12V bed plug, best source and cable size?

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Finally getting around to installing a 12V plug in my bed (left rear stake holder).

For those using hese, what is the best source of power and what gauge cable do you recommend?

I installed it while traveling and used the 12g wire the kit came with. I clearly see a big voltage drop and was considering either running a monster cable back to the battery.

Can the trailer harness supply decent current? (see my other post re burning up the harness on my trailer).

Any other thoughts? thx

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David_VT. . Morning... welcome back

What is your 12v plug to be used for ??
just a source at the rear ??
rear jumper plug??

IMHO. . run an O size direct to battery and never worry again #ad



[This message has been edited by willyslover (edited 08-12-2000). ]

 

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David_VT,
Hadn't seen you on since your call for help. I was sure hopein' you didn't get lost in Canada #ad
.

As willlyslover said, bigger is better. That goes for the connector as well. Anytime the conductor gets smaller, that's a point for a voltage drop.

If you can, you might try measuring across the connectors when they're mated. The amount of drop will be dependant on the current being supplied and the resistance of that point.

If you're measuring the drop on the trailer side (comparing to a measurement at the battery?), you could have a poor ground connection. It would act as a series resistor and give a similar result.

From your post, I know you reaize there might be some voltage drop. How much of a big drop are you seeing and where are you measuring?

Comment on 'burning harness post': You would think therre would be some standard for connections. But as you unfortunately found out, that ain't so. Hope your OEM wiring is ok.

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[This message has been edited by Rattlin (edited 08-12-2000). ]

[This message has been edited by Rattlin (edited 08-12-2000). ]

 

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I ran #2 welding cable direct from the battery for my rear jumper cables took about 24 feet on a 3500 Quad cab.

 

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I'd do what Harvie did and put a big circuit breaker close to the battery to prevent a meltdown or fire in case of a short.
Andy

 

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Originally posted by David_VT:
... For those using these, what is the best source of power and what gauge cable do you recommend?

... Can the trailer harness supply decent current?

How much current are you drawing?

20A - 12 ga.
30A - 10 ga.
40A - 8 ga.
50A - 6 ga.
60A - 4 ga.
400A - 500 MCM
I think these numbers are reasonably correct. Any electrical supply house will have a reference handy. You can probably scale the wire down for less than 50'; note that the wire from the PDC to the alternator is *not* huge, but handles 140A. Wire size is based on current, not voltage.

For every 50' length longer than 50', increase to the next bigger wire. (Of course, on a pickup itself, you won't exceed 50', but adding a trailer could well put you into the 50'-100' range. Use a good screw compression joint on outlets and other connections. A heavy-duty crimp will work where you can bolt a lug onto a connection, but can require a hefty crimping tool.

A voltage drop is generally due to resistance. Too small of a wire for the current drawn causes a voltage drop. Insufficiently tight joints cause a voltage drop. Ensure all connections are sufficiently tight. Ensure the wire is big enough.

For high-current circuits, crimping or compressing is about as good as you can (or need to) get. Soldering is really only needed for low-current electronic circuits. Welding is needed to ground antenna towers for lightning protection (well, code in *some* areas calls for the grounds to be welded onto the tower legs. )

The biggest thing is to select the proper size wire and connectors rated for the expected current draw.

[A pair of 500 MCM (mean circular mils) wires is about adequate for 1600A. A 12" length of 500 MCM makes a very nice truncheon!]

In audio applications, bigger is generally better, when dealing with low frequencies. If the audio signal indicates a need for 100A output, the sound could well be distorted if the speaker wire can not handle the current without a voltage drop. Power systems are more forgiving; turning on a switch generally demands infinite current for an instant, but systems generally tolerate a momentary voltage drop until the current stabilizes.

These are, of course, general guidelines. Gospel can be found in the NEC and other electrical reference tomes.

Fest3er

 

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Hey David, I put a 12V outdoor cigaretter light type plug where you speak and used #10 wire with a 25A fuse at the battery. I ran my own wire straight to the battery so it would be a always on seperate circuit.

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TAZ... 2001 2500 SLT+ 4X4 Auto ETC Cummins, LSD 3. 54,Quad Cab, Long Bed, Agate Leather, White/Driftwood Exterior, Sliding rear window, Camper Special Group, Towing Group, Cab clearance lights, Diesel Dynamics Stage-3's, DD Boost Module,SPA-Technique Digital Dual Gauges (Pyro/Boost, Trans pressure/temp) Aux. Backup lamps. BNM 5th Wheel Hitch, Additional Body Molding on Bed.

2000 32' Aljo Triple Slide 5th Wheel.

http://www.ramtaz.com

Add on's to come: Exhaust Brake, Torq-Loc, Line-X bed-liner, and any other Ram Runner required modification...

 

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I have not fried any of the #8 wire that is used for camper/trailer wiring so that seems to work for me.

[This message has been edited by BV (edited 08-14-2000). ]