Dolly break Away switch

[Americanrascal]

I am planning to install a break away switch on my tow dolly. Anyone had any experience installing them? My brake controller is mounted on the dolly and is activated through the tail lights when brakes in the MH are applied (Flat 4 connector) , so I guess I need to find a 12 volt continuous power supply somewhere.

Advice or thoughts would be appreciated.

[wa8yxm]

I am thinking you are trying to make a problem.. IF the dolly brakes lock up sudenly without the motor home to drag the thing, your car will do it's very best to somersault over the top of the dolly or swap ends and roll sideways down the road... I'm thinking that would be a bad scene.

BUT,, That said, this is tangental at best to my training, So keep reading and hopefully someone with the proper training will chime in with better info..

So my post is "Concerns" not necessary fact.. Any mechanical engineers out there who can predict this stuff.

[Scarab0088]

A break-away device makes good sense. A constant power source is needed to make electric brakes stop in a run-away situation. That break-away device is made up of a battery to be carried on the towed vehicle (trailer or dolly) and a switch with cable to the tow vehicle which pulls to activate in a break-away...like:
https://www.etrailer.com/dept-pg-Tra...kaway_Kit.aspx

-BUT- one thing sounds wrong with the OP's description. A 4 prong trailer plug DOES NOT usually carry a signal to the electric brakes. There "should" be at the least, a 5th wire connected to a brake controller, to carry power to modulate the electric brakes.
See: http://www.etrailer.com/faq-wiring.aspx
If the brake light wires (there are actually 2, for Left-turn/brake and Right-turn/brake) are activating the electric brakes, then the dolly brakes are going to full-lock every time the brakes are applied. And when the turn signals are blinking, the electronic brakes are getting a pulsing signal.

I suspect there is more to this story

[Americanrascal]

Yes you are correct I owe a bit more info perhaps. American Car Dolly- what I have- uses a 4 pin flat connector that supplies power to a Redline brake controller on the dolly when brakes on the MH are applied. The power goes through the connector (tail light circuit) to a brake controller mounted on the tongue that activates the dolly brakes. It works very well , and is a good set up, and I have had not one problem . I do like that brake controller on the dolly rather than sitting under the dash.

My understanding from what I have read is that many states and provinces require break away switches on towed vehicles and dollies. Thus I have ordered a break away system.

However for a break away switch I must wire in a constant battery supply from the towing vehicle. I am guessing the only place I can get that is back around the connector at the hitch. (DC wiring is not one of my strong points)

If thats the case I think I may have a yucky dolly wiring set up in the end???? Not sure how I'm going to make this work. May have a mess of spaghetti in the end around the hitch

[Bfmorgan]

Many of the breakaway switch kits come with their own battery. A plastic box is mounted on the tow dolly and holds a small battery, which supplies power when the breakaway switch is activated. I have included a link to an article on breakaway switches: Break Away Switches for Towing

[Scarab0088]

Originally Posted by americanrasc

Yes you are correct I owe a bit more info perhaps. American Car Dolly- what I have- uses a 4 pin flat connector that supplies power to a Redline brake controller on the dolly when brakes on the MH are applied. The power goes through the connector (tail light circuit) to a brake controller mounted on the tongue that activates the dolly brakes. It works very well , and is a good set up, and I have had not one problem . I do like that brake controller on the dolly rather than sitting under the dash.

My understanding from what I have read is that many states and provinces require break away switches on towed vehicles and dollies. Thus I have ordered a break away system.

However for a break away switch I must wire in a constant battery supply from the towing vehicle. I am guessing the only place I can get that is back around the connector at the hitch. (DC wiring is not one of my strong points)

If thats the case I think I may have a yucky dolly wiring set up in the end???? Not sure how I'm going to make this work. May have a mess of spaghetti in the end around the hitch

Looked at the American Dolly website and see that they use an "external brake controller". If is works - that's all that matters.
EZ Brake Instructions | American Car Dolly

To add a break-away device, you are right...will need to run a 12Volt constant power source to the bumper and add a plug to the dolly for power to charge the break-away device battery. 12Volt constant can be found in many locations, just have to find it and add the wire (be sure to avoid sharp or hot surfaces under the tow vehicle). The ground lead is already wired in with the brake lights.

