Do two 14awg equal 10awg?

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Do two 14awg equal 10awg?

Postby Gerdo » Mon Oct 31, 2005 10:07 am

If 14awg can carry 15 amps then can 2x14awg carry 30 amps? I need to run a charge wire from my tow vehicle and I know that it needs to be a 10awg. I would like to run a SJO type wire so I am thinking of running a 14-2 SJO. Any thoughts?
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Postby vairman » Mon Oct 31, 2005 12:04 pm

Hummm 2 #14 huh? why not go to HD and get some #10 THHN wire and not have to worry about it... I would have some insulation Issues with the SJO wire.... Just my thought....

Greg :thinking:
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Postby vairman » Mon Oct 31, 2005 1:38 pm

Opps, I ment THWN...


Greg :oops:
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Postby BrianB » Wed Nov 09, 2005 3:48 pm

IHNI what you GATA but it's INTL.
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Postby angib » Wed Nov 09, 2005 5:51 pm

BrianB wrote:IHNI what you GATA but it's INTL.

I have no idea what you Gold Anti-Trust Action Committee but it's international?

Que? :thinking:

Andrew
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Postby BrianB » Thu Nov 10, 2005 6:42 am

I have no idea what you guys are talking about but it's interesting nonetheless.
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Postby Cutterpup » Thu Nov 10, 2005 4:21 pm

Don't worry Brian
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THEY DON'T EITHER
Just kidding you guys are just talking over our heads and the quicksand is too deep! :rofl: :rofl2:

Dan
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Postby vairman » Fri Nov 11, 2005 8:57 am

THWN Wire Info......

Trade Name: Mosture and heat-resistant Thermoplastic

Max. Op. Temp: 75C. or 167F.

Application provisions: Wet and dry Locations

Insulation: Flame-retardant, mosture and heat resistant thermo-plastic

Outer Covering: Nylon Jacket or equivalant.

FYI Greg :twisted:
Women are angels, but, when someone breaks their wings, they simply continue to fly on a broomstick.
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Postby jimqpublic » Mon Nov 14, 2005 1:17 pm

I really wish I had the old post from my charge system design. What stops good battery charging in the trailer is having too little voltage differential between the battery and the supplied charge voltage- at the battery not at the alternator.

Yes, you can parallel conductors to improve your charge rate by lowering resistance. You won't get 30 amps of charge from #10 wire though. It all depends on your tow vehicle's voltage regulator, system resistance, tow vehicle battery state of charge and trailer battery state of charge.

Personally if I were paralleling wires I would protect each independantly with an appropriately sized self-resetting circuit breaker.

More random notes:
I have a continuous duty starter relay (rated at 65 amps continuous) switched by an accessory circuit in the car and a self-resetting breaker. I used 6AWG Anchor brand marine grade stranded cable with soldered lugs and adhesive lined heat shrink for the charge line in the car. On the trailer end I used 4AWG battery cable from the end of the trailer cord (which is 10AWG) to the batteries, which are at the very rear of the trailer.

After looking at all the appropriate cable options- Marine cable is the most expensive, battery cable is next, and welding cable is cheapest. For 4AWG the marine grade is $2.25/foot, battery cable is $0.99, and welding cable doesn't come that small but 2AWG is just over $1/foot.

With my car I get great charging. The total cable length is quite long - believe it or not the total wire run is almost 50' even though the car+ trailer is only 33' long. I have two big golf cart batteries in the trailer and a small starting battery for the car. My alternator keeps pumping out 14.4-14.5 volts to keep the batteries charged. In a system with higher resistance and a bigger vehicle battery/smaller trailer battery what happens is once the vehicle battery is fully charged the voltage regulator cuts back the voltage to prevent overcharging. Then with voltage output down around 13.4 the trailer battery accepts very little charge.

What pushes the charge rate is the differential between battery voltage and charge voltage at the battery. If the battery is 50% discharged its voltage will be around 12.3. If the alternator is putting out 13.4, and there's a bit of resistance in the system, the charging voltage at the trailer battery might only be 13. So there's only 0.7 volts of differential to "suck" power into the battery.

On the other hand my system has lower resistance. With my alternator putting out 14.5 volts there's 2.2 volts of differential. The trailer batteries suck a lot of juice with this much differential. As amperage goes up there does start to be some voltage drop due to the system resistance but not until there's a pretty high charge rate.

I'm probably messing up the real science here but it seems to work.

By the way, two winters ago we camped four nights up in the snow at Sequoia National Park with our furnace burning through 20 pounds of propane. That means the blower was on for 21 hours using 73 amp-hours. Plus lights- probably another 27 amp hours for 100 total.

We hitched up and drove to Yosemite National Park. Probably about a 5 hour drive. According to my voltmeter the batteries were basically fully recharged at 12.7 volts.
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