Auto Reset Circuit Breakers

[brulaz]

Have been told that the electrical motors on Lippert Stab jacks should stop when the motor current rises causing the 12VDC auto resetting circuit breaker to pop (or you take your finger off the button). The breaker *should* protect the arms from kinking under heavy load. Unfortunately mine weren't working that way. The motors would stop when fully retracted up against the frame, but when extending the arms, it was possible to kink the arms first.

Think these circuit breakers are the lozenge shaped items I once saw deep under the trailer floor near the battery. etrailer sells them: http://www.etrailer.com/dept-pg-Accessories_and_Parts-pc-Circuit_Breaker.aspx
My trailer has about 4 or 5 of them down there IIRC.

Is this a general approach to motor control in RV's?

Just looked at my trailer's slide mechanism and can find no limit switches, so perhaps it works the same way? Unlike the stab jacks, the motor does stop at full extension and retraction. But I'm having problems with shear pin popping when retracting against the shell (and now a mangled drive shaft). The motor doesn't seem to stop soon enough.

What about the electric awning?

But I've also read on this board: "It is a thermal auto reset breaker. Keystone customer service told me that if it has tripped and reset 5 or 6 times it is time to replace it." Which doesn't fit with these circuit breakers being used as a routine motor switch. We've probably used our slide and electric stab jacks close to a hundred times so far. But maybe there are different types of circuit breaker. Is it a difference between "thermal" and "auto resetting" circuit breakers?

If these are being used to cut the juice to a motor, their current limit needs to be better matched to the mechanical system. The auto-recyling ones on the etrailer site range from 20A to 50A in 10A increments. Would it be reasonable to buy a few and try reducing the current cut-out value to my slide? (the stab jacks have already been fixed by strengthening the arms)

Has anybody done anything like this?

I would appreciate an education on these devices and their usage as they are totally new to me.

[daviddarwin]

It makes sense to make a great investment in your car's electrical system, such as a Bussman shortstop circuit breaker. It will prevent short circuits and current overloading in your fuses and the electrical system. Additionally, since you won't have to repair your fuses every time an electrical problem arises, you'll be able to save money.

[brulaz]

OK, my bad.

All these motors stop so fast; I was sure there was an auto-cutoff switch involved (I had been told earlier that it was the auto reset breaker).

But I just checked the stopped awning motor with my clamp-on ammeter, and it was still drawing 9A. So it was "stalled", not "off". Of course the current went away when I released the manual button.

It's harder to separate the wires for the Stab Jacks to measure current, but Lippert Tech support told me the reset breaker is NOT used to stop the motors. Sometime I may double-check that, same for the Slide. I expect them to "stall" just like the awning motor.

This is consistent with what most of you are saying. The motors quickly stall (stop, but with current still running through them) and are not auto-switched off when the limits are reached.

Some motors like the tongue jack and some slide motors may be exceptions; these have an auto-clutch mechanism that you can hear operating.

Thanks for all your help. But it still leaves me with an over-energetic slide motor ripping up its drive shaft coupling. That's another issue though.

[brulaz]

ktmrfs wrote:

...
On my slides, once I hit the outer limit I hear the clutch start to ratchet. That's enough for me to stop.

On the in I hear the slides stop, very noticeable, motor stalls. However, I've never held my switch long enough to see what happens beyond that.

Thanks, that's useful.

Except for the tongue jack, none of my motors have a clutch, that I can hear anyway.

Maybe I shouldn't be waiting for the motors to halt before releasing the button. Perhaps by doing so those auto-reset breakers are being used when they shouldn't be. But I do want the slide, and awning, and stab jacks to be fully retracted when traveling.

Guess for now I'll just pay closer attention to what's happening when we next close up for travel.

[time2roll]

When you release it just right the motor will stall at end of travel under no power.

[ktmrfs]

brulaz wrote:

ktmrfs wrote:

brulaz wrote:

ktmrfs wrote:
IMHO toss any autoreset breakers in the trailer and replace them with the same footprint "push to reset" or remove and reinsert to reset type. they cost very little more and AFAIK for every autoreset, a manual reset version is available. yes, a little more inconvienent but WAY safer.
...

Manually reset the breaker after every opening and closing of the slide?

Some trailers have 4 slides and 2 electric stab jacks.

breakers should NOT ever trip when using the slide. I've opened/closed my slides hundreds of times and NEVER had a breaker trip.

OK. So back to my original question.

Everybody seems to agree that that these breakers are not used to control the motors.

So what stops the slide/stab jack motor if you continue to hold the button down when the slide reaches it min/max extent? The motors do cut-off automatically.

:h

I've found the wiring diagram for the Lippert electronic wireless remote control receiver in my trailer, and it looks like the manual controls are wired in parallel to the receiver. And these trailers are sold without that wireless receiver anyway, so I'm thinking that centralized electronic motor control via the receiver is not the answer.

Over limit control built-in to the motors? My tongue jack has a mechanical clutch that gives way, but it doesn't turn off the motor.

And I just found the installation instructions for the Lippert electric stabilization jacks. It says: "The supplied 6A reset breaker must be wired in line to rear stabilizer jack" but doesn't say anything about whether it's used routinely or only exceptionally.

On my slides, once I hit the outer limit I hear the clutch start to ratchet. That's enough for me to stop.

