Advances in LED lighting, and Li-Ion batteries have made BRIGHT lighting for cyclists reasonable and cost-effective.
The picture doesn’t do it justice; these lights are very very bright; I have been running them in daylight on their lower-power setting and they are quite visible.
The lights I stumbled on are sold on eBay “direct from China”; from seller “lifebike2011” for ~ $30 (the price has been going down) for a kit that includes a light head; handlebar mount; head strap (that i’ve never used or tried) and a 4-cell Li-Ion battery pack (which is wired in parallel, by the way; i.e. nominal voltage is 4VDC).
The build quality of the light head is excellent, though it offers only 3 “modes”: hi – lo – flash (the flashing is pretty scarey, it alternates between hi and off at maybe 300Hz). The actual emitter is a Cree XM-L at the T6 “brightness bin”. They claim a very inflated 1800 lumens of light output; 950 or 1000 is more realistic. Negatives about this package are the battery pack isn’t sealed against weather really in any way. the end caps are cardboard. Although the runtime is quite acceptable (e.g. lo power for over 8 hours), the light seems to “die” quickly; I mean without much warning. There is a pilot light in the clickey that is normally blue when the light is on; and switches to red when the battery power is low. (the clickey does a quick-flash blue when the light is switched offf). There is no manual or instructions whatsoever. Standard warnings and precations against Li-Ion explosions should be taken.
I currently run a headlight with a clear diffuser lens; the default beam is like a tight spotlight. For the taillight; i am running two red diffuser lenses (at 90 degree angle) to spread the taillight equally in all directions.
This light is very similar to the Magicshine MJ808 which apparently sells for around $80; The magicshine has a nicer, water-sealed battery pack; uses the same cree XM-L emitter, but at the next brighter U3 bin; and has more “modes” (5 modes as opposed to 3). The magicshine, by the way, uses 2 cells in parallel in their packs, so their nominal voltage is 8VDC.
bits and parts
Y-cable (to run 2 lights at once from one battery; at half the runtime, of course) action-led-lights.com ~ $5. This cable doesn’t have the same threaded plastic couplings; but the plug itself is the same.
Diffuser lenses, available in both clear and red, action-led-lights.com for ~ $4 each.
Power jacks are the most common DC-power plug style: 5.5mm OD w/2.1mm pin. Monoprice has them very reasonably: male is 0.26 each and female is 0.46 each. They, however don’t have any water protection.
I picked up some dedicated DC voltmeters on ebay for less than $2 each; http://www.ebay.com/itm/380687977328. I built a quickie extension cable with one of the voltmeters so I could monitor the charging. The meter, by the way, sucks about 17mA so it would be a pretty big drain on the battery if it was left on all the time. I was hoping to find a DC LCD voltmeter that could be left on forever but it didn’t see any that were cheap like the led one.
Jelly / Tie-on Lights
The light I purchased (three sets so far!) come with two red jelly / Tie-on (they’re just like the big silicon rubber band) as a freebie. These use one CR2032 (these are VERY common size) cell and is easily attached to bike, and even battery replacement without tools.
These types of lights may be useful for give away lights at safety events. E.g. i saw a pair of the rubbery ones (one red, one white) with coin cells at dx.com for $5.20/set shipped. Though, that particular model uses two CR2025 coin cells. Two cells means a higher life-cycle cost, compared to one 2032 like the lights i mentioned above. (i mean if they were to ever be replaced). hmm