The break-away device output will splice into the output wires of the brake controller (actuates the brakes if needed).

It is not too complex if using a break-away kit.
Best luck

[Americanrascal]

Installed the set up yesterday and it worked!!! Pulled the pin after finishing the mounting and wiring and it worked. Took about 1/2 hour in total.

I still have one outlying task that I need to figure out. I still have not made the tie to power (12v) to charge the break away system battery I set on the dolly. Today I intend to call the manufacturer to determine if its necessary to have that power supply established at all times when on the road, or if the battery included on the break away system is adequate to sustain a safe level of operation for a few days operating time. If so, then I could just occasionally charge it with a separate charger and not worry about a tie in to the MH battery system. Hope that works out.

I see no reason the battery (which includes a battery level test and a recharge light when it is low on charge) could not be just occasionally charged with an off rig charger sitting in a campground or at home. After all the power on the break away battery is not called on unless the trailer switch is pulled in a break away.

If I do need to make a tie in to the MH battery power for constant charging ,then I'll need to see if that line needs a fuse---- or if if the battery wire at the rear of the 7 pin connector on the MH is already fused? (It normally would not be for any other install?)

Its always a happy day for me when I install or repair something and it works with out a glitch on the first shot!

[Scarab0088]

CONGRATS!

The constant power pin on a standard 7 pin trailer plug "should" be fused. If you have that type plug, why not use it?

Your suspicions are probably right - the break away device might be able to stay charged for a long periods. But I doubt that maker will tell you it is OK to not wire a constant power lead...liability and that kind of stuff, because they cannot ensure that an owner will charge it as needed.

Best luck

[Americanrascal]

Thanks!

Could not connect with the manufacturer today- closed for the holiday. I've been researching around the web and apparently the battery will hold a charge from 3 to 6 months. If thats the case I think I'd rather connect the charge line every few weeks to a battery charger. My biggest concern is that I'd walk off and leave the battery line to the MH connected and drain the house batteries-- and from all I've read there is no apparent need for 24X7 charging or even constantly while running. I also saw where they make some of these without built in chargers and disposable batteries- although I never ran across one specifically.

Normally I would use the 7 pin connection and just go ahead and connect the battery line but this adapts from a 7 pin to a 4 pin and activates a controller on the dolly when the brake lights are activated on the main rig. I think I may have convinced myself just to routinely charge the break away battery with a charger???

[Dblegg1]

You can go buy a solar battery charger that plugs in to the cigarette lighter cut the end off and hook it up to the battery and charge it just mount it so it doesn't fall off or just use the battery from the car on the dolly just two wires from that battery autozone/oreilly/Napa have a two wire flat that will work so you can re/dis/connect it when you to load or unload your car you can also plug it in to the cigarette lighter plug if it is live without the key on

[Americanrascal]

Originally Posted by Dblegg1

You can go buy a solar battery charger that plugs in to the cigarette lighter cut the end off and hook it up to the battery and charge it just mount it so it doesn't fall off or just use the battery from the car on the dolly just two wires from that battery autozone/oreilly/Napa have a two wire flat that will work so you can re/dis/connect it when you to load or unload your car you can also plug it in to the cigarette lighter plug if it is live without the key on

Thats a great idea I had not thought of . Thanks! I have one of those sitting out in the garage on a shelf and haven't used it in years!

Good way to clean some junk off the garage shelf and solve my problem.

The manufactures said it didn't absolutely need to be charged from the MH power supply. I could charge it with an independent charger--- which I did yesterday and all went well. But I do like the solar charge concept.

[Peddler]

Originally Posted by americanrasc

Thats a great idea I had not thought of . Thanks! I have one of those sitting out in the garage on a shelf and haven't used it in years!

Good way to clean some junk off the garage shelf and solve my problem.

The manufactures said it didn't absolutely need to be charged from the MH power supply. I could charge it with an independent charger--- which I did yesterday and all went well. But I do like the solar charge concept.

I put a permanent pigtail on the toad battery and plug the break away switch to that. Never have to worry about charging the battery.

[Dblegg1]

Just make sure to wire the solar charger for proper polarity if you cut the end off and hard wire it in