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• This looks really neat, but no mention of what he powers it with. Am I supposed to know that? I.e. I know 10W halogen is a standard bike light size - is there a 'typical' rechargeable source for that? I asked the author directly and if he responds I will post.

  Posted by: uberstar on September 1, 2005 at 11:55 AM

• You can calculate it pretty easily. Any good-size 12-ish volt battery pack ought to be able to run it for quite some time. 10W at 12V is just shy of 1 amp, so say 1A, just to have some margin of error. If you find a 12 volt battery with 5AH of juice, it'll run that light for approximately 5 hours. A 9 volt RC-car battery pack would probably work, but the light might be a bit dim. Those are commonly available and have ready-made chargers all set to go (or you could make your own very simply).
  
  
  
  -Jesse

  Posted by: jcantara on September 1, 2005 at 12:15 PM

• I emailed the author and apparently he uses a 12v7Ah battery. I mentioned my concern of the weight, but didn't seem an issue for him.

  I recently ordered a 12v3.4ah battery+recharger and am still deciding how bright to go. I don't even need an hour per trip, so considering 35watts. The reason I like the 12v3.4ah is that it'll fit inside a water bottle (cage) and only weighs a couple pounds. Tripling that weight so I can pedal for 6 hours in the dark isn't interesting to me.

  -Sean

  Posted by: SeanYunt on September 1, 2005 at 4:22 PM

• Hi, Jake here,

  I use lead-acid gel cells for power. Gel cells typically weigh 1 pound per Amp hour and a 20 watt bulb will burn for about 35 real world minutes per Amp hour. They are available in lots of sizes at Home Depot in the lighting section and are sold for emergency and exit lights. They are also used in computer UPSs and there is no cheaper rechargable power source.

  I use a 7Ah battery to power my lights and charge it once a week. With an hour's ride in the evening I have plenty of juice. I made a 20 Watt light for my brother-in-law for his bike, his uses a 4 Amp hour gel cell. He has an hour commute and charges it daily while at work. My brother-in-law uses a 12 volt "wall wart" supply to charge his and I use a Vector "Smart" automotive battery charger.

  While seven pounds may seem like a lot to a cyclist, it is really not. In reality it works out to a matter of seconds - important in a race - but not to a commuter. Better to see and be seen. When I flash the 50 watt high beam oncoming cars always dim their brights.

  Jake.
  Bus and Bike Stuff
  Kerosene Lamps

  Posted by: vonSlatt on September 1, 2005 at 5:50 PM

• Ok, this does it for me:

  "When I flash the 50 watt high beam oncoming cars always dim their brights."

  I am SO there. Thanks for the great site - I'll be building this weekend.

  Posted by: uberstar on September 2, 2005 at 8:23 AM

• Jake, I love your bus page. Now I think I want to convert a bus. Thanks for all of your info.

  Posted by: jmassaglia on September 2, 2005 at 10:29 AM

• Great stuff Jake. How do you have the battery and switch set up? i.e. waterproofing and mounting.

  Posted by: cycloscott on September 3, 2005 at 1:46 PM

• Yes - I had the same question as the last poster - switches for that '50-watt' flash?

  Posted by: uberstar on September 4, 2005 at 9:34 PM

• Hi Jake Here!

  The links in the story all still work but I've moved the site to Jake's Recumbent Bicycle Projects

  Posted by: vonSlatt on November 1, 2005 at 3:13 PM

• To answer the other questions: Battery is a 7 ah 12 volt gel cell which I just keep in my Hardshell bike trunk. For the highbeam switch I use a simple mini-toggle and a 12 volt relay. However, with an SPDT automotive switch you could eliminate the relay. -Jake

  Posted by: vonSlatt on November 1, 2005 at 3:21 PM

• I use lead-acid gel cells for power as well. Is there any area I need to pay special attention? By the way, I have great resource for fioricet you may wish to check out. Thanks. BUY-fioricet
  

  Posted by: caan on November 21, 2005 at 12:53 AM

• Here is an $10.98 garden spotlight from Lowes instead of Home Depot. (12 volt MR16 20 Watt bulb, fixture, adjustable base included) mounted on my electric bike:

  http://www.healthebike.com/lafree/bikelight.JPG

  
  

  Posted by: healthebike on May 25, 2007 at 8:44 PM

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