Extended battery not charging

[tituswife]

Several times recently, my extended battery refuses to charge, once it gets to about 75%. Nothing unnecessary running, I shut down autosync, gps, brightness, etc. I've had to power off, and it takes six hours or more to fully charge, or, I've switched to the standard battery, and put extended battery in dock to charge. Any ideas? Thanks.

Sent from my stock Thunderbolt