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Re: 500 Lumen Bike Light For About 10 Bucks

Hah, scooped ya!!!
<grin>
Seriously though, it's a pretty cool article and I'm surprised nobody's commenting.
 
Re: 500 Lumen Bike Light For About 10 Bucks

Thanks for that link - it is a great idea but with the 10 or 20w lights he's talking about you will get the lumens but not the Kelvins... an orange/yellow beam at best especially with the energizers sagging under load to about 10.5v.

I will try the same project but using 11 x Sub C IB4200 in a PVC tube mounted along the underside of my top tube where the pump normally sits. with this set up I'll use a 50w MR16 and I guess I better keep pedalling so the breeze stops it from melting the plastic housing.

You can really drive these low wattage bulbs hard - I've run 14 cells on a 20w and they just get brighter & brighter. I'll try 11 or 12 cells and see how I go.

Depending on how well it works I'll see if I can get someone to machine a small cap tube for a Mag head and a proper mount so we can get a quality light happening.
 
further down in the post another user mentions he uses this set-up in 24 hr mtbike races. I would assume if it can make it through those it is a keeper!
 
Re: 500 Lumen Bike Light For About 10 Bucks

zespectre said:
Seriously though, it's a pretty cool article and I'm surprised nobody's commenting.
Click to expand...
It's interesting except that in general 500 lumens aren't needed for cycling, and since it's incandescent it's prone to self-destructing from vibrations the first time you hit a really bad pothole. If I really needed 500 lumens for cycling, I could buy about 8 or 9 Crees for ~$30, use an old flashlight reflector to focus them (won't be a tight beam but then neither is an MR16), and I'll get probably 2 to 3 times the runtime on any given set of batteries, plus a more useable, whiter light better for actually seeing things. Of course, not $10, probably closer to $40, but still not terribly expensive either. A third alternative is to use about 70 50,000 mcd LEDs (~$21 shipped) each driven at 30 mA. At approximately 7 lumens each, they'll give you ~500 lumens while consuming only about 7 watts (even less than the 10 watts the Crees would use).
 
Re: 500 Lumen Bike Light For About 10 Bucks

Good point, jtr1962 - the track lighting bulbs used in the light were designed to be hung from ceilings, not bounced over potholes.
 
MR16 are a popular lamp for home-brew bicycle lights. The're already sealed, which instantly solves an important issue. As far as longevity, that DIY should do pretty well. Many MR16 bulbs are rated for 3000 hours or more at the nominal voltage. In fact, since the life is so good at 12 volts, you can overvolt pretty hard and get a wicked bright light and the replacement bulbs are cheap. I love my HID, but just might build one of these bad-boys with dual 10/20W lamps. I just need to make room for an 11 C-cell battery pack. 🙂
 
I don't know a lot about 12V sealed lead/acid batteries. Could someone elaborate about their use in this application? Some of these are less than 2 lbs. Would the runtime be better? can they take the abuse of mountain biking?

Thanks,
Bernie
 
MR-11 works too. A ABS pipe-coupler for $~$1.75 can be sawed in 1/2 making 2 light-holders. Leave the backs open; the lamp itself is sealed {the ones I bought have a lense}. SOlder the wires to it and paint connections with liquid electrical tape or RTV or hot-glue {save socket cost} and use trailer light plugs no on/off switch. Grease or spray the contacts.

I have not proven my theory but many dead laptop batteries are only dead in a few cells... LiION cells harvested from dead laptop batteries should be nifty {only some are bad when pack die}, but if weight and sub-32 degree operation is no issue buy 12V 7AH batteries on eBay and afix to rear rack w/ Velcro straps and zip-ties or sling under the top-tube.
 
Re: 500 Lumen Bike Light For About 10 Bucks

lightlust said:
Good point, jtr1962 - the track lighting bulbs used in the light were designed to be hung from ceilings, not bounced over potholes.
Click to expand...

I've read that mr11 and mr16 were originally designed for projector lamps.

They were later adopted for interior lighting.

Most rechargeable bicycle lighting system utilize a nominal 6v mr11 bulb. Some use 12v mr11 bulb. I haven't seen any that use a mr16, which would actually be a better lamp.

Most of these are also overdriven, 7.2 v / 14.4 v. This apparent cuts lamp life my a factor of 10.

My marwi light i bought in 2001 is still on the original lamp. I have at least 500 hours on it, probably more like 750. These lamp are actually really tough. Not that much vibration reaching the handlebar of a bike after being dampened by tires/tubes/air then shock/carbon fork etc.

MR16 lamps can be had for 3-5 bucks at the lowes/home depot. Get yourself 4a-hr of nimh batteries at 14 volts and you have a super bike light for under 80 bucks.
 
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