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Re: [LUG] Battery power for Pi etc

 
Quite a lot of the circuits I've seen just use a predefined time limit when they switch to battery backup to shutdown safely before the power has completely run out, such as: 

http://www.repairhub.co.uk/content/resources/raspberry-pi-battery-backup

Not ideal but a simple solution.
Some others attempt to implement detecting voltage drops below a predefined threshold to detect that a shutdown is required as battery power is running out (I believe this is what you are after): 

http://raspi.tv/2013/controlled-shutdown-duration-test-of-pi-model-a-with-2-cell-lipo
You'll have to do some experimenting with the battery type you are looking to use but hopefully the link above should give you enough to get started.
Keep us posted with how you get on as I'm currently also looking into UPS and battery backups with the Raspberry Pi for some projects I'm working on. 

On 04/09/15 15:00, Tom wrote:

On 04/09/15 14:35, Ben Whorwood wrote:

I use a similar setup for using 12v lead acid batteries from phone
systems as "power banks" at festivals and such for charging devices
using their USB chargers.

You'll need...
http://www.ebay.co.uk/itm/Motorcycle12V-120W-Car-Motorbike-Boat-Tractor-Cigarette-Lighter-Power-Socket-New-/350864583010?hash=item51b128a962 


(Other variations exist (such as crocodile clips for connecting to the
battery), this is just the first one I found similar to the one I have.)

And then a standard cigarette lighter to USB charger (check the specs
for amps you require and that the 12v socket is capable of supplying
enough power for it):
http://www.ebay.co.uk/itm/Micro-Mini-Car-Cigarette-Lighter-to-USB-Charger-Adapter-for-MP3-/251478257627?hash=item3a8d45afdb 


With double+ USB adaptors (ones that have two or more USB sockets), test
before charging using both USB sockets as they have been known to melt!

This creates quite a nice future proofed setup as most things charge
from USB these days.

Depending on the type of battery used it can be set up as a UPS with
trickle charging into the battery as required.

Another cheap option for RPi UPS (mileage may vary):

https://www.youtube.com/watch?v=qev1E7bqNjA

On 04/09/15 14:12, Tom wrote:

Just wondering if anyone knows of a cheap (or DIY Pic job??) Car
Battery to 5v Pi/USB sort of UPS arrangement?
Google is not my friend today....
Tom te tom te tom





Cheers for all the responses.
I was looking for one that actually lets the Pi know the 12V is getting low so the Pi has time to shut-down cleanly (after sending appropriate messages to base ) hence the UPS bit. I've looked at about 100 options (out of several 1000) but none do the battery getting low thingy. 
Tom te tom te tom





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