Nissan 370Z Forum - DIY: Battery Relo

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My PC680 finally started giving out a bit. It was possible to charge it and use it for a few days, but it was giving out too quickly between charges. So it made it a bit over 2 years of abuse, which isn't bad. I had been wanting to re-work my old battery relocate job anyways, so I took the opportunity to kill two birds with one stone and both replace and re-relocate my battery.

My old relocation (pictured earlier in this thread) had two things going for it that I don't like anymore:

(1) The far rear location was more ideal for weight distribution for me, because I was placing a heavy tool/emergency bag in the forward part of the trunk on the street that outweighed the battery significantly, and that left room for it.

(2) After removing all the other crap in the trunk (subwoofer, spare, etc) there was a fair amount of vibrational noise coming through the trunk floor, so I had Dynamatted most of the trunk to make up for it.

Now that the car is increasingly becoming more track-ish (where the tool bag is not an issue, and the noise level isn't either), I've moved the battery forward to the same rough location as travisjb's install (but using the solid aluminum box I used before). Technically this is also safer in the event I get rear-ended. I also stripped out the Dynamat (leaving some ugly tar residue I may go after someday with some degreaser).

I also got rid of all the hokey hardware store connections I made before (they worked, but probably more resistance than necessary) and soldered on proper terminals and connections this time around, and reduced the overall positive cable run length.

I'll start with basic pics of the new install. These two pics are the overview of the new install. Notice the ugly tar residue from trying to remove Dynamat. All cabling is still solid copper 1/0 gauge stuff. The battery terminals and the ground lug are soldered to the cables using solder slugs, and the terminals got color-coded heat-shrink wrap and rubber covers. The battery itself now has Odyssey's own add-on standard SAE brass terminals to fit regular ring-style battery terminal connectors.

http://www.the370z.com/members/wstar...9-overview.jpg

http://www.the370z.com/members/wstar...nd-breaker.jpg

Getting this box with its large flat edges mounted in this position turned out to be pretty tough. The metal surface of the car here isn't at all flat, and there's no easy way to reach the "inside" of that channel to put nuts on bolts. My compromise solution was:

(1) Using the larger circular holes the car comes with, it's possible to barely reach the spot of the center bolt holes of my box. I drilled these, taped the M6 bolts (with large washers) to my fingertips, and managed to delicately put the bolts in from the rear. So at least the center hole on each side of the box has a good solid bolted connection.

(2) For the outer 4 holes that can't be reached by fingertip, I used self-drilling sheetmetal screws, 1/4" wide by 1" long. These are tricky and I don't trust them as much for holding power, but they do in a pinch. The tricky part is it's easy to overshoot the drilling phase and strip the hole so that the bolt won't hold. You have to be very careful and try to back off the drill before it fully sinks the bolt, and then switch to a wrench. I got 3/4 of the holes done right, and the lower left one I stripped, so it's empty in the pics. I'll go back to this later with a slightly larger diameter (5/16") regular sheet metal screw to fix it.

(3) To get the box to hold flat as it's compressed into place by the 6 screws, and to reduce any bouncing or vibration, I added some closed cell foam weatherstrip onto the metal of the car before mounting the battery. I bought a couple different thicknesses (3/8" and 1/2"), and basically put it underneath the battery and in the "low spots" on the wall. It's obvious when you're doing it in person.

As for the ground lug on the other side of the channel: I re-used an existing factory threaded hole and the matching bolt, which originally held an audio amplifier bracket, and sanded off the paint in the vicinity for a good connection.

Pics of this stuff up close:

http://www.the370z.com/members/wstar...dware-foam.jpg

http://www.the370z.com/members/wstar...-foam-hole.jpg

http://www.the370z.com/members/wstar...-foam-tape.jpg

Parts lists from my various parts orders for this:

From Del City:

(the extra negative terminal stuff was to make a charging cable: the big 25-amp charger instructions say you need one on the negative side for a little resistance when using it).

