Rechargeable batteries can only be recharged so many times, and each time that one is recharged, it loses a little of its lifespan. In other words, the second-go won't last as long as the first-go and the third-go won't last as long as the second-go. Eventually they die and have to be replaced. They're also more expensive, I believe. Might be cheaper to simply buy regular batteries. Then you don't have to worry about buying a battery charger and waiting an hour or so for your batteries to be usable again.

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