crwdns2933897:0crwdne2933897:0

battery charge life only 4 hours

Why does my kindle voyage battery charge last only 4 hours. I have it on Air plane mode.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0
crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0