Code:

Qty        Item                                               Price       Item Total

------------------------------------------------------------------------------------



1          8920      Liquid Flux, 2 oz No Clean (1 MIN)       $5.05       $5.05

4          900935    Battery Terminal Solder Slug, 1/0 Ga, Bla$0.83       $3.32

1          901715    Straight Terminal Insulators, 2 & 1/0 Ga,$0.75       $0.75

2          901725    Straight Terminal Insulators, 2 & 1/0 Ga,$0.75       $1.50

1          907445    3/8" Heavy-Duty Copper Lug, 1/0 Ga (1 MIN$1.91       $1.91

1          909145    Straight Barrel Battery Terminal, 1/0 Ga,$3.13       $3.13

2          909155    Straight Barrel Battery Terminal, 1/0 Ga,$3.13       $6.26

1          980735    6" Red Triple Wall Heat Shrink, 2 - 4/0 G$1.88       $1.88

1          980745    6" Black Triple Wall Heat Shrink, 2 - 4/0$1.88       $1.88

------------------------------------------------------------------------------------

And from Amazon, the SAE terminal adapters for the PC680: Amazon.com: Brass SAE Automotive Battery Terminal Set for Hawker Odyssey Batteries: Electronics

And of course the closed-cell rubber weatherstrip stuff, the self-drilling screws, and various regular M6-sized machine screw hardware all came from a local hardware store (Ace, in this case).

Also, if you've never soldered battery terminals to cables before: the solder slugs make it much easier, and you need a torch (a handheld propane torch is fine) to heat it all up. There's some youtube videos of the process you can google up.

how hard is it to remove the glove box and a/c thingy? Is the wire run along the passenger side near the door or under where your feet are?

Removing the AC blower is a little tricky. Putting it back in is a total PITA. I ran my cable on the outside by the door, just under the carpet alongside where the existing wire loom runs. Also, while I drilled through for mine, another option I've seen people use is just to go through the big rubber grommet you can't miss in the upper passenger corner of the engine bay that carries a ton of small ECU-bound wires through (assuming your cable is flexible enough for that route).

reped guys, awesome thread. I'll be doing this very soon. Great write up WSTAR. I'll PM you when I start this little project, maybe you can swing by the shop and coach! Looking forward to getting the Z on the track this year!

:happydance:

Quote:

Originally Posted by wstar (Post 82352)

Adding to travisjb's pics/info with my own. Keep in mind I've never done a battery relocate project before, so I'm not saying my way is the best. I just kinda guessed my way through the process and it seems to have worked out, and hopefully will provide more data points / ideas for others.

Standard disclaimer: I accept no responsibility for you destroying your car and everything around it in the process. Don't attempt this if you don't have at least some rudimentary understanding of how batteries and electricity work. I've glossed over some finer points like how to use a freaking screwdriver, and how to not short out your battery and/or electrocute yourself like a moron. If you have any doubts, have a professional do it.

Tools (other than the obvious normal stuff like sockets and screwdrivers):

Electric drill with 1" hole-saw bit:

Any chance of taking a picture of exactly where you drilled the 1" hole? I am pondering doing this and just wanted a good reference point to start.
Big-*** wire cutters and pliers for working with large cable.

http://www.the370z.com/members/wstar...7-hole-saw.jpg

http://www.the370z.com/members/wstar...ers-pliers.jpg

Parts:

PC680 Battery + Bracket from DDM
http://store.doubledownmotorsports.c...e=125&fileout=http://store.doubledownmotorsports.c...e=125&fileout=
Everything else below was found at Home Depot:
An assortment of M6 x 1.0 thread pitch hex cap screws, in various lengths (I found 16 and 20 mm lengths the most useful, I think all total I used about 8 screws, mostly 16s). Also lots of lock washers and nuts to match, 2 lock washers and a nut per screw.
Cable connection blocks. These ones I picked up at the hardware store are little blocks of Aluminum that can hold a 1/0 gauge wire on one side, and be screwed to something else with the M6 screws on the other side. I used 4 of them all total (each end of my positive and negative battery cables).

http://www.the370z.com/members/wstar...-connector.jpg

16+ ft of 1/0 Gauge 19-strand copper wire. This is really thick stuff and it's hard to work with because it will have a natural coil to it and it's very difficult to bend it into the shape you want. From a pure "Can it handle the amps without melting" standpoint, this wire gauge is overkill for this application. However, by going oversized, we further reduce the resistance of the long positive-side cable run, which reduces voltage drop, which will make it less likely for you to have a starting or charging problem down the road.

