rpi-28d+ 5v power supply recommendation

[janastas]

I've been running the an rpi 3b+ and the rpi28d+ hat off a 5V 3A power supply I picked up from Jaycar.

5V DC 3A Slim Power Supply 7DC Plugs | Jaycar Electronics

Regulated output voltage, small size and higher power output make these AC adaptors suitable for thousands of different applications.

www.jaycar.com.au

I've just realised that the requirements for an rpi is 5.1V so that .1V has been causing me issues for some reason over the last few days (undervoltage warnings from rpi)

I switch over to at 12v 0.5A power supply to run from the 12v terminal and it seems to run fine now.

From a 5V or 12V perspective does it make a real difference what voltage I run the rpi and 28d+ from? Note that I'm powering the rpi and 28d+ off the CN5 from the hat.

Could I even run the rpi and 28d+ from the rpi's micro USB port?

 

[BAZMick]

I suspect the 3amp power supply didn't have enough grunt. The RPi requires a minimum of 2.5amps alone to run.

 

[Pavle]

I'm using Alan's 70A 5V power supply (here) and I still had the same issue with my pi.
The solution was to bypass the hat's power output to my strings and power them directly from the power supply - system has been up 24/7 for past 3 weeks without fault

 

[janastas]

I'm using Alan's 70A 5V power supply (here) and I still had the same issue with my pi.
The solution was to bypass the hat's power output to my strings and power them directly from the power supply - system has been up 24/7 for past 3 weeks without fault

Hmm, my issues is not even that.

I just had the 5V 3A power supply connect to the 5v and 0v power input on the hat and i was getting the under voltage issue.

No pixel strings attached to the hat at all.

If I connect the power directly to the Pi via micro usb I don't get any voltage issues so wondering if there's something wrong with the hat's 5v input.
I haven't checked if the hat still works if connected to the pi power input via micro usb but will give it a try.

 

[janastas]

So I ran a few more tests at lunch time today.

The 5V 3A power supply is connected to a dc barrel plug that has a negative and a positve terminal.

Checking the the voltage with a multi meter at that point shows 5.1V

The next check I did was remove the hat from my rpi3b+ and powered up the pi via the microusb port and check the voltage on one of the 5V GPIO pins (and GND) and that also said 5.1V

I reinstalled the hat to my rpi and plugged in the 5V power adaper to the 5V and 0V power in terminals on the hat then checked the voltage again on the 5V GPIO pin and I got a reading of 4.9.

Does this mean there's possibly something wrong with the hat?

Quick screenshot of were I was getting my reading.



The GPI pins i took the reading from were as follows:

 

[AAH]

The 5V connection on CN5 connects directly to the GPIO header with some connections to a diode, 2 capacitors and the regulator (which doesn't get used when running off 5V). I have 2 rpi-28D+'s and 1 rpi-28D all running off 5V power supplies connected to CN5 and I've never had a problem. I haven't actually measured the voltage drop from the 5V terminal to the GPIO pin but I would have expected more like 50mV difference rather than 200mV. I'll measure 1 later today when I power things up.