It is hard for me to imagine a pump motor for dump trailer drawing 270 amps. Although amp draws certainly vary between pump motors, that kind of draw should flatten your dump battery very rapidly. It also will exceed the output of your alternator.

It strikes me you should be able to calculate the amp draw using Ohms Law if you measure the resistance through the motor. I know that may not be spot on, but should be close. You can also get a good idea by knowing the cable size feeding the motor or the rating on the relay. It is often stamped on them. Just a thought.

Steve

 

ok ... so knowing you already have the wire and connectors, here is the approach i would take.

i know you've had bad luck with the trailer battery, but i would get a new deep cycle and wire that in for sure in this case. here's why:

a good deep cycle battery should have at least a 70Ahr (amp-hour) rating. Sear's batteries are up around 115Ahr, so even a walmart or farm store (exide) should be plenty good. get the big ones, group 29.

if run at maximum for 30 seconds, and assuming that motor is pulling 275Amp (which i doubt) you are only using (275*30/60/60) 2.3Ahr from your battery. roughly 3% of your total reserve. (assuming 70Ahr)

by doing this, the wiring from the front of the truck to the back only has to carry enough current to recharge the trailer battery. the current in your new wire will be based on the voltage drop from the front battery to the trailer battery. So if your trailer battery is dropping to 10v under load, and your truck battery is running at 14.4v, then the current flow should be based on the 4.4v difference between the two batteries.

your new feed wire should be able to recover the charge in the trailer battery very quickly.

that's how i would do it, anyway.

if you have a micometer, you could measure the existing wire to the pump and compare it to this chart: American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire strength
that would give you an indication of what size wire the pump was originally equipped with.

as for the solder ends, you could either solder your crimp on ends (which i have done with a great deal of success). just tin your wire and your end separately, then assemble the two ends under heat ... usually works pretty good.

or, you could crimp and wrap them in heat shrink. that would be second best. try to get a dual wall heat shrink tape. Lawson products makes them, if you can find a supplier that carries them.

alternatively, if you want to run it directly off the truck battery, you could get another run of 4awg wire and double up your supply line. that would be roughly equivalent to a 2awg wire, and would cut your voltage drop in half as compared to the 4awg. it is probably cheaper to do this than to get the 1/0awg. I'd rather use the wire i already bought, than to waste it with a mid project plan change.

RVTech says that 4awg is pretty common for that type of use on RV's, and they work well with very long runs ... i'd trust his judgment without question. if he says that 4awg will work, i'd trust him.

theory is great, but doing it is better.

either way you go i think will be successful.

keep us posted!

 

Meborder - I agree that RV_Tech sounds knowledgable too. I also agree that a new battery would be better, but the one I have now is still working. It may be getting old and tired (Like me), but is not dead yet. A new one will be in the future but not now.

What I decided to do is contact Del City and see if I can return the items and then buy 1/0 wire ($2.87ft) and connectors (Solder of course). I did open the shipping box, I have not opened any package or even uncoiled the wire so all should be resellable.

It may take a couple of weeks before I tackle this task, but I will post how it goes. It's hard to believe that there are not more projects like this out there. Looking forward beyond this project, I could see many uses for having a decent 12v supply at the back of the truck (Jumper, Lighting, Fridge, Heater, Blender, Marguritas etc,).

 

All the ppl I know around here run a winch wiring setup.
http://www.summitracing.com/parts/wrn-32966
I believe these are available in other awg sizes as well. My cousin has a solenoid mounted somewhere, with a hand control on it to run the pump. (Probably just the one the Dump Trailer came with, patched in.)
Edit: The Summit racing link should include everything you would need. It may be cheaper to piece it together, but this would take all the guess work out of the equation.
Another thing to consider, Ford's alt's are generally garbage, and barely adequate to run the truck's electronic's. You may eventually need to upgrade to a better alt.
(I'm not sure of the 2008+ truck's alt abilities though.)

 

2006Lariat - Thanks for the info. The set from summit looks about right although I was looking for 1/0 wire. 2g isn't bad though and the price is right. Will check on wire size option. Don't plan on replacing the alternator. Assume it will handle the load.

