino-5V-New/32390536994.html

[Sparkman]

@TD22057 The relay coil will draw a certain amount of current at 5 VDC. Using opto-couplers does not change the amount of current the relay draws. However, some of the relay modules will use transistors, etc. to ensure that the current for the coil is not supplied by the digital output pin of the Arduino as the output pins can't typically source enough current for that.

Cheers
Al

[RJ_Make]

It's a strange problem. In most of my "projects" I power the relays directly from the power supply, home built or mfg and other than adding some capacitors have not seen these problems. Now I aways use Opto-controled relays so I don't have to use any diodes...

[rafael.brasilia]

@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!

[Sparkman]

@rafael.brasilia I'm wondering if the relays are actually 9VDC or 12VDC relays that are misprinted as 5VDC. What happens if you power them with a 9V battery as a quick test? I use old phone chargers with similar 5V relays and never had an issue with powering them that way. Do you have any other relays you can test with?

Cheers
Al

[sundberg84]

I thought the same, it was how i detected i had 12v relays instead of 5v. I just quickly powered with 9v bat and then the relay clicked.

[rafael.brasilia]

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.

[Nuubi]

You should probably draw a circuit diagram about your connections?

[rafael.brasilia]

@Nuubi
This is how I have my connections:

Is there anything wrong with it?
Thanks!

[korttoma]

Try adding a wire between the GND on your relay board and GND on your arduino. Even if they have seperate power source you stil need to connect GND between them.

[Nuubi]

Exactly that is the reason. Yep.

[rafael.brasilia]

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!