DIY: Battery Relo
 

I had this relo done by a shop here in Phoenix, AZ... didn't do it myself, but I'll try to capture some of the details to help those that DIY

Materials:

• odyssey pc680 battery
• 15 ft 0/1 gauge wire
• fittings to connect to terminal leading to starter, e.g., Taylor Cable 21414 - Taylor Battery Cable Terminal Kits
• fittings to connect to battery, e.g., Taylor Cable 21405 - Taylor Battery Cable Terminal Kits
• Finally, a fitting to connect to a point on the frame for negative, e.g., (you can prob do better than this one but here you go) Taylor Cable 20215 - Taylor Diamondback Shielded Battery Cables
• battery hold down bracked such as this one from DDM Universal Mounting Box for Odyssey PC680 Battery

Steps (roughly):

1. Remove old battery
2. Remove old negative cable
3. Connect 12ft line to starter teminal
4. Re-use red plastic cover
5. Run 12ft line through point as shown in pic below
6. Run line along passenger side under carpet
7. Run line into rear compartment... you will have to decide where to mount... mine pictured below
8. Install battery with hold down
9. Connect battery leads
10. Grind a spot on the chassis, to reveal bare metal
11. Drill a hole or use existing hole and enlarge, suitable for fastening negative terminal... connect terminal

I realize I'm not going into much detail but just wanted to get the thread started... others can fill in the blanks... good luck

Pics:

http://i656.photobucket.com/albums/u...b/IMG_3366.jpg
http://i656.photobucket.com/albums/u...b/IMG_3367.jpg
http://i656.photobucket.com/albums/u...b/IMG_3368.jpg
http://i656.photobucket.com/albums/u...b/IMG_3369.jpg
http://i656.photobucket.com/albums/u...b/IMG_3370.jpg
http://i656.photobucket.com/albums/u...b/IMG_3371.jpg

Very nicely done and the wiring doesn't look too difficult at all.

It should be straightforward... my job was easier b/c I stripped the rear interior long ago... I do recommend this location for the battery, there is a safety issue here... want the battery to be very secure in event of any impact, and this location will provide retention in the event of frontal g's

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:
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.

Great write-up as a follow up to travis' DIY, wstar, thank you. Good idea no the kill switch. Just thinking out loud, would it be better to route the positive cable through behind the panel and driver's side, so as to have a kill switch on that that could be located somewhere in the panel? Considering this is more of a race car than a street car, I was just thinking if you get into a track accident you might want to kill the battery for whatever reason.

Actually, it's more a street car than a race car, my street cars are just a bit different in focus than most I guess :) I am actually going to get a cover made for the new battery area and then put some carpeting back in so I can throw groceries and luggage back there.

A driver-reachable killswitch isn't a bad idea, although I don't know if I'll do it personally. It would probably be better to set up a remote switch rather than run even more length of positive battery cable. Something like this sort of kit: Painless Wiring 30204 - Shop For Painless Performance Remote Master Disconnect Kits Battery Disconnect Switch - Toggle - 250 Continuous Amps Rating - Kit 30204 at StreetPerformance.com (not that I'm endorsing them specifically, that was just from a quick Google search).

Actually a good compromise for my case would be to use a breaker for my rear switch, so it will trip in the case of a short. I'm not sure what amperage rating will work or who makes an appropriate application at this point though.

Very interesting kit, the one you found, with a solenoid, good idea!

You're right, your street car is pretty race-focused... :)

Wstar, great adds ! thanks... helpful to see 2 versions of this project

So back on the breaker / disconnect ideas, this looks nice, as it accepts 1/0 wire directly: Lightning Audio LCB200 Larger than 100A total fuse rating Circuit Breakers Amplifier Installation Car Accessories and Installation Car Audio and Video - Sonic Electronix

200A sounds like it's probably plenty for the starter (yet still way way below short circuit current), but I really need to measure the current draw when starting my car to verify (with one of those clamp-on amp meters, I think I have an attachment for my multimeter for that around here somewhere). Looks like a decent solution though, and any time I'm working on something on the car that requires the battery be disconnected, I can just hit the manual trip button.

I don't have specs on the starter but it could potentially pull over 300A, provided the battery can deliver that much.

The service manual only quotes 'less than 110 amps' under unloaded conditions (like spinning it up on a bench), which isn't really helpful. In general, I'm not finding a whole lot of definitive data anywhere on the net about the cranking current of a starter motor when actually starting an engine. I suspect this lack of data is because the real answer is 'it varies a lot depending on conditions'.

