Trailer wiring

[John316]

I know that this has been beaten to death, however, we want to install our trailer plugin. We will be hauling a 16 foot tandem axle trailer (with a ramp, for those who care ).

The trailer will obviously have electric brakes, marker lights, and turn signals. We will also have a battery for a breakaway switch (which we will need power for). I have looked at gumpys page, some, and I am now going to step outside for some fresh air to clear my mind . No really, I thought he did a good job.

However, I also know that Sean has a system. Anybody know what that is?

Any other tips, tricks, ideas, comments, suggestions, or just general helpful advice?

Thanks a lot.

God bless,

John

[bevans6]

I contacted Gumpy (Craig) and he was kind enough to make a version of his system for me, the modification was to include a 12 volt feed to the brake controler.  Normally it has 12v stop/turn left, stop/turn right and tail.  I confess that things caught up with me this summer and I haven't actually installed it yet.

For me there are a couple of issues.  You need to arrange a good, solid 20 amp 12 volt supply at the front where you will mount your brake controller.  After much thought, I have decided to use the bus 12 volt feed from the Vanner, which is a 30 amp fused supply (change the fuse to an auto-reset breaker).  I also run a radio, two 6" dash fans, and my power seat from that feed, but the amps add up OK (unless I have maximum brake draw and maximum power seat draw at the same time, which I won't).  You then need to arrange a 10 gauge wire from the brake controller to the back of the bus.  I don't want to string wire, I have a half dozen spare lines that are 14ga to 16 ga, I am going to parallel them up to create the needed ampacity.  I am going to use one of these lines as the signal line from the Gumpy box to the front to tell the brake controller when the brakes are on (current on this line is essential zero).

The second real issue is a solid 12 volt supply at the back of the bus.  My bus doesn't have one, and I don't have sufficient spare wires to run one, plus I don't feel like I should take that much more current from the Vanner.  I have decided to install a 20 amp 24 volt to 12 volt converter in the engine bay, probably installed in a weather-proof vibration isolated box with the Gumpy box.  I will use this converter (which is also a battery equalizer if you hook it up that way, which may be handy for someone who doesn't have a Vanner).

http://store.solar-electric.com/12to24or24to.html

With that I have 20 amps to play with for lights and I can wire a fused lead to charge the breakaway battery, which is a good thing.

I have the 24/12 converter on order, and I should be good to go and do some installing soon.  I plan to take a trailer to Savannah in December.

Hope this helps you out.

Brian

[JackConrad]

I believe Sean's system is similar to the one I used on our MC-8.  Ours consist of 4 30 amp cube relays.  The relay coils need to be the same voltage as the bus voltage.  Jack

[Len Silva]

If you don't have a Vanner or other 12 volt supply, I think that just center tapping the 24 volt string for the trailer brakes ONLY, would not be a problem.  I don't think that the short intermittent use for trailer brakes would do any harm to the batteries.

[Nick Badame Refrig/ACC]

Hi john,

Craig made my set-up and it works perfectly...

Good Luck
Nick-

[bevans6]

You have to plan for a 10 or 15 amp continuous load for the trailer lights, worst case, there are 17 (I had to go out and count them) running/clearance lamps on my trailer, two brake lamps, and the up-to 20 amp brake controller load, plus the trailer interior lights which would rarely be on, and charging the little breakaway battery.  I agree the brake load is momentary and probably won't do the batteries any harm, and I honestly have no idea if a 10 amp continuous load to light up all the brakes would either.  I had the Vanner, so it was a no-brainer for me, and I'm using the 24 - 12 converter to get out of running wires to the back frankly, so chalk it up to lazy.

Brian

[belfert]

My lighting is 12 volt so I used a Drawtite Modulite for the trailer lights.  The Modulite needs a 15 amp circuit.  It basically does what all the cube relays do.

I thought my first Modulite was bad so I bought a new one.  It did the same thing.  It turns out the wiring on one of the vehicle lights was screwed up.  I ended having a minor issue with the replacement Modulite this year so I put the first one back in.

[rv_safetyman]

Hi John.

I wrote an article on this subject for the March 2009 issue of BCM.  Had some good help from Criag, Jack and Sean.

I got interested in the subject after two of the cheap aftermarket 5 to 4 converters failed in short order.  The system I recommend uses the "Bosch type" mini ISO relays.  They are very durable and quite inexpensive.

In that article I go into quite a bit of detail including using relays with diodes in them.  I also listed some sources.  Covers both 12 and 24 volts.

If you can get your hands on that issue, your questions should be answered.

Jim

[John316]

Thanks Jim. I knew you wrote the article. I am getting a copy right now, since in the move I misplaced our copy.

Thanks a lot.

God bless.

John

[busshawg]

I ordered mine from Gumpy and it also works perfectly.

Grant