• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Relocating the battery to the cargo area

austinaubinoe

NAXJA Forum User
This jegs kit is on sale and I think it would be cool to get the battery out of the engine bay.

I mean I spent $200 of the yellow top, I think it would be good for it to be in that protective box. Space is not an issue, I have a 2.5 gallon tank mounted right behind the rear bench, and a basket in front of the tank.... so there is extra space behind the rear bench next to the tank.

Here is the kit: http://www.jegs.com/i/JEGS/555/10260/10002/-1?parentProductId=752213

So you think it would be a worth wile project.
 
Shouldn't be a big problem - I've seen it done on racers for better weight distribution, I've seen it done to keep the battery handy for easier attachment, I've seen it done to make accessory (rear) leads shorter, and I even did it once for a stereo install (all of the high-power gear was in the boot, and he wanted to keep all of those leads short and fused.)

There are a couple of catches to doing it, these are both general and XJ-specific:

1) Make sure the wire is large enough! If you're not sure, hit me backchannel and I'll help you get sorted.
2) Run the main power lead down the right side, since the channel under the doorsill trim is clear (the one on the left is taken up with the front-to-back lighting harness.) That channel is fairly large - I think you could run up to 00AWG in there (but you probably don't need to.)
3) Make sure all of your engine bay ground are properly treated. Clean the contact patch (about the size of a postage stamp, centred on the attaching screw) down to BARE METAL and apply a corrosion inhibitor on assembly (like Gardner-Bender Ox-Gard. Not "liquid electrical tape," not WD-40!)
4) Run the engine-to-battery ground to the chassis at the fenderwell, treating as in (3). Yes, dual grounds to the engine is a very good idea.
5) You can ground the battery "locally" behind a trim panel somewhere. Treat the connection point as in (3).
6) You're running a long lead to the battery - fuse it! A 200A fuse will still allow you to run the starter motor (effective draw: 160-180A,) but will protect you if the wire shorts through (effective draw - dumps the battery. Probably 3000-3500A.) If possible, put the fuse or circuit breaker on the battery box, or very close to it.
7) Vent the battery box to the outside of the passenger area - no matter what battery. All automotive batteries will outgas when charging (usually hydrogen,) and can outgas if they have problems (SO2 or H2SO4.) You don't want to breathe that stuff - especially the last! Sulphuric acid attacks flesh by dessication (removal of moisture,) and the mucosa lining your respiratory system doesn't like to be dried out. H2SO4 has an especial affinity for bodily mucosal membranes (which is pretty much any internal system exposed to air - nasal cavities and passages, sinuses, mouth cavity, respiratory system, ...) Is it likely that you'll get acid vapours? No. But, why take chances?

Apart from that, it's certainly not a bad idea. Any further questions, feel free to ask!
 
wow man, did not expect that response!

The the 20' of 2-gauge copper positive should be hefty enough to handle the power correct? I mainly wanted to buy this kit because I was about to spend the $100 or so on the jeepers creepers kit. Figured this would be a fun project and would clean up my engine bay.

Thanks for the tip on running down the right channel, and on how to relocate my grounds, The kit only comes with 3 ft of ground cable, so I figured I would be grounding it to the sheet metal locally.

As far as venting the box, does the vent tube need to exit the cherokee higher then the battery? Do I need to silicon the rest of the box shut? I do often hear my optima venting.

And finally the circuit breaker is just needed because of the higher chance of rupturing the cable correct? How much do they run, do you have a link to an example of one that would work?

Thanks alot for the help.
 
I wouldn't use 2ga cable. It's a little small for the starter circuit, when you are talking about 7-10ft long run. 2ga will drop ~.6v (or 5%) over a 10ft length at 200 amp draw.

I'd belly up to 00ga to insure adequate current delivery to the starter. Also consider you may want to install a winch in the future. For that, the 2ga would be inadequate.
 
As long as its a gell cell or closed case you can have it in the cab. Never put a regular Lead Acid battery inside due to the toxic fumes it puts out, not to mention in the odd case of battery explosion, that would be a mess. Ive actually been thinking of mounting a gell cell on its side up underneath the body.
 
well If you follow the jegs link you will see the kit im planning to buy. The only reason im thinking about it is because of the good price.

