MoPi, a battery hotswap power board for the Pi: https://pi.gate.ac.uk/pages/mopi.html
And
PiConsole, a serial and Bluetooth console board: http://openelectrons.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=81
The idea is to have an off-the-grid Pi with a camera that I can get a console on from my phone or tablet.
Both boards were incredibly easy to get working, the console just required an app download on my Android devices and a Bluetooth pairing, and the MoPi needed a software daemon installing via apt as well as battery connectors attaching to its terminals.
In the end I will use NiMh cells, but yesterday I used a couple of alkaline PP3s I had to hand. No problems running a model A from a PP3, and I expect the A+ to be even more frugal. I will have to wire in an external power switch for this board.
The console is super responsive via Bluetooth, in fact I found it better than SSH into a Pi from the same tablet.
So I have an off-the-grid Pi. Better use it I suppose :)
Jenny