Also some 1/2" corrugated plastic sheathing, to help protect the wire's jacket from getting nicked or rubbed during install (or later when driving). I bought enough (in 7ft sections) to cover the whole cable, and put it on the cable first before I started the job. It will be slit, so wrap with electric tape to keep everything in place (doesn't need to be 100% coverage, can use a wide diagonal angle with lots of space between tape stripes).

http://www.the370z.com/members/wstar...ble-sheath.jpg
http://www.the370z.com/members/wstar...2894-cable.jpg

You'll also want a 1" grommet for the hole being cut later.

Also grab some some anti-oxidant, it's a liquid in a little tube you'll find near the connectors/cable, which you apply to the ends of the big cables when you put them in the connectors, to reduce rusting of the cable ends in the long term.

Procedure:

First remove everything from your trunk. All of the plastics and tools and styrofoam chunks, etc. It should be bare metal throughout.

Then find a location to mount the battery and mount it. There's a lot of personal preference here. Since I'm not planning to put my spare or sub back, I mounted in the center rear, with the battery laying down flat:

http://www.the370z.com/members/wstar...ry-mounted.jpg

Finding a good spot is tougher than it seems. On the trunk surface, you have to find a spot where the bracket will lay flat given all the ridges and bumps and whatnot. Additionally, look on the underside of the car and make sure you can reach where your bolts will come through, so that you can put nuts on them and tighten it down. At my chosen location, the nuts come through above the heat shield which is above the muffler. I had to loosen that heat shield and push it away a little while drilling the holes and screwing down the mount.

My next step was to go to the other end of the car and prep that side of things. Remove the existing factory battery, disconnecting the negative cable first, then the positive, then remove the bracket and battery (it weighs a freaking ton and has no handle by the way, it's kinda annoying lifting it out of there).

You can completely remove the factory negative battery cable, it simply runs to the body nearby and attaches there with two screws. On the factory positive side, remove the red cover, unscrew the round post-mount from the rest of the fuse assembly, and replace it with one of our new connector blocks using some of your M6 screw hardware.

The result should look something like this:

http://www.the370z.com/members/wstar...-conn-inst.jpg

Now it's time to route your main length of cable. This is going to be your positive battery line, running all the way from the PC680 in the trunk to that lug we just attached to the inline fuses up in the engine bay. It will be annoying because the cable is so thick and resistant to bending.

Basically you want to pop off all the paneling along the passenger side of the interior of the vehicle, and remove the glove box and the A/C blower from the passenger footwell area. Then route it along the passenger edge of the car coming up into the footwell area.

Find an appropriate place in the upper footwell area (the other side of this metal is the rear wall of the original battery area), and drill a 1" hole here using your hole saw. Put a 1" OD grommet in this hole to keep the sharp edges from scraping your cable run.

Once you have the cable routed end to end (and trimmed down to the correct length at both ends), go ahead and connect the positive cable at both sides. On the battery side, I used the supplied 90 degree copper "posts" from the PC680, screwed to one of our hardware store aluminum connector blocks.

Once that's done, you want to drill one more hole in the trunk floor at any convenient location (well, close to the battery is better), and mount your last connector block there. Sand off the paint under where the block will mount to get a better connection. Then use some of the leftover cable from your positive-side run to make the short run from the negative battery terminal to this new ground lug.

Note that when you make this final ground connection, there will be a spark, and your electric system will come back to life.

Things should look something like this, at this point:

http://www.the370z.com/members/wstar...-connected.jpg

http://www.the370z.com/members/wstar...nk-routing.jpg

http://www.the370z.com/members/wstar...connection.jpg

Finishing Up

Now, before you go reinstalling all of that interior, etc, test-fire the car. Start the car and let it run for a while. If it fails to start, obviously you've got a bad connection somewhere. Keep an eye on your connectors, etc at both sides during the first run, and watch your voltage gauge.

Assuming that all went well, you might want to do some final sealing of the positive cable ends (I wrapped up both connector/lug areas with electric tape to reduce chances of a short) and reassemble the interior of your car.

I also went back later with some Black Silicone RTV-type stuff and filled in my grommet on that front hole, to provide better cable protection and to weather-seal between the engine bay and passenger compartment.

Of course, by using screw-down lugs everywhere, I've got no easy way to disconnect my battery now. My next step on this project is to add a kill switch to the negative battery cable in the trunk, so that the battery can be disconnected when necessary, but I haven't located or ordered one yet.

