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Tuesday, February 5, 2013

Battery Cabling Upgrade - The BIG 3 (Jeep TJ)

Short Story First

I started looking into this after 10 yrs of owning and using my Jeep because of the general purpose battery I picked up Summer of 2012.  I made the mistake of getting a replacement battery quickly as the last one was not holding a charge and giving me trouble with starting the vehicle.  So after getting the new battery from from a local auto parts place (not blaming them by the way) all was back to normal.  Then I forgot about the reason you don't by just any battery for a vehicle you wheel/offroad - battery acid leaking from the top.  So after a few months I had trouble starting the vehicle again.  Long story short, the negative battery terminal corroded so much I could no longer keep the ground terminal connector on the battery.  I had to brush the terminal every day and carefully twist the connection in order to allow the Jeep to start.  Never mind the problems this could cause to the entire electrical system in the vehicle (i.e. main computer going bad).  So instead of jumping to buy a new battery, I decided to first change out the wiring and connectors for the starter and charging system, then buy a good battery shortly after (spill proof).

Upgrading the BIG 3


A few concepts you should know:
(1) I am NOT looking to install a high end audio system in the vehicle, but if I do, this will still apply;
(2) I did NOT change my stock alternator to a high output alternator - working just fine (should know, however, that if you plan on needing more power, more often, keep in mind the need for a high output Alt.  If you push it to the peak often it will die.  They have a normal operating range and a peak range.  Peak is meant for spike only and not continuous draw.)
(3) I AM looking to upgrade the stock wiring in case of potential changes in the future with the need for higher draw of the electrical system, but for now, starting the vehicle and the basic electrical system running like a champ is the primary focus (no more dimming/flickering lights, difficult starts, etc).


In a TJ, the engine start and main power distribution consists of:
1) Battery Positive to the starter positive
2) Battery Positive to the Fuse Box
3) Alternator Positive to the Fuse Box
4) Battery Negative to the Chassis
5) Battery Negative to the Engine Block


Overall this is not expensive.  If you went to the dealer for a replacement harness, you would be paying about the same thing or more and still only have the same stock kit, and that's if you install it yourself.  So why not upgrade?

Parts you will need:

The better quality parts you buy the better life expectancy and performance you will gain.  Make sure all the metal parts are copper as it is the best/most common electrical conductor.  Some parts may be tin dipped for corrosion protection, which is common for the lugs.  This is a fine quality to have.  The copper should be stated as oxygen free copper (OFC).
  • Power wire/cable (went w/ 4-gauge due to cost, flexibility, and its ability to supply the power necessary for this application.  When doing installs for accessories such as lights, amp, winch, etc you'll have different needs, but will not impact this upgrade.  Those wires are separate.)
  • Lugs 
    • @8 - straight 4-gauge 3/8" hole
    • @2 - 90 degree 4-gauge 1/4" hole
  • Heat shrink
  • Terminal connectors @2 (preferrably polarized)
  • Terminal protectors (optional)
  • Electrical solder (silver rosin is fine - again a great conductor of electricity)
  • Gas torch
  • Lug hammer (clamps lugs onto cable)
  • C-clamp or hammer for the lug hammer tool (I prefer a c-clamp)
  • Quality cable cutters (like a hot knife thru butter)


Some of my order details (priced around and these were the best parts for the price):
Cloud Electric
LU-1823HD: Lug straight heavy duty 4-gauge 3/8' hole [copper and tin dipped] $0.86 ea.

