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ScottG

Bothell Wa.

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Posted: 01/19/20 04:49pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

ScottG wrote:



Per the OP's first post, he has a travel trailer so there are none of the interlocks customary to a MH. Further, it has simple rack and pinion type slides so no controller.

Lastly, I'm sorry but some of your assumptions about DC motor current are not accurate.
IE, "lowering the voltage raises the amp draw of a motor". V=I*R. The "R" or resistance of the motor is set. The watts of the motor (P=I*V) is determined by the voltage and amps. It will only deliver the specified watts if the voltage and amps are the ones specified. So if you say a motor has 100 watts for example.....you can't say if I connect half the voltage to it, it will automatically double the amps. Doesn't work like that. The actual voltage and amps given to the motor determined by the RESISTANCE of the motor will determin your power (P=I*V) or ((V^2/R)=P) or (I^2*R=P) The first of the formulas are first and formost determinded by V=I*R. It rules it....it owns it. The other two formulas above have R in them.....these you can use. Take the second one ((V^2/R)=P) for example. We just went from 12 volts to 8 volts. Lets say for the sake of the argument.....the ohms (resistance) of your motor is 1 ohm. (12^2)/1=144 watts. Lower it to 8 volts.... (8^2)/1= 64 watts.

Source https://www.physicsforums.com/threads/current-draw-of-a-motor-under-different-situations.585336/

Cheers,
Scott


Well then disregard the interlock info. There IS a controller for the Rack and Pinion Slide. It may be hard to find (I had to use an electronic bloodhound) but there IS a controller of some kind the full motor current would melt the switch in the wall.

That the motor used by Power Gear increases current as speed drops is a proven fact..

Having visited you link I understand your confusion however. But I also studied motors and there are multiple types of motors.

For example one motor tries to run at a constant speed if you slow it down it will Draw more WATTS (normally this means more current) but try to maintain speed.

Another type of motor.. Well this one is used in electric lawn moweres and Black and Decker in the owner's manual yammered about a "Sensor" the increased motor power to handle taller grass.. Kind of made me laugh (Series wound motor) As the motor slows it REALLY draws more current (more watts too) so as to keep turning...

My little electric marched through knee high grass on a neighbor's yard his gas powered unit would not even touch..

I once worked in a feed mill.. The grinder no load full voltage abou 50 amps.. Feed it corn and it would easily hit 300-400 amps as the load increased and the mill slowed a bit.. I even have been trained as to why but alas. Have not refreshed that memory in many years.


As a retired EE from the aviation industry, I can assure you that *I* am not confused. It is you that is confusing AC and DC motors - 2 very different animals. The motors you wrote of have no bearing on this application.
The OP's slide has very simple DC motors. It has no circuit to increase power when needed and most of all, it does not draw more current when the voltage is low.


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organcory97

West Columbia

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Posted: 01/20/20 06:43am Link  |  Quote  |  Print  |  Notify Moderator

IB853347201 wrote:

The issue appears to be a 12 volt issue. I would guess that the trailer house battery is either dead or low on water, or both. Converter alone does not have enough output to power slides without reserve from battery.


It is very possible. The battery is most likely dead. It was also a cold morning.

organcory97

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Posted: 01/20/20 06:44am Link  |  Quote  |  Print  |  Notify Moderator

ScottG wrote:

The 120V breakers had nothing to do with it. You have a 12V auto-resetting breaker that is tripping for what ever reason and your problem is going to return.
I would find the 12V breaker and replace it (they're cheap). Otherwise you are going to get stuck someplace with the slide out.

The part will look something like these and you will need to get the amp rating off it: ***Link Removed***

Good luck,
Scott


Would there only be one of these auto resetting breakers?

ScottG

Bothell Wa.

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Posted: 01/20/20 08:53am Link  |  Quote  |  Print  |  Notify Moderator

organcory97 wrote:

ScottG wrote:

The 120V breakers had nothing to do with it. You have a 12V auto-resetting breaker that is tripping for what ever reason and your problem is going to return.
I would find the 12V breaker and replace it (they're cheap). Otherwise you are going to get stuck someplace with the slide out.

The part will look something like these and you will need to get the amp rating off it: ***Link Removed***

Good luck,
Scott


Would there only be one of these auto resetting breakers?


Most often yes, they have just one but on rare occasions someone will install two in parallel.
I had one where they mounted the breaker under the trailer, next to the motor. Some others were mounted up near the front just behind the batterys. There are breakers designed to be installed in wet locations but they never seem to use them. Instead they use cheaper breakers designed to be installed inside. Those really dont do very well out in the weather and if they actually get road spray, they corrode.

Scott

BFL13

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Posted: 01/20/20 11:41am Link  |  Quote  |  Print  |  Notify Moderator

IB853347201 wrote:

The issue appears to be a 12 volt issue. I would guess that the trailer house battery is either dead or low on water, or both. Converter alone does not have enough output to power slides without reserve from battery.


Parallax 7355 converter on the 5er we had with its 14ft slide had no trouble running the slide in and out with no battery at all. Just have to join the two wires that go on the battery positive post (vise grip pliers eg) so there is a path from converter to slide motor.

Lippert specified a 30a fuse for the slide, and Trimetric showed it pulled about 25 amps at most for the hard part bringing it back up over the hump at the edge of the main floor. Was about 15 amps on the straight and level part.


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organcory97

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Posted: 01/20/20 04:23pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

IB853347201 wrote:

The issue appears to be a 12 volt issue. I would guess that the trailer house battery is either dead or low on water, or both. Converter alone does not have enough output to power slides without reserve from battery.


Parallax 7355 converter on the 5er we had with its 14ft slide had no trouble running the slide in and out with no battery at all. Just have to join the two wires that go on the battery positive post (vise grip pliers eg) so there is a path from converter to slide motor.

Lippert specified a 30a fuse for the slide, and Trimetric showed it pulled about 25 amps at most for the hard part bringing it back up over the hump at the edge of the main floor. Was about 15 amps on the straight and level part.


I have a couple pictures but not sure how to post them on here to show you.

organcory97

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Posted: 01/20/20 04:52pm Link  |  Quote  |  Print  |  Notify Moderator

organcory97 wrote:

BFL13 wrote:

IB853347201 wrote:

The issue appears to be a 12 volt issue. I would guess that the trailer house battery is either dead or low on water, or both. Converter alone does not have enough output to power slides without reserve from battery.


Parallax 7355 converter on the 5er we had with its 14ft slide had no trouble running the slide in and out with no battery at all. Just have to join the two wires that go on the battery positive post (vise grip pliers eg) so there is a path from converter to slide motor.

Lippert specified a 30a fuse for the slide, and Trimetric showed it pulled about 25 amps at most for the hard part bringing it back up over the hump at the edge of the main floor. Was about 15 amps on the straight and level part.


I have a couple pictures but not sure how to post them on here to show you.


BFL13

Victoria, BC

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Posted: 01/20/20 04:55pm Link  |  Quote  |  Print  |  Notify Moderator

http://photoposting.is-great.net/?i=2

organcory97

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Posted: 01/20/20 05:18pm Link  |  Quote  |  Print  |  Notify Moderator

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organcory97

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Posted: 01/20/20 05:55pm Link  |  Quote  |  Print  |  Notify Moderator

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