Battery Relocation

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Ray
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Battery Relocation

Post by Ray » Wed Jan 30, 2008 7:41 am

I wrote the following for another forum a couple years ago, and figured the information might be useful here as well. Maybe a FAQ idea if those who know best deem it so. Note: The following was written for a Ford Focus, so some items may need to be modified. I removed some information already that's focus specific, but in general the following applies to the XR (with the addendum of bolt sizes, drill points in the firewall, etc.)


Purpose

This has been brought up a few times, and I'd like to start an informative thread on the subject. Comments that do not pertain to the subject will be removed.
Other opinions on technique, correcting faults, etc, are welcomed. If you have done this and have pictures, those are welcomed.

Now,

Battery Relocation, be it for performance, lack of room under the hood, a short run of wire to your amps, or simply because you want a battery back there is something that has been touched upon in this forum and others but we have not had a real say all to what should be done. I'm going to break my post into a few sections, if you have your own input, use whatever format you want.


Safety

First and foremost, a battery isn't something that should just be placed in your trunk / hatch. It has to be secure. A lot of these are filled with acid and can weigh 30 lbs. Imagine what would happen in the case of an accident with this acid filled brick flying at your head? The answer would have to be - nothing good can come of something like that, which isn't secured properly.

There are several kits out there for battery relocation. And i say most of them are fine, but we can build a better one ourselves, if we know how. and probably save a little money in the process. The battery box is something that is necessary for ANY acid filled battery. This box bolts to the floor of the vehicle, and i recommend using large washers underneath to spread the load so the nuts wont pull thru the floor in case of any accident. Now we have a box bolted down. If you have an acid battery you'll need a vent. You can punch a hole thru the bottom, then insert a hose, seal up around it, etc. This should work fine. (in theory) The battery needs to be held down. Most autoparts stores sell universal kits to strap them down consisting of some threaded rod with a 90* bend on the end. These work fine but can fall straight down when you pull the battery back out and can be a bitch if you are trying to install a battery. Normal threaded rod with a nut/ washer on each side of the box (ie, outside the car, inside the box) might be a better option. Who knows.

That being said, now we have our location for our battery, and the battery and box securly fastened to the car. I'm only going to touch the next part once, assume it for every hole we drill - rustproof the damned thing.




Fusing

Our oem alternators put out something like what, 140 amps? When i measured starter draw on my car with an ammeter, i got 39 amps. With these two numbers we can size our fuse. I would think that anything over 140 amps should suffice. 150 would be fine. Make sure you place your fuse within one foot of the positive terminal on the battery. The closer the better. I believe mine is 6". Note: XR alternators aren't as powerful, but the starter draws more current. I recommend a 200a fuse for XR's @ the battery.



Sizing Wiring

Another possibly touchy subject is proper wire size. Many people say 0/1, some say 4awg is fine, and some go with 2awg. In my focus I use 2awg from the front to the back, then a 2awg and a 4awg for ground. (to the same point). Given the fact the starter draws only 39-45 amps, 4awg should be fine. Given the fact the alternator could theoretically put 140 amps thru the wire, 2awg is a better choice. Honestly i think 4awg should be the minimum sized considered. And bigger is better, unless you're building a pure racer and care about the extra few pounds of weight you're gonna get. Your call.



Running Wiring

Okay, now we have our box mounted, our battery strapped in, our fuse placed, and our several feet (16 should be more than enough) of large gauge cable sitting next to us. Where do we go? Well, front to back, right? I would start from the center of the car. Pull out the driver's seat. (T45 and T40 bolts, IIRC). Pull out the seatbelt rail on the side bottom. Remove the kick panel, and the lower scuff panel. remove the rear seat bottom, and if you want, the upper part of the seat back. Then remove the B pillar panel, then the quarter panel piece. Sounds like a lot of work, but will save you a lot of time. After you've done this once or twice you can get all this out in 20 minutes.

Okay, now pull up the carpeting (4 plastic clips under where the scuff panel was). Fold the carpeting up and back out of your way. Imagine where you are going to run this wiring. Now, if you bought cheap wire here is where you will pay. Most low strand cables dont like to bend. And you're gonna need some flexibility here. I've found knukonceptz cable to be very high quality and a great price - (shameless plug) that is VERY flexible.

