Battery or Alternator issue

[Tedshuey]

Met the Wife for dinner last night, she had driven our 2000 EB Explorer, She mentioned over dinner that the battery light had come on her way there. I drove it home, It started fine but then headlights dimmed, most interior lights went out, windows wouldn't operate. Since we live only about a mile from the restaurant and the town is well lit I drove it home. The interior lights would come on and off intermittently, the engine would stumble at low speeds. Got it safely to the driveway and shut her off, tried to start it immediately but got only the rapid clicking sound. Waiting for it to get light out so I can take a look under the hood. Is this a case of a dead battery or might I have an Alternator problem?

 

[Thuggsy]

at this point... both

replace the battery, benchtest the alt.

 

[Tedshuey]

Update:

I jumped it and it starts will run at idle, battery gauge is showing L. As soon as i rev the engine it starts to stumble and die. Will not restart on its own. Minimal corrosion on cables(cleaned up). Battery looks relatively new (inside 3 years). Checked all relays and fuses. How can I confirm Alternator at this point?

 

[koda2000]

Update:

I jumped it and it starts will run at idle, battery gauge is showing L. As soon as i rev the engine it starts to stumble and die. Will not restart on its own. Minimal corrosion on cables(cleaned up). Battery looks relatively new (inside 3 years). Checked all relays and fuses. How can I confirm Alternator at this point?

the only thing that will cause the BATTERY light to come on is if the alternator isn't charging. it has nothing to do with your battery. there is zero evidence that you need to replace the battery. it will need to be charged however. your alternator is probably shot. remove it, take it to the parts store and have it tested, but plan on replacing it. once you've charged your battery (with a charger, not the new alternator) have it tested too. if you don't have a battery charger, the auto parts store can recharge and test it for you too.

 

[SoNic67]

With engine running, readings with a voltmeter on alternator should show 14.2...14.6V. If less than that - you need new alternator.