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Re: Battery Question

Subject: Re: Battery Question
From: Dave & Liz DuBois <>
Date: Wed, 13 Aug 2003 14:41:13 -0700
Stu - The 10.5 volts (or more correctly 9.5 - 10.5) is the point where 
the fuel pump quits working and if you were to do the math, I suspect 
that the coil output would be reaching the lower lever where a spark 
will be produced.

John - I had a similar experience with my MGB, but I only got about 40 
miles out of before it shut itself down. Of course this happened at 0 
dark thirty on a rainy March morning in the Puget Sound area of Western 
Washington state.  I had no choice but to run with headlight, wipers, 
O/D and heater (for defrosting) so my range was greatly limited.  It got 
me close enough to my destination that a friend could come and pick me 
up.  I guess that to get maximum range on battery alone, one would have 
stay out of O/D and get out and disconnect the field windings from the 
generator - these draw 2 amps starting as soon as the ignition is turned on.

Jim - The LED lights look intriguing, but one needs to be careful about 
using them in place of the running lights and the tail/brake lights if 
their car has turn signals.  The flasher would have to be changed to a 
heavy duty flasher if the LED lights are used.  Why a heavy duty, when 
the current demand is reduced?  The standard flasher requires a set 
amount of current passing through it in order to flash properly.  The 
amount of current required is, conveniently set at the amount drawn by 
all the light bulbs used to indicate on one side of the car. This is the 
turn signals come on steady when one of the bulbs is burned out - lets 
you know something is wrong. The heavy duty flasher's rate is 
predetermined and independent of the amount of current being drawn by 
the bulbs, so it doesn't care if the bulb current is 0.1 amp or 10 amps, 
it will flash at the same rate.  It also will not let you know if a bulb 
is bad.  The worst case scenario would be one LED and 1 standard bulb on 
each side. You would need a heavy duty flasher to operate in that 
condition, but you would still have an incandescent bulb in use that is 
prone to burning out.  Sigh - everything is a trade off.


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