2005 Dodge 3500 Laramie Dually-- I have an electrical short that makes my batteries weak enough in one day to where it won't start. If I run the truck every day , no problem. But if I skip a day, it won't start the next day. If it sits for several days without running the batteries are shorted and cannot be recharged. The batteries I have are Duracells and they are almost new. If I pull the fuse that is marked "Radio, Cluster, and under hood light ", the short is no longer there. Can anyone tell me what might be the cause?

 

The cause might be the radio, cluster or the hood light.
Unhook each one to see if it goes away.

 

^^^ That wasn't a very constructive answer, though not wrong. I had an issue with my stock under hood lamp that used to drain the batteries down. The lamp on my 12, possibly still the same as the older trucks, used a brass looking ball to roll back and complete the circuit when the hood was up. It somehow got bent, tilted, stuck and the light was on when the hood was closed. I agree with PWong though, unhook items powered by that fuse one at a time to see if the problem goes away and you will have at least narrowed it down. Do you have a wiring diagram for what else is on that line?