Arduino shields drawing too much.

For the life of me I just can't think of a good solution to my Arduino sucking so much power...or it seems.

Basic setup of boards:
Arduino
2.8" LCD with touchscreen and sd card slot
2 x 5v relay boards (4 channels each)
RTC 1309
8 x temp sensors with 10K resistors (2 per box/tent)

I connected everything up and it had been running for a few months without problems.
Removed the temperature sensors due to upgrading to better ones at end of this grow with humidity and temp in 1 unit/part...this was about a month ago.
Shortly after removing the temp sensor parts/pieces 1 relay board kept having issues turning the lights on, but unplugging the power connector and plugging it back in once or twice fixed it, daily, but I wanted to find the issue once this grow finished.
I also wanted to clean up the wiring and few other small things while I was at it...1 at a time though...lol
Currently stuck at the relay boards sucking a lot of power and not working. I can connect just the Arduino (+LCD shield) and 1 relay board and RTC and things work, but as soon as I try to connect a second relay board the proper 5v drops to about 3.5 and the relays wont latch. Switch relay boards and same problem.
I thought without the sensors I'd be using less power, but for some reason 5V @ 2.2A isn't enough to run the project anymore.
Any ideas on what I could do to beef up the juice and not fry the Arduino...may try to use a separate 5v source for relays and link grounds (-)...just seems odd that it worked fine and now its struggling with less components.

How are you powering the Arduino board, via USB? Which Arduino is it we're talking about here?

Does it still fail regardless of which relay board you add first? Sounds like you may have an incidental short somewhere that's drawing amps needlessly.

When using relays that switch mains power, I like to power everything from an external 5v source, then use the Vin pin to power the Arduino board itself.

If you have an ammeter, try connecting each device (relays specifically) to a 5v source through the ammeter and see what kind of mA you're drawing. This will tell you if something is drawing too much current where it shouldn't be.

spek9 said:

How are you powering the Arduino board, via USB? Which Arduino is it we're talking about here?

Does it still fail regardless of which relay board you add first? Sounds like you may have an incidental short somewhere that's drawing amps needlessly.

When using relays that switch mains power, I like to power everything from an external 5v source, then use the Vin pin to power the Arduino board itself.

If you have an ammeter, try connecting each device (relays specifically) to a 5v source through the ammeter and see what kind of mA you're drawing. This will tell you if something is drawing too much current where it shouldn't be.

Click to expand...

Oh yes sorry didn't even think of those questions...lol

1-Arduino 2560 Mega on USB power.

2-Converted a USB hub power supply, not using the hub itself, into a single USB plug with 5V @ 2.2A.

I tried using different supplies prior , but it need to be linked in some way...guessing now its the Vin line?
How does that work when I dont need another 5V going into the device, but need more amps to run more shields?
Sorry, not sure how to word that properly...brain is fried thinking on this all day...lol

These are the relay boards...both are the same as the bottom one now...changed 2 of 4 relay on each board to handle amps needed for lighting...they were 2A, but now are 5A.

Use a laser thermometer and while powered, check the relay pcb for hotspots.

Arduinos have shitty power regulators because they're built into the microcontroller so any decent amount of current draw will max them out. Use an external power supply, like this:

https://www.amazon.com/HiLetgo-Supply-Module-Prototype-Breadboard/dp/B00HJ6AE72/ref=sr_1_10?keywords=arduino+power+supply&qid=1578027221&sr=8-10

SPLFreak808 said:

Use a laser thermometer and while powered, check the relay pcb for hotspots.

Click to expand...

Its not a heat issue...just when 2nd relay board is connected it all goes down hill and stops working due to not enough power to latch the relays and when I checked with a meter it was like 3.x volts from the previous 5 (think it was 4.7 with 1 relay attached)
Going to do some current checks tomorrow...just didnt want to rip it all out if I didn't have to.
Thanks for suggestion though...appreciate an ideas at this point...lol

LarsVegasNirvana said:

Arduinos have shitty power regulators because they're built into the microcontroller so any decent amount of current draw will max them out. Use an external power supply, like this:

https://www.amazon.com/HiLetgo-Supply-Module-Prototype-Breadboard/dp/B00HJ6AE72/ref=sr_1_10?keywords=arduino+power+supply&qid=1578027221&sr=8-10

Click to expand...

Its not draw from the Arduino exactly...its everything combined seems to pull more then 2.2A now when I dropped the temp sensors and not sure why.
I'm starting to think its the relays I swapped out before. I used coil relays and took out solid states...gonna order some 5A ss relays and see if it helps...maybe even see if I have any SCRs around that can handle the amps...hrrmmm
I'll draw up a quick plan of it later...maybe some pictures will help my explanation better.

The LCD shield covers almost all of the Arduino Mega and pulls power from the Arduino.
The other shields all have pins for external power, but draw a lot of power it seems when all are connected together.
Hope this helps a little more.

Get a 5v meanwell psu. Power all your 5v devices off that (including the arduino via it's 5v and ground ports). As stated above, the power regulator on them sucks and I like to provide a stable 5v source while bypassing the regulator. Coil relays use more power than SSRs. I also like to connect the psu to a UPS to really make the power stable.

friedguy said:

Get a 5v meanwell psu. Power all your 5v devices off that (including the arduino via it's 5v and ground ports). As stated above, the power regulator on them sucks and I like to provide a stable 5v source while bypassing the regulator. Coil relays use more power than SSRs. I also like to connect the psu to a UPS to really make the power stable.

Click to expand...

Power supply isn't the issue...well mostly.
The shields are not powered from the Arduino...they all share the same 5v source with the Arduino. So changing PSU won't do much of anything.
I do believe its a problem from the coil relays drawing more then I expected...new 5V @ 5A SSRs have been ordered
And I'm not sure the regulator is used in the USB port...just the other power plug...will have to look that up again...my memory isn't what it used to be...lol

Who gives a shit how much current relays use? Just provide the necessary current and the shit will work.