Strange coincidence: yesterday I pulled both batteries while I was installing new intercooler boots. Got it all back together last night, started and backed it out of the garage. This morning the batteries are dead. The batteries are 4 years old and have not given me any problems. I wire brushed the terminals both yesterday and today with no luck. The truck is currently on a charger.
Any insight other than bad luck?

 

Maybe an inside light left on ? Check your mirror lights too,on the visors, if u got them. We had one stay on one time even though it was closed and ran my wife's batt down. Just a thought

 

Thanks- could've been a lamp.
These batteries are almost 4-years old (~25 thousand miles)...it may just be their time.
Is this a standard life for batteries in our trucks?

 

Mine lasted 5 years - Different driving habits probably change batt. life. Have em tested- Maybe just a fluke, hopefully

 

My Wal-Mart batteries get right around 3 years on the button. The originals got 4 years.

 

Okay- I think I've got it. No problem yesterday after having the batteries on the charger all Sunday night. Drove fine on Monday...however this afternoon, after 2 days of great starts and stable voltage, while driving home I noticed that the voltmeter had tanked at "8 volts". I was able to restart after getting home.

I assume this is the alternator...anything else? What is the best alternator for my rig?

 

I can say -I bot one at autozoo & it lasted about 1 year & had to replace it. Was in warrnaty but--- I would recommend OEM, or if u have a good rebuild shop close to u, check into that

 

Have you checked the plug into the alternator? Is the alternator charging?

 

Also check if the light under the hood is stuck on. I know my 03 will shut off after so many minutes but am unsure if all of them do it.

 

Only way to know for sure is to test the alt. and load test the batteries.

 

Roger that- I've got an appointment with the alternator doctor this morning.

Wow- I didn't realize how complicated Intercooler boots were to replace!

Update: Just got back from the the alternator shop. The mechanic described my alternator as, "Stone dead". It is a Motorcraft unit that he is now rebuilding for pickup this afternoon. Case closed.

 

You should look into this. IF this plug is not connecting to the Alt properly, you will have this problem all over again.