2000 F250 dead in the water

[colocat]

so the other day i went out to start my truck its dead nothing,so i put a charger on the passenger side battery ,didnt help pulled the battery and found it to be bad ,so i replaced it and charged it like they said and took the truck to have the system checked ,alterator was bad so i replaced it ,the driver side battery showed ok.well went to start today and same thing dead! i shut everything off before i left where do i go from here is the driver side battery Bad???? any help would be great sorry for the long
post

[mudseeker]

if your alternator is in fact doing it's job, then i would look for a parasitic drain. have you done anything to the truck lately?

[colocat]

no i havent done anything this just started is

[mrjohnwayne]

good rule of thumb if one battery is bad replace both.. I would have the new battery checked also. it does not take long for a bad alternator to kill batteries.

[colocat]

looks like the other battery was bad charged all night had it tested today
i hope thats it didnt get a chance to try today so the main battery (passenger side) is mainly for starting and the other battery is for accesseries is that correct or close???and if one battery is bad your dead in the water

[mrjohnwayne]

No both batteries serve the same purpose. They are tied together, and both are needed for starting etc...

[leolkfrm]

Do you have a camper pkg on the truck? or is it diesel? camper pkg usually has an isolater on them which can go bad

[SureBert]

Have you noticed if either the bed light or interior light stays on or comes on in the middle of the night? I had a similar problem on my 00 250. Took it to an electrical place and had it checked for any shorts. Nothing. A little more diagnosing on my part and I found a small leak coming in from the left windshield channel and dripping into my fuse block (under the dash). Researching Ford trucks I found that when they, the factory, installs the windshields they don't mount centered al the time, and this leaves a gap for water to get into the channel. These are the steps I took to resolve the problem:

1. Replaced the windshield. When they took the glass out you could see mineral deposits from the water running down the channel. I used 3 Diamond Glass and I would recommend them as a dealer. $140.
2. Replaced the battery with an Interstate $180 but WELL worth it. Tried Die Hard, Exide, and some other brand I can't remember but none of those three provided the power, nor the durability, for my truck.
3. Sealed any areas on the firewall where I could see even the tiniest bit of light coming into the interior. This would be where there are wire harnesses coming through, or where a firewall plug is worn or missing. I used Silicone sealant.
4. Treated all of the door gaskets with Silicone Lubricant (forget Armour All - it's ****)

The first two were the most important, the last two was to prevent any moisture, whether from the road or air, as that leads to a condensation buildup. If you've ever noticed when you get in the truck that there's moisture on the inside of the windshield that's a good indication that moisture is getting into the cab. not only should you notice a decrease in moisture, but a decrease in wind noise. I re-treat the gasket every time I change the oil.

I've recommended the above to a few other people with 250's and it took care of their problem as well.