A:Answer As far as I know once the Mophie has been fully charged, all 4 lights light up, it remains that way until hooked up to a device. I would imagine like most charged devices that over a significant amount of idle time, the Mophie will gradually start to lose it's charge. If you think the problem is significant enough, like a manufacturer defect you can either go to www.mophie.com or call 1-888-8mophie to get help. Hope this was helpful.