I am kicking around an idea of adding a 3rd battery and I would like to mount it under the truck somewhere on the frame rail under cab. I know I have seen somewhere that someone made a bracket to mount one under the truck. But I can't find the thread. So have any of you guys mounted an extra battery in or under your truck?

My plan is to find a of the place and way to mount a 3rd battery or maybe even 2 batteries as a 2nd bank of batteries. I also plan to wire the 3rd battery as a house battery like you would in a boat. Charging will be handled through a marine battery isolator and I will run a main power lead back to the main batteries with a marine power supple switch. That way I will also have a built in jump unit. Also part of my plans are to install a 800 watt inverter, a couple of 12v cig & usb supply ports and in the bed cap some lights & another 12v supply. With my long term goals I really don't want to tie all these into the main battery bank. My main concern is when I install the inverter I want to mount it under the rear seat or in tool box in bed and after looking at amp draw and the size of awg wire I would have to run it just makes sense to add another battery. I almost forgot a amp for a sub woofer system.

I use this link to help me figure out what size awg I need when I am installing things on boats and I also use it on any 12v system I am working (Car, truck & RV's) I always try to use marine rated wire instead of SAE rated wire on all jobs but sometimes on truck or RV due to cost I'll use SAE. But either way this is a handy link to use when wiring.
Circuit Wizard by BlueSea
Circuit Wizard - Blue Sea Systems

So I hope to see where and how others have mounted a 3rd battery or 2nd battery bank. As of now I am thinking of making a battery tray that will go on the Rt side frame rail. But I am not sure if I will go inside or outside of frame.
Any input would be apperciated !!

 

I have seen frame mounted batteries on some E series chassis . You may get a Box from a salvage yard and adapt it to your truck .

 

Never done it before, but outside the frame would be my best guess to mount it. Inside the frame I believe there's too much stuff already there. An already made box drilled to bolt to the frame would be the easiest option I would think. You would definitely need to cover the top to keep dirt and rocks from getting up there, as well as a solid front to protect the batteries.

 

Look down in the OBS section.

https://www.ford-trucks.com/forums/1...p-started.html

 

Since you have a cap on your bed have you thought about getting a battery box and mounting it in the bed or in a truck box if you have one? I would think that might be the easiest.

 

Unless you already have selected your inverter, I noticed TSC sells a 1500w-3000w inverter for $150.


Tossing around the idea of getting one myself.

 

I run a third battery in one of the compartments of my F350 utility body, but my former truck (97 E350) had the OEM frame rail mounted battery. It wasn't as convenient as under the hood or in a compartment but it worked well enough.

The battery sat in a steel box with a plastic cover and was attached to the frame with bolts and keyhole slots that made it relatively easy to remove. There were also a pair of steel cables that supported the battery box in the down position. I don't know if the E350 and F350 frames are similar enough to swap it over but it's worth a look.

I have all of my aftermarket radio equipment on the third battery and am using a battery separator to disconnect it when the main voltage drops below about 12.5V. Here is a link: 1315 Sure Power Battery Separator 100A Bi-Directional

 

Thanks guys for all the great input !! I am liking the look and finish of the E series battery boxes. They are not cheap but it looks like when installed it belongs there on the frame rail. I am not sure what these boxes are on but it is a good photo of a E series van battery box.
http://i45.tinypic.com/rjegbr.jpg
Also as far as the van battery boxes go here is a thread I found with part #'s and the battery size is the same as 99-03 truck BXT-65-850
https://www.ford-trucks.com/forums/8...tery-tray.html
I also liked the boxes that Darin made on the thread in OBS section that Chris pointed out. The only down side to that set up is by the time you take labor and material into account in making the boxes I think I would be cheaper off just buying boxes.

I also found Torklift makes a set up but I don't like that it does NOT bolt to frame rail. So if I went with this set up I would bolt to the frame.
Under Vehicle Battery Mount - HiddenPower | Torklift International

There were a couple of cheaper set up's I found on Jegs just didn't have a box and I want mine mounted in a box. Also the ones for Jegs is for a group 24 battery and I want to install a group 27 battery.
JEGS Performance Products 10224 JEGS Battery Mounts - Free Shipping on All Orders @ JEGS
JEGS Performance Products 10225 JEGS Dropout Battery Boxes - Free Shipping on All Orders @ JEGS


Rob as far as mounting it in the bed I have a aluminum tool box that fits in the bed and takes up 2' of the bed and is 54" long. So there is no room to put it next to the box and I have no room in the box with all my tools and parts in there. The other draw back is that it would be a longer run wiring wise. Now the only reason I am going with a 800watt inverter is because I already have it. Chris thanks for pointing what battery isolator you used because that is another area I'll be doing alot of research on. You do have that work truck set up very nicely. What brought me to the point of wanting to use a battery isolator / charging separator is my old motorhome uses a solenoid that only allows power to flow to the house battery when it is running but it is such an out of date set up and has never done a very good job charging the house battery.