TracyRX7

So I've been reading around on here about putting your battery in one of the boxes behind the seats and well I value my bit of cargo space too much so I decided to move my battery to the trunk area under the strut bar on the passenger side.

Parts:

(1) Large battery tray ($6.99 at Kragen)
(1) Bag 12-16 1/2" self tappng sheet metal screws ($3 at OSH)
(1) Summitt trunk battery relocation kit for a '65 Mustang (Free since its been laying around my garage for years) [Kit consists of 20' 2 gauge positive battery cable, 5' 2 gauge negative battery cable, connectors, marine battery box w/ strap --you can buy all of this stuff at Kragen too--]

Time:

About 1-4 hours depending on your tools and how hard you want to work

1. Disconnect your old battery.

2. Wrap up and ziptie down or remove your existing ground cable.

3. Remove existing battery tray

4. Get inside your car and drill a hole through your firewall where my hole is (see picture) big enough to fit your cable. If you want it really clean make it fit a nice grommett you can put around the cable, if not try to make it so your cable barely squeeze through (as not to leave an airgap).

5. Remove the kickpan, driver's side pedal area sidepanel, driver's side seatbelt interior panel.

6. Run the positive battery cable from the trunk forward. Leave yourself a good amount of slack in the trunk.

7. Pull the cable through your hole in the firewall. You'll need to unbolt maybe one thing in your engine compartment to reach the cable coming out of the hole. If you have a hard time pulling it through the hole in the firewall try making a "pull string" by wrapping some electrial tape around the end and then make a 2-4" tail of just tape past the end of the cable. Thread the tail through the hole and pull.

8. Get your battery box, put it on the tray and slide it as far to the passenger side corner of the trunk area as you can under the strut bar (for me there was a bolt coming up through the tan plastic under the strut bar that just fit in the front/passengerside most corner of the tray tiedown).

9. Line the tray up straight and put the battery box strap under the tray before screwing it in.

10. Pick some spots and either get under the car and make sure you aren't putting a hole through to something important or pray. I poked my head around some, had a rough idea of where I was going through and prayed (sort of like a golfer throwing some grass in the air during a tornadolike storm and guessing which way the wind is blowing -- but it worked ).

11. Pull up the rest of your trunk matting and find a bolt to screw the ground cable down to and connect it. I found one about 6" behind where my battery box is (see pictures).

12. Toss your battery in the box, hook it up, slide it into the tray, bolt and strap it down. Hook up the positive terminal under the engine to the cable you ran out there.

13. Fixup some carpet to go around it (if you want cleaner looking you might consider putting carpet under it. I didn't really want the softness of the carpet wiggling around I figure I can fashion up some carpet/wood pieces to look "good enough".

tt2323

Wow very nice write up. One of the few mods to add extra weight but better weight distribution

TracyRX7

I'm not entirely sure it distributes the weight that much better (well if you are the "average size driver" Mazda expected in the car). I'm a bit bigger I'd guess than they expected so it probably helps me out some (about 220ish).

I am sure it removes a big heat soaking brick from my engine compartment making room for me to do other stuff with down the road. The other thing it does is extend the life of my battery a ton as it doesn't have to get fried all the time as I drive the car hard.

Next up for me is a custom air intake making use of the big open passenger side grill I have on the C-West front piece (since I have a single oil cooler). I might try and take some during photos this time.

tt2323

Yes let me know how that turns out, i was going to do the same using the stock bumper for now. I put on a 2row and am using a hawker680 14lb battery in the stock location. i look forward to seeing a similar write up for the intake ducting

tt2323

Yes let me know how that turns out, i was going to do the same using the stock bumper for now. I put on a 2row and am using a hawker680 14lb battery in the stock location. i look forward to seeing a similar write up for the intake ducting

BigIslandSevens

iTrader: (4)

I do this exact thing for ALL the FD's I work on. It doesn't ADD weight if you use a smaller battery.( just as if it were in the bin.)But even the standard Dry Cell battery is good( Optima)

One point I'd like to make is that you should route the power wire under the rear carpet. I just put a little slice in the carpet( not even noticable if you ever went back stock)
Same thing with the ground to the bolt by the spare tire.

Nice work though BTW!!

Another question...Do you have to take the strut bar off every time you want to get into it? I found that it is needed. Not anything to complain about just curious if you have the same size box.

skunks

dont go with the hawker, it has too little cca, check out the model 800 with 800cca http://www.batcap.net/Model800.html

also i would have went thru the driver side fender. make sure to use a grommet if you go thru the firewall like that. looks nice though good job

TracyRX7

No, I left enough slack in the cables that you can undo the strap and slide the box out to the drivers side. Once out you can pull the lid and do whatever.

On the carpet stuff it'll get cleaned up sometime here soon. I want to get some tan carpet for the trunk so I just hacked a few pieces to make it look 'ok' for now.

And for those of you not wanting to lose trunk space vs. the bin space. It goes under the strut bar so you're only losing 1-2" of "trunk" space. If you had a sub box or something else under the strut bar before then yeah that space is gone.

rallimike

iTrader: (1)

Anyone have any clever ideas for an external cut-off switch. Local dragstrip will not allow you to run without one, if you relocate the battery. I don't want to drive around with that switch sticking out the back of the car.

amp

iTrader: (50)

make sure you grind the sharp edges prior...

DamonB

I would never, ever run the positive cable through the firewall with no grommet around the cable. The grommet isn't there to seal the hole, it's there so that the sheetmetal of the firewall doesn't cut through the insulation of your postive cable and then melt your entire electrical system.

I would also never, ever drill another hole in the firewall that is so close to the steering column and the pedals when there is already a HUGE rubber grommet directly behind the fuse panel. Run your cable through there and it will be completely protected as well as offering a straight shot to the door sill and towards the trunk.

