Motor Problem; won't work under load

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Did I read that the voltage drop was only occurring while the motor/drive was loaded with the boat weight?

So no boat, the motor runs fine, very little voltage drop.

But with boat, the drive/gear reduction binds, the motor stalls, the current increases dramatically, and the voltage drop is experienced.

The motor stall/amperage draw causes the voltage drop. Not the voltage drop causes the motor stall and amp increase....

That is just my guess.
 
crossman said:
Did I read that the voltage drop was only occurring while the motor/drive was loaded with the boat weight?

So no boat, the motor runs fine, very little voltage drop.

But with boat, the drive/gear reduction binds, the motor stalls, the current increases dramatically, and the voltage drop is experienced.

The motor stall/amperage draw causes the voltage drop. Not the voltage drop causes the motor stall and amp increase....

That is just my guess.
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crossman said:
Unfortunately, you and I are not there to take that reading. All I can do is hazard a guess from the given, and I feel my guess is the most likely scenario.
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Well, without treating brantmacga like a customer, let's assume we have been given good data. Let's also consider your hypothesis concerning the no-load scenario.

If the motor has rated amps of 13.?, what no-load scenario causes the 2-3 volt drop in the 50 foot of #12? I'll answer that: full load current. Will the un-loaded motor draw full current? Maybe the hoist mechanism adds enough load to cause the motor to draw rated current?

What about one additional scenario where the boat load is causing the hoist mechanism to bind (bad pully, cable, etc)?
 
mivey said:
If the motor has rated amps of 13.?, what no-load scenario causes the 2-3 volt drop in the 50 foot of #12? I'll answer that: full load current. Will the un-loaded motor draw full current? Maybe the hoist mechanism adds enough load to cause the motor to draw rated current?
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My take is that trying to diagnose the issue based on limited voltage drop information and assuming it is an electrical problem is less likely than it being a mechanical issue with the lift.

Hopefully we get more info back from the OP so we can see what the actual problem was.
 
crossman said:
That's what I had in mind in post 21
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I thought you were focusing on the gearbox. I am giving the designers the benefit of the doubt that they have the correct gearbox and motor, but it would not be the first time a manufacturer sent the wrong parts.

Could be a bad gearbox, but I would think there is a chance the installer botched up the cabeling, pulleys, etc