Here's why its imprtant to note the battery charging or not.
Engine running and Battery getting charged.
Orange arrows represent current flow from the alternator.
View attachment 1715949261
The alternator is producing voltage higher than the battery.
The amount of current that flows depends on the downstream needs.
In the illustration above, the battery is drawing about 15 amps and the ignition and field about 6 amps.
If the voltage difference between the alternator output terminal and the battery positive was zero, then there is no resistance between those two locations. In reality, with 20 to 25 amps going through the bulkhead connection, then 15 or so amps through the ammeter connections, the bulkhead, the fusible link, and the relay junction, a little voltage drop is expected.
Once the battery is charged, then only 3 to 6 amps is flowing through the alternator output wire.
The voltage drop between the alternator batt and the battery positive will be less than measured when the battery charging. The resistance hasn't changed, its only the amps through the resistance that changed.
View attachment 1715949269
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