Any chance you could take a picture of exactly where you drilled the 1" hole? I am pondering doing this and wanted a good reference point before drilling takes place.:happydance:

Quote:

Originally Posted by wstar (Post 82352)

The car is off at the cage builder right now, so I can't snap pics. TBH, you don't really need to drill that hole anyways, it's just what I did because it was expedient at the time to stop thinking and just do something :) You can always run the cable the way travis did, up through the rubber grommet that carries a bunch of ECU wiring through the upper corner there near the battery tray / AC blower. Or if you're doing an all-out race car conversion and killing the AC anyways, there are multiple leftover AC-related holes to reuse.

I ended up unrelocating my battery at the end of the day. What's far simpler than relocating any battery is to put a ultra-super-light battery in the stock location. This 3.5lb battery works fine on our car: Batteries - Ballistic Performance Components , and you can buy them from several places if you google around. The downside is ~$200+, and it's very risky to drain them (basically, you risk ruining the expensive battery permanently if you let residual drain take it below 8V, which isn't hard to do if anything's running without the engine). But honestly, that's worth not doing the battery relocate work, and this battery weighs about as much as the wiring and circuit protection for a relocate job, much less the (larger) relocated battery itself.

Another interesting option is this thing: https://www.pegasusautoracing.com/pr...sp?RecID=10410

It's 8.4 lbs, same internals as my tiny battery (but even more capacity than mine, and mine starts the engine fine), and they've built the battery manager into the unit so that it can't be killed by draining and always charges optimally. If you're more concerned about draining and battery ruin, it might be worth the 5lbs extra weight and $600 more to have a battery that will really last and doesn't have to be babied, but is still light enough that it makes sense to retain the stock location.

Cool,

Thank you for the information. What are your thoughts about the Odyssey batter?

I had a couple of Odyssey's PC680's in the car (meaning one eventually went bad after a long time, then I put in another) before I switched to the little Evo2. They work great in this car, and they're considerably lighter than stock no matter where you put them. TBH, you're getting most of the benefit just putting a PC680 in the stock location. Everything beyond that (relocation and/or smaller and more-expensive battery) is just hyper-optimizing for smaller gains. I mean, I do it, but that doesn't mean sane people should do it :)

I am going to go with the PC680 trunk mount. I have the cables (free) and battery mount (also free). I will only need to purchase the battery so why not. Thanks for all the tips and advice.

How do these smaller "race" batteries compare to the stocker with respect to cold cranking amps, lifespan, and reliability?

It's hard to directly compare on the numbers, the numbers all mean different things for different battery technologies. The PC680 is pretty much universally fine on this car, though, assuming you're don't have a huge stereo and/or leave anything electrical on with the engine off for extended periods. The little LiFePo4 ones, though, are pretty marginal - fine for a racecar, but probably not a reliable DD option. They struggle in the cold (it does warm itself with each start attempt though, so it usually catches by the 2nd or 3rd try even in near-freezing temps) - and it's easy to destroy them by over-draining them.

Would it be okay to use a 4 gauge wire instead of the 1/0? Also, am I able to use the same kind of wire people use to power amplifiers for sound systems or does it need to be a specific kind?

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Quote:

Originally Posted by josemartinrea (Post 3613175)

Would it be okay to use a 4 gauge wire instead of the 1/0? Also, am I able to use the same kind of wire people use to power amplifiers for sound systems or does it need to be a specific kind?

I wouldn't recommend it. 4 AWG wire is only rated for about 90 Amps while 1/0 AWG is rated for about 170 Amps. The voltage drop (and heat generated) will be greater at high loads (eg, starting).

The conductor material is not important but you will have to use a larger conductor if you use aluminum instead of copper. The total resistance of the wiring run is the critical factor - bigger wire has less resistance per foot. You can use "exotic" stereo wiring, but it's expensive and not cost-effective for the minuscule gains.

The more strands in the conductor, the more flexible the wire will be (assuming the same insulation). 1/0 AWG with a solid conductor is VERY stiff and difficult to install; 1/0 AWG welding cable (~1000 strands) is down right limp.

Quote:

Originally Posted by SouthArk370Z (Post 3613245)

Thanks for the info. So definitely 1/0 AWG.

Sent from my iPhone using Tapatalk

https://m.lowes.com/pd/1-0-AWG-Stran...-Foot/50101588 would this work?

