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From: Don Dement (no email)
Date: Wed Aug 18 1999 - 23:23:59 EDT
Jim -- I've used halogen bulbs for other purposes, not running lights. Sounds
like a very good deal you've described. However ... some random thoughts.
There's always a however. I've had three halogens of various types burn out
after only a few minutes (!) on a fresh battery. That was a few years ago, so
maybe there's some industry experience by now to make them a bit more
voltage-rugged.
Bulb lifetimes vary exponentially, inversely with the operating voltage. I'd be
concerned that these halogens might be designed with a lifetime based on a
12.6v or less battery, but when you're running the engine your system will be
operating at 13.6 to 14.4 if your batteries are being charged. Although it
would apply to any bulb, that would surely shorten life. In effect, you need a
14-15v halogen if such exists. Are these spec'd for mobile use, or for a
flashlight (no active generator)?
Even if they pop more quickly, at that price you might come out ahead if
replacement (at night in an awkward place) is not too difficult. As you
probably know, you can't touch the bulb's glass. Your fingerprint will cause
rapid failure, so factor that into the replacement-at-night scenario. You wear
rubber gloves or use a paper towel if you have to press them into place.
Hopefully they aren't the kind with one screw-in wire terminal.
Can your light fixtures stand the additional heat? Yes, I know they're using
less power, but the halogen bulb surface gets hotter and can melt a plastic
lens if it's too close. Running lights being outside should alleviate this
situation as long as there's some room inside the fixture, and there's actually
not much overall heat difference. If it's burned out it will have cooled by the
time you need to touch it.
For running lights that use fresnel lenses, the shape of the filament is
important. The lens is designed for a vertical filament in order to max the
emitted light (meet emission specs) in the horizontal plane where it's useful.
The halogen filament should be the same shape as the ordinary one.
As to "energy hogs," your numbers don't show a lot of difference. 23 watts
versus 20 watts? Used four at a time (port, stbd, steaming, stern) that's only
12 watts more for ordinary bulbs; or at 12V, a 1 amp excess (over a load of
6.7 amps for halogens).
But, back to money. Why do "ordinary" bulbs cost $13? Wow. The replacement
sockets and your labor must be considered zero value for this to be a bargain.
All else being equal, the most important question is not energy or money but
whether halogens are more tolerant of "higher" voltages to sustain output over
a realistic lifetime. I'm sure you'd hate to be converting back again, but I'd
save the old sockets.
Regards --- Don Dement -- Annapolis
Jim Isbell wrote:
> The 23 watt 21CP 12 volt tungsten lights in my side lights are $13 a pop
> and they are energy hogs.
>
> I have aquired some 20 watt 25CP 12 volt halogen bulbs ($1.00) that put out
> more light for less current and have a very long lifetime. I am now
> retrofitting my running lights.
>
> Anyone out there ever use halogen bulbs?
> Cheers
>
> Jim Isbell
>
> http://members.tripod.com/~Jim_Isbell/
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