Here is DV4mini setup...
The Pi is now powered by 2a wall wart, but I have 12 Vdc adapter to go in a car or battery pack and I also have solar panel to charge up my battery pack that I made up years ago for all my radios to operate off the grid.
Here is the Pi / Dv4mini fully operational with wifi to hotspot on my iPhone
And all of it controlled by my iPad on the same hotspot from my cellphone.
Of course when at home I would not use my iPhone as hotspot by the house wifi or ethernet cable.
My "home made" power pack with lighter socket at one end and standard banana jack at other end and both ends with LED strip for emergency light or connecting and disconnecting to battery pack at night. I do have 6in pig tail with Anderson connector and USB cigarette lighter adapter but thinking of having those incorporated in the power pack, less parts to lose.