There will be no problem in charging your Kindle. I charge my Ipad and laptop and wife charges Kindle all the time on ships.
NAVIGATOR OF THE SEAS - 7/6/14
NAVIGATOR OF THE SEAS - 9/14/14
NAVIGATOR OF THE SEAS - 9/21/14
OASIS OF THE SEAS - 10/14/14
NAVIGATOR OF THE SEAS - 11/4/15
NAVIGATOR OF THE SEAS - 1/11/15
The only problem I have had with my nook onboard is that I don't get a chance to read it in public. There is always some nice passenger stopping to ask if I like having one - then the conversation starts :-)