What is the best way to route a cable to the engine compartment?

andyj

andyj

TJ Enthusiast
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Hi TJers,

I need to route a 8mm cable from the main battery to the auxiliary battery in the back. What would be the best spot to get through the wall between engine compartment and the inside of the car?

I thought I could go through the holes for the removed A/C but that ends up in the black box for heating, so that doesn't work unfortunately.

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There are a few rubbery plugs in that wall but quite low, so I could get wet feet if it rains.
 
Maybe come up through one of the body drain plugs in the floor right behind the driver seat? Would be kind of a built in grommet.
 
mjonesjr84 said:
If you are running battery cables between the batteries, you will be better off running them under the Jeep, drilling a hole in the rear floor, and putting a rubber grommet in the floor. You don't want the battery cables running through the cabin.
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There's already enough wires running through the cabin to burn the rig down, one more won't hurt done the same way.
 
andyj said:
I need to route a 8mm cable from the main battery to the auxiliary battery in the back.
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IIRC, I ran some wiring through the firewall, passenger side, below the hvac.
I think I had to (temporarily) remove the battery to drill and add a grommet.

I would use a sleeved grommet or something like this to help keep the water out.

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I risked it and drilled a hole in one of the plugs.

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That one is on the passengerside right next to the cable channel there.

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Why would it be a problem to have cables in the cabin?
 
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I would go through the firewall, left of the steering column. Route it under the door seal, and to the rear. There are lots of cables along that route going to the rear that you could strap your cable.
 
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ChasUGC said:
I would go through the firewall, left of the steering column. Route it under the door seal, and to the rear. There are lots of cables along that route going to the rear that you could strap your cable.
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That's what I did in the end. It's the passenger side where I hang around ;)

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Done, just in time for our Easter short holiday. This time with a working fridge. 😊
 
ChasUGC said:
I would go through the firewall, left of the steering column. Route it under the door seal, and to the rear. There are lots of cables along that route going to the rear that you could strap your cable.
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That means your cable goes from the battery, across the firewall, firewall to cargo step, then back across to the other battery. It is far better to go from the same side the AUX battery is on and go straight back from the underhood battery to it.
 
I don’t like the idea of a battery in the passenger floor but You might consider Weathertechs in the floor under that battery, maybe a marine battery holder, not sure how your throw rugs will hold up, just sayin
 
MutantNinjaTJ said:
I don’t like the idea of a battery in the passenger floor but You might consider Weathertechs in the floor under that battery, maybe a marine battery holder, not sure how your throw rugs will hold up, just sayin
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When we do it, we copy the factory routing and tie the cable up under the door sill on the right side to match the harness on the left. It then goes behind the leg on the B pillar, and snakes around to the top of the battery which would never NOT be in a battery box. Battery boxes typically have entry points for the cable that route the cable up from a lower point to the top of the battery to limit exposure of the cables.
 
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Not only does the battery need to be in a box but it should be a sealed type battery in the cabin.
Secondly, what gauge and insulation rating did you use for the power cables. At 12v, larger loads at distance adds to wire size in a hurry.
 
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flyinfish said:
Not only does the battery need to be in a box but it should be a sealed type battery in the cabin. Secondly, what gauge and insulation rating did you use for the power cables. At 12v, larger loads at distance adds to wire size in a hurry.
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Absolutely on all that, especially on avoiding an unsealed battery inside the passenger compartment. Personally I'd go for a sealed AGM there.
 
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mrblaine said:
That means your cable goes from the battery, across the firewall, firewall to cargo step, then back across to the other battery. It is far better to go from the same side the AUX battery is on and go straight back from the underhood battery to it.
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Is it opposite for a RHD? Unless his pic is posting a mirror image, that's what it looks like here.
 
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