In a message dated 1/10/99 10:19:51 AM SA Eastern Standard Time,
rrobertsmg@hotmail.com writes:
> I was kind of wondering the same thing. Although my red alt. light
> never comes on I have about a 2 volt drop when I apply the brake lights
> or heater fan.
Where did you measure this voltage drop at? The battery? At the back of the
alternator? Inside the car?
> So I bought one of those radio shack alternator battery
> testers and it said my alternator output was marginal. I began to think
> though, the leds on that thing were probably calibrated to 50 amps or so
> for modern day cars, not my Lucus 35 amps.
If you are talking about one of the little testers that plug into a cig
lighter and have three or four LEDs that light up, the answer is neither.
This type of tester is calibrated for voltage, it has no way to know amperage.
>
> Does anyone know the peak voltage those alternators should put out?
>
13.5-14.5V is considered normal for alternators. A fully charged battery has
12.72 volts available (excluding surface charge). There is two-tenths of a
volt of resistance per cell that must be overcome to charge the battery. So
if you add 12.72 + (6x.2) = 13.92 volts required to fully charge a battery.
Note this voltage is measured at the battery, no inside the car. I suspect
that you have taken your measurements inside the car and Mr. Lucas is rearing
his ugly head. <G> If you have marginal connections in the harness, then
when you increase the load the available voltage is going to go down.
Hope this clears up some of the fog.
Rick Ewald
67 B roadster
99 Volvo S 80 T-6
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