Electric Slides Motor

[organcory97]

Need help I was opening up the slides this morning and all of a sudden it just stopped. No noise or anything. I checked the breakers and fuses at the inverter but all looked good. I looked at the breakers in teh house and all was good as well. All the other power is on in the camper. Where can i look to find another fuse or motor. The awning isnt opening either. This is a Dutchmen Classic 315BHds 2011 model.

[organcory97]

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.

[ScottG]

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.

[wa8yxm]

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.

[IB853347201]

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.

[ScottG]

wa8yxm wrote:
If the slides are power gear there are several interlocks and other things that can stop them.. NOTE not all interlocks are present on all systems and then there is the controller....

Ignition interlock, Some want it on. some off
Parking break interlock Some insist on parking brake set
Transmission interlock, only in park
Turn key interlock (mine failed, it's a basic switch)

These can become... iffy

Next is the switch.. Sometimes switches get dirty and won't switch and/or have to be presseed "Just so"

Now the controller
Power gear controllers sense current. If anything causes the current to climb above the set point they shut down.

LOW BATTERY VOLTAGE on a motor causes higher current.
Binding, some obstruction. Higher current.

End of travel.. Well that's a given stalling the motor = Higher current.

I know one would think that as voltage goes down so would current but Motors are variable inductors (Inductance varies with speed) and because of this the slower they go (lower voltage) the higher the current.

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

[Lwiddis]

Waiting several hours and it works indicates overheating to me.

[wa8yxm]

If the slides are power gear there are several interlocks and other things that can stop them.. NOTE not all interlocks are present on all systems and then there is the controller....

Ignition interlock, Some want it on. some off
Parking break interlock Some insist on parking brake set
Transmission interlock, only in park
Turn key interlock (mine failed, it's a basic switch)

These can become... iffy

Next is the switch.. Sometimes switches get dirty and won't switch and/or have to be presseed "Just so"

Now the controller
Power gear controllers sense current. If anything causes the current to climb above the set point they shut down.

LOW BATTERY VOLTAGE on a motor causes higher current.
Binding, some obstruction. Higher current.

End of travel.. Well that's a given stalling the motor = Higher current.

I know one would think that as voltage goes down so would current but Motors are variable inductors (Inductance varies with speed) and because of this the slower they go (lower voltage) the higher the current.

[ScottG]

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

Good luck,
Scott

[organcory97]

So i went back out there after letting it sit for several hours. Switched off all the breakers and back on and now all seems well. Not sure what happened there but oh well.

[2oldman]

My slides have a thermal cutout that will stop everything if they overheat. They're in the basement. I just wait a sec and then things work again.

Breakers are for 120v, not 12.

[BFL13]

Often the slides (and awning?) are powered directly from the battery, not from the DC fuse panel. Might be two positive red wires on the battery, one for the DC fuse panel (and converter) and the other for that.

The positive wire for the slides should have a fuse on it near the battery or maybe a DC circuit breaker that can be reset.