Locate an area on the firewall to drill (this is how i do it, if you have a different way, post up). I tend to use the area above the clutch pedal, and about 1" below the green tab. This brings the wire out under the fuse box. After you drill the hole, deburr it, then rustproof. Insert the grommet, and feed your wire thru. Having a friend at this point can help route the cable, but you can do it on your own. Figure out where you want the cable to end, then seal the hole (excess in the grommet) with RTV / silicone / etc.

Now go under the hood and secure the wire with cable ties in the desired location. You already know not to attach it to things like your shift linkage, i hope. Keep it simple and away from any moving parts. Remember - your tranny mount moves. It will wear a wire thru if you just simply rest it on there.

Route the wire to the rear of the car. At any point where the wire has the slightly chance of chaffing, protect it. Wrap it with tape. Wrap it with split loom, do whatever you have to do. Secure the wire at regular intervals. Also please keep mind to the size of the cable you are running and where the carpeting lays. If you put it above the seat supports, you might have clearance issues. If you put it near where the seat bolts down you, you might have some issues with pinching it. Avoid these situations. You'll see where the factory wires run towards the rear. You can follow those except where it goes above the seat rails (in my opinions). Also PLEASE do not run the wire under where the rear seat folds down. This will chaff the wire thru. Especially a large gauge cable.

Bring the wire to the back of the car and secure it as necessary.



Putting it all together

Alright, now we've got a wire under the hood that goes to the back of the car near a battery box that has a fuse near it. All areas of the wire are protected, and it's not near any moving parts or sharp edges. The wire is at no point bent in a tight radius, nor looped in some ridiculous pattern.

How do we connect it to the factory wiring? Well you have a few options. What i like to do is use a ground distribution block (read - unfused dist block) and cut the factory wires off the factory battery terminal, then insert them into the block (tinning the wiring helps keep it secure). Then all you have to do is insert your new battery wire to the same block and voila.

What about the ground? Well, that's more of the same. I used the factory ground wires and grounded them to the front frame rail, using a bolt that used to hold down the battery box. I polished the metal CLEAN (ie, didn't use a dremel and scratch it all to hell), then crimped, soldered, and heat shrunk a lug onto the wire. Tightened the bolt, then protected the surface with electronic clear coat.
I would also recommend the use of some extra wire to run a few more ground cables under the hood (ie, frame rail to motor) if you have any.

Now all we have to do is connect the new battery wire to the fuse block, put on our ground cables for the battery (you can use any THICK metal surface that has a good ground to the engine. Where the rear seat belt bottoms bolt down is a good choice. Where the spare tire bolts down is a good choice for length of wire as well. Again, protect the surfaces after you sand clean and install the cabling.

Now, for the test, before we reinstall the interior. Go over everything you just did. Make sure all wiring is secure and where you intended it to be. Install the battery terminals on the battery, with the wires connected, and install your fuse.

If for some reason the fuse blows instantly, you messed up. Go over it again and correct any mistakes.

Once you have all the wiring installed make sure everything works as it's supposed to.

Few pics of my XR's relocation:
Here is the battery, which is located behind the passenger seat. You can see the ground wire (grounded to the seatbelt slide rail bolt), and the main power wire, fused with a 200a ANL fuse.
Image

Here is how the power wire is secured - self drilling screws with cable tie clips, and cable ties, every 6".
Image

not the most recent, nor best pic of my distribution block, but it gives you an idea.
Image
i'll have to take another when the snow melts off the car cover.
-Ray
1985 Ford F150 - Tow Missile
1985 Merkur XR4Ti -#141 CP "Miss Daisy"
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Post by Stealth_xr » Fri Feb 01, 2008 8:20 pm

Instead of the junction box you could just mount everything right to the solinoid on the positive side. I made a new chassis ground. IMP it looks a little tidier, so thats an option

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Post by 86XR4Ti_John » Fri Feb 01, 2008 11:05 pm

If you are going to do ANY racing or sanctioned competition, you will have to adhere strictly to thier rules on the subject.

