My 2005 was on it's original batteries - the ones that came with it from the factory - and they were finally starting to show a little tiny bit of needing to be changed. Truck needed a boost after I left the lights on for an hour (I was troubleshooting trailer lights, and this trailer has like 25 running lights, all of which have never worked at the same time), and voltage went sorta low on the first start after a two week rest. I went to my Great Northern Battery warehouse - they are a major battery wholesaler up here in Canada, and picked up two of their brand Johnson Controls 900 CCA Gp 65's for $98 each, I thought a screaming deal. I wish I could say they made a huge improvement, but the truck is acting exactly the same as it did on the 7 year old batteries, but I bet that when it gets to be below zero this winter I'll be happy...

Brian

 

Make sure you measure your voltage.
Could be your alternator. Voltage is
critical to ficm health also...

 

I have an Autometer voltmeter and of course the SGII can read voltage. It's the original alternator, but from the life of the original batteries it's doing a fantastic job.

 

Just keep in mind it seems that the Batterys and Alternator all seem to go fairly close to each other

Thats how mine was anyway

DC Power makes the Best alternators out there so start saving Pennies the electronics on this truck relie heavily on Solid charging system

and clean the grounds where they mount to engine and frame