Hello to all. New F250 owner (Formerly a Cummins), and new to this site. My project is wiring 12v to run the hydraulics on my 7 x 14 dump trailer. What I have purchased so far is 25ft @ 4 ga red and black cable, heavy duty connectors, and lugs. Plan on purchasing a 150A - 200A circuit breaker, similar sized solenoid. Will be connecting solenoid to upfitter switch. May or may not keep battery in trailer. I may buy a small gel cell battery for break away.
My questions are:
1. Will this be good enough for a 14k trailer? (Do not know amp draw for hyd. pump)
2. Will this setup keep the electronics in the truck safe? (Warranty?)
3. Is isolator needed or required?
I should mention my goal here. I am having trouble with existing battery goining dead before done using dump. (About 6 dumps). Currently carrying 3 battery jumpers to complete tasks. Existing battery is old enough to need replacing but will still have same issue. So I am thinking for the cost of a new battery (Maybe a little more) I can have an unlimited supply of voltage for the dumper and not need to replace a battery again with an added benefit that no one (friends/family) can borrow it.
Greatly appreciate any and all suggestions

 

Questions and a thought. If I am reading you correctly, your intent is to connect to your engine battery?

I would encourage you to keep the battery on your dump trailer along with an operative break-away switch just in case.

It would really be helpful to know the amp draw of the motor on your hydraulic pump to offer help with wire sizing, etc. The should be some kind of label on the pump with a rating.

I was also wondering about the absence of a charge lead between your truck and trailer to recharge the dump battery in between runs. I am guessing your truck has a seven pin at the bumper?

Steve

 

Yes. My intemt is to use one of the truck batteries to run the dump traler. I may keep the old battery in the trailer for use with the break away system and it may be less taxing on the alternator However, some one has told me that I can get a small gel cell battery ($20) to use only for the break away which could eliminate the need for a full size battery.

There is a small label on the pump motor: SPX fluid only. Part number 1787*AC. 12VDC Standard Duty. There is also a label on the resevior: Relief pressure 3200 and it has a space for the amps but is blank. It also has ser. num. etc. I will do some research on the company "Sunsource" to see if I can figure out the amp usage.

I do have a 7 pin trailer connector at the rear bumper but this does not keep the battery charged enough to make more than 6 dumps per daily use.

 

If you are going to use a small battery just for the breakaway, historically gel cells are voltage sensitive during charging and have a somewhat checkered past so you may want to simply use a small battery or the one already in place.

It looks to me like Sunsource is a distributor rather than a manufacturer so it might be best to simply get their number off the Internet and call their customer service. I would think someone there could answer your question over the phone as long as you have the model number.

If I were guessing I would say 80 amps of less for start-up and then an immediate drop to 50 or so, but that is simply based on the stuff I work on so I may well be off. What is it fused at now? There must be a fuse within 18 inches of the battery on the lead to the pump.

Steve

 

Thanks for the quick response. I wasn't aware of the shortcomings of a small gel cel battery. Good to know. I will be keeping the old battery in the dump trailer. It will be easier to wire to the old battery anyway. I left a message at the online customer service at Sunsource about the amp rating on the pump. If you are correct about 80amps does that mean I should have a circuit breaker of the same or less to protect the pump? Or would a 100amp work? Also, will the solenoid protect the truck electronics? Some one mentioned an isolator but I'm not sure if it is needed or how it should be wired in.

I hope this is doable. I found some youtube videos that only ran wires from truck battery to connector at the rear bumber, But my common sense tells me it is not a good idea to have a constant live heavy wire without any safeguard.

 

Good idea about looking at the fuse in the dump trailer. Will do that tomorrow. Thanks

 

You will be sizing the wiring to carry your load and you will need a fuse at or near the truck battery to protect the wiring back to the trailer as fuses protect wiring.

My initial thought is to use a switchable relay at the truck battery so you can turn the power to the dump trailer off and on, although I am sure others on this forum will have ideas as to that also. I am not sure what you have in mind as a means to tie the wiring to your truck battery.

Steve

 

Along with the 4G cable, you can use polarized connectors like Warn, Ramsey use for plug in winches. As a side benefit, you can use this power plug for jumper cables as well.
......assuming its a diesel you have 2 batteries connected for 12V at double the amperage, with probably 1/0 or 2/0 battery cables to connect the Batt's........plenty of people hook up 12V electric winches, all the way up to 12-20K lb capacity, many of which will draw 400+ amps at full load, and your starter and engine preheat stuff draw a lot of amps. Assuming you leave your engine running while dumping, most of the power should be required for the lift stage of dumping, many hydraulics are "gravity" only for lowering, rather than requiring much of any amperage for that.

 

Thanks again for all the replies. I appreciate bouncing my ideas off someone. Helps me to pay attention to the detalis.

Got home late tonight so did not look at the fuse on the dump trailer.

I plan on using a manual reset circuit breaker near the truck battery positive (Yes it is a diesel). I understand the passenger side battery is the one to use. Probably 100 amp breaker. Then run the hot wire to a solenoid (Input). Solenoid will be under the truck somewhere (No room under hood). The switch leg of the solenoid will be connected to an upfitter switch so the hot lead will not have constant power. Then hot lead from solenoid (Output) to rear bumper. The ground wire will probably be connected to the negative battery side or engine or frame. I will be looking for an existing heavy ground location. The ground wire will only go to rear bumper from this grounding location. All connections will have crimp on lugs at battery, ground point, and solenoid, The "Plug in" connector at the rear bumper is the same as a winch. The connectors were purchased from Del City and are rated for 175 amps.

