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Re: Lights out!!

To: Glen Eldridge <glenel@infobahnos.com>
Subject: Re: Lights out!!
From: Robert J Donahue/DELCO <RJDONAHU@mail.delcoelect.com>
Date: Mon, 17 Jun 1996 13:35:50 +0000
>> 
>>>but poor Lucas electrical design that keep you bulb burning. Bulbs are
>> designed to have a certain life at a certain wattage. The wattage of
>> the bulb is obtained by applying the correct voltage to the bulb.
>> 
>> Let's look at an example I am familiar with. A certain 12V 100W quartz
>> halogen projector bulb life is rated at 25 hours. Not to long. But if
>> the voltage is reduced, the life goes up exponentially. Running this
>> bulb at 8 volts the calculated life is >20,000 hours.
>> 
>> Now with all the Lucas connectors and grounds that corrode the full 12V
>> never gets to the head lights thus extending the life dramatically.
>> 
>> - -Mark "My bulbs last longer than my connections" Jurras
>
>Mark et al.,   From the depths of my rusty store of electrical formulae, 
>mean that the amperage goes up.  I don't know how much current that 
>headlight circuit is fused for, but a drop of 4 volts in a 12 volt 
>circuit means an increase of 50% in the amperage flowing through it.  
>Somewhere, something has got to give; let's hope it doesn't require a 
>fire extinguisher! :-)
>
>Regards,
>
>Glen Eldridge
>
>glenel@infobahnos.com
>
>'64 Midget Mk1(stage 3 1275)   '95 Nissan Maxima
>

Incandesent lamps draw a nearly constant current independent of voltage.
This is because their resistance changes with temperature. The hotter
the filament gets, the higher their resistance gets. The situation is
different when you first turn it on though. If you measure the 
resistance of a cold bulb, you will find it is nearly a short. And
at the instant it is turned on there is high inrush current, but only 
for a very short time. Electric motors also have a high inrush current
untill they get up to speed. Unlike light bulbs, motors will draw MORE
current when the voltage is low. And, they will over heat on low voltage.

Bob Donahue (Still Stuck in the '50s)
53 MG-TD
71 MGB

To:
jurrasm @ genesis.torrco.com (Mark Jurras) @ USDESMTP

cc:
mgs @ autox.team.net @ USDESMTP (bcc: Robert J Donahue/DELCO)

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