Charging circuit - reduced load on ammeter circuit
Dana,
If those leads had good contact to the posts, then there is way too much resistance between them.
The resistance across any section of the circuits should not be readable on a standard multimeter.
from Charging system road rage, measured resistance of three ammeters
And the results are...
Zero, Zed, Nada on the meter!
So less than 0.1 Ohms plus/minus accuracy of the meter which I'll look up later.
The meter with the alligator clips together. 0.1 to 0.2 ohms. So that's our baseline reading.
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Hawk gage set.
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Same with the RAC gage set.
And the here's the rally ammeter.
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Here's a back view of the shunt.
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Now lets determine the impact of 0.5 ohm resistance in an ammeter.
Voltage difference is caused by current flowing through resistance.
V=I x R
R= 0.5 Ohms
What sort of current does an ammeter see?
Well it varies depending on how low the battery charge is.
Lets take a higher but still normal charge rate of 25 amps right after starting.
25 amps x 0.5 Ohms = 12.5 Voltage drop.
Now obviously that isn't going to work.
With that much resistance maybe 5 amps will get through to the battery.
5 amps x 0.5 ohms = 2.5 Volts drop.
That at least is plausible with an alternator producing at 14.5 V and battery
below 12 Volts.
Even .05 Ohms in a main circuit connection is a lot.
