I recently came across one of these devices.
If you need back up charging of all your electronic devices then this is the beast for you.

Its capacity is a whopping 12000 Mah 
It has 2 USB ports to charge 2 devices at once.
You can jumpstart your car even with it with a current output of 200-400 A
Comes in a nice carry case.
Obtainable from Hunting and Fishing and Repco at a cost of $199
Comes with vasrious adaptors for all the major mobile phones



Disclosure
I have no connection with the company or the retail outlets involved