My battery started charging again after reseating the 5amp charge fuse on backside of battery under flap.  It wasn't blown.  But taking it out and putting it back in fixed the problem.  Worth a shot. 

I had this problem develop after some bumpy terrain.  Reseating the charge fuse under the rubber flap on the back of the battery did the trick.  This is odd.  As the fuse fits tightly. The fuse wasn't blown.  But the battery charges fine now.   So go figure.