A daily pack out of my gear always includes Portable Power, since starting to play Ingress it seems I am usually carrying two power packs. Everyone is making Portable Power packs these days, but not many manufactures are producing power packs that are capable of charging at 2 amps.
The RAVPower RP-PBOZ has the capability to charge at both 1&2 amp on separate ports. It has a 10,400 mAh battery and weighs in a lot less than compareable chargers at 8.04 oz. Compatible with a huge number of devices.
I used the power pack for a couple of weeks and it delivered power without fault to a variety of mobile phones & tablets.
Priced at $37.99 you really cannot beat the price with free shipping available on Amazon.