Isnt 2 gauge bigger than stock? And I have a yellow top, so its completely sealed.

If I was going to mount an electric winch I would wire it directly to the battery, but im probably going with a WARN hydraulic.
 
OEM/stock is 8AWG. Unless you already have - or plan to - upgrade your alternator significantly, the 2AWG should be sufficient (as long as you're getting at least 13.4VDC at the battery posts now. That .6VDC loss is very real, and you'll want to keep it somewhere above 12.6VDC at the battery to maintain effective charge. This is figuring the typical actual value of 2.1VDC/cell for an automotive battery - 12.0VDC is merely "nominal.") 2AWG should have exactly twice the cross-sectional area as the OEM 8AWG (this doesn't automatically mean double the ampacity, but close.)

Where's your alternator at - for current capacity and voltage - now?

The battery box need not be sealed, and the vent can exit the side. However, any vapours you're likely to get from the battery (except hydrogen) are heavier than air, so venting it downwards does help. The hydrogen will be pushed out of the vent tube simply by positive pressure inside the box, as long as the box is closed. You don't want to seal it tight - if something goes wrong, how would you know? Smell can be an important cue (most of it will go outside the body, but not quite all of it.)

Any battery may be mounted in the cabin, provided proper precautions are taken. A gel cell or an AGM is still a lead-acid battery, they're just built to not spill (the electrolyte is either gelled, or absorbed into a glass mat between the plate - therefore, AGM for "Absorbed Glass Mat.") The energy density of the battery usually does go up by alternate construction, but the chemical action doesn't change, and the rest of the risks don't go away (spillage does - you can mount gel cells or AGM batteries upside down. Still gotta vent them, keep metal stuff from falling on top of them, &c. &c.) The only "risk factor" you lose going to a gel cell or AGM is spillage from position. Period.

2AWG should be fine for the starter circuit, as that circuit has an agreeably low duty cycle (bear in mind that Warn provides 1AWG cable with their kits, and Patriot and Ramsey provide 2AWG. Those loads are much higher than a starter motor - you're looking at 300-600A, vice merely 160-180A!)

If you use a rigid pass-through going through the firewall (you should!) you're going to end up limited by the ampacity of that post. That figure is typically 200A @ 100% duty cycle. Going higher means cutting the duty cycle, just like anything else (nearly any ampacity rating is going to be pessimistic at 100%dc. My current ratings are especially pessimistic - but I also try to account for environmental conditions as well!) Mounting a winch will be difficult - the intended run for the 1AWG or 2AWG wiring is only a couple of feet, and you'll really want to change out your feeder for something closer to 00AWG or 000AWG or so! - but you'll be fine with 2AWG until then.

The circuit breaker is there because there's more cable, it's routed under where the passengers enter, and there's greater mechanical risk to the cable. As I'd said, I'd probably mount the breaker to the side of the battery box (use CRES hardware!) run a short "jumper" lead from the battery to the breaker, and then the main lead going forward. Don't expect the breakers to be especially cheap - you may want to use a MEGA or ANL fuse, which will be cheaper (you'll just have to keep a spare or two handy in the road box - which you really should do anyhow.)

Anything else?
 
Just noticed you have 17,000 post, and I have 400. Im on this forum every day, so you must be on every day, and the days in between hahaha


For rigid pass through you mean something like this right? http://www.jegs.com/i/MSD+Ignition/121/8211/10002/-1

Jegs has a cheaper one, but there all the same design. How exactly do I attach the wire to it? And im guessing you would never think of running the main power through the firewall with a grommet....

I was looking up circuit breakers and the 200a ones are like $100! definitely dont have those funds, more then the cost of the entire kit! So can you make a realistic suggestion of what I can use?

Finally, I understand the installation up to the firewall. Ill describe what I would do, and it would be nice if you could correct me:

-ground lead bolted to rear sheetmetel

-Positive 2 gauge to starter

-attach included braided wire ground to engine block ( gonna keep the stock ground)

- Is that it, any modifications needed to the alternator connections?

oh and I have a newer 117 amp alternator.

Thanks again for sharing your knowledge!
 
The pass-through you've noted is for ignition - note the spark plug-style terminals.

