Before you begin this process make sure you have the tools necessary and know how to use them. Results vary so prepare to be innovative. I do not believe that this is the only way to accomplish the job at hand. You will probably find improvements on what I did. Try to have all the parts necessary to do the job. Repeated trips to get stuff slow things down considerably.

Read all instructions and look at the pictures. There should have been more.

Tools required: Basic hand tools, American and metric. Screwdrivers, hammer, file, and wire brush. Hand grinder with a 4 1/2-inch cutoff wheel. A good jig saw.

Desirable Tools: Air compressor and 3/8 drive air socket wrench. Bench grinder with medium wheel and wire wheel.

Parts required:

Sears Diehard battery part number 31247. This is one of the "international batteries" and I remember being a replacement for Jaguars. Cost $100.00 with trade. Don’t trade in your old battery. Find a junk one or pay the extra cost for no trade in. The day I did the conversion I went to 3 or 4 battery sellers after finally settling on Sears. I really wanted to get an Interstate battery but could not find one open. Compare the cranking amps of the diehard to your original battery. I am very happy with the Diehard and the warranty. Whatever you get make sure it is sealed and no maintenance.

You will need a universal battery case. This consists of a plastic base, two J hooks, and a metal frame top. Each sold separately.

You will need new Battery cables. A Black negative and a Red positive, 9 to 12 inches long, 6 guage I think is what I bought. Available at parts stores and stores that supply lawn tractors and batteries.

A piece of 2 X 6 pressure treated lumber about 12 inches long.

A length of all thread 3/8 ". All Thread is a rod with threads, as in a bolt, across its entire length. Any hardware store.

 

 

Open trunk and fold back trunk liner. Fold back from left to right placing something heavy enough on it to keep it out of the way.

Remove 3 fasteners that hold the carpeted battery cover in place.

PrimaryBat Cover Exposed.html

 

 

Note: there are two types of fasteners on mine. The easy one and the hard one.

The easy one looks like a button with a center circle that youi push in with a small screwdriver. You can then lift it out with your finger or use a flat screwdriver to pry it out. Examine it carefully for its operation. I just described how you remove it. To put them back, slide the pin in the opposite direction. Push the fastener in the hold. When in place, push the pin home. Try to buy some of these for extras to replace any you screw up and to replace the hard ones.

The hard ones are basically nylon screws that have a weird head, looks like a Honda emblem. To remove them, pry a screwdriver under one edge and with a pair of slip joint pliers, rip those suckers out. You will probably destroy them taking them out. If not you can reuse them simply by pushing them back into the hole it came from. I recommend replacing them with the easy ones above.

 

I do not have any pictures of the next few steps. All pics were taken after I did the mod, which was several months ago,

Remove two 10mm bolts that hold aux battery cover and set aside. 

As you face the battery, the negative terminal is on the left and is black. The positive one on the right is red and connected a convoluted junction box with a red cover.

Disconnect the negative terminal by removing the 10mm bolt holding it to the floor of the trunk. Tape the end you just removed with black electrical tape to insure no accidental reconnections.

Next remove more fasteners, 3 or 4 holding the carpet to the edge of the trunk around the outer rim. Remove enough of them so that you can fold the carpet over into the trunk exposing the entire battery compartment.

 

BatCompartmentExposed.html

 

Next you will notice a red cover over the mentioned junction box. This has to come off. It has two tabs, one either side and is a bear to remove. Using whatever tool you can to get it off, just do it. Once removed, take it out into your back yard or other suitable area and throw it as far as you can.

Once removed you will notice two connections to the junction box, a black one and a white one. Press a tab on the front of the black one and remove. Press a tab on the back of the white one and remove.

Also notice the 12 mm bolt connecting this assembly to the battery. You could disconnect at that point but mine was on so tight that I would have destroyed it trying to remove it.

Anyway if you have done the steps above, all electrical connections are disconnected and it is now time to remove the hardware that holds the battery in place.

There is an L shaped bracket with two bolts, remove the bolts and the bracket. You will not be reusing the bracket.

On the left side of the battery is a black rubber tube connected to the battery. With a little persuasion and some silicon spray you can remove this tube. Try not to destroy it, as it will be reused in the final application.

You can now remove the battery. The positive terminal will have to be removed. You can do it in the car or out, which ever is easier for you.

You will notice a plastic vent pipe about 2 1/2 inches in diameter that is definitely in the way. Remove 2 10 mm nuts that hold in place and pull it out and away from its seat that is located at the back of the trunk and terminates in the bumper. You will need the extra space to install the new battery. Also you will not replace the lower of the two nuts.

Vent Tube.html

 

Next remove the remaining battery bracket. It is held in place with 2 bolts or screws can't remember. Once removed, it will not be reused.

Now look at the pic of the two batteries. The old is tall and skinny; the new one is short and fat. Side by Side.html

Look at the pic Vent Tube.html and inside the trunk while locating the trunk side of the wheel well. You will notice a metal edge where the two pieces of the wheel well were welded together. It protrudes about 1 inch and is in the way of placing the new battery.