I know NHRA want relocated ones in approved boxes and with clearly labeled kill switches located and labeled on the outside of the car.

One of the reasons I just went with an 11lb Oddessey racing battery in the stock location in my Talon(same place as in the XR)
John

86 Xr, lowered, cossie rear sway bar, wheels, intercooled, big vam, PE superchip.
91 Talon TSi, well modified, 5spd all wheel drive, runs 11's.

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Post by DPDISXR4Ti » Sat Feb 02, 2008 12:16 pm

Good timing on this Ray, as I've been recently giving this topic some thought. One of the things I wanted to do was use the 175A MEGA Fuse, as Ford uses on the Contour, F150, and probably several other applications. The question I had was whether that could be used on the main 12V+ circuit.

Dimitri sent me the link below, which indicates that the 175 amp MEGA fuse is rated to hold 400 amps continuously for 10 seconds, so the answer would seem to be "yes".

http://www.littelfuse.com/data/en/Data_Sheets/298.pdf

I've already acquired several of the fuses and one of the holders, so it's pretty much a foregone conclusion that I'll be using it, just a question of whether it's on the alternator circuit or the main 12V+ at the battery.
Brad

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Post by anglin » Sat Feb 02, 2008 1:26 pm

Thanks for starting this thread, Ray. Good to know your work (to the car and typing the info) is getting spread around.

I've done a battery relocation in my racer for performance purposes. I chose the Odyssey PC680 like John. I posted a pictures of the work in my "racer build thread" in the Project section (page 1):

http://forum.merkurclub.com/forum/viewtopic.php?t=7210

Of course, my work wasn't just moving a battery to a different location. I changed several things including installing a kill switch, relocating the EEC ground points and installing a lightweight starter with a solenoid mounted to it.

My threads tend to be directed toward the performance aspect of stuff, so forgive me if this focuses too much on the racing reasons for everything. I chose the battery location because it put the battery very close to and below the center of gravity. Here's a thread about the advantages of the PC680:

http://forum.merkurclub.com/forum/viewtopic.php?t=5786

Here's a thread that goes a little bit more into the reasons for why I put the battery where I did:

http://forum.merkurclub.com/forum/viewtopic.php?t=4255

Of course, none of this covers how I did it. If you don't care to visit the thread that discusses the build up of my racer then I'll here's a picture.

Image

That's not a picture of the completed product, but it's close. I looked through my other pictures and there really aren't any great descriptive pictures that I have taken. The pictures would require substantial explanation to understand what's going on in them. I might as well just mention the important details here.

Now that I have blabbed about a bunch of crap that may not interest 95% of you guys, I'll discuss my experience with the battery relocation.

Here's what I consider the single most challenging problem facing someone who is relocating a battery in an XR4Ti - the negative battery cable that goes to the OEM battery contains two ground wires for the ECM (the computer that runs the engine). These have to be grounded somewhere after you remove the negative battery cable. Perhaps you are comfortable with crimping a ring connector on the end of the ECM ground wires and running a self-tapping sheet metal screw through the ring connector and into some bare, exposed piece of sheet metal somewhere, but I prefer not to take that approach.

I actually relocated those wires to the inside of the car (which is where they came from to begin with) and connected them to the stock ground point on the passenger side kick panel area. I also used this point as a ground point (one of two additional which I added) for the cables coming from the relocated battery.

In order to do this work I pulled the ECM harness through the firewall into the engine bay. I was able to dismantle it while standing next to the fender. I believe it was a lot easier to pull the whole harness through than to try to fish the individual wires through the big firewall grommet.

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Post by BeefFajitas » Sat Feb 02, 2008 2:13 pm

Are those fuses available from an aftermarket source? Junkyards around here suck.
-Nate
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Post by John Brennan » Sat Feb 02, 2008 2:14 pm

OK, here's the big, dumb question: are these types of batteries even remotely suitable for a street car?
This is my car, and these are my people!
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Post by anglin » Sat Feb 02, 2008 3:32 pm

John Brennan wrote:OK, here's the big, dumb question: are these types of batteries even remotely suitable for a street car?
John, I think this question is directed at me. Ray is talking about a general relocation and I'm speaking to my racing-specific relocation. Of course, the question is hardly dumb, but it is certainly a big question. (What is it that makes a question "big" anyway?)

