Battery/Electrical Troubleshooting

[SoonerSailor]

A merger is for testing insulation, not low resistance wiring. There are ohm meters that read in the milliohm range that could help in your diagnosis, but try this: measure voltage at battery terminal during cranking, then measure voltage at the starter motor terminal during cranking. That will tell you if you have too much voltage drop.

[Nemo55]

After all the good advice, and still no joy,,i would take the starter back out and take it apart,,look for wear marks along the armature and the Field coils.
If the armature is being driven off center from a little bearing wear or miss-alignment,,then the motor will bind and draw a lot of amps and create alot of heat.....My two cents (i think everyone else has covered it all)

[WrenchBender]

Voltage drop test is easy. Voltage meters display the "difference" in voltage between the leads. With this in mind! Connect one lead on one side of a suspect connection, then connect the other lead on the other side of the same suspect circuit connection. Crank or load the circuit and watch the meter while it's loaded.
If there is a "difference" in voltage from one side of the suspect connection to the other side while current is flowing you have voltage drop in that connection. Just remember, ALL connections have some voltage drop. Expect .25 at starter cable connections as a norm. Good luck. Dan

[sailorboy1]

Originally Posted by Mickeyrouse

Battery cable at 1/0 ga. Is same or larger than original builder installation, better grade, and terminals shiny clean.

So if you are convinced that the batteries and cables are good; replace the starter!

If the system is drawing so much current to heat up the starter and cable under normal conditions and the starter is still having trouble, well the starter is bad.

[Nemo55]

+1 for Don

[Mickeyrouse]

UPDATE:
Problem solved!
It was none of the above. The 1/0 Ga. Cable from the disconnect switch to the starter motor had a defective terminal. A 2/0 terminal was used on a 1/0 cable, thus did not fit as snuggly as intended. Even though the terminal was crimped and soldered to make up the gap, there was still wiggle room. Which thanks to vibration, it did. Thus, there was enough contact to make continuity, and if the batteries were charged to the max, enogh current would pass to start the engine. But the bottleneck of the weak connection resulted in those frustrated elections having to do something, so instead of turning the starter motor, they heated the cable.

Lesson: unless you're in a critical have- to situation, use the proper size. In retrospect, 2 ga. cable would probably have worked better than 1/0 cable and improperly sized terminals.