iPod <answer>batteries</answer> are not designed to be removed or replaced by the user, although some users have been able to open the case themselves, usually following instructions from third-party vendors of iPod replacement <answer>batteries</answer>. Compounding the problem, Apple initially would not replace worn-out <answer>batteries</answer>. The official policy was that the customer should buy a refurbished replacement iPod, at a cost almost equivalent to a brand new one. All lithium-ion <answer>batteries</answer> lose capacity during their lifetime even when not in use (guidelines are available for prolonging life-span) and this situation led to a market for third-party battery replacement kits.
Which iPod component did Apple somewhat inconveniently made non-replaceable?
batteries