Have an 02 ex, 7.3L. Been kinda slow to start lately. Got in it today and it would crank over real slow about 3 cranks and then flatline, and all the gauges would do a full sweep. battery light came on as soon as you turned the key on. All fans, radio etc, were also off. Threw it on the charger for a few min and used the boost and it fired right up. Jumped in it and took it down to oreillys and they put their alternator tester doohickey on it, and said the alternator was good. putting out about 13.25v and 31 amps? (at idle with ac running on max)

The batteries were replaced by a kwik oil change place in january of 2011, and they put interstate batteries MT-65's in it.

I left oreillys and went to an interstate batteries dealer, and they swapped them out under warranty (as only being 18 months old). They said the MT-65's were too small for the truck, which probably led to the early demise, and put in MTP-65's in their place, and only charged the difference in price between the 2 batteries.

So my question is, does this seem like it was just a battery issue, or do you guys think the alternator is on the fritz? Or do you think both is a factor?

One other thing, the batteries were very warm to the touch when they were pulled out of the truck, the guy said the terminals were hot too. It even looked like there was some pinkish liquid that had run down the side of the batteries at one time as well. On the happy side, my SES light is off now...

 

If the alt. tested good, then it was probably just the batteries.

(Not a fan of Interstate batteries. When I sold cars, it seems every time I had one that needed jumping off, it had an Interstate battery in it.)

 

voltage should be higher at about 13.7 or higher. the batteries being dead and the alt trying to charge dead batteries could have caused the demise of the alt. but, i would do it again with the new batteries and all of your accessories on. a/c, headlights, hazzards, rear defrost, radio, wipers. it should not dip below 13 volts. it doesnt mean that your alt is bad, it means that its worn and cant keep up with the demand. when voltage drops below 12.6 volts, you are no longer charging.

 

Just ran it down and had it tested again with the new batteries.

At idle with both front and rear ac's on max, the drivers side tested at 13 volts, the passenger side tested at 13.25 volts and about 15 amps... looks like we're gonna be in the market for a new alternator here real soon. Any recommendations?

 

If your truck is stock, then anyone should work. If you want REAL power and you will never have to worry ever again, go to www.dcpowerinc.com . I have their biggest alt in my x and it charges 5gell cell batteries and I regularly pull over 250 amps from my stereo and my voltage never drops below 13.9 volts. They are expensive but remember, you get what you pay for. Again, if it's stock, I'd just get any replacement alt. just my opinion. But we know what they are like. Good luck.

 

Also remember, you alt will only put out what is needed. That's why since you have fully charged batteries, your amps are low.