REMY Battery
4266-001: Brute hammer tool [didn't use a hammer but a c-clamp to control the squeeze on the lug; simple and less chance for error and things getting broken] < $14
5952-050DL: Lug 90 degree 4-gauge 1/4" hole

KFX4BK Kolossus Fleks Kable 4 Gauge Power/Ground wire (Black) [per foot; I ordered 10ft]
KFX4R Kolossus Fleks Kable 4 Gauge Power/Ground wire (Red) [per foot; I ordered 10ft]

Cable cutter that would cut 4 ga cable (not easy to find in most local stores it turned out) ~$26
Electrical tape (just in case) < $1

Harbor Freight
Zip-ties ~$2

Racer Parts Wholesale
FAS-405-911: Fastronix Military Spec Battery Connectors - Negative Terminal  $5
FAS-405-910: Fastronix Military Spec Battery Connectors - Positive Terminal  $5

Car Quest
TA21: Heat Shrink - Heavy Wall Polyolefin Heat Shrink W/ Sealant - 6" - 1 Red - 1 Black <$10

New Red 4ga Cabling
New Black 4ga Cabling

The Results

Steps to Create the Cables

Before cutting the cable to size, be sure to take measurements.  There are many ways of doing this.  I prefer to keep this simple as it doesn't need to be exact, need some slack, but not too much.  I put one of the new cable at a stock connector position in the engine bay and unrolled the new cabling to stretch the length of the stock cable to a connector at the other end.  Using the cable cutters, clipped the new cabling.  I did this one at a time 'til all were measured and cut.  Be sure to remember which one is which for when you install and also for when you create the fuse box connections as they are the smaller lugs.

1 - Cut wire a box cutter/razor blade a little over 1/2" of the insulation off the cable end

2 - Pull the insulation off to expose the copper wiring and carefully with clean fingers, pull'push the strands of wire together so their aren't any strays.

3 - Carefully insert the exposed copper strands into a lug

4 - Using the hammer tool, crimp the lug so that it squeezes the copper strands

5 - Solder the connection making sure not to burn the cable insulation.  This will make the connection incredibly solid.

6 - Protect the connection by sealing it with heat shrink.  Place the shrink over the connection area and lightly apply heat from the torch to the shrink by going back and forth over the heat shrink with the torch flame.  Eventually you will see it shrink and possibly some of the sealant come out.  When you see no more gap, stop.  Should take more than about 30 seconds to complete.  Be careful not to set it all on fire!  You left the flame on the shrink to long - wave the flame over the shrink, back and forth to prevent this.

7 - Repeat for all cable ends, then your done!

Before and After Shots

Stock wiring pulled
* Didn't use the box cutter to remove; just put in the pic to give context

Before - Alternator

After - Alternator  

Before - Fuze Box (all positive connections) 

After - Fuse Box (All positive connections) 

Before - Starter 

After- Starter
* First pic shows both the stock and the new cable & lug side-by-side

Before - Overview Stock setup

After - Upgraded New Setup

Negative (Ground) to Chassis off Battery

While I was in there, I pulled the battery (new one going in soon) and cleaned up the pan and its mounting brackets

*10 Yrs of abuse and it is still in really good shape - nothing a little loving care can't fix



  1. So what do you do about the fusible link? Just go without it? It's there to protect your electrical system if the alternator goes out. With the upgrade you did, the proper size fusible link is 8 gauge (hard to find) or double up with 2 10 gauge pieces approximately 6" long (max 9").

  2. Not complete certain what you are referring to; however, if you are referring to introducing a new fuse inline from the alternator, one wasn't there per the stock design.

  3. So did you run your positive cable from the alternator to the battery or to the fuse box?? Sorry the picture isn't really clear.

  4. So did you run your positive cable from the alternator to the battery or to the fuse box?? Sorry the picture isn't really clear.

    1. Yes I believe so. Been years since I looked at it closely. I just replicated the stock configuration.

      It's still going strong! Instant start ups.

  5. If you look at your image of "stock wiring pulled", notice the positive cables. One of them comes to heat-shrink and then to a smaller wire before connecting to the terminal. Under that heat-shrink is a soldered connection creating the fusible link. The design of this is so that when you have (lets say 4g wire as your main) you use 4g smaller (8g) as a fusible link in case your alternator overcharges via a short or some other issue and prevents a fire, ect.