I imagine if for some reason your engine was incapable of turning over (somehow seized up completely) that the starter motor stalling out against it would probably become damn near a short circuit and probably fry the battery. This is probably why the factory wiring on every car runs the starter wire separately without a fuse, whereas everything else on the car is fused.

I changed my mind about trusting a clamp meter before I even tried it, once I remembered that they only really measure AC amps, not DC amps, so it wouldn't really give any sort of accurate reading.

Are there any special considerations due to mounting the battery on it's side?

You can measure DC current with a clamp, the hall effect is still valid.
AC/DC Current Clamp

Not with the battery I used (the Odyssey PC680). The manual states that any mounting position other than inverted (as in, battery terminals facing the floor) is good.

Apparently my DMM must be too slow to see the cranking amps through the clamp. It does work for DC, I could see the amps moving around in a reasonable range as I turned headlights on/off, etc. But I tried to measure engine start 3 times, and the highest it ever briefly flicked to was 18A, which is way too low. The meter simply lacks the responsiveness.

Just disconnect something that won't allow the engine to start so it will crank for longer :). Or run out of fuel :):):)

I've measured the stall current on a 540 can 27 turn motor at 90A... thats just a tiny little motor you'd find in a power drill or R/C car. I suspect under stall conditions a starter could draw more than double that but that's just a guess. Depending on the resistance in the fuse you will probably be droping some voltage on the fuse -not a lot but some. My other concern would be ground loops. I'd definately run a heavy ground up to the front of the car with the positive cable. I would also make sure all the car's computers are grounded to the battery directly to eliminate any issues....

We'll find out tomorrow if the 200A breaker works.

As for the grounding issues, I don't see any point in running a separate ground wire along the length of the car. The car's body itself should provide more ground path than any reasonable wire could hope to.

Agreed. FricFrac, can you add any info tho why you'd recommend that?

Installed the breaker this evening. The car started fine without tripping it. Then again, it's a hot summer-ish evening and the car had only been off for 5 hours. Might be different on an ice cold morning in the dead of winter with a car that hasn't been run in 2 days. We'll see when I get there in the winter :)

I also went ahead and prewired a little harness for my trickle charger in case I need/decide to use it. The breaker is mounted to the top of the battery box with superglue (I know, how ghetto of me).

But anyways, yes, the Lightning Audio LCB-200 seems to do the trick, providing short-circuit protection as well as a convenient way to kill the battery power when working on the car.

http://www.the370z.com/members/wstar...-just-case.jpg

The conduction of steel is poor compared to copper. Typically copper is used as the baseline as its is the most common and almost best conductor (wow that english sucked but carry on...). Copper is only surpassed by silver for conductivity at about 106% as conductive as copper. Steel for the record sucks hard at electrical conduction ranging from 2 to 18% for pure steel in comparision to copper. I'd expect our sheet metal to be somewhere around 12% ish.

One of the main issues you are going to have with a vehicle electrically is a good path to your power. Grounding to the chasis is good enough for most applications but when you start involving multi sensors and multi computer controlled systems to your vehicle small glitches in signals and poor grounds can cause problems. IIRC Stillen makes a grounding kit for the car computers because of this very issue. In the olden days if you got 14.4V to the coil or 14.3V who cares - its not gonna make a difference but if a signal gets lost and isn't part of a calculation you carputer need to make a decision you aren't going to perform optimally. That's just voltage I'm not even getting into eddy currents, etc. The car is a horribly noisy environment electronically which is why the basics are so important.

The other issue is your connection to the chassis. Once that iron starts to oxidize you are adding resistance which means power loss. Don't forget that bitty screw in the sheet metal is the best contact point to the steel but you've probably got three or four dissimillar metals there. Dissimmilar metals cause corrosion as well. Although you've got huge surface area in the sheet metal your contact point basically negates its huge current carrying capability. In real life these are minor points but in racing most of us want to know the little details and determine whether they are worth addressing or not.

So in short (oh didn't plan that pun...) your set up will work but we are pit racing here so if you wanna squeeze every last drop or optimize your system that's why I'd recomend running a ground line. At the very least I'd run ground wires from the carputers directly to the battery because they are the most likely to suffer ill effects but that's just me....

I'm well aware that I have several junctions of dissimilar metals, but I don't plan to let anything corrode significantly. That's why all those joints got coated in anti-oxidant, and why I'll be checking and cleaning them on a regular basis.

