[Healeys] Alternator, Follow up

WILLIAM B LAWRENCE ynotink at msn.com
Fri Aug 22 18:59:47 MDT 2008


The load on the charging system is determined by the amount of electricity
used. The alternator operates by establishing the overall voltage in the
electrical system slightly above the nominal voltage rating of the battery.
This is set at about 13.5 volts. Because of the set point the battery charges
to match the system voltage by simple equilibrium. (This is why an ammeter in
a car equipped with an alternator is only so much excess weight. The only time
it changes enough to be perceptible is on starting, and then it quickly
returns the system to the set voltage and stays there.)

When the system voltage is at set point the alternator idles. The amount of
work the alternator does to maintain that equilibrium is totally dependent on
the load from the power using systems in the car. Typically the load for a
Healey consists of the power used by the ignition, lights, overdrive solenoid
and radio (if the car is so equipped). These are the same loads you would have
if running a generator. For that reason the alternator will usually not
produce any more charge (amps) than a generator. If you are loading the car up
with a lot of extreme high power use accessories (hydraulics, 1000 watt amp,
aircraft landing lights?...) you may approach the limit of the power carrying
capacity of the charging wire. Nothing else should be affected.

The extra generating capacity of an alternator may be useful if you are using
a mix of accessories that exceed the charging capacity of the generator, but
for the most part it will not be used. There are a lot of good reasons to use
an alternator, but a 75 amp charging capacity is probably not one of them.

Bill Lawrence
----------------------------------------
> From: lapierrem at sbcglobal.net
> To: healeys at Autox.Team.Net
> Date: Fri, 22 Aug 2008 17:57:54 -0400
> Subject: [Healeys] Alternator,  Follow up
>
> Nothing?     Everyone must be alternatord out.


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