The Odyssey PC680 battery that I used has only 220 cold cranking amps. Personally, I would be a little bit concerned about relying on that battery to start my car in the cold of the Ohio winters. Would it do it? Probably. I don't think I would put the battery in my commuter car. Some folks might, but they may also not mind daily driving a car with a stripped interior. I just don't think the Odyssey PC680 is a good, practical battery. It is, however, perfect for my racer which gets driven March to October where the temps are mostly above freezing.

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Post by 86XR4Ti_John » Sat Feb 02, 2008 11:17 pm

if you drive it regularly or keep it on a trickle charger when not driving it, its fine, fine, fine.

I drove it full time for a few weeks once. NO problems at all.

Course that was not in the cold winter, and I have no radio in my Talon, but I do have power locks and windows, and a security system.
John

86 Xr, lowered, cossie rear sway bar, wheels, intercooled, big vam, PE superchip.
91 Talon TSi, well modified, 5spd all wheel drive, runs 11's.

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Post by DSPXR4ti » Sat Feb 02, 2008 11:35 pm

anglin wrote:
John Brennan wrote:OK, here's the big, dumb question: are these types of batteries even remotely suitable for a street car?
John, I think this question is directed at me. Ray is talking about a general relocation and I'm speaking to my racing-specific relocation. Of course, the question is hardly dumb, but it is certainly a big question. (What is it that makes a question "big" anyway?)

The Odyssey PC680 battery that I used has only 220 cold cranking amps. Personally, I would be a little bit concerned about relying on that battery to start my car in the cold of the Ohio winters. Would it do it? Probably. I don't think I would put the battery in my commuter car. Some folks might, but they may also not mind daily driving a car with a stripped interior. I just don't think the Odyssey PC680 is a good, practical battery. It is, however, perfect for my racer which gets driven March to October where the temps are mostly above freezing.
Mr Anglin,

What class are you running in solo 2?

Ben
85 DSP XR4ti, 2009 Solo 2 National Champion, burns muffler, 3in exhaust, Mc2 Full suspension, 325 hps & 328tqr, GMR Intake, Wilwood brakes, Eaton LSD, stand alone ECU. Working on being SM National Champion.

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Post by Colin » Sun Feb 03, 2008 7:26 am

I copied Anglin.


Image
Image
Image

I used a 200a ANL fuse and a Moroso firewall pass-through.

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Post by Ray » Sun Feb 03, 2008 8:55 am

BeefFajitas wrote:Are those fuses available from an aftermarket source? Junkyards around here suck.
Are you asking me about the ANL's or Brad's comments about the 175A mega fuse?

the ANL's are available all over the place. Car audio sites have them. Probably the same for the mega fuse, as well.
-Ray
1985 Ford F150 - Tow Missile
1985 Merkur XR4Ti -#141 CP "Miss Daisy"
2005 Subaru LGT
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Post by DPDISXR4Ti » Sun Feb 03, 2008 11:20 am

demonfire wrote:
BeefFajitas wrote:Are those fuses available from an aftermarket source? Junkyards around here suck.
Are you asking me about the ANL's or Brad's comments about the 175A mega fuse?
In case it was me, it's a stock part used on every Contour and probably a bunch of other Fords, so I'm sure it's available new from the dealer. Perhaps I should start collecting more on junkyard trips. I haven't looked, but I wouldn't be surprised to find them on eBay.
Brad

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Post by Colin » Sun Feb 03, 2008 6:49 pm

Colin Doyle
'89 Scorpio | Volvo B234F head | Holset HX35 | Megasquirt | T5 | 8.8 IRS | mc²racing suspension
File to fit, paint to match.

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Post by BeefFajitas » Mon Feb 04, 2008 11:44 am

Sweet.
-Nate
'85 Merk. Back together. Only thing stock is the head and block.

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