Running a power line to the rear of the truck

[AuroraGirl]

Would running 2 gauge off a relay or high amp switch be excessive? At most a winch of unknown quality or power demand would be run at once. I figured bigger cant be a bad thing for that purpose.
Likewise, running power to my front hydraulics Im going to increase the cable thickness and have it connected by hard wire rather than its current.... jumper cable clamp.

 

[Snoots]

2 AWG is going to handle it. 4 AWG may also do a good job.
I'd use welding cable.
It all depends on the total amp draw on what size would be best to use. Go 25% more than what your total draw would be.

Use RTV and heat shrink at your connections.

 

[AuroraGirl]

Is welding cable special beyond being thick? What gauge?

 

[PrairieDrifter]

Is welding cable special beyond being thick? What gauge?

The wire strands are different, and are of higher quality im sure. 2 gauge or 1/0 gauge

 

[AuroraGirl]

Can you buy welding cable in lengths to 20 feet? (Im not sure how far it would take to go to rear from near the battery, a relay mounted somewhere.

 

[75gmck25]

You can buy it by the foot from this place, or other online sources. https://www.wireandcableyourway.com/welding-cable/

If you are going to run a cable that size for intermittent use (winch, etc.) I would also take a look at what you might use for a fuse or breaker at the battery end to protect the wiring. If you ever accidently grounded it somewhere along the frame you could have a lot of amperage flowing if its a direct connection to the battery and has no fuse or breaker.

Bruce

 

[TubeTruck]

Too bad you're not close. I have a 100ft spool of 4/0 welding cable. A bit much but it would be free, lol. Any welding supply house would have it. Airgas, Weldstar, etc. and you can get any length you want.

 

[Crispy]

May I also suggest marine battery cable. Oil and salt resistant. Also cover the wire in loom for additional protection. 2 awg will be more than enough which is what I would run.

 

[Snoots]

Fused near the battery, relay near the load. 4/0 should handle 200 amps.

 

[80BrownK10]

Too bad you're not close. I have a 100ft spool of 4/0 welding cable. A bit much but it would be free, lol. Any welding supply house would have it. Airgas, Weldstar, etc. and you can get any length you want.

You also can buy it by spool or by the foot on Amazon and eBay. Not sure how price compares between welding supply stores or Amazon/eBay though.

 

[Blue Ox]

Welding cable has more, thinner strands to make it more flexible. Unfortunately the jacket is not as oil resistant as battery cable. Marine cable is similar to regular battery cable in that it has more oil resistant insulation. In addition, the strands are all tinned to help with corrosion resistance. It's also a more expensive.

DC circuit capacity is determined by the total length of the circuit, so from the battery to the load and back to the battery. Then acceptable voltage drop. 3% or 10%. So let's say you need 20ft of 2ga cable to get to the plug at the bumper and another 20 ft to get back to the battery. Allowing a 3% drop in a 40 ft circuit you can carry 30 Amps. If 10% voltage drop is acceptable you can carry over 100 Amps.

There are formulas for this, but it's easier to use a table like this:

https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

Circuit protection is a must as stated earlier. You can probably get by with a fuse if you go with such heavy wire since you'll have excess capacity, but circuit breakers are available too. Just more $$$. Also as stated earlier, proper terminals, properly crimped and sealed with adhesive-lined heat shrink will go a long way to keeping everything working as intended.

 

[Matt69olds]

May I also suggest marine battery cable. Oil and salt resistant. Also cover the wire in loom for additional protection. 2 awg will be more than enough which is what I would run.

Beat me to it. Welding cable insulation doesn’t hold up to grease and oil. Battery cable is more expensive, but the insulation is durable and will last.

If this power feed is for occasional use, I’d get a battery kill switch like for drag racing. You definitely don’t want a unfused power cable of that size running from the front to the rear. Mount the switch near the battery, flip the switch when you need to use the winch.

 

[AuroraGirl]

I was thinking relay in engine bay and switch in cab, like my other switches.

 

[bucket]

On all our field service trucks, we just buy good long jumper cables that are heavy gauge, then chop the clamps off the ends. It's a cost-effective way to get good strong power to the rear of the truck. While I'm sure that there are technical downsides to that method, we haven't found them yet. We run a breaker at the connection to the battery.

The trucks are used year-round and they haven't been affected by road salt, water, oil, fuel, etc.

 

[Frankenchevy]

If you can find a remnant piece at your local electrical supply house or hardware store that has “SOOW” or “SJOOW” stamped in the jacket (in the gauge needed) that may be a cost effective solution as well.

Sometimes when my supply house is near the end of the spool they’ll cut you a good deal. I pick up the 6-10’ pieces of 14/3 and 12/3 for tool cords for nothing.