On the in I hear the slides stop, very noticeable, motor stalls. However, I've never held my switch long enough to see what happens beyond that.

[brulaz]

MEXICOWANDERER wrote:
Limit switches are the way to go. Use them to interrupt a coil signal on a single power relay. Most limit switches are adjustable.

I've looked and cannot find any limit switches on the slide or stab jacks. Can sort of see why: these mechanisms can be exposed to the elements, mud, salt and grime. Maintaining limit switches could be pretty tough under those conditions.

[brulaz]

ktmrfs wrote:

brulaz wrote:

ktmrfs wrote:
IMHO toss any autoreset breakers in the trailer and replace them with the same footprint "push to reset" or remove and reinsert to reset type. they cost very little more and AFAIK for every autoreset, a manual reset version is available. yes, a little more inconvienent but WAY safer.
...

Manually reset the breaker after every opening and closing of the slide?

Some trailers have 4 slides and 2 electric stab jacks.

breakers should NOT ever trip when using the slide. I've opened/closed my slides hundreds of times and NEVER had a breaker trip.

OK. So back to my original question.

Everybody seems to agree that that these breakers are not used to control the motors.

So what stops the slide/stab jack motor if you continue to hold the button down when the slide reaches it min/max extent? The motors do cut-off automatically.

:h

I've found the wiring diagram for the Lippert electronic wireless remote control receiver in my trailer, and it looks like the manual controls are wired in parallel to the receiver. And these trailers are sold without that wireless receiver anyway, so I'm thinking that centralized electronic motor control via the receiver is not the answer.

Over limit control built-in to the motors? My tongue jack has a mechanical clutch that gives way, but it doesn't turn off the motor.

And I just found the installation instructions for the Lippert electric stabilization jacks. It says: "The supplied 6A reset breaker must be wired in line to rear stabilizer jack" but doesn't say anything about whether it's used routinely or only exceptionally.

[ktmrfs]

brulaz wrote:

ktmrfs wrote:
IMHO toss any autoreset breakers in the trailer and replace them with the same footprint "push to reset" or remove and reinsert to reset type. they cost very little more and AFAIK for every autoreset, a manual reset version is available. yes, a little more inconvienent but WAY safer.
...

Manually reset the breaker after every opening and closing of the slide?

Some trailers have 4 slides and 2 electric stab jacks.

breakers should NOT ever trip when using the slide. I've opened/closed my slides hundreds of times and NEVER had a breaker trip.

[Chris_Bryant]

I would say that the motors are being stopped by the electronics, not the breaker. Lippert has a bunch of systems- but I believe all of them are fairly intelligent.

[MEXICOWANDERER]

Limit switches are the way to go. Use them to interrupt a coil signal on a single power relay. Most limit switches are adjustable.

[brulaz]

Chris Bryant wrote:
Those breakers are not meant to provide motor control- most rigs use electronics to limit the current to slide rooms- jacks are a different issue- you are expected to look and not run them to the limits. If they will break if run to the limit, they should have torque limiting clutches in them.
Using breakers as motor control means the OEM cut corners- bad design.

OK, so it could be electronics and/or torque limiting clutches in the motors instead of the breakers.

The trailer does have a Lippert electronic box that can provide power to these motors. I always assumed it was just a receiving unit with electronic switches controlled by the remote. But maybe the manual switches go to it also, rather than just run in parallel. And possibly the auto motor current cut-off is happening there?

The slide, stab jacks and awning motors can all be controlled by the remote control via this box (and lights). It seems to be an all Lippert system (ouch) as I believe even the Al-Ko RBW slide mechanism is owned by Lippert now.

As for the stab jacks, I've always retracted them until the motor cuts off automatically as it's very difficult to gauge just when to release the button, just like the slide. There's a time delay, if you don't get it fully closed you have to press the button again and again. I always felt that this repeated jerking was harder on the drive train and motor than just letting it go until it automatically cut-off. No?

[Chris_Bryant]

Those breakers are not meant to provide motor control- most rigs use electronics to limit the current to slide rooms- jacks are a different issue- you are expected to look and not run them to the limits. If they will break if run to the limit, they should have torque limiting clutches in them.
Using breakers as motor control means the OEM cut corners- bad design.

[brulaz]

ktmrfs wrote:
IMHO toss any autoreset breakers in the trailer and replace them with the same footprint "push to reset" or remove and reinsert to reset type. they cost very little more and AFAIK for every autoreset, a manual reset version is available. yes, a little more inconvienent but WAY safer.
...

Manually reset the breaker after every opening and closing of the slide?

Some trailers have 4 slides and 2 electric stab jacks.

[brulaz]

ScottG wrote:
I think your expecting the breaker to trip under normal conditions - like extending or retracting the slides. THey aren't meant to be electrical stops under those conditions. They are meant to trip during an abnormal overload.

So there's something else that shuts off the slide and stab jack motors when when they stall?

Because the motors definitely do shut off when fully retracted, even if you still have your finger pressed on the open/close button. It's just that, for the slide, the motor doesn't shut off soon enough and ends up popping the shear bolt.

I'll look some more, but as far as I can see there is nothng else between the motors and the battery: just the open/close switch and breaker.

Maybe the motors have built-in cut-offs? If so, there's nothing I can do about the current setting.