The red light on my MagicShine is utterly useless. I've had it come on after 30 minutes and the light continues to run for 2 hours, or I've had it stay green until 5 minutes before the battery died.
The new ones are probably better, mine was one of the first. I don't pay any attention to the stupid thing, I just charge it every 3 or 4 days.
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Work: the 8 hours that separates bike rides.