Backup power supply


#1

Hi all. I am looking for a way to supply a Pi3B+ with an independent 5volt supply so that I can use/build a safe shutdown backup power supply. I am only really interested in bringing the Pi to a safe sleep state and not to run it for any length of time
Currently the Pi is fed via one or several 5volt gpio pins from an IQAudio Digiamp+ which has a 19volt supply connected to it.
What I am hoping would work is to cut off the 5volt gpio pins through which the digiamp is feeding the 5volts to the Pi.
Anyone got any ideas/views on that?


#2

Our OnOff SHIM is designed for pretty much that exact purpose. You’d have to get a little creative and hack a micro-USB cable apart to connect to your Digiamp+, or you could use a male micro-B breakout board.



#3

Hi Sandy.
Thanks for the reply but not what I am asking my question about. I have already set up a button to initiate a safe shutdown/startup.
What I am trying to get around is the problem with having a 19 volt supply at present and the need for a delayed soft shutdown in the (frequent) event of a mains power outage.
There are devices out there to do just that but I need to separate the power supply that currently feeds the Pi via 5volt gpio pins from the hat and be able to feed the pi independently.


#4

Ah, ok, so like a battery/UPS kind of solution?


#5

Yes Battery/UPS for which there are a couple of ways to go. BUT my problem remains in that I need to separate the 5volt supply which comes via the gpio pins to the Pi from the Hat.


#6

You’d have to run the HAT off the Pi (i.e. with the I2S and any other necessary pins wired with jumper wires), or cut the 5V supply from the HAT to the Pi.


#7

Hi. We seem to have gone round in a circle with this one. The standard setup is that the hat supplies the Pi supply voltage.
My origional post was to ask if I could cut out the 5volts feed from the hat and feed the Pi with an independant 5volt supply.


#8

I think we’re both saying the same thing. :-D You could, but the only way to do that would be to run the HAT off the Pi, so that the 5V pin wasn’t connected between the HAT and Pi, or to desolder that pin from the Pi or something. And then you just connect your separate supply from something like an Adafruit Powerboost or whatever to either the 5V pin, one of the test pads on the underside of the Pi, or straight to the micro-USB power input. Does that make sense?


#9

Yes that makes perfect sense - What I talked about in the first post. I am simply asking if in anyone’s opinion this might throw up other problems. For instance the 3.3v would still be connected between Pi and hat and i do not know what this would cause.