battery relocation question

[90T04]

So if you wired it like in this diagram:

You would have your IG input to your alternator going directly to battery voltage at all times. In the caption it says "alternator with internal regulator" which is what we have, but our field input (IG) is ignition powered. We cant wire it this way because as soon as 12V is present at IG, the regulator puts a small current to the field windings of the alternator.

 

[JesseH]

Double odd (00) guage? Dude how much amerage you running through that? 1000amps?

If you got it for free that is great but for anyone else thinking about buying it.. OVERKILL. 1/0 guage and then 2 gauge will do it as equally without the weight.

Of course you can always do 4 gauge Tefzel/Spec55 and double up on that.

oh I know its overkill, but since I got it for free and it will always support what i have to throw at it...why not? lol

 

[honestabe]

I finished my relocation a couple weeks ago. I have my grounding cable bolted to the chassis via a custom mounting plate. I took a grounding tester to if first to make sure it was good and confirmed that it works fine. I am running 2 ga wire, and the battery kill switch is being installed shortly either in or next to the liscese plate at RRev Motorsports. As for the box, it's a sealed 0.034" aluminum box, with a battery tie that's bolting the battery down, and a cover with wing nuts on top to hold the top down (with an inch of thread to make sure the plate doesn't accidently come off somehow).

 

[Dan_Gyoba]

Well, it was a cheap solution when I did it. I don't know about now.

on the underside of my car there is a length of 1/2" copper plumping pipe that runs along the driver's side chassis rail, bolted to the frame. I did that in preparation for my stereo system with the amp rack in the back.

The copper pipe isn't as fancy as the stranded wire, but it was cheaper than the expensive audio wire, even cheaper than welding cable. (Not needing to be flexible, or insulated, after all.)

I got a 12' length of copper pipe, which was more than enough to run from the firewall to the rear subframe. I cut the pipe to length, crushed the ends flat, soldered them shut, and drilled holes in them. There's a 4 gauge wire from the negative battery terminal bolted through the firewall end, with the bolt going into the frame provision for the grounding cable. I crushed and soldered the rear end, and ran another 4 gauge wire to a ground distribution block at the rear end.

I didn't see any need for insulation on what's effectively just a big ground wire. What's it going to do, short to the chassis?

 

[MDCmotorsports]

Welding cable is excellent. I would also install an inline fuse in the front.

I was just about to say the same.

 

[DegreE]

I never ran a master on/off switch.

I just ran a 0g wire from teh existing + cable under the hood and ran it to the back. Grounded the battery in the trunk too.

This was in my Eclipse, had it like that for a year and never had a problem.

 

[figgie]

I never ran a master on/off switch.

I just ran a 0g wire from teh existing + cable under the hood and ran it to the back. Grounded the battery in the trunk too.

This was in my Eclipse, had it like that for a year and never had a problem.

first off it is not about having problems. It is about being SAFE! The reason SCCA, IMSA, NHRA, WRC etc REQUIRE that the battery have a cutoff switch out back, if there is an accident, the firefighters can TURN the battery off that way they won't deal with a live circuit (and since the chassis is part of that circuit, it takes one postivie wire to cause a spark which in an accident is not good!) Hence why you need a battery cut off switch to kill the ENTIRE circuit.

Remember life above cars unless you have a death wish!

 

[selfinfliction]

Remember life above cars unless you have a death wish!

even if you have a death wish, have consideration for the rescue workers trying to get your body out of the car :biglaugh:

 

[figgie]

even if you have a death wish, have consideration for the rescue workers trying to get your body out of the car :biglaugh:

correct!!


We don't want to mame a firefighter using the jaws of life on your vehicle and finding a hot wire and frying or popping the jaws of life! :biglaugh:

 

[IJ.]

When I crashed my Twin Turbo V8 240z I actually had the presence of mind to shut the batteries off with the isolator just before impact.

The Fire guys that got me out visited me in intensive care and praised how the car was laid out and that they had minimal work to do to extract me and no danger of live power in the car. (normally here they cut the battery cables to be sure no matter what mine were intact)

 

[bryanintexas]

Agreed

the chassis especially after all this time is a terrible electrical path.

