Raspi Power Options

#1

This was kind of a side note in my home automation project that seems to be an issue. Lots of Pi’s are being used as the controller/server for automation software and the easiest way IMHO is to run them headless and probably in a remote location like a closet or server rack. You have to start thinking about powering the little booger up and the options are relatively decent but stuff is getting more and more murky. I have POE switches in my network so grabbing power that way made sense. September of last year I bought a Navolabs POE hat but didn’t realize that it would only work on a 3B+ so my 3B’s wouldn’t work. So, last week I bought a 3B+ and swapped the SD out of my working OpenhabianPi. The hat works great!. I bought a case with a small fan in it and had to modify it so the hat would fit but it powered up and all seems well. I went on to Amazon to look at other hat options for my 3B’s and found that the NavoLabs hat is unavailable and that Navolabs website has done dark. Wonder what happened.Seems to be an awesome product and the reviews are all stellar.

Navolabs POE Hat

The Raspi official hat seems to be having issues with power smoothing. There are external adapters for POE as well that I have looked at with mixed reviews. I have also had lots of problems with wall wart supplies saying they are rated appropriately but have fallen far short of needed limits. I just bought a PWR+ wall wart that I will be trying on my Pi that is home in my toolbox at work. Yep… toolbox with computer and internet :sunglasses: I am hoping that this one will actually power it without issues.

PWR+ Wall Wart

#2

The lack of an onboard regulator has been the #1 thing that bugs me about the RasPi, so last year when my friend Nick wanted me to teach him about PCB design I suggested that a regulator hat would be a good project for him to start with. This is the result. It’s a very simple hat with a switchmode regulator module on it, so that I can just plug in a random power supply. Input range is 7-28Vdc.

The regulator is only rated to 500mA so it’s no good if you need to power other things from it or the Pi is working hard, but it’s super handy to get things running quickly.

This doesn’t solve your PoE problem, but I like it :slight_smile:

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#3

I am not familiar with how exactly the Pi’s fall short in the regulation department but I am starting to see an issue with the power supplies all around, not just POE. I have my Pi 3B in my toolbox that is just a Jessie box that I play Pandora on. It had a supposed 2.4 amp wall wart that was running it but with issues. I bought the Power+ unit that I listed in the top post and that won’t power it up if I have the HDMI to VGA adapter plugged in. I am going to try 5v directly to the GPIO header with a regulated buck converter that can give it up to 3.5 amps (but not before an inline meter tells me what it is doing first) and see what story the thing tells me. Feeding it with a fire hose isn’t usually a good idea but at this point, potentially sacrificing a Pi for science (and morbid curiosity) doesn’t hurt my feelings. Won’t go that far but… maybe it will :grin:

Is the 500mA limitation due to single component design or was it just to keep the number of components down for first build simplicity? I assume the power supply is the black cube on the board?

#4

Yes, the 500mA limitation is just the K7805 switchmode regulator. It’s intended purely to be a pin-compatible drop in replacement for a cheap 7805 linear regulator, which normally tops out at about 500mA anyway. Ideally the hat should have a higher rated regulator but these little K7805s are cheap and super convenient, so we put one on the hat just as a quick and dirty solution to see how it goes.

If I was going to release this hat commercially I’d put a higher rated regulator on it, but even with this limitation it’s perfect for quick setup of a new Pi on the bench when I just want to plug it in and set it up, before it’s installed somewhere else.

#5

I’ve been using these active splitters for over a year on a half dozen pi’s both at home and commercially with great success. DSLRKIT Active PoE Splitter Great on the bench also. I should note they’ve only been used with 3Bs not 3B+

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#6

Those are interesting. Nice find!

#7

@polargeek NICE! I started looking around and found a lot of sellers hawking them and it’s funny how they can be priced from $9 US to $89 US for what appears to be the exact same device. Have you had any longevity issues with them by chance? The reviews are all over the place but for the price, it seems like not much of a gamble if you did have a failure.

Oh yeah… and welcome to the group!

#8

I’ve had 2 of them in service for over a year and another 3 about 9 months now