Newsgroups: rec.bicycles

In rec.bicycles, koren@fc.hp.com (Steve Koren) writes:

 >    * A Sylvania plastic car headlamp.  Very light weight.  The model
 >      number is HP4656, and it is a halogen lamp in a rectangular
 >      configuration.  I got mine at Checker Auto Parts.  35 watts.  Price:
 >      $12 to $16.  Be careful to get the HP model and not the H model,
 >      which is similar but made of heavy glass instead of lightweight
 >      plastic. 

This is the low beam from a car with four rectangular headlights.
These things are great.  I have a couple of them, one on a mtn bike and
one I'm setting up for my commute bike.  They put out lots of light near
the bike, off the sides, and straight ahead.  Nothing else comes close.
And you have a high beam for cars that are blinding you.  

One note:  the 35 watts is when you run them at 14 volts.  A car's electical
system is around 14-14.5 volts when the engine is running.  The light is
rated for about 200 hours at 14 volts.  At 12 volts they run 30 watts, but
are still good and bright, and will probably last forever.  I have some
2V 5AH cells that I was going to rig into a 14V 10AH battery and try it
out, but I haven't done that yet.

I am mounting the commuter bike headlight on the front of a front rack.
I have a milled plate to fit around the headlight.  There is a hinge to
bolt to the rack on the bottom and a turnbuckle to hold the top and allow
up/down aiming.  The batteries go behind the light on the rack, and it
fits below the handlebar bag.  

>     * A 6 watt red car or truck marker light.  I payed $2.50 for this at
>       K-mart.  Its much brighter than most bike taillights, especially if
>       you tape a bit of aluminum foil behind each bulb to reflect more
>       light.  Its about 4" wide, 2" tall, and 1" deep, in a rectangular
>       plastic case with rounded sides, and very light weight.  It also has
>       a wide beam dispersion angle, which means it can be seen by someone
>       off to the side, unlike many commercial bike taillights.  Price:
>       $2.50.  It looks somewhat like this from the front.  Inside there
>       are bulbs where the "BBB"s are.

I use similar tail lights, one yellow with a flasher circuit, and one red.
I used the round single bulb side marker lights.  They came with the same
3 watt bulbs, but I ditched them and use #90 bulbs (interior dome light
bulbs-the socket fits through a hole I drilled in the back of the housing)  
These are 6W @ 12V or 8.4W @ 14V, rated for 750 hours at 13V.  
One 6W light is brighter than two 3 watt lights.  Cheap and effective.  
The flasher runs at 80 flashes/minute.  I'd post the schematic if I didn't
have to convert it to ASCII.

>     * A 12 gel cell battery.  The following company has batteries ranging
>       from 1 to 20 AH.  The minimum practical capacity for running this
>       head/taillight combination is probably about 5 AH.  After 12AH the
>       battery gets very heavy, so the reasonable range of batter sizes is
>       around 5 to 12AH.

Gel-cells are cheap and weigh a ton.  Check out local electronics surplus
places-you can often get them new or close enough for very cheap.

>                   American Design Components
>                   1-800-776-3700 or 1-201-941-5000
>                   815 Fairview Ave
>                   PO Box 520
>                   Fairview, NJ 07022

>       Price: $18 for 7AH @ 12V. You can trade off weight for running time

That's an excellent price for new batteries. About 1/2 of Digi-Keys price.        
>       want, but just getting 12V is a bit more convenient.  To find out
>       the AH capacity you need, given your desired running time of X
>       hours, use this rough indication:

>            capacity = X * 3.5 * 1.5
>                       ^    ^     ^---- derating capacity for cold, safety
>                       |    \--- Current draw of headlight + taillight
>                       \-- Your desired running time in hours

>       For example, to insure about 1.5 hours of running time per charge,
>       you'd need about 7 to 8 AH.

The amp hour rating is for a 10 hour discharge rate:  a 10 amp hour rating
means it will put out 1 amp for 10 hours.  If you draw 10 amps it won't
last half an hour.  It isn't linear.

>     * Transformer to use as battery charger (if you don't already have
>       one).  Cost: $10.  Available mail order, or from Radio Shack.  The
>       transformer should put out 14V@1A in order to charge the battery.
>       12V won't work, although some transformers rated at 12V put out a
>       bit more even under load.

Too low a voltage will slowly lower the batteries capacity.  Too high will
shorten the battery life.  I charge my 12 volt batteries at 14.3 volts.
This is based on some curves in a technical note from Gates Battery.

>   I've been running a system like that for about 4 months now, and I love
>   it.  Using both an auto taillight and headlight gives you great visibility
>   in traffic.  The headlight is also great for lighting up dark roads and

Better visability than in the daytime.  It is safer riding around town at
night with good lights than in the daytime.

>    16. Look at the Sylvania headlamp.  It has 3 terminals.  In various 
>	 combinations, these can make a 10 watt, 35 watt, or 70 watt light.
>        (There are two filaments in the lamp which can be run singly or in
>        pair, and in addition, at half intensity).  Apply voltage to these to
>        find which two terminals make the 35 watt light.  Soldier short 4"
>        pieces of wire to them, and put push-on connectors on the ends.

There are two filaments.  One for a high beam one for a low.  I set it up
so that I can choose between them.  Forget running them both at the same
time.  I even took a LED and made a high beam indicator (put an LED in
series with a 1K ohm resistor and put them in parallel with the high beam).    

The only other thing I would like to add is that I recommend adding a fuse,
as close to the battery as possible.  These things can be dangerous if
short circuited.  If you can handle the weight this type of system is
unbeatable.

Frank Ball   1UR-M          frankb@hpsad.sad.hp.com
Hewlett Packard   	    (707) 794-4168 work  (707) 538-3693 home
1212 Valley House Drive     
Rohnert Park CA 94928-4999  KC6WUG Seca 750 XT350 IT175 DoD#7566 I'm the NRA.
Newsgroups: rec.bicycles