Originally Posted by
San Pedro
What I've been doing the last week is using my Cateye on the bright level, not flashing, and the helmet light flashing. I'm still considering a brighter light, but I don't like that the battery life is about 300 charges (according to Cateye on their Volt series). I like battery lights, just for the longer life span, less frequent charging. I'm also thinking to get a safety color long sleeve jersey. Once it's cold enough I'll wear my blinding Pearl Izumi jacket.
That battery life is common for almost all lithium-ion batteries. It's a function of the chemistry and engineering of the battery cell. If you stay away from proprietary batteries like the Cateye and Cygo, replacement batteries are fairly easy to find and relatively cheap. The Magicshine clones that you find on Fleabay and Amazon for about $20 use 18650 Li-ion cells in a 2s/2p (two in series/two in parallel) configuration and a fairly standard cord that are around $10 to replace.
If you want or need more run time, you can get battery packs that use 26650 cells for about $20 in the same configuration. They have about twice the run time of the 18650 cells. I get 2 to 3 hours of run time on the smaller cells and 4 to 6 hours on the larger cells if I run my lights on high. Personally, 4 to 6 hours is more than I've ever needed on a night time ride.