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Battery relocation

1094 Views 40 Replies 15 Participants Last post by  indiana
Can I get some pics of your trunk-mounted battery setups? I'm looking for inspiration. I'm going to be moving the battery to the rear passenger corner and wanted to see how you guys have physically mounted the battery to the car (what style tray/holder) and where have you mounted any fuse/relay panels. I'm not looking for electrical advice, only mounting configurations. Thanks!!

This is my starting point:



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So I鈥檝e been using the sucky ones all this time? 馃槅

Pretty much :p conventional AGM all they way now
Standard lead acid batts are easier to care for, and keep in good condition. sla or agm batts are finicky, and neither types will deal well with our charging system hitting130A of charge current. It just makes a standard one need water,lol.
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Standard lead acid batts are easier to care for, and keep in good condition. sla or agm batts are finicky, and neither types will deal well with our charging system hitting130A of charge current. It just makes a standard one need water,lol.

I run dual AGM's in my 01 7.3 diesel, work better than anything else I've had in it over the last 22 years. The Optima's in the winter if it didn't start right away would run out of juice quickly. That's when I quit using them.
When agm batteries form bubbles, the bubbles can't move, and it decreases the cranking amps, or total power.Same thing with gel cells.Bubbles in standard batts just float to the top and pop.
Pretty sure NHRA rules state that battery bracket must be bolted through frame rail with at least (2) 3/8" bolts. Not just bolted through trunk sheet metal. That's how i mounted mine in my fox.
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I will try to get some pictures for you.
I did this mod as one of my very first, so it has room to grow. While I intend to put in the NHRA legal box and kill switch, for now it's still a street car application.

I used a battery tray from AutoZone and bolted that to the right side trunk floor, through the carpet. The battery is held in place with universal hold down j bolts. I used a plexiglass panel to cover the battery to prevent a crowbar incident. The plexiglass is also a great spot to bolt in a fuse or breaker panel and a local disconnecting means.

I ran my positive connection from the engine bay fuse panel to a hidden 300Amp 12v disconnect switch in the jockey box, and from there to the battery. In hindsight, I should have gone to the starter and then to the fuse panel. I am a fool for grounding and bonding so my negative wire goes from the battery to the engine block, with extra grounds locally in the trunk near the battery. I also ran a bond from the engine block to the firewall.

I ran all my cables through the OEM wire tray where possible, penetrated the firewall at an existing gland. From the jockey box to the battery, the POS wire lays under the back seat. I put this section inside a garden hose for added protection. Don't run your wires outside the car, especially beneath the car for obvious reasons.

I was really surprised by the handling difference this made to my car. I upgraded my suspension, steering, wheels and tires after the battery relocation, so I did get a good comparison. The car feels lighter and the front stays well planted without any pushing. It feels safer, more solidly connected to the road in turns.

Incidentally, I did this before I re-geared and added traction lock to the car and it made a big improvement in traction. My car used to do the one wheel peel or with trac assist on, fight with itself trying to launch. Neither was good. Moving the battery allowed me to shut off the trac assist and get both wheels to spin better than previously.

I don't drive my car in snow, but I imagine it would help there as well.

I like to run two batteries in boats and trucks, with the appropriate bat 1, bat 2, both switch. This allows running an inverter without concerns.
It seems like too much added weight for the Cougar to have 2 batteries without obvious benefits. I have taken some weight out of the car with the engine swap, RLCAs, diff housing, etc.




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I was really surprised by the handling difference this made to my car. I upgraded my suspension, steering, wheels and tires after the battery relocation, so I did get a good comparison. The car feels lighter and the front stays well planted without any pushing. It feels safer, more solidly connected to the road in turns.
It reallly made that much of a difference?? I really wanted to try this out next weekend. Only trouble I have is where I should run the ground wire.
It reallly made that much of a difference?? I really wanted to try this out next weekend. Only trouble I have is where I should run the ground wire.
I had done this years ago to older cars ('70 Charger, '70 Cuda) and those old torsion bar cars responded well, but not as well as the Cougar.
So, I knew it would change the car somewhat based on previous experience. My experience with the Cougar has been that it responds to appropriate mods exceptionally.
Basically, the stock location is as far forward and to the left as it can possibly be, and the battery is about 60 lbs.
So moving that same 60 lbs as far back and to the right as it can possibly be is a pretty dramatic relocation if you think in terms of weight and balance. The arm on the moment is a long one, and the weight is fairly substantial so it is a dramatic physical change.
These cars already handle pretty well, and I will attest to a significant performance handling improvement doing this mod.

There are those opposed to this mod, attributing blame for electrical problems to the battery relocation. My opinion is that they likely used poor technique and chose components poorly. I have had zero battery or charging issues even with the added disconnect switch in the jockey box.