The object is to flatten the edge against the wheel well to gain the space required. I did this by cutting slits along the edge forming tabs about 1 inch long. It will look like a hair comb with big teeth. Cut all the way to the bend of the well to gain as much space as possible. Each individual tab you have made can be easily bent with a hammer, bent flat against the wheel well. I used a hand grinder with a 4 1/2-inch cutoff wheel. If you have never used this tool be prepared for lots of sparks as you cut. Use safety glasses and be cautious, BUT do not loose your nerve. Just do it. The area covered in this process is from the bottom where the old battery sat, up at least 7 inches. This is probably the most difficult part of the process. The links above show this process completed. Vent Tube.html

Notice the cavity where the battery sets. It gets smaller with its depth and is too small at its lowest depth to accommodate the new battery. You will need to build a platform to set on top of the old platform to raise its height.

Fortunately a 2 X 6 is perfect. Cut a piece of pressure treated 2 X 6 to a length of 10 inches. See pic. TwoBySix.html Cut a notch in the left and upper end, 2 inches into its length and 1 1/2 inches into its depth. In order to mount the piece, drill a 1/4-inch hole to accommodate a 9-mm bold or screw. Center point is 4 3/8 inches from the right end and 1 5/8 inches from the bottom. Once the hole is drilled, use a 1/2 or 3/4-inch spade bit to create a countersink to accommodate a 1/2-inch washer used with the 9-mm screw, which needs to be 2 1/4 inches long. Once this is done, place the 2 X 6 into position on top of the old platform and bolt in place.

 

Next the Battery itself. It is a Sears part number 31247. Looking at the battery follow the sides down to the bottom where the side juts outward forming a hump at the base. These are there for mounting tabs in other applications, not ours. However, since space is a premium, these, the one on the front and back, have to be cut away making the front and back totally flat. I sat the battery on a workbench with the edge slightly over the end. Then using a jigsaw held upside down cut the hump off allowing the blade to follow the battery case. You won't find in the owners manual of the jig saw a recommended use of this tool in this manner, however it worked for me.

Next is the new battery case, which is actually a frame, made up of a plastic base, J hooks and a metal top frame. Each of these can be purchased separately at most auto parts stores. Get familiar with separate pieces, how the J hooks connect to the base and how the top bracket attaches to the J hooks.

About the battery, it is sealed but has a vent tube. While working with the battery, fold the tube over itself and tie with a twister tie to prevent water (acid) from spilling out while working with or moving the battery. Tipping only slightly will cause water to spill from the tube. If you do spill any wipe up immediately. If it gets on your skin, flush with plenty of water. If it gets on your clothes put the clothing in the washer immediately. Any cloth contaminated with battery acid and left alone will be destroyed.

The plastic base has to be cut to the exact dimension of the new battery. There may be several ways to do this. Here is what I did. Set the plastic base on a workbench; set the battery on the base. Cut the base around the battery using a jig saw held upside down following the battery case as a guide.

Once this is done you can secure the new base onto the 2 X 6 with 2 wood screws. Alignment is not critical but the J hook mount should be approximately in line with the hole where the old L bracket mounted. It is probably easier to put the J hook on before securing the base to the 2 X 6. The other J hook cannot be used. Instead get a length of 3/8 all thread and cut to a length of 4 1/4 inches. This will screw into the threaded hole in the trunk where the old L bracket was secured. The threads won't match exactly, one is metric and the other is American, but unless you can find 9 mm all thread, it will work just fine. If you have not worked with all thread, you must know that where you cut, the threads will be screwed up and will require some grinding and buffing with a wire wheel to get threads to work properly. Do not install this piece at this time. I provided its description at this time for clarification of how the battery is held in place.

Next the battery preparation. BattWithJunction.html Attach the 12 inch (6 gauge is what I used) black negative wire to the battery terminal. Attach the 12 inch red positive wire to the positive terminal. Black on the left, Red on the right. The posts are different diameters so it is impossible to hook them up incorrectly. Wrap the loose end of the black wire with tape. If you haven't already done so remove the weird positive junction box from the old battery connector. As I said earlier, I had trouble with this one. Being so tight that the torque required to loosen it deforms the base. I used a 3/8 air wrench to apply pulsing torque to get it loose. Once done attach the weird junction to the loose end of the positive wire.

Now you can place the battery in the new case in the trunk. The one J hook should be in place. Don't make any electrical connections yet. Install the all thread you made above and put the case top on the J hook and the all thread and tighten moderately. Use the mounting hardware from the unused J hook on the all thread piece you just made. Position the weird junction box on top of the new battery and using a tie wrap, secure it so that it won't move. I looped the tie wrap through the new battery top and around the positive cable itself. The stiff wire along with the tie wrap is sufficient to secure the junction box.

Slide the original rubber drain tube into the existing drain tube on the new battery. Use silicone spray if necessary.

Plug the two Positive connectors into the junction box. Bolt the negative terminal to the same spot as the old one. It will spark slightly when you connect it. As you tighten the bolt position the wire in a clockwise direction, as close as possible to perpendicular to the car frame. You need to do this to make enough room to put the primary battery cover back in place.

I made one additional mod you may be able to see in the pictures. Using a 2-pole trailer connector, I cut off one end and attached round electrical connectors to each wire. Red goes to positive, white goes to negative leaving the trailer connector with a male white and female red terminal. A convenient place to plug in a charger or other stuff, like a direct connection to the cig lighter making it always hot. Might as well do it when it is all apart!

Replace the primary battery cover, as I said you might have to readjust the negative terminal slightly to accommodate the cover. Put the carpet back in place and secure with fasteners you removed earlier (or new ones if necessary).

Now you are done. You will find that you have lost your radio settings and the clock. Other electrics seem OK.