Originally Posted by
mcours2006
I've owned a set of the eBay/Chinese CREE lamps with the separate battery pack. While they were quite bright, the battery didn't last very long, requiring a charge twice a day (once at work and once at home). That in itself was a PITA, but then there was the charging wire that failed which required minor surgical splicing, and then the cable from the battery failed, and again, more surgery. The mounting was also a hassle. In the end I just gave up, or rather, it gave up.
I'm currently running two 'self-contained' units. One requires charging once a day as I run that one at full power. The other at night time flash, and then day time flash. Much simpler.
In terms of how much power you need, more is better.
I have a Cree from Amazon, $20. Battery pack unplugs/unstraps from the bike. The ONLY issue I've ever had with the unit was the absence of the low-charge feature, which promised to switch to low-light mode when the battery was near discharge. The light is bright enough to make cars flash their brights at me, I recharge it 1x/week, no problems for 3-4 years.