OT: Automotive type jumper cables

On Fri, 6 May 2005 16:04:54 -0500, "David Courtney"


Last time I was in one of my "secret sources" they had a bin full of electric forklift charging plugs, male/female inlines. I could be persuaded to go pick up a couple sets
Gunner

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Biggest soruce of voltage drop is at the connectors, crimps, etc. More than likely your gain from running the heavy cable on the trailer would be negated by the extra connection.
Chief McGee wrote:

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<snip>

4/0 copper is 4/0 copper. Many fine wires or few thick wires makes no difference to the current capacity. So, you might as well use welding cable, unless you have one on hand for free and the other is a need to buy item.
You may not need to go to such heavy cable if the backhoe battery is basically OK. What you can get away with for topping up and recharging a good battery .vs. what you need to have a hope of actually cranking via the jumpers is quite different. A couple of 10 or 12 gauge wires hooked in to trickle-charge the backhoe while you were hauling it might be all you need.
Just out of curiosity, how does that haul, and how much backhoe have you got? I've got a ~7-8000 lb backhoe which I don't haul anywhere, and a 1-ton crew-cab pickup. I've always suspected that if I did decide to get a trailer that could take the hoe, it would be the tail that wagged the dog on that truck (about 6000 lbs empty and 20 feet long).
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Ecnerwal wrote: -snip-

I used to drive a truck for my dad's company in the summers. It was a 1972 3/4-ton truck pulling a 20-foot gooseneck trailer. We ran it up to 16000 pounds combined GVW and it towed just fine. With the gooseneck putting the weight ahead of the rear axle it basically towed like a semi (so I've concluded, that truck was the biggest I've ever driven). There was no sign of the trailer wanting to whip or jacknife, the combination handled nicely around corners, etc., etc. The ride was considerably rougher, and of course the thing neither accelerated or pulled up hills with any speed (we were running a 350 with a 4-speed), but there were no _handling_ problems at all.
Of course it beat the hell out of the pickup, but Father has replaced the bed floor and all of the rivets in the chassis -- it's fine now.
--

Tim Wescott
Wescott Design Services
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How about building a charging system to keep the backhoe's battery at full charge and an inverter to keep the engine warm via a block heater. Make sure to use a diaode to protect the truck's alternator and battery. Hope this helps..

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I am pretty much in agreement with John D. I would run something like 6 or 4 gage to the back of your truck. Then have jumper cables that would connect so you could quick charge the backhoes battery. But also have a connection on the trailer to top off the backhoe battery while you are driving. Plus add a heater for the backhoe battery that would run off 12 volts. If I recall correctly batteries lose a lot of power when they are cold. I think you could have the backhoe battery in an insulated box and keep it warm. I doubt if a block heater would help a lot with the air blowing by the backhoe as you drive.
Dan
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| I pull a backhoe on a trailer behind a 1-ton GMC truck. Sometimes when it | is cold I need to "jump off" the backhoe from the truck's two batteries | while it is loaded on the trailer. Since the jumper cables are too short to | reach the tractor from the front of the truck, I would like to run two | permanent cables to the back bumper of the truck . Then I could hook | regular jumper cables from the tractor to the terminals on the back bumper. | Question is: What type and size cable should I run? Would 4/0 copper | "entrance" cable do? This is stiffer than welding leads, therefore, harder | to work with. But if it gives me more cranking amps it would be worth the | trouble. Does a 4/0 copper with a few thick strands carry more CRANKING | amps then a 4/0 with many finer strands? Thanks, Chief
Most RV's have a setup that allows the main battery to charge the RV batteries as you're driving around. Check with an RV shop about upgrading your wiring connection point and making a suitable connection to the tractor. If you'd rather go the jump start routing, Anderson mutipole connectors are used all over for battery cable connections on heavy equipment and battery powered equipment like forklifts and such. If I ever was to hook up a set of jumper cables into my crew cab, I'd use a set of these. If you look at cop cars and whatnot you'll see them hanging out the front and/or the back. http://www.andersonpower.com/ and you can get them from many sources. Battery shops, better auto parts stores, RV shops, and heavy equipment suppliers.
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Chief McGee wrote:

I learned sometime somewhere that that an electrical current runs along the skin of each individual strand. More surface area = more current capacity. This makes your find-strand welding cable much better. It would also be less susceptible to vibration failure. I would think a simpler solution would be a hi-amp booster pack. You could leave it in the cab, charging off the power outlet so it's hot all the time. Say you jumped it off your truck, backed down the trailer, then stalled it behind the trailer. The booster pack would then be easier to restart with, than moving your rig around where you could reach it with the cables. In some situations that might not be possible. I used to run a small-gauge wire from the tow vehicle battery positive back to the towed vehicles battery. The towed vehicle was also grounded to trailer with tie-down chains. This kept the battery hot in transit and it was at peak when I got to the track. Similarly, I have connected the trailer running lights to charge the battery of the car on the trailer. Just had to run with the park lights on, not a bad idea anyway.
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| I learned sometime somewhere that that an electrical current runs along | the skin of each individual strand. More surface area = more current | capacity. This makes your find-strand welding cable much better. It | would also be less susceptible to vibration failure.
This is called "skin effect" and is in effect only at alternating currents, and the higher the frequency the less time the current spends "inside" the conductor. There's tons more theory and stuff to this I don't recall, but in a nutshell it's what makes waveguides work at high frequencies. For DC it's not all at part of the picture, but strand count does play a small part in the picture. When you compare stranded wire, the lower strand count means that the empty spaces between the conductors is larger for the equivalent area of circular area to pass the necessary current. Finely stranded wire has less open space, so in diameter is actually smaller. Often made up by having larger insulation in welding cable, needed for durability. High strand counts tend to make for more flexible wire (so the insulation has to be equally flexible,) which is why my favorite set of jumper cables is made of welding cable, and is just as flexible in the snow as in the baking sun. Now if I could just get end clamps that were half as good!
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wrote:

Skin effect is a total non-issue on DC, and a virtual non-issue at 60Hz.
It DOES become important in the RF and even the high AF range, apparently.

And a BIG problem if, for some reason the battery was low enough in charge to require more current than the 7.5 amp (commonly) or 15 amp (less common) tail lamp fuse was good for. Putting in a heavier fuse just makes the wiring harness into an expensive fuse.
DON'T DO IT.
I run a #6 wire back to the hitch on all my towing vehicles, protected by a circuit breaker, and switched by a solenoid so the hitch connector is NOT live unless I tell it to be (makes for a WHOLE LOT less green stuff on the connectors ------)Keeps the house battery on the travel trailer fully charged, and is good for keeping the breakaway box well charged as well. The solenoid makes a diode type battery isolator un-necessary - (good riddance!!!)
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I used a 16 gauge wire, which limited things to my satisfation.
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