Electric Slides Motor
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 brea...
Forum Discussion
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