The truck will always be running when dumping (Power up, Gravity down).

I considered a relay but did not know how to connect a 4g cable to the small relay spade connection.

So what do you all think? It seems easy enough, Bata boom, bata bing.

 

sounds like a workable plan, i would only offer the following thoughts/suggestions:

retain the trailer battery, and utilize it in conjunction with the wiring modifications above. the only reason it goes dead on you is the inability of the factory wiring to charge it, your modifications fix that problem. by retaining the trailer battery, you are doubling your reserve capacity as compared to the truck battery alone. no reason not to use it, IMO.

try to find a solenoid rated for continuous duty. this is just the first one i could find:
and is rated to 85-Amp continuous. A standard solenoid is not rated for continuous draw, and may become problematic when used in that manner. They are out there, it would be worth your effort to find the right one, i think.

use solder on connectors instead of crimp connectors. using a crimp on end in an external applications like this is a recipe for problems. After getting all of this wired up, you won't want to do it again in any hurry, so do it right and do it once.

i would use larger wire than 4awg. according to this: American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire strength 4awg is only good to 60 amp continous when used as a transmission line. I would upsize to 1/0awg. to find wire that large, check out shops that service Agricultural equipment, or Semi tractors. that size of wire is commonly used in those applications. Bring your check book. I had to buy some earlier this year and i got the "good guy" deal at $5/ft. it's expensive, but as i said, i'd rather just do it once.

4awg may work just fine, but it might get warm on you. Another consideration, though, is voltage drop. 4awg will show a drop of about 1.5v @100amp. whereas, 1/0awg will only show about .5v @100amp

just some thoughts ...

 

My thought regarding wiring size is the run time for the pump will be pretty brief and I will be surprised if the pump draw is actually more than the 4 ga. will carry, although I tend to oversize wiring myself. With the engine running, the output from the alternator should handle any drop due to run length.

Another thought is the piece of the puzzle that would really be nice to have is the actual amp draw for the pump taken with a meter at the pump.

When I thought about this I conceptualized it as similar to the large diesel motorhomes I work on where the batteries are all the way in the back and the pump for the leveling jacks is at the front bumper so the wiring run might be near 40 feet.

Steve

 

run time does factor in, for sure. do i think you are going to melt a 4awg wire? no. but you will be generating some heat, and there will be a noticable voltage drop. and keep in mind, that as the temperature of the wire goes up, so too will the voltage drop.

the voltage at the front battery will be 14.4ish, the voltage at the pump will likely be closer to 13ish when the pump is on. now whether that makes a difference to the pump, i do not know. my guess is that it wont, and it would run all the way down to 11v without much problem.

keeping the battery on the trailer will help stiffen the voltage curve when the pump is on, and with a 4awg wire to feed it, the trailer would recharge very quickly.

just my thoughts.

 

this looks like it may be your pump motor?
KMD1 12 VOLT DC SPX POWER UNIT MOTOR

is capable of drawing a LOT of current.
not sure what it actually draws while in use, though. Would be hard to measure directly, unless you have a industrial size ammeter.

 

All it takes to get amp draw is just a clamp meter. I do it all the time on RVs. Of course, a decent clamp meter does cost, if used only infrequently. Can't do it on a regular multi-meter for sure as it will blow the fuse on the start-up.

I agree, a 1 volt drop would be about standard. I seldom see anything bigger than 4 ga. on the pumps or accessories save for battery or inverter cables. The pumps I see on the dump trailers I rent look to be the same as the ones used on RV slide-outs, but I never did a one-to-one comparison. The normal operating range is normally 10VDC - 16 VDC.

Curious to see what the existing fuse is for the pump on this trailer.

Steve

 

Wow. Great replies. Thanks guys.

Ok. Finally got to look at the fuse on the dump trailer. 10 amp fuse (What!!). It turns out the fuse is for the switching system on the trailer which looks to be a 12g wire. There is nothing on the large guage wire running between the existing trailer battery to the pump. I have no ammeter or clamp on meter. So, no way to know the amperage use.

As far as run time, voltage drop, or overheating the wire. The run time is usually less than 30 seconds. After several dumps the run time is longer due to the battery running dead. Of course, the heavier the trailer load, the longer it takes to dump. Although even a heavy load is just 5 -10 seconds longer.

Meborder - I can't tell if my pump motor is the same as the one on your reply since I have all the other electrical "stuff" on there. But if it is similar, that shows 270A draw. That is more than I expected.. Also thanks for the info on the soloenoid. I knew I needed a continuous duty, but other than that I don't know one from another.

Man, I could kick myself for buying the 4g wire before doing this research.

So as it stands for now, my plan, while not perfrect, is doable, except for 1/0 wire and solder connectors.

I will check on costs of 1/0 wire in my area. As been said here and as I said earlier, I would only want to do this once, correctly.

I will be checking this thread often so if anyone has any other suggestions or if I have more questions.

Thanks RV_Tech, you have been very helpful.