This makes me ask a question. Is 1/0 awg wire the same as 1 gauge wire? I always thought that the wire size gets bigger the lower the number gauge until you get below 1g. Then from 1/0 the wire gets bigger as the number goes up. So this means that 1/0 wire is two sizes bigger than 2g wire. Or three sizes bigger if 0/0 is a size. Is my thinking correct?

 

if you follow the link i posted above it lays it out pretty well.

0awg is the same as 1/0agw. it is just a slightly different way of annotating that it is a "single ought"

so 1awg is one size bigger than 2awg. and 0awg (1/0 - single ought, or zero gauge) is two sizes bigger than 2awg.

from 0awg, it goes 00agw, 000awg, 0000awg (single ought, double ought, triple ought, four ought [should be "quadruple ought", but four ought is easier to say])

does that make sense?

 

I highly doubt a 12vlt hydraulic pump motor, on a dump trailer, is gonna pull more amp's than a 10,000, 12,000, or 16,000 winch, fully loaded, and pulling the duration.
I would think that 2 gauge would be fine. (I'm no electrician though. I would run that Warn setup, or lay one just like it out.)
This is where the others come in.
Hope that helped out enough with a direction, I'm out!

 

Here is something else to consider: look into installing another battery on your dump trailer. Run 2 of them just like the truck has. you double the reserve and the power while retaining the independence of the trailer. (You never know when you won't have YOUR truck to pull the trailer.) I run a power up and power down 12,000lb dump trailer, I use a fork lift style deep cycle battery made by interstate ( can't remember size but it almost doesn't fit in the box) and mine will do 6 or 7 dumps without a charge. But when my trailer is parked it is plugged in charging. Something else I have in the cab is a booster pack battery (JNC660) just in case I get the trailer in the up position and then it won't go back down because of a low battery. ( Happened once.) -Jason

 

noplugs4me - No room for a second battery. But I will keep a working battery in the trailer. I do charge the batt after heavy use but 100ft ext cord across driveway is sometimes in danger of vehicles driving over it. Also have a small solar trickle charger to keep the charge while parked and not in use,. This has worked well for the occasional 1 or 2 dumps per use. But still does not get me more than 6 dumps at a time. I carry 3 battery jumpers which gets an extra 4-5 dumps. This wiring I will be doing should solve any potential power problems in the future and I think it is a good thing that no one else can borrow my dump trailer without me going with it.

I appreciate all the replies so far and welcome any ideas and opinions.

 

Finally got this installed. Took some time returning original purchase of 4ga wire and fittings. Props to Del City for keeping me informed and follow ups.

Some minor problems with the install of 1/0 wire due to the stiffness of such a large gauge wire. The solder connections work great and make a solid, tight connection with the dual wall shrink tubing. The circuit breaker is near the battery (First defense in case of elect. short), then ran 1/0 to weather proof solenoid mounted to frame under cab then to rear bumber. Ran 12ga wire from solenoid to upfitter switch. What a PITA to get to those wires. I learned that on a four post solenoid one of the small posts need to be grounded. 1/0 ground wire from rear bumber to frame.

Overall, not quite as professional as I would have liked, but do like the safety features in case something goes wrong. Have not had the need for several dumps at a time yet but confident this will work well for me.

Thanks for all the help from FTE. You guys are great!!

 

Rather than using battery cable, you can use welding cable......its got, thicker more durable insulation, and more strands of finer gauge wire, so its more flexible than battery cable of the same gauge. Its what i use for battery cable, winch power leads, jumper cables. its also much more cost effective

 

I have run several dump trailers and never had a problem dumping 10-12 loads per day without the battery having an issue. Are you sure that the battery charge relay was installed and that circuit had power? Sounds like a trailer battery charge issue. But I see that you solved the problem, so I guess it's a moot point.

 

I did not know that welding cable came in this gauge. It would have been alot easier to work with since I had to get wire in position with one end soldered only to remove it to solder the other end on, then re-install. Have not had the need for multiple dumps yet but I believe this will solve my problem.