Electronics, Lighting, & Gadgets - NOS Marwi Viewpoint Halogen Light Bodies-Worth Fooling With?

http://classifieds.mtbr.com/showproduct.php?product=40258&cat=27

These are some NOS Marwi halogen light bodies for $10. I was wondering if I could put together an inexpensive 6V battery pack using a standard holder or use a 6-battery holder and overvolt to 7.2 volts. I would prefer C or D batteries since I have a charger or could do AA's if there is enough capacity. There are 6V pre-made 5-battery packs with Trail Tech connectors and wrapped in shrink wrap that would require me to purchase a charger and would cost around $50 for 4000Mah capacity. I would also need guidance on a battery pouch to hold the batteries to the bike. I know where I can purchase a Trail Tech 4-ft coiled lead wire that I could attach to a plastic battery holder but I want something that is plug and play since I am not very good at soldering.

In addition to the light head I need is Marwi light body ($10) bar mount ($8.75) + shipping, batteries and recharging capability, battery holder, battery pack, and velco strap. Am I missing anything?

You seem to be missing the fact that Doug Hoffman also sells a complete kickass P7 bike light. You can also buy parts from him and DIY for less. His parts and design are pretty dang good, except for the emitter itself, an old C bin. You could get a more current D bin and 100 extra lumens, with lower Vf, for nearly the same price - look at CPF marketplace.

I have an old Marwi Nightpro Elite (dual lamps). I used it for ~3 years. Must have recharged those NiMHs 750 times. They still worked in the end. This light originally used 6v MR11 halogens (expensive, hard to find in the wattage/angle you may desire, quality highly variable) and was powered by 6x1.2v NiMHs (7.2v nominal). Mine used 4/3A cells.

You'd be better off building a 13.2v MR16 light. Lamps are cheaper and easier to find. Slightly better efficiency at higher voltage/lower amperage due to less loss thru wiring.

Your best bet is to order the aforementioned P7 light kit and battery holder and DIY. This save labor cost. Get your 18650s and charger from DX.

Seeker333 - Thanks fo the information. I entered the completely assembled package (light, charger, batteries, mount, nylon bolt kit, and labor) into the shopping cart and it came to $179.55.

Is this a higher quality light than the Magicshine?

What would you recommend for a battery pouch since that seems to be the only item he does not supply?

Do you think he will be updating the package soon for the most current emitter?

Is this a higher quality light than the Magicshine?

The quality bar on MS is pretty low, so my opinion is yes. Especially the assembly quality, since Hoffman's main business seems to be making high fidelity amplifiers for professional musicians. He purchases the emitter, switch and charger from DX, so these are always suspect IMO. He manufactures the rest of the parts, except for wiring, resistors and the original Marwi housing. My main criticism of his design is that the custom-machined DX P7 reflector does not appear to mate precisely to the Marwi body. This means poor heat conduction away from the emitter, resulting in high temperature in the core of the emitter, and reduced light output on the order of 10%@70C and 18% @100C junction temperature. The Magicshine light has a similar deficiency. Ideally the emitter would mount to single, massive block of Al alloy for good heat conduction. This is what the custom builders do - cut mounting holes and cooling fins out of a block of Al.

If you buy this light, you should operate it only when moving so there is adequate cooling. It's direct-drive operation means the emitter is getting >3A for a longish period - till the battery voltage drops from original 4.2v to about 3.9v. SSC rates the emitter to 2.8A maximum, so 3A will result in higher junction temperature, which shortens emitter lifespan from the rated 275,000 hrs down to perhaps 27,500 hours, worst case. This is all info you can read yourself from SSC's P7 pdfs.

If you ride at 10mph, this means the overdriven P7 in Hoffman's life is good for only about one-quarter million miles.

So, even though it's overdriven, you're getting the maximum output out of the emitter, reducing the lifespan by 90%, and BFD, a new emitter is 20 bucks. The better D bin emitter is not even 30. It's highly probable that this emitter will be obsoleted by a brighter, more efficient emitter long before you burn it out from normal use.

Be aware that the lack of constant-current regulation in Hoffman's light means the light output will drop with time, just like every P7 single-18650 cell flashlight. This feature was not incorporated due to the lack of a reliable, affordable 3A driver. A good driver would add $20 cost to a light design that started out at $60.

What would you recommend for a battery pouch since that seems to be the only item he does not supply?

Anything will do - waterproof if you like. I'd look for a very small camera bag at Walmart, since they're cheap, padded and offer some protection for your bike's finish.

Do you think he will be updating the package soon for the most current emitter?

Doesn't seem like it. He's currently having supply problems on DX's C-bins. SSC has had an irregular supply of P7s for a while now, and this being "light season" makes the situation worse. Why don't you discuss this subject with him - he is very receptive to good ideas. Posts regularly at http://forums.mtbr.com/forumdisplay.php?f=124