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Wednesday, October 10, 2012

Trailer Break-Away Switch Operation

Gary, I have several questions about the break away switch on a travel trailer. First, thank you so much for all of your time at the Hershey Show. You went way beyond what was expected to answer questions. My wife, Jayme, and I have attended several of your sessions over the years. I have always learned something from each session, even when I attended the same session two days in a row! 
Now for the questions concerning a break away switch on a travel trailer. Is the power to the brakes directly from the battery or is it routed through the converter distribution box? Should a travel trailer be stored with the pin in or out of the break away switch? With the break away pin out, do the switch and the brakes consume much power from the battery? If you have the ability to keep the batteries charged during storage, should you remove the break away pin? Is it best for the trailer brakes to be set (pin out) or open (pin in) during a month or more of storage? 
Also, I had an inverter installed with an automatic transfer switch so that all the 120V outlets and systems will work in the trailer. It is not powerful enough to run the microwave or air conditioner, but can power anything else in the trailer. Besides using the TV while boon docking, my main use is so I can run the absorption refrigerator using electric during travel. I have to engage the battery disconnect switch before I turn on the inverter and keep it disconnected while the inverter is on. If I have the inverter on and the battery disconnect switch engaged during travel, will this effect the operation of my break away switch? 
Thanks for you help in understanding the break away switch and the impact on the batteries and brakes. Graham & Jayme M., (Jeffersonton, VA)
It was good to have you at the seminars in Hershey, Graham and Jayme! The break-away switch on a towable RV is always powered by the battery bank on the trailer. That way, if the tow vehicle and trailer ever part company, the brakes will be activated and remain fully applied. It should not be connected through the converter since the converter is only activated with the application of 120-volt AC power.

Always leave the pin in the switch. Once a year, jack up one or two tires on each axle, spin the tires and pull the pin to be sure the brakes are fully activated. The tire/wheel assembly should immediately stop with the pin pulled. (This is also a good time to determine if the brakes need adjusting. To read about trailer brake maintenance, check out this article).
While the pin is out, spray electrical contact cleaner inside the switch housing to keep those contacts fresh. Then fully reinsert the pin. When the pin is out or not fully inserted, the brake magnets will continue to draw power and eventually drain the battery bank. The brakes can draw a lot of current; upwards of 3-amps or so for each magnet, depending on the size of the brakes. So the bottom line is never remove the pin except once a year for cleaning and testing.

While driving, you’ll want the alternator of the tow vehicle engine to keep charging the battery bank on the trailer. If you disconnect the battery, it won’t be able to accept that charge. I’m not sure why you need to disconnect the battery to activate the inverter while traveling. You should be able charge the battery while driving AND operate the inverter to power the AC side of the refrigerator. In this manner, nothing will affect the break-away switch. Even with the disconnect activated, the break-away switch should still be able to power the brakes in an emergency. Easy to test....activate the disconnect switch, spin the tires and pull the pin. You might need to have your tow wiring evaluated.

Besides using the inverter, you could also run the refrigerator to get it cold overnight, and turn the whole refrigerator off while driving. Without opening the door often, the contents will typically still stay cold enough as you drive. Once you stop, light it on propane, turn on the inverter, or plug into shore power. A couple different options to consider....

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