power supply cutt off switch

My batteries have been going from totally charged to deader then a door nail if i let her sit for more then a couple of days.. someone told me that the power supply cut off switch or something along those lines was bad. does anyone know anything about this on an 06 670? were it's located, is it an actually switch somewhere, is it that big a deal to change or should i just install an aftermarket switch?

 

yeah im not seeing anything like that in that area. ive looked all over. seems there's cables running from the batterys directly to the fire wall in the engine bay with nothing in between.

 

no but i did take them to auto zone today. they put them on a trickle charger for around 3 hours. 2 took a charge and the other 2 were still dead so i will be going to kenworth to get them replaced. im trying to find a aftermarket disconnect switch but can't seem to find one that looks like it would work well. tried ebay and amazon so far. the picture below is one that says will work with kenworth mac etc but it just doesn't look like it would work well from what i can tell. seems like they should have a better design then that bolt deal to hold the cables. this ones 45 bucks..

 

I just realized that those battery cables have a loop on the end so it would work fine. i guess ill have to get a short cable and crimp some loops on it to run from the disconnect to the batterys though or just buy one from kenworth.

 

I do not know. I'm going to check. I'm assuming your wanting to know what the voltage is from the alternator right?