2 of 2 people found the following review helpful
very poor charge levels on first attempts,
This review is from: mophie powerstation reserve with 30-pin connector (700mAh) - Red (Wireless Phone Accessory)
I bought a couple of these in preparation for a 5 day festival (Glastonbury) in order to keep my phone topped up throughout. I don't know if they need to have a initial number of full charges before they hold more juice but neither of these charged more than 12% of my phone's battery.
Luckily Mophie do a larger battery pack B006L9I43O that does hold a decent amount of charge. It's slightly more expensive but is well worth two of these and will charge any device via USB