10.5 volts is the industry standard for minimum operating voltage. Except
for ignitions, which are required to work down to 6 volts. Ignitions must
provide spark during crank when the voltage can really drop. (Been in the
OEM automotive electronic biz for thirty years.)
Bob Donahue (Still stuck in the '50s)
Email - email@example.com
52 MGTD - NEMGTR #11470
71 MGB - NAMGBR #7-3336
----- Original Message -----
From: "James Fischer" <firstname.lastname@example.org>
Sent: Wednesday, August 13, 2003 5:14 PM
Subject: RE: Battery Question
> > QUESTION: Why 10.5 volts? What's magical about that number?
> > Will the MG not run below 10.5 volts?
> To have a standard, one has to have a "standard test".
> Since most car electronics designed for 12 volts will
> not function below 10.5 volts, how long a car battery can
> "live" is defined as "how long before it drops to 10.5 volts".
> > I have added equipment that exceed the generator's capability
> > at night.
> More amps than horsepower, eh? :)
> I'd guess that your lighting system switch needs a relay
> to keep it from overheating and melting.
> I had the same problem with a 72 MG Midget. The lighting system
> was nice and bright, but the real answer was a bigger alternator.
> I have no idea what one might fit to a 1951 TD, but our 1952 TD
> looks like it could take quite a few different generators if one
> were willing to mess around making a few brackets.
> Have you considered the new LED lighting systems?
> Super-bright and expensive, but much lower current
> drain. Less energy is wasted as heat, and the result
> is more light with less current drain.
> > (plus Radio/CD, etc.)
> A CD in a TD??? Sacrilege. :)
> > If my calculations are right, I can drive under those
> > conditions for 7.5 hours before the voltage would get
> > to the 10.5 volt level, more than enough to get across
> > Florida from weekend car shows.
> ...and if you are wrong, you end up stranded on the Florida
> Turnpike, Alligator Alley, or the Tamiami Trail at 2am.
> If this happens, remember that your starter crank (you DO
> have a starter crank, don't you?) not only will start the
> car on a dead battery, but also makes a handy club for
> keeping the gators at bay until you get the car started. :)
> james fischer
> MGs in Summer, Volvos in Winter,
> so wrenches are constant companions
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