Re: Ford Explorer problem....battery or alternator
This is my favorite topic!
The best way to test to figure out the problem is the battery or the alternator is what you should do as the following:
1. Definitely yes, you can unhook the positive battery terminal to test the battery while the vehicle is running. Why? It will not damage to the alternator or the charging system if you don't drive the vehicle. During the idle of the engine, the charging system don't really produce much current into the battery at all. Moreover, you don't really leave the engine runs for a long time during the testing cycle.
In this case, if you unhook the positive terminal and the engine is still running, you know that the charging system is about to be ok. There is another way to test if you have a DC Volt meter with you: if you have 14v +/- while the engine is running with the battery hook on, you definitely have a good charging system.
2. You said that you could not start the vehicle after you park it for a while, right? When you start it, did the vehicle starter run at all? Can't start or the engine won't run? If your engine spins but won't start up, I'll will tell you how to fix it. Just come back and ask me.