And while mild steel may have roughly one tenth the conductivity of copper, there's still a lot of it between the battery and the various sensors and computers you're talking about. It really just comes down to the junction points, and they're sufficient in size for the amperages involved (think about it this way, 1/10th the surface area of that lug screwed into the trunk is still more than enough width of copper for the current involved).

As for the Stillen grounding kit, its primary function is to help ground the engine block to the body. I have it installed in my car. One end does go to the negative battery terminal as well (or did, before I pulled the battery), but clearly its primary purpose is to ensure a good engine-to-body ground, so that a potential difference doesn't develop between the two.

I'm not saying you don't have a point about the cleanliness and stability of the ground reference in the car, but I think you're being overly paranoid about it. If you'd like, I could go measure the resistance of the car body from the current battery ground point to the old one up front for you, and we can compare that to the known resistance of my 15 ft run of 1/0 copper for the positive side, if that provides any insight. I don't think there will be a difference worth caring about.

..... and I don't disagree with you and I'm also not trying to nit pick on your excellent work. I'm just pointing out some things that may be of intrest to others and things to take into consideration. It may even help people with trouble shooting down the road to have the info - nothing to do with being paranoid. These are the fine details and its up to the racer to decide to what level any of this matters. Like I said its just pit racing...

*STUPID QUESTION ALERT* I am sure most of you assume if I post its a stupid question and I am full of them, but why relocate the battery? Like what point does it serve?

There are no stupid questions, only stupider askers :rofl2:

The car is front-heavy from the factory, and so you want to remove weight from the front if anywhere to help get closer to neutral weight balance. Removing weight from the top of the car will lower the center of gravity, giving handling advantages again. Reducing overall weight of course also increases the horsepower:weight ratio, which gives better acceleration, as well as again improving handling (less weight to throw around, so to speak).

So, depending on your priorities, you want to drop overall weight, and you especially want to drop it from anywhere towards the front and/or top of the car. This is where the battery comes in.

The battery is really heavy as far as car parts go. Ours weighs 35 lbs. One option is to simply move the stock battery to the trunk, shifting 35 lbs from front to rear to help balance. Another is to leave the battery where it is, but use a lighter one, shedding weight from the front but not adding any to the rear. The DIY in this thread does a little of both, it removes the 35 lb battery from the front, and replaces it with a 14 lb battery in the rear, giving an overall reduction of 21 lbs, and a 14 lb shift in weight to the rear.

Hi Solus... this car has too much weight on the front... it tends to 'dive' under braking with stock suspension and the rear gets a bit light under hard braking... if you push the car to its limits, you may want to tinker around with the weight distribution to get closer towards even front/rear... some quick google searching on 'race car weight distribution and handling' should give you lots more info if interested

I am sorry but why in the world would you want to put your battery in the rear. Nissan setup the car for the battery to be in the front.

See the two posts above yours.

Got ya LOL

good grief ! LOL

Guys quick question, after you install the battery, is it possible to put the spares and other junk back on!! Cause that stuff weighs like 55 pounds and the battery only weighs 14 pounds...Doesn't that worsen the weight distribution and also I am going to use the car as a track day car, but I also need the trunk once in a while for daily driving...So can you put the excess weight from the trunk back in?

Hey Travis, what shop did you use? (PM me if you want to keep it out of the thread). Thanks mate.

Vivid racing... any shop can do it

Yeah, I know most can do it. I just wondered who you trusted with your car. :tiphat:

Redline Motorsports in Tempe, AZ
SRD Performance
UMS Tuning
DIY

Actually, according to the weight reduction thread, the stock battery is 35 lbs, the stock spare is 35 lbs, and the stock subwoofer is 8 lbs. So by removing all 3 and adding a 14 lb battery in the trunk, your net change is a total drop of 64 lbs, 35 removed from the front and only 29 removed from the rear, which if anything is a slight shift in the "good" direction. (note this doesn't consider the weight of the battery holder or the wiring, but the battery holder is like 1lb or less extra in the rear, and the wiring runs all along the car).

I ended up just leaving the styrofoam junk in the rear, as well as the plastics, and then put the stock cover board and carpets over it all. So basically my trunk is configured exactly like stock, except the sub and spare are missing and the battery is back there. This leaves the trunk functional, although the floor is a bit "unsupported" since there's a hollow round hole underneath the carpet + board. Honestly though, there aren't many things I would throw in my trunk heavy enough to cause an issue with that anyways.

nice write up!..+1 rep

Nice write up, and long overdue Monster rep. :D

thanks trips.... good to see old threads are still of some use

+1 rep sent to you as well:tup: