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05-27-2018, 03:59 PM
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#1
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2 Rivet Member
2017 27' International
Lewes
, Delaware
Join Date: Jun 2010
Posts: 46
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To brake or not to brake
I recently spoke with another airstream owner at a campground. I noticed that he had removed the breakaway pin from the small box for his trailer brakes. I asked him about that and he said he does that to lock the trailer brakes when parked. As I understand it, the emergency braking is electric and depends on the battery if the cable is not connected to the tow vehicle. If the trailer is parked and the pin is removed, wouldn't that drain the battery if the trailer is not connected to an electrical hookup?
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05-27-2018, 04:14 PM
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#2
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Rivet Master
Currently Looking...
Walnut Creek
, California
Join Date: May 2015
Posts: 3,952
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Yes - Not a good idea. The break away switch is for a disconnect excursion. Retain the system at full capability. It is not a parking brake. Use tire chocks to keep the rig from rolling. Pat
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05-27-2018, 04:22 PM
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#3
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Rivet Master
1974 27' Overlander
Baltimore
, Maryland
Join Date: Mar 2016
Posts: 1,042
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As I understand it, that's a good way to fry your brakes. My breakaway switch even came with a warning not to use it as a parking brake. That's what chocks are for.
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05-27-2018, 04:27 PM
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#4
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Retired.
Currently Looking...
.
, At Large
Join Date: Jun 2003
Posts: 21,276
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One of our "new" customers did this, unknown to anyone at the dealership. We replaced both AGM batteries, solar controller, and he will probably need new brake magnets, as well.
The story I got back through channels was "nobody told me I couldn't".
So, with that in mind:
ahem....
NEVER, ever, ever, never, in any manner, attempt to use the breakaway switch as a parking brake, ever, for any reason, ever. At best, you will drain the batteries. At worst, you will damage a lot of other expensive equipment, and possibly weaken other components to the point they may fail just when you need them most.
Most breakaway switches have a warning label admonishing users to not attempt to use the device as a parking brake. And they mean it.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
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05-27-2018, 06:42 PM
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#5
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4 Rivet Member
2017 27' International
Lake Havasu City
, Arizona
Join Date: Feb 2017
Posts: 310
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Terry, I can understand the batteries and brakes being damaged, but I'm curious about the solar controller. How was it damaged? What brand/model was it?
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05-27-2018, 06:51 PM
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#6
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Retired.
Currently Looking...
.
, At Large
Join Date: Jun 2003
Posts: 21,276
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Quote:
Originally Posted by Paprika
Terry, I can understand the batteries and brakes being damaged, but I'm curious about the solar controller. How was it damaged? What brand/model was it?
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It was apparently damaged when the person plugged his trailer in to 30 amp service, and left it that way for some time, and it didn't like the current going in the wrong direction. I saw one of the lugs had what looked like it had been overheated. Without knowing what the cause was at the time, because the customer was not very forthcoming with information, it was replaced.
__________________
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
Terry
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05-28-2018, 12:34 PM
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#7
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1 Rivet Member
2018 28' Flying Cloud
Ammon
, Idaho
Join Date: Apr 2018
Posts: 6
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My 2018 Flying Cloud manual says DO NOT remove the pin for more than a few seconds. Not complying with this will damage/destroy the brake magnets.
One thing I've learned in ten years of RV'ing is to learn new things, but always verify before taking action.
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05-28-2018, 12:37 PM
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#8
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Rivet Master
2014 20' Flying Cloud
Sag Harbor
, New York
Join Date: Jun 2015
Posts: 17,523
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More fertile ground for folks who don't read their owner's manuals, and thus over-think the "logical" solution IMO.
Pull pin and pay for new brake magnets and batteries maybe.
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05-28-2018, 12:51 PM
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#9
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Rivet Master
Currently Looking...
Walnut Creek
, California
Join Date: May 2015
Posts: 3,952
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Every other way, your creativity is needed and expected to survive in the RV world, but for this issue you are supposed to follow the manual to the letter. Now how is a person to know when and when not? Such an odd world. Pat
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05-28-2018, 01:26 PM
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#10
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3 Rivet Member
1998 34' Limited
Lawrenceville
, Georgia
Join Date: Jul 2008
Posts: 220
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For those who understand the concept of "electric brakes", this is an no-brainer. For the rest, there really should be a sticker on the tongue warning against this practice, because it certainly will fry the brakes, and possibly other things. In the absence of understanding how they work and the consequences of long-term engagement, there is an element of logic here. They ARE brakes, after all.
And... we do have warning tags on hair dryers cautioning us not to use them in the bathtub.
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05-28-2018, 01:50 PM
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#11
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4 Rivet Member
2022 27' Globetrotter
Asheville
, North Carolina
Join Date: Jan 2017
Posts: 396
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Ok. I’m dumb. Other than using up the batteries, what is different about keeping the magnetic brakes engaged than say running down the batteries by using the furnace till the batteries can no longer run the system. How can something else break?
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05-28-2018, 02:13 PM
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#12
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4 Rivet Member
Byron Center
, Michigan
Join Date: Aug 2017
Posts: 275
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Quote:
Originally Posted by AirstreamCSH
Ok. I’m dumb. Other than using up the batteries, what is different about keeping the magnetic brakes engaged than say running down the batteries by using the furnace till the batteries can no longer run the system. How can something else break?
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The easiest way to explain it is that the electric coils which when energized activate the brakes are not designed for 24/7 use. The coils are only designed for intermittent use while driving. If on full-time, they’ll build-up heat, which will damage the coils. Damaged coils will not allow the brakes to work correctly.
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05-28-2018, 02:22 PM
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#13
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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The motor in the furnace has a 100% duty cycle. Which means it is designed to run all of the time.
The electro magnets (brake coils) do not have a duty cycle that high. Maybe 40 %.
Enegizing the brake coils continuously for long periods of time will cause them to overheat and burn up. ie no brakes.
If you have a tandem axle trailer there are 4 brake coils which will consume power at a much greater rate when compared to the furnace motor.
It won't take long to drain the battery if the brake coils don't burn up first.
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05-28-2018, 03:24 PM
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#14
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Rivet Master
2002 30' Classic S/O
Fleming Island
, Florida
Join Date: Nov 2013
Posts: 4,667
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Another thing is the brake stopping power is derived from the wheel rotation. The magnets grab the hub face and rotate one shoe out to make contact with the drum. A linkage turns the force trying to rotate that shoe into force to push the other shoe out. Depending on the grade you are parked on there may not be enough brake force generated to hold the trailer in place.
Each magnet draws around 3 amps at 12 volts, or around 36 watts. If you want to know how much heat that is grab a lit 25 watt light bulb. The magnets are not designed to dissipate that much heat for very long.
As an aside, the furnace blower draws around 7 amps IIRC.
Al
__________________
“You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
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