View Single Post
Old 04-20-2009, 10:14 PM
Earthman's Avatar
Earthman Earthman is offline
Motorized Bicycle Senior Member
Join Date: Mar 2009
Location: Pittsburgh, PA
Posts: 82
Default Re: What wattage headlight to use?

Thanks for all the feedback. For experimenting with different wattage bulbs, Iíve built a headlight out of a 4Ē dia., Schedule 20 PVC cap, some scrap aluminum, and a 12VDC, 11 Watt landscaping flood light (photos attached). I like the look of a larger headlight Ė I think other motorists will see it better as well.

The flood light Iím experimenting with now makes a rectangular beam that is about 20 deg. wide by 3 deg. high (see photos). I donít know if its brightness is adequate for night driving because itís raining here and I havenít been able to go for a ride to test it. But, I like the pattern of light it projects.

As far as batteries go, Iíve just about given up on using a lead-acid gel cell and will probably end up using nickel metal hydride batteries. This is because of the following:

Lead-Acid Batteries:
1. Relatively inexpensive, but heavy (so am I, so I want to keep the weight down).
2. Their discharge curve is such that the voltage keeps dropping with time, so the headlight will dim as well. This is annoying.
3. They donít self-discharge as readily as other types of batteries, so chances are the battery will not be dead when I need to use it. I donít plan to ride at night very often.
4. Discharging lead-acid batteries below about 10.5 volts is bad for them Ė it decreases their service life.

Nickel Metal Hydride Batteries:
1. Theyíre relatively expensive, but much lighter than lead-acid. Also, if properly maintained, they may be less expensive than lead-acid over the long run.
2. Like nickel cadmium batteries, their discharge curve is relatively flat until just moments before they die. In other words, their voltage is nearly constant until they die quickly with little notice.
3. I can have a battery pack made to just about any voltage in steps of 1.2 volts. If I what to ďoverdriveĒ the bulb for additional brightness, but shorter life, I may be able to do it as long as I can make or buy a proper charger for the battery.

Right now, Iím thinking of carrying two nickel metal hydride battery packs of about 4 A-hr each. That way, if one dies, Iíll be able to swap in a fresh battery pack. This way the ďdie with little warning syndromeĒ wonít be as much of a problem.

Anyway, thatís where I am today. I may change my mind again after I tinker some more with my new headlight.
Attached Images
File Type: jpg CIMG8490.JPG (517.7 KB, 387 views)
File Type: jpg CIMG8491.JPG (115.0 KB, 83 views)
File Type: jpg CIMG8492.JPG (196.3 KB, 68 views)
File Type: jpg CIMG8495.JPG (658.6 KB, 116 views)
File Type: jpg CIMG8487.JPG (532.9 KB, 114 views)
Reply With Quote