First, why are you more worried about losing or damaging a battery than a media player?
Secondly, wow - that's a long time. I thought mine was bad taking about 30 seconds from cold.
Thirdly, spare battery for mine is about £7.48 including a desk charger. High capacity battery is about £3.75 by itself.
Finally, I just swap them over once one is charged and then keep it safe in a little bag. Or rather I used to when I actually carried a spare battery. I might have to get one actually. Probably worth it for £3.75

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