charging problem

I will try to explain about voltage drops. It goes back to Mr. Ohm, he figured out the relationship between current, resistance and volts. V = I x R. An Ohm meter applies a know regulated current, and measures the voltage to measure Ohms. The meters are are designed to force only a very small current, and also limit the maximum voltage. This is done so sensitive electronic circuits may be measured without damage. Ohm meters are only used in unpowered circuits, because the circuit currents and voltages will result in improper readings or damage meter.

An Ohm meter does a poor job measuring low Ohms. The voltage method is far better. So if current is flowing, measuring voltage across the resistor, shows the is a drop. If you do not know the current, you still know the voltage drop will be enough to be a problem. A few tenths may be OK. A few volts is not.

A regulator is simple, it measures the IGN voltage with respect to the case ground. It has an internal voltage reference set to about 13.8V. If the IGN voltage is less than 13.8V the regulator output goes low, pulling one field wire low. The other field connection is powered by IGN, so the field is energized. The current builds and the alternator responds, increasing voltage. If the voltage increases above 13.8V, the regulator output opens, shutting off energy to field. All this happens fast, the field is controlled in an on-off fashion, but the field current ramps up and down because of the inductance, it smooths, the voltage, along with battery, also a good filter and storage unit.

So that ground at the regulator is very important, it serves as the measurement reference point on the input, and also has to supply the ground return for the field current. All hell happens with a voltage drop there, because of unstable operation, the output, results in a change in perceived input voltage.

So follow all that 67dart273 suggest, it is all good. Not because I said, it follows all the rules of Ohms law, good trouble shooting skills and more.