I'm thinking something more like the pic I've attached (my own part number.) It's a 3/8" stud, so standard ring terminals work. It passes through a hole in the firewall (I can send you an instruction sheet if you like,) and bolts in place using to smaller screws - about #10, as I recall.

No, I'd not run the main power through a grommet - through any bulkhead! That's just asking for an electrical fire...

No change to the alternator connexion directly, unless you get an upgraded lead and it doesn't fit in between the "fences" on the guard. Correcting that is a simple matter with a hacksaw - just cut the straight parts of the fence off and leave the round, or replace the guard in toto with a flat one.

I'm pretty much on here (and three or four others) every day - but I have 17k posts because I've been here a long time! Probably since about 2000-2001 or so... (I think I found this forum right after I bought my first XJ and got married - and that's been eleven years and change!)

You can simplify things somewhat with running the main power from the battery to the pass-through post, and then running three leads off of the pass-through: one to the PDC, one to the alternator, and one to the starter motor (you can run the alternator to the PDC and cut out a lead for main power that way, but you've still got the wire, and it will still want to be fused. If you've upgraded the alternator and plan to use it, you're going to want to fuse it accordingly. A 136A alternator is well-served by a 150A fuse. Your 117A will be served with a 125A, 130A, or 150A fuse - whichever can be readily found.)

POST-2.jpg
 
If you could send my the instruction's for that sweet passthrough that would be great!

You have definitely cleared up all my wiring confusion, but now im a little more confused about fuses.

So you have the battery..... then a 200A fuse........then positive lead to firewall.....then I need FUSED links to the ALT, Starter, and PDC (what is this?)

Or do I just need to fuse the alt link? Why are these fuses necessary if they were not already present, and I already have a fuse at the battery?

Oh and again, do you know the cheapest way to get 200A of protection at the battery, breakers are to much money.
:worship:
 
If you could send my the instruction's for that sweet passthrough that would be great!

You have definitely cleared up all my wiring confusion, but now im a little more confused about fuses.

So you have the battery..... then a 200A fuse........then positive lead to firewall.....then I need FUSED links to the ALT, Starter, and PDC (what is this?)

Or do I just need to fuse the alt link? Why are these fuses necessary if they were not already present, and I already have a fuse at the battery?

Oh and again, do you know the cheapest way to get 200A of protection at the battery, breakers are to much money.
:worship:

Ship me your email addy - if you want to email me directly, you can find my addy on my site (link in sig) on the "Contact Us" page (or in various other locations.)

If you don't want to do the breaker, then either an ANL or MEGA fuse will be the way for you to go. Link again.

There is a fuse in the alternator output lead - it often masquerades as a piece of sub-gage wiring, and it's called a "fusible link." This is a bit of wire made of a special low-melting alloy, with a special insulation (to give a visual indicator when it blows,) that is four number gages smaller than the circuit it protects. It's generally a different colour. This fuse should be retained.

You need to add a fuse at the battery (put your fuses as close to the source as practicable,) and it wouldn't hurt to put a fuse just before distribution (but not strictly necessary.)

PDC = Power Distribution Centre, a common feature on 1991-up Jeep vehicles (prior to that, they usually used a convenient point for gathering the fusible links for the main feeds. The PDC is a gathering point for underhood fuses and relays as well - it's a large black box that is fed directly by the battery.)

Ideally, I think I'd put a fuse at/near the battery, and a fuse on the firewall side of the passthrough (theoretically not necessary, but it's cheap insurance. I've had to put out plenty of engine bay fires caused by other people's shonky work...)
 
Just bumping this up since I'm in the process of doing my relocation.

1 gauge wire can be had at O'Reilly Auto Parts, along with the 1 gauge ends (they have them in back. The counter jockey probably does not know they do, but they are a Borg Warner item.

The circuit breaker can be had here- http://cgi.ebay.com/ebaymotors/400-...036346?pt=Car_Audio_Video&hash=item41500f06fa

For the battery vent, you can steal the vent tubes from a Miata or newer LeSabre, as both of these vehicles have batteries within the cabin.
 
oh if you do please post some pictures!

I still have done nothing with my battery (money went elsewhere), so its still a future project.
 
When I had dual batteries my secondary was in the rear and I was able to fish both the ground and the power line through the passenger side frame rail.
 
Back
Top