It should measure the same, since the voltage at the battery terminals, when
the altenator is active, is the altenator voltage. The altenator runs at
13.5-14.5 V, depending on the level of charge on the battery. If the altenator
is not in the circuit (engine speed is low enough that the altenator's output
voltage is generally below about 13 V,) the regulator removes the altenator
from the circuit, and the voltmeter will drop to about 11 V. The difference
between the battery's natural voltage (12.64 V) and the altenator's 14V is
enough such that the the altenator charges the battery (14V - 12.64V = 1.36V)
is enough the keep the battery charged. The voltmeter thus will only see the
altenator's voltage when the regulator allows the altenator to be in the
circuit.
David Massey wrote:
> Message text written by Paul Mitchell
> >What does the voltmeter in the car show? Is it the voltage across the
> battery terminals, or the output of the alternator, or should they be
> the same thing?
>
> TIA
>
> Paul
> <
>
> Paul,
>
> They should be the same. The only time they would be different would be if
> there is a heavy electrical load. So shut off all lights, wipers, heaters,
> etc. and measure at the battery.
>
> Dave
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