I’ve been using mophie battery cases for a few years now when I travel as the iPhone doesn’t seem to last all day when I use it extensively. Granted the iPhone 5 has gotten better, but I typically use GPS to track my run/walk if I’m in San Francisco for WWDC or somewhere else. Every now and again when I’d charge my case, I’d get the message “This accessory is not compatible with the iPhone”. mophie’s FAQ gives some lame answer on how to fix this problem.
Recently I bought the charging dock for my juice pack and was getting this message every time my phone got to 100% charge and then overnight my phone would start to drain. After a bit of searching, I found a reference to charging cables on Apple’s support site. While this wasn’t my problem as the dock has an integrated cable, it got me thinking. My dock was plugged into a USB hub instead of directly into the wall or my Thunderbolt display. I switched the dock to plug into the Thunderbolt display and bingo, the problem went away. This tells me that the current supplied by the hub (it’s an unpowered hub as I don’t want to plug in the power supply) isn’t enough to keep the iPhone/mophie case happy.
Such a simple fix for a problem. Maybe mophie can update their FAQ with this information and save others from returning their products or contacting support.