Check the charging system. Use a digital voltmeter to measure the battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it is low, suspect the generator.

Answered by caradiodoc (expert)
17,324 answers provided

I wouldn't assume the battery is good. Before you get you testing the charging system, you first need to charge and test the battery itself to determine if it's even capable of holding a charge. Once you have a known good battery, then you should proceed to testing the charging system. If you get to that point and the charging system tests good, then you would move on to testing for a parasitic draw on the system.

Answered by Wrenchtech (expert)
14,749 answers provided

You're right, but he's tried three batteries. Too bad we don't know if those were new or used batteries.

Answered by caradiodoc (expert)
17,324 answers provided

That's my point, and we don't know if any of them were tested.

Answered by Wrenchtech (expert)
14,749 answers provided