Seven Gen GP Battery Relocation

[Last Indian]

1997-2003  Battery Relocation Project

I’m posting this because several folks have asked me about this & just how to accomplish it.

First of all I need to preface this with the edict, that this project is quite involved! If done in this manner. It will require, if done as described in these instructions, more than one day. & at least the partial removal of the interior.

 

You will need at least 25 ft. Of 2/0 welding cable for the + side & at least 30 ft. of 1/0 welding cable for the – side. I would recommend you make accurate measurements of both first before you buy, as welding cable is not cheap. You need welding cable because it well deliver the most power with the least loss of amperage over these long runs of cable. This is due to the fine strands of cooper wire. Additionally welding cable is very flexible, which you will need for this installation. You will also need high quality lugs that will be crimped on to the ends of the cables so you will need a crimper or a means  that is big enough to do that. You should also consider heavy gage shrink tube to seal the lug ends to the cable. You’ll need a 300 amp mega fuse & holder that will mount in the trunk area. This is needed for safety, just in case something shorts for any reason! Even an accident could cause this occurrence. That fuse will blow keeping the battery from shorting & causing a fire!

I mounted the battery, which is a Odyssey battery PC925, under the spare tire. This batteries specs are more than sufficient & is the only style that will fit in this manner, which is to have the least amount of impact on the aesthetics of the trunk compartment. This configuration works very well, but requires the removal of the jack & it’s components, but not the spare. The jack & it’s components we’ll need stored elsewhere. You will need a battery hold down setup that can be bought at most auto parts stores. The following materials will be approximately the length of the bridge/brace you see below in fig.1  & by a width that will hose the battery. So the following will be needed, a 12”x?”x1/2” sheet of nylon, a 12”x?”x1/4” sheet of nylon & a 12”x?”x1/4” sheet of neoprene. These will be used to make the mounting base for the battery. You are going to remove the large styrofoam disc that the spare sits on as well as the threaded shaft assembly that holds the spare down & set them aside for now.

So starting with trunk mounting setup, I’ll use some pictures.   (Figure 1 below)

 

This is the bare spare tire area, above. The factory bridge/brace is used as the anchor point for the mounting.

I do not have the dimensions that I used for the nylon plates, but you should be able to determine them based on the pictures that will be provided & the basic spare tire floor configuration & battery footprint. The 12”x?”x1/2 nylon plate should be cut so there are two pieces. One goes on one side of the bridge/brace & the second piece goes on the other side. When cut to their finished size, their combined dimensions, plus the width of the bridge/brace front to back, will determine the dimensions of the upper 12”x?”x1/4”nylon plate. Which will end up the size you determine.

(Figure 2 below)

 

In this picture you can see the corresponding screws that attach the assembly to the bridge/brace as shown in fig.1. You can also see that the ½” piece of nylon adjacent to the two rubber knockout plugs is relieved to clear the trunk floor upsets it lays over. What you can’t see is that those two pieces of ½” nylon are attached to the ¼” nylon piece with screws on the underside, so that this becomes a one piece assembly to install. 

You also need to drill a clearance hole for the spare tire threaded shaft assembly. Now cut a piece of the neoprene to a dimension that is slightly larger than the battery footprint. Next you need the battery or at least the battery footprint & the spare tire styrofoam. Cut a square out of the center of it, but much smaller than you need & Install the styrofoam back in place using the tire threaded hold down as a locating guide. Lay the neoprene in the styrofoam & center it in the middle. When you are sure it’s where you want it mark the styrofoam for cutting, fig. 4. After cutting the styrofoam mark the nylon like you see in figure 3. Remover the styrofoam & place the neoprene on the nylon as in fig. 3. Referencing to  fig. 5 you will see the type of battery hold down I used. Using the top piece of the hold down as a guide, mark where you want the holes for the threaded rod to be used for the hold down. I used 1/4x20 all thread,  drilled & tapped the top nylon plate & used a double nut on the backside. You can see I made brass L brackets to use on the battery terminals to keep the profile low. I also needed to carve some of the styrofoam out of the spare tire styrofoam to allow access to those L brackets. Fig. 6 shows the assembly without the clamping bracket in place. Fig. 7 shows the entire assembly with the spare tire styrofoam installed.

(Figure 3)below

(Figure 4)below

 

(Figure 5)below

Figure 6)below

(Figure 7)below

Next is the 300 amp fuse/holder installation & location. If you remove the trunk liner padding you will find the rear valance bracing panel. Within that panel is where you can place this fuse & it’s holder. From the battery I recommend that you run 2 negative cables. Both will run into the valance brace panel. A shorter one will route to the far left & attach via a bolt to that panel. The other will run inside of this panel as well, but will go to the right (passenger side & exit the panel out the end. Then you will run a 2/0 + cable from the battery to the inside the panel to the 300 amp fuse holder located on the far right (passenger side). On the other side of the fuse holder you’ll connect the main long run 2/0 cable that will run all the way to the front of the car. This cable will also exit out the end of the panel. These two cables positive & negative will run together. Snake these cables along the floor where the floor & inner fender/body panels meet. Using aluminum tape, the type they use on heating ducts, attach the cables to this area in a continuous manner. In this way you create electronic noise shielding, cable protection & assure yourself it stays put. These cables will run inside of the car. So this is where you’ll need to remove the rear seat, top & bottom the front passenger seat & the carpet. Either remove the carpet, which will require the removal of all seats & console or lift up the carpet & hold it out of the way while you do the work. You will want to attach the with the aluminum tape to the vertical portion of the inside rocker panel, but near the floor. You need to run it this way all the way to where the floor starts to transition into the firewall. 

 

In the picture below (fig. 😎 you can see the two cables exiting through the plastic body plug. You need to locate this plug, which is just inboard of the subframe at the firewall & remove it. Than reference it location relative to it position inside of the car. You will than need to drill two holes large enough to put in rubber grommets that each cable can pass through. You need the rubber grommets to protect the cables from getting cut by the sheet metal over time. Than these cables will pass through the opening were the plastic plug was. Cut two holes in the plastic plug, put the cables through each hole respectively & reinstall the plastic plug.

More to come!
 

Edited January 16 by Last Indian

[Last Indian]

Figured 8

 

Next would be front connections. You can make these connections how you wish. This is how I made mine. I kept the original basic connection concept for several reasons. One if I ever wanted to go back to a front mount battery, it would be easy. And secondly the original positive cable setup incorporates the supply to the main under hood fuse box & starter cable. Which if removed meant making some other setup, which just didn’t make sense to me. So below are pictures of how I made mine.

 

Figure 9

 

Above in fig. 9 is the original battery tray & the original positive & negative cables. The positive cable: I made a Nylatron stanchion, this is a nylon with a molybdenum material, which makes it a better insulator. This stanchion is about 4.5” tall. It has a stainless steel wrap at the top with a 3/8 through hole that allows the new positive cable from the rear battery to connect on one side to the original positive cable on the other side.
Figure 10

 

Above in fig. 10 is the negative cable connection it is made at the alternator. I made this the grounding point for the rear ground cable because the biggest issue for long run cables in a DC condition is voltage drop. So the biggest drop will be under engine cranking conditions. Since the original stock cable is still connected, fig. 9 the rest of the system is adequately supplied. 
Figure 11

Edited January 16 by Last Indian