Run a HUGE ground cable to the front (2 guage or even 1/0) and then branch it off via ground distribution blocks to the engine.

I had a tech @ work tell me that I should not have my ground wire from the battery over 3' in length. He suggested I run the ground from the battery to the sub-frame and chasis in the rear, and ground the block to the sub-frame and chasis in the front. From the hatch to the block is well over 3'. Would this not be correct or work?

edit: I'm using 2 gauge welding wire

 

[figgie]

I had a tech @ work tell me that I should not have my ground wire from the battery over 3' in length. He suggested I run the ground from the battery to the sub-frame and chasis in the rear, and ground the block to the sub-frame and chasis in the front. From the hatch to the block is well over 3'. Would this not be correct or work?

edit: I'm using 2 gauge welding wire

here is a thought to ponder....

you are already running positive line to the front of the car. What difference will it make if you run the ground too?

Increased resistance? Actually quite the opposite as the 2 guage or 1/0 guage will have a lot less resistance then the chassis will.

Ground loop? As long as you have the same ground (battery) for all electronics, then it is irrelevant.

EMI/EFI. You get more of that from the ignition system than anywhere else.

Electricity does not care what it is used as a medium for conducting electricity as long as its resistance is not to high for the length and current it will be seeing it will work.

 

[JesseH]

what size fuse should be used up by the battery?? I tried a 100a and that popped right when I tried my first start on my new motor....I have 150's that are suppose to arrive tomorrow.. should that be a safe level to sit at??

 

[MK3.0dudeman]

I'm so happy this thread poped up.I was about to start one because I couldnt find anything good on this topic.


I just got my box the other day

 

[figgie]

what size fuse should be used up by the battery?? I tried a 100a and that popped right when I tried my first start on my new motor....I have 150's that are suppose to arrive tomorrow.. should that be a safe level to sit at??

Here is the thing

the starter takes about 200 amps if not more. That is why it is direct connected to the battery without no fuse or anything.

 

[c_ronius]

I have 120A on my main batt + cable, hasn't tripped since I installed it... :dunno:

 

[c_ronius]

So if you wired it like in this diagram:

You would have your IG input to your alternator going directly to battery voltage at all times. In the caption it says "alternator with internal regulator" which is what we have, but our field input (IG) is ignition powered. We cant wire it this way because as soon as 12V is present at IG, the regulator puts a small current to the field windings of the alternator.

Can you just put a ignition switched relay on the IG line? Any reasons why not to do this?

 

[Dan_Gyoba]

here is a thought to ponder....

you are already running positive line to the front of the car. What difference will it make if you run the ground too?

I posted this elsewhere, but I do feel that it's relevant.

For ground, I have a length of copper pipe that runs from the firewall to the back of the car. This is a MUCH better conductor than the chassis is, and becomes the path of least resistance. That my amp rack is connected straight to the pipe... Well, that's what it is. No gr ound loop problems, even though there's nothing that prevents the copper from "shorting" to the chassis at any point. I don't think there's ever enough voltage potential across it to make any real difference. It's lighter per foot than 2AWG wire, and I can't see it being unable to carry less current than 1/0 AWG wire. In addition, I can run it underneath the car, so no worries about routing issues.

For power: Remember that with the stock location, the starter is basically unfused. 100A is nowhere near enough to crank the starter. A no load test is supposed to draw up to 90A -- that's without the starter doing any actual WORK, just spinning itself.

If you look at the TSRM for the starter system, there's a direct line from the battery to the starter. It does not even pass through the main fusible link, it goes directly fom the positive terminal of the battery to the starter. This is one of the biggest issues with battery relocation, is getting that monster amount of current from the battery to the starter.

If I had o place a guess, I'd say that a 250A wouldn't be unreasonable for the starter to draw when it's cold out.

 

[Enraged]

do you guys run the wire inside the car, or outside, back to the battery in the hatch? if on the outside, how/where do you attach it/run it, and how to you protect it?

 

[NashMan]

i am have a back feed issue like mad to try to kill the car thought i had it fgure but the stuip back feed form the ig

right now i just may put in manule alt kill wiht big red botton pain less sell's it

i have some other idea's but we will see

or duble pull switch with i have yet to find