I had a charge problem with Nook HD. There are lots of posts to read. The post that I tried had me try the cable with different sources until the reader said "charging." I'm using a USB to socket/car lighter recharger and the nook HD cable. (No lights appear on the cable, even when charging.) Some people say the charging lights on the cable don't show up until 98% (yellow) 100% (green).
The lights on my hd+ have never changed colors when charging