Harvs
Posts: 7
Joined: Thu Feb 26, 2015 11:58 pm

UPS / Backup Power RaspPi

Mon Sep 05, 2016 12:54 pm

So I have a pi for home purposes, and I want it to be able to survive a power loss.
I also have a spare anker 10000mah battery. A while ago I contacted Anker and they said that one could, but should not daisy chain charge with them (i.e dont have a wall wart powering the Anker and then the Anker powering a device) as it doesn't have pass-through and so the batteries are continually charging/discharging

So the solution I dreamed up was the following
Get a wall wart with two USB sockets
Get a cable such as this (Y cable with 2xUSB A and 1x USB micro) http://www.netstoredirect.com/startech- ... 0wod9-ACFw
Get a normal USB Micro cable

Plug the normal micro cable from wart socket 1 to the Anker
Plug one USB A from the Y cable into the remaining wall socket
Plug the other USB A from the Y cable into the Anker
Plug the UBS Micro from the Y cable into the Pi

Would this work or would the Pi just simultaneously take power from the wall and the Anker, thus defeating the whole point?

mosespi
Posts: 508
Joined: Mon May 12, 2014 3:35 pm
Location: 34,-118
Contact: Website

Re: UPS / Backup Power RaspPi

Mon Sep 05, 2016 7:14 pm

I would not recommend this with consumer power supplies. Two concerns.. due to differences in the supplies you don't know which will feed more or less power. Second, one supply may end up backfeeding the other and potentially cause lots of problems such as overheating and fire. You can engineer such a circuit from scratch, picking suitable power supplies, diodes, etc.. but picking off the shelf consumer supplies and tying them together is generally just trouble.

Search for 'diode OR' power supply on the internet, for similar circuits. You basically put two power supplies behind diodes, with one supply having a higher voltage then the other. It supplies power most of the time, until it fails or gets overloaded then the other takes over.

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

texy
Forum Moderator
Forum Moderator
Posts: 5161
Joined: Sat Mar 03, 2012 10:59 am
Location: Berkshire, England

Re: UPS / Backup Power RaspPi

Tue Sep 06, 2016 10:21 am

Harvs wrote:So I have a pi for home purposes, and I want it to be able to survive a power loss.
I also have a spare anker 10000mah battery. A while ago I contacted Anker and they said that one could, but should not daisy chain charge with them (i.e dont have a wall wart powering the Anker and then the Anker powering a device) as it doesn't have pass-through and so the batteries are continually charging/discharging

So the solution I dreamed up was the following
Get a wall wart with two USB sockets
Get a cable such as this (Y cable with 2xUSB A and 1x USB micro) http://www.netstoredirect.com/startech- ... 0wod9-ACFw
Get a normal USB Micro cable

Plug the normal micro cable from wart socket 1 to the Anker
Plug one USB A from the Y cable into the remaining wall socket
Plug the other USB A from the Y cable into the Anker
Plug the UBS Micro from the Y cable into the Pi

Would this work or would the Pi just simultaneously take power from the wall and the Anker, thus defeating the whole point?
Unnecessary poll removed.....
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

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