Originally Posted by HarryT
If you're getting a significantly shorter battery life after 18 months, you should contact Kindle CS and report it. That's definitely a fault and, 12 month warranty or not, Amazon should replace it. A Lithium battery should last a LOT longer than 18 months.
I'd rather buy a new battery than send my Kindle in for them to replace it and lose the use of my Kindle for a week while they do for me what should be a user replacement operation and even with the stupid design of the product is simple enough to do even for the relatively non tinkering consumer.