JonesersRX7

Yes. Any ideas to this. I would like to relocate but I want to be able to do the occasional run at the strip.

- Jonesie

PVerdieck

#1, I wouldn't recommend going through the steering gasket.

#2 There already is a hole, and it is big enough, I think:

1) Remove driver's front tire.
2) Remove rear piece of wheelwell liner.
3) Look. There is a big hole there, which comes out near the fuse boxes. This is where I ran my boost cable, and I will run some other stuff there as well. You can route cables down to here, and through pretty easily.

spurvo

The hole inside the fender liner is definately big enough. It also has a rubber cover that can be used for running things through. I just ran my 2 gauge monster cable through there for my bat relocation. Worked very nicely. I went with two sealed Exide motorcycle batteries in the bins. 500 CCa, 36 AH combined, works very nicely so far (2 weeks).

Crash Test Joey

iTrader: (1)

Yes. Mount one in your license plate. Summit racing has a good one part number MOR-74101. Just drill right through the center

suprfast

okay, i see all this hype about running batteries to the back. I would like to do it just for the reason of cleaning up the engine bay. What i would like to know is what are the rules for the battery in the rear for racing. i want to know for drag racing, tracking the car, autoX. Anything that means racing. if it means that i have to mount a damn kill switch then probably never mind.
kris

Crash Test Joey

iTrader: (1)

http://www.nhra.com/contacts/tech_faq.html

For drag racing (NHRA) this is the standard:

"I have a street car that I occasionally run at the strip. I've relocated the battery to the rear. What else do I need?
Any car with a relocated battery must be equipped with a master electrical cutoff, capable of stopping all electrical functions including ignition (must shut the engine off, as well as fuel pumps, etc.). The switch must be located on the rear of the vehicle, with the "off" position clearly marked. If the switch is of a "push / pull" type, then "push" must be the motion that shuts off the switch, and plastic or "keyed" typed switches are prohibited. Also, the battery must be completely sealed from the driver and/or driver compartment. This means a metal bulkhead must separate the trunk from the driver compartment, or the battery must be located in a sealed, metal box constructed of minimum .024 inch steel or .032 inch aluminum, or in an NHRA accepted plastic box. In cars with a conventional trunk, metal can simply be installed behind the rear seat and under the package tray to effectively seal the battery off from the driver. In a hatchback type vehicle the battery box is usually the easiest solution, since the alternative is to fabricate a bulkhead which seals to the hatch when closed. At present, Moroso is the only company which offers an NHRA accepted plastic battery box, part number 74050.

But I drive on the street. I don't want a big cut off switch hanging on the back.
This solution takes a little work, but it solves the problem. Install the master cutoff inside the vehicle, positioned "sideways" so that the toggle moves forward and back. Drill a hole in the toggle handle, and attach a steel rod that will run out the back of the car, through a hole drilled completely through one tail light assembly. Have a spare tail light assembly on hand, so when you come home from the drags, you remove the rod and put the cherry tail light back in for street cruising. Next time you plan on going to the drag strip, swap lights and reinstall the rod. Since the drilled light is for the strip only, you can also have it marked "PUSH OFF" in big letters so the Tech Inspectors will think you're cool."

RX7UP

Nice Job.

turbojeff

iTrader: (30)

Not to be old and grumpy but putting that battery in the back is the last place I'd want it.

Weight distribution doesn't need any help, +/- 30lbs front or rear doesn't really affect a car with 50/50 already. I wouldn't want to wreck the car with a battery there. Likely won't pass tech at many tracks/events.

That hole through the firewall is a fire waiting to happen...

Just my opinion, no flames...

BigIslandSevens

iTrader: (4)

Sorry to bring this back, but i saw people were wondering about cut-out switch location.

I haven't done it yet but was thinking of using the hole where the key lock is for the hatch. I don't know if just the key section can be removed and still have the hatch lock down. But if it can, than you would be able to pull the lock and install the cut-out switch for the weekend events.( Assuming you pass all the other tech requirements.)

Just a thought, and I will look into the operation of the locking mechanism tonight. Unless someone already knows and wants to shed the light...

TracyRX7

Thanks for the constructive suggestions. I'm going to wrap the positive cable in a sheathe and seal the gap around it.

*Wish I could edit the initial post to change this section in it after DamonB's comments above about a better way to route the cable*

For anyone else running it I'd suggest using the spot behind the fuse panel to bring the positive cable through to the engine bay. (I didn't know the spot behind the fuse panel existed and my car already had a hole there in the firewall that was unused. The hole was from a big stereo system a previous owner had in it. Seeing DamonB's very good suggestion above I do not recommend anyone put a hole where my hole is.).

As for moving it for weight, I didn't do that (It probably does help me out a bit since its on the passenger side and I'm guessing Mazda didn't plan on the driver weighing 220lbs.

I was mainly looking to get extra space in the engine compartment to look at the possibility of mounting a larger intercooler down the road or moving the stock one some depending on how my intake piping goes.

suprfast

Exactly what i would want it for. Otherwise it would be a sealed optima battery(51 series).
kris

jimlab

Circuit breaker?

PVerdieck

I still have a question on how the postive lead is connected.

From what I understand, Pettit and some other people run the positive to the starter.

Some other people have ended up running their line all the way to the old positive battery connecter, but that isn't necessary.

Now I looked under my car, and found the starter, near the oil pan, and the subframe. There is at least one dorky shield there.

TracyRX7

My positive is run to the old positive battery connecter. I don't really want to mess with any of the electrical until I figure out long term what/how I'm going to make use of the space. When I have that figured out there are a lot of things in the engine bay I could see moving around at this point (but that isn't something to rush on).