That's what I'd get. I kinda dig the "cobbled together" look.

Right, well, if you're going to overvolt *that* much then, yes, you can greatly increase the lumens/watt efficiency (which is what I assume you're saying in talking about increasing the "watts of light" of a 20W bulb).

Even with drastic overvolting, though, I doubt you could really get 50 lumens per watt out of a halogen light. If you overvolt to 133%, which is what you propose, I don't think you would get a *real* increase of more than 266% in light output, which is what you would need to do to match the HID light efficiency. (I admit, though, that isn't certain given the information I have available to me. See the link below. But, even if we suppose that efficiency of overvolting continues undiminished beyond overvolting of 120%, you'd still only be in the ballpark of total lumens-watt compared to an HID lamp, not "blowing it away". See the link and see what I mean.)

But most manufacturer's specs for overvolting halogen give lumen-watt increases of only about 20% or so. In fact, I don't know how much more efficient the lights get beyond 20% overvoltage, exactly. According to the GE specs for overvolting within about 20% of the rated voltage, though, moving from 12v to 16v should more than double the light output, but cut the bulb life by over 97% (!)

See this (p. 8) (You need Acrobat reader):

https://web.media.mit.edu/~ladyada/ad...logenstech.pdf

There's something else to say about overvolting, though. It doesn't really give much advantage over HID, if it does, in total cost of use for a given light output. See what I mean.

Now, you say the overvolted 12v bulb will last about 20-30 hours, which is roughly consistent with these figures in the link applied to a 2500 hour bulb, though perhaps life dives down even more than the figures in the link indicate. I'm not sure, but we'll use your figures derived from real life.

If you overvolt to the extent you do, the cost of bulbs for your light system brings the price of using the halogen system much closer to HID. Sometimes it will still be significantly cheaper, sometimes more expensive, depending on which bulbs you get and how much they cost.

Now, maybe you can get 12v halogen bulbs for $3 a piece, but some of them are about $6 or so retail. Let' s just use $6 for now.

You said you can put together a bright halogen bike light system, with charger and all the rest, for about $200. We'll compare that to the commercial L&M Metal Hydride ARC at, say, $360.

Let's just assume the battery voltages are adjusted so that brightness and run times are equal. We're not comparing battery drain here.

Now, L&M say their HID lamp will last 700 hours before replacement. You may say you don't believe this, but as I mentioned on another thread I've had my HID lamp for ~250 hours of use, and it's doing fine. But anyway, let's just be very conservative and say that the L&M lamp will give out at 400 hours, not 700 hours.

If you get 20 hours out of each overvolted halogen bulb, and they're $6 a pop, then, you've added $120 dollars to the price of your halogen system for 400 hours of use. That makes the halogen system $320 compared to $360 for the HID system for 400 hours of use.

If we consider the price of 700 hours of use of the halogen system, which is how long L&M say their HID lamps last, then that's an additional $210 dollars for the halogen system, which would make it *more* expensive than the HID system over the life of the HID lamp: $410 vs. $360.

If you get the bulbs for $3 each, though, and if you can get 30 hours out of them, instead of 20, then things work out better for the halogen. The cost of 400 hours of use would be $42, which would save you a little more than $100 compared to the HID system. 700 hours would be $72, which still makes the whole set up cheaper than the HID light.

Still, I haven't figured the cost of labor in putting together these halogen lights, which is unfair since one *could* make an HID light, too. I've also assumed that the price of halogen bulbs stays the same during what would normally be years of use. Then there's the hassle of replacing the halogen bulbs every few weeks.

More importantly, though, after working through this one would have to ask why not just get (or make) a more heavily powered halogen system with bulbs not so drastically overvolted. Yes, you'd add battery weight compared to the HID system and to the overvolted halogen system to keep the same brightness and run time. However, you'd save *money* on the bulbs for the same light output with the more soberly volted halogen system compared with the overvolted halogen system. Extra battery capacity is cheaper than buying a bunch of bulbs, after all. But now you're talking about the logic that leads to something like the high end halogen Jet Lites, as an alternative to HID. And much of what I was saying above applies to this kind of comparison.

I'm not reading all of that. that's all there is to it.

I can't say I'd be too interested in building one myself.. but there's something to be said for having made your own lighting system. I'd still rather purchase one simply for the technical support and warranty. Building one sounds cool, just not for me

It does have a nice "rough around the edges, total utilitarian" look. But the things are very nicely built, sturdy as heck. The mounting system is a snap, very easy to move the rig fron one ride to another.

As for the charger, I have no qualms about just plugging it in for 10-12 hrs. $7 for a cheap timer ensures I don't overcharge em.

It looks like something I'd build. Totally functional, a tad overbuilt, but not the most attractive thing in the world . The timer is a great lo-dough idea.

yes if I overvolt it's better to do more then less.


I can ask how much since the guy measured the bulbs I use.

a HID bulb life is really dependant on how much it is turned on and off. that wears a bulb out. the gap in the arc gets bigger and bigger each time it is turned on.

you can build a HID but it is pretty tricky as the ballest is hard to make. you can use a automotive HID foglight as the basis. then you get more light then a bike HID. but it is more work then I would want to do.

I only need a runtime of about 1 hours so I use a 35 watt bulb and it works great without overvolting. but it does prevent me using larger capacity smaller batteries. I have to use sub c cells that are only 3.0 ah where I could use 4/3 aa at 4.8ah if I used a smaller bulb and overvolted. but I would not want to have to replace the cells and all. I get enough runtime for my needs.

but you don't know how well the cells are charged or if they are fully charged. you won't get the full life or runtime out of them.

Given a batteries rated capacity, the efficiency of recharging (~66% with Nicads) and the output of ones charger, it's not to difficult to calculate the time required. While not dead on, if one is consistent and keeps note of the performance, one can obtain upwards of a thousand cycles from the battery.

And when it's spent, I'll get another for $20-$30.

you get more chargers with a cood charger. if you use the rigth one you can use it to charge other cells too.
they are NIMH cells not nicad's and they cost 58.00 right now to replace. thats if you can get them when they die.

Mine are NiCads (older version). Nobody says I have to buy the battery from him. Heck, I can wander down to my cellar and grab one of my B&D batteries if I really wanted to.

You say potatoe, I say potato.

here is my homemade headlight and how I mounted my flashers. I plan on adding more reflective tape. I ordered some black that will match the bike.
the headlight is homemade. it uses a car fog light (mr16 based halogen bulb. I have some nice looking mr11's too) I use a 35 watt solux bulb. it has a slight blue cast to try to be a 4100k color. it is pretty white looking and very bright. brighter then a HID setup. though it sure sucks the juice out of cells and I only get about 1.5 hours runtime. but that's all I need so I can get away with a larger light. no car can miss this light and I bet I blind a few drivers (G) I could even overvolt it to 16v and really blind everyone. but UFO's tend to attack me when I do it.
on back is a sparky xenon flasher and a new Cateye rear light. it has LED's on the ends for great side visibility. you have two separate controls so one line can flash the other can be solid. I just used a piece of PVC pipe with reflective tape on it. so far with this setup on my bent and before on my road bike I have less problems at night then in the daylight.

Steve,

Could you post a beam shot, perhaps comparing the light to some known device or something like that?