2002 Explorer charging issues

[02Explorer80]

Hello everybody. I have an 02 explorer with a 4.0. Recently while driving the battery light would come on and the battery gauge would drop while driving. If I charge up the battery it holds the charge until the vehicle is running. Then after about 30 minutes the gauge drops and the lights windows turn signals etc don't have enough juice to work. It drops so much that the fuel pump doesn't have enough power to get fuel to the engine and it starts to barely run. I've checked battery and its good. I've checked all fuses and they're good so I'm pretty sure there's no draw and that the alternators not charging the battery while it's running. I know you're not supposed to take off the positive battery cable while running but I wanted to see if it would run when I disconnected it. As soon as I disconnected the positive cable the car shut off so I'm saying alternators not charging. This is the 3rd alternator in 6 months. I want to replace the cables from the battery to the starter and alternator. Here's my questions. What do I set my volt meter on and exactly how can I check the alternator to see if it's actual bad? Secondly does anybody know how difficult it is to change the wiring from the battery to the starter and alternator? Any diagrams and or help would be greatly appreciated. Thanks everyone

 

[BrooklynBay]

Welcome to this forum! Take out the alternator, and have an auto parts store check it. Get an alternator with a lifetime warranty. Check all of the high current cables for corrosion, and use an anti-oxidant cream on the terminals.

 

[2000StreetRod]

Charge diagrams

Set your voltmeter to DC volts and select a range with a maximum of at least 15 volts. With the ignition off measure the voltage between the + and - battery posts. It should be at least +12 volts. Then measure the voltage between the + battery post and ground. It should be the same reading. If not, clean the + and - terminals of the battery cables and the connection to ground. Then start the engine and measure the voltage across the battery posts. It should be about 13.6 volts with the engine at idle. If not, then measure the voltage between the alternator B+ terminal and ground and the alternator A (armature) terminal and ground with the engine off and also with it running. CAUTION Be careful to avoid any rotating parts (i.e. alternator pulley, serpentine belt, cooling fan, etc.).

 

[02Explorer80]

02 explorer charging issues

I'll do all that today and update you. Thank you