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i would go more strands than that. thats like a commercial/industrial installation 1-0 check local electrical suppliers more so than lowes/home depot etc. they will be able to access a much more in depth selection of wiring for you. aside from this wire being extremely uncooperative to run through a car then you also have to deal with crimping lugs on, or sourcing a heavy duty lug to terminate the wire to the battery. To simply put this is overkill" for a car. like Ark said you can always check local stereo install shops for wiring. while this stuff is usually around the 12-20$/ft mark it is plenty stranded and tends to have a nice protective gel coating perfect for installations such as this.
Good luck with your hunting man!

Thanks man! I've called a few stereo shops and it seems that's it's something they don't carry in stock. It sure is a hunt! I'm also having trouble looking for a battery box so I'm thinking I'll have to make one.

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Quote:

Originally Posted by josemartinrea (Post 3613769)

they honest to god are'nt really tough to fab up yourself if you have a vice and a drill with a good set of bits. The wiring you're trying to source is pretty install specific so I'm not surprised you're having some troubles there. I did as well until an actual sound competition shop moved in locally to me, and they tend to have that stuff ready at all times in case they need to build/change a system on a whim.

https://uploads.tapatalk-cdn.com/201...69531e2b00.jpg
Managed to scoop this from Fry's Electronics. $53 17' 0 gauge and 3' negative 0 gauge.

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It also comes with zip ties, grommets, and six screws, and wire is crimed with rings.

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hell yeah man nice! get on with the install and let us know how it goes!

https://uploads.tapatalk-cdn.com/201...09b8155b81.jpg
Sorry this taking me forever. thoughts on this fab box?

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Alright! So The battery works. Everything is mounted and attached. I'm not cranking the car until Friday since it's in a storage unit 1 hour away and I'm going back to finish installing brake pads and SS lines that I am working on as well. I'll let you guys know if it cranks on Friday!

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looks good man! where did you end up securing it in your car? where the spare used to be i assume?

Yeah right on that hump lookin thing. Haha made the bracket/box out of sheet metal i bent into shape that I got from Home Depot for like ~$8

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battery + connections right atop the gas tank,,let me think on this one a minute...

So if you guys don't hear from me in about six months you'll know how I died.

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Quote:

Originally Posted by josemartinrea (Post 3615212)

So if you guys don't hear from me in about six months you'll know how I died.

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He died the same way he lived... a quarter mile at a time.
:wtf2:

Btw I forgot to mention. You can Get through to the wire boot thing on the passenger side without removing the ac blower which is a huge pia to put back. Also, didn't know this was a feature. https://uploads.tapatalk-cdn.com/201...cd968097c8.jpg
Trunk release.

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i guess da question is why. why u screwing with the corner weights of da car..

So it's been about five months since I put this battery in. I've let the car sit for four days at a time since I have a work vehicle hat I use daily. Cranks just fine every time. Encountered a water leak when I removed the boot because I broke the tabs that hold the boot in place. I used windshield urethane (I work in the autoglass industry) to stop the leak. https://uploads.tapatalk-cdn.com/201...348a82d663.jpg https://uploads.tapatalk-cdn.com/201...2cbe701a22.jpg https://uploads.tapatalk-cdn.com/201...f1dd6e9356.jpg

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:facepalm: Sorry to revive this old monster however I'm interested in knowing what did all of you do with the battery current sensor?

It looks like the Battery Current Sensor just monitors discharge for smart charging purposes and Battery temp.

Why go through all this trouble. Just stick an Anitgravity battery in there. Phunk sells them at CJ Motorsports.

I agree on that. The questions I have are more in regards of swaps and since this is the only info close to the deletion of this sensor I figured I'd start here.

This is stupid. Buy a lithium battery and save your poor car the mutilation with a clean plug and play option.

Quote:

Originally Posted by viiv (Post 4004948)

This is stupid. Buy a lithium battery and save your poor car the mutilation with a clean plug and play option.

Uh….thread started in 09….on a track focused car that ultimately became a gutted track car. Different times = different solution.

Quote:

Originally Posted by Spooler (Post 4004558)

Why go through all this trouble. Just stick an Anitgravity battery in there. Phunk sells them at CJ Motorsports.

Quote:

Originally Posted by viiv (Post 4004948)

This is stupid. Buy a lithium battery and save your poor car the mutilation with a clean plug and play option.

Although most of us are thinking of F/R distribution when moving the battery to the rear what about L/R distribution? I figured moving the battery to the back would give better F/R distribution but also maintain the left and right distribution as well. Unless this isn't the case?