Double towing with electric brakes

[STEVEBROOKS]

Hi all,

I've been double towing an 8-foot bed flat trailer behind my 5er for years, with no issues. I'll soon be adding another, similar trailer but this one has electric brakes (and keeping the 8-footer too). I'd like to not have to add a 7-pin receptacle at the 5er's rear in addition to the 4-wire one that's already there. That said, to access power for the new trailer's brakes (and lights, of course), my thought is to plug the 5er into the 7-pin connector in the truck bed as always, then use the 7-pin at the bumper for the new trailer.

I'd appreciate any inputs anybody might have on this. Thanks in advance for the help!

Steve

 

[AH64ID]

I’ve thought of this several times and always come up with either wanting surge brakes or a separate controller. The odds of the 2nd trailer needing the same gain as the 5th wheel is pretty low.

 

[mpaulson]

I’ve thought of this several times and always come up with either wanting surge brakes or a separate controller. The odds of the 2nd trailer needing the same gain as the 5th wheel is pretty low.

This, as mentioned above.

 

[Cummins12V98]

The biggie is how do you know if the second trailer brakes are working?

depending on the second trailer’s weight the brakes may not be needed by law.

 

[Hoefler]

Get a trailer with surge brakes

 

[GAmes]

I double trailer a 3000 pound boat behind my 5er and can't imagine the hassle of having to manage electric brakes on both trailers. For sure you couldn't do it with one brake controller. It would be a wiring nightmare to start with. I think it's a bad plan.

 

[NIsaacs]

Hi all,

I've been double towing an 8-foot bed flat trailer behind my 5er for years, with no issues. I'll soon be adding another, similar trailer but this one has electric brakes (and keeping the 8-footer too). I'd like to not have to add a 7-pin receptacle at the 5er's rear in addition to the 4-wire one that's already there. That said, to access power for the new trailer's brakes (and lights, of course), my thought is to plug the 5er into the 7-pin connector in the truck bed as always, then use the 7-pin at the bumper for the new trailer.

I'd appreciate any inputs anybody might have on this. Thanks in advance for the help!

Steve

The way I read your post, is, you want to tow triples? As far as using your bumper plug to power a second trailer, I see nothing wrong with that, just that it would take a super long cord. Then somehow thread it down the length of the fifth wheel.

As far as brake gain, wouldn't the current equalize/spread out over three or four axles the same as if the axles were all on one trailer? I can see a possible issue if the back trailer is small and light. If the gain was set for that trailer, it might not be enough for the heavy fifth wheel. I think if it were me, I would try it

If it don't work, just disconnect the brake wire on the back trailer and tow without, like you have been.

 

[STEVEBROOKS]

Yea, I can see where my wording was a little confusing. I'm not going to tow a third trailer, just a larger second one with electric brakes. A big reason I thought about wiring it the way I mentioned is to cut down on the amount of splices/etc needed. I've already spliced into the 5er's wiring at the back to add the 4-pin for the smaller trailer, and then would have to splice in even more to add a 7-pin for the larger trailer that replaces the 4-pin.

I'll chew on it a while and report back as to direction taken. Appreciate all the replies!

Steve

 

[AH64ID]

The way I read your post, is, you want to tow triples? As far as using your bumper plug to power a second trailer, I see nothing wrong with that, just that it would take a super long cord. Then somehow thread it down the length of the fifth wheel.

As far as brake gain, wouldn't the current equalize/spread out over three or four axles the same as if the axles were all on one trailer? I can see a possible issue if the back trailer is small and light. If the gain was set for that trailer, it might not be enough for the heavy fifth wheel. I think if it were me, I would try it

If it don't work, just disconnect the brake wire on the back trailer and tow without, like you have been.

The gain likely won’t equalize out and the required gain for the 5th wheel would likely cause the 2nd trailer tires to lock up easily which will make for potential issues.

The only saving grace would be the voltage drop from the length of run.

 

[STEVEBROOKS]

Yea AH64ID, I factored in that same thought too. It'd be easy to fab up the needed long wiring and temp install it for an ops check, so probably wouldn't hurt to try. I could set up the approx gain/etc and have a buddy drive the rig down the road while I drive beside the second trailer and check for brake lock/other problems...

Steve

 

[Hoefler]

You will need a dedicated controller for the second trailer

 

[Topzide]

The biggest factors in this type of setup would be;
1) the gain difference between the 5ver and the lighter trailer,
2) the voltage loss on the longer run of cable to the second light trailer.
You could use the round 6 pin trailer plug on the back of 5ver for it's size, but you would need adapter for using behind the truck.

 

[STEVEBROOKS]

Greatly appreciate the replies y'all! Will advise back on what I decide to do with this.

Steve

 

[Cummins12V98]

Surge if you NEED brakes on second trailer IMHO is only real option.