I did this mod as one of the first on this car after we changed the heater core (core is also grounded to the firewall, bonded to the block). I was really happy with the result and it definitely indicated that these cars were given deliberate room for improvement by Ford engineering.
I have continued to mod the car and have been really happy and impressed by the results.
The way the car responded to the battery move inspired more mods to suspension, steering, running gear, engine and drivetrain.

I am glad I did the battery move and full j-mod as first projects. I managed to get good advice, and I think I got a lot of bang for the buck especially with the battery.

You can run your negative conductor to a number of places. I sent a home run to the block and a secondary to the ground post on the subframe right there in the trunk on the right. That ground stud is about 20" from your new battery location.
You may be able to run your primary negative to that secondary ground alone if you run your positive primary directly to the starter. That requires a secondary positive from the fuse box to the battery. I guess that would save some black wire eliminating the run from the neg post to the block.
This is a great time to look at your charge wire (alt to fuse box) and upgrade that.
While you are wiring, I would add a ground wire from the firewall to the block some place. The balance of the harness grounds are very good in these cars, I just made sure they are all connected properly, clean and tight.

For primary conductor I used welding lead, which has a monster cross section and excellent insulation. The only problem I ran into was terminating that heavy guage into automotive #6, #4, #2 spaces. In some cases I bought industrial lugs and modified them to fit. (Like at the fuse panel and the disconnect switch)

I pulled out my seats to do this, pulled back the carpet and pad to get to the wire tray, and took special care fitting the new wire alongside existing when penetrating the firewall.

Good luck!
I look forward to the pics and reading your assessment.

Some people say it's not worth it until you go to the NHRA switch and have a 10 second car...
Which completely ignores the handling aspect.

RD
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I didn't trust going through the firewall with a grommet for 2/0 power wire, so bought a heavy duty marine style bulkhead connector instead. Couple more terminal lugs but more peace of mind, no way the wire will chafe and short.
MSC and mcmaster sell a bulkhead passthru called a sealcon, and those have a rubber insert that makes a seal for water ingression protection,I use those.
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This is how I did the bulkhead passthrough - note this won鈥檛 work on 89-95s with ABS as those use this hole for wiring. Though the鈥済rommet鈥 in this case is a modified abs harness boot, the center is a cut down hockey puck with the cable fed through




This is where the cable grounds


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That's where my amp is currently grounded. I pulled out the 2awg wire and started to get it ready to go in. I weighed the other cable, a 30' length is 100lbs. of solid copper, lol.
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This is how I did the bulkhead passthrough - note this won鈥檛 work on 89-95s with ABS as those use this hole for wiring. Though the鈥済rommet鈥 in this case is a modified abs harness boot, the center is a cut down hockey puck with the cable fed through

View attachment 53601
View attachment 53602

This is where the cable grounds

View attachment 53603
View attachment 53604
TPB style - love it!
This has been on my list of things to do for a while. Also replacing the 65 series battery with a 58 or 59 saves a few pounds. IMO the factory size 65 is kind of overkill unless you run a big stereo.
This is how I did the bulkhead passthrough - note this won鈥檛 work on 89-95s with ABS as those use this hole for wiring. Though the鈥済rommet鈥 in this case is a modified abs harness boot, the center is a cut down hockey puck with the cable fed through

View attachment 53601
View attachment 53602

This is where the cable grounds

View attachment 53603
View attachment 53604
Is the ground wire grounded directly behind the battery? It鈥檚 kinda hard to tell front the picture.
No, it's bolted to the bracket where the trunk arm is attached. That's also where I bolted the ground fro my amp. I get some alternator whine sometimes, and it seems to be the body connection changing as I drive. This car doesn't have any broken spotwelds like lazarus. That's why I'm considering running the ground as well. Either way, the relocation of the battery to beside the amp can't hurt. I also have a 1F capacitor I'm adding, once I get the charging circuit figured out. You have to limit the current so it doesn't explode when you hook it up the first time. :)
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Nah it鈥檚 pretty much right behind the battery, the solenoid on the other side of the sheetmetal is the gas cap popper opener. The cable is only about a foot in a half long to it.

It鈥檚 an existing ground point, the factory JBL system grounds the amps and CD changer there, since I removed that whole system, harnesses and all, it was a perfect spot to place the negative cable
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It looks good. I'm going to hit the boat place, and see what they have for battery boxes.
That鈥檚 shhweeeetttt, I鈥檓 running this kit from sky high before it shot up to this price. My ground is connected on the wall of the tire well passenger side and it never gave me any alt noise running JL audio 300/4 450/4 and a Rockford r500 for the sub. Makes it easier having that ground location right behind the battery. So far I have a 250amp circuit breaker and was planning on using the stock battery tray and 3/8鈥 all thread to tie that ***** down. Am I missing anything?


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