Trailer Brakes - Opps! - ????

[Adony]

Just returned from a trip where during the 3 days of camping, the power center in the trailer was constantly running (fan).. Until the morning we departed, I had no idea what was causing it but when we hooked up, the brakes were locked... investigation found that the breakaway switch had been pulled the entire 3 days.. Must have happened during the un-hooking or someone tripped it it by accident (caught cable on shoe).. Once I reset the breakaway switch, I had no brakes for about 15 minutes but gradually they came back to normal (cooled down magnets?) for the trip home. I did have to readjust the controller when they started to work again.. Anything special that I should do or inspect after this event?? I did inspected for burnt wiring and it was all Ok...Is there any kind of warning light I can install to see if this happens again??

[Herk7769]

The system breakaway switch ports battery power directly to the camper's brakes by energizing the magnets when the plastic "isolator" is removed completing the circuit. A 12 volt light bulb in any part of the wire in or out of the breakaway switch would light if the breakaway was pulled.

There are 12 VDC LED flasher circuits that can be wired in as well.
LED Flasher Solid State 12 Volt DC - Automotive LED Lights - Other LED Lights - Other LED Lights - LEDLight

[SpringerPop]

Originally Posted by herk7769

A 12 volt light bulb in any part of the wire in or out of the breakaway switch would light if the breakaway was pulled.

There are 12 VDC LED flasher circuits that can be wired in as well.
LED Flasher Solid State 12 Volt DC - Automotive LED Lights - Other LED Lights - Other LED Lights - LEDLight

What a GOOD idea! I would only put the indicator on the "cold" side of the switch, however.

I suspect the test light would also illuminate (or flash) anytime the brake controller was outputting (especially near maximum), but that's no inconvenience.

It would be especially useful if mounted where it could be seen in the driver's rear-view-mirror to assure brakes have power when towing. Mounted on the front of the trailer, it would be hard to miss if on when parked, too.

To stay "legal" (due to the placement), only an amber LED or bulb should be used.

It's going onto the "to do" list!

Pop

[Herk7769]

Originally Posted by SpringerPop

I suspect the test light would also illuminate (or flash) anytime the brake controller was outputting (especially near maximum), but that's no inconvenience.

It would not since the LED is a diode and (assuming you did put it on the cold side) the power be on the wrong leg of the diode. On the hot side it still would not work without a ground.

If you used a regular light bulb, it would still need to find a ground to work since in the breakaway circuit there would be no continuity without the breakaway isolator pulled.

[SpringerPop]

Ahh, your proposal was to just put the LED ACROSS the switch. That will work!

EDIT......

Err, hold on! A light across the switch will light only if the breakaway is NOT pulled.

I will run the ground wire and just monitor the magnet voltage.

When parked, or rolling down the highway with no brakes applied, that light/LED will be (should be) off.

Pop

[Herk7769]

Originally Posted by SpringerPop

Ahh, your proposal was to just put the LED ACROSS the switch. That will work!

EDIT......

Err, hold on! A light across the switch will light only if the breakaway is NOT pulled.

I will run the ground wire and just monitor the magnet voltage.

Pop

No Pop, in series. Just locate the "light assembly" in series on the hot side (battery to switch) or cold side (switch to magnet to ground). The light assembly has a red and black wire to indicate polarity for the LED.

[SpringerPop]

Originally Posted by herk7769

No Pop, in series. Just locate the "light assembly" in series on the hot side (battery to switch) or cold side (switch to magnet to ground). The light assembly has a red and black wire to indicate polarity for the LED.

That would necessitate the battery's magnet current passing through the bulb to activate the brakes in a true emergency situation, wouldn't it?

The brakes wouldn't be activated at all, but the light would sure light!

Am I missing something here?

Pop

[Broadway Joe]

SpringerPop is correct, the light should be hooked up with positive on the brake wire after the breakaway switch, negative to chassis ground.

[fonzie]

Herk is correct: If an LED is used, the right size (need to know the total current the brake magnets use when energized)then it needs to be in series with the break away switch circuit. If a light bulb is used then it needs te be in parallel with the circuit to the brake magnets.

[Herk7769]

Pop is correct.

The LED or bulb would blow and you would lose brakes.

The fix is what Joe said.

[SpringerPop]

Originally Posted by joenic53

... the light should be hooked up with positive on the brake wire after the breakaway switch, negative to chassis ground.

That's the way I see it.

A refinement might be a time delay before the light comes on so that it doesn't illuminate during short durations of brake application, to avoid a distraction in the rear-view-mirror.

Another possibility might be a self-flashing LED (again, amber, not red).

Pop

[Herk7769]

A high current diode could be placed after the light reverse biased to the brakes. That way the light would come on only when power was being supplied through the break away switch.

Power coming up from the brakes would hit the diode and stop.

40EPS08 Type 2 Pin Terminals Rectifier Diode 40A 800V | eBay

[SpringerPop]

That would sure work, Herk, but you have then added potential failure points (only if the hitch actually breaks and the system is needed), including the diode and its connections. Also, you then don't achieve the on-road "applied brake" monitoring function.

Should the system actually be needed and not operate, the accident re-constructionists and lawyers would have a field day, I'm afraid!

In the same vein, is there not a "breakaway switch" periodic test requirement of some sort? The switch itself could fail, the cable could become brittle enough to not be able to pull the pin out, etc, etc, etc.......

My switch is looking like it might need to be replaced (just old), and the pin was really difficult to pull out when I ran a functional test last month. The pin looked like it was designed to NOT be able to be pulled.

Pop

[Herk7769]

PA requires an annual inspection and a function test of the break away is required.

[SpringerPop]

I think I'm going to just replace mine, then.

Thanks, Herk!

Pop

[Herk7769]

On second thought; not going to mess with mine.

[thebrakeman]

This was just a fluke accident. Not worth a lighting mod.
I'd rather find out how the pin got pulled so easily that nobody notice. Mine is VERY hard to pull. If I were to trip on that thing hard enough to actually pull it, I would probably have landed on my face, too.
Pull that thing intentionally, and see if something is messed up in there to make it pull so easy.

[stevem]

so is there a risk of damaging brake/wiring components if the breakaway is "broken away" ie applying the brakes for an extended period of time?

never happened to me yet, but it could of course

[Hob]

Is there such a thing as OVER-engineering something?

[Herk7769]

Originally Posted by stevem

so is there a risk of damaging brake/wiring components if the breakaway is "broken away" ie applying the brakes for an extended period of time?

never happened to me yet, but it could of course

Yes, the magnets draw a lot of current as they are sized to grab a wheel spinning at 70 mph or so and hang on while the pads are jammed into the drum.

That current is converted to heat and will eventually burn out the coil.

Folks have asked about using the breakaway as a chock, but that will not work because the wheel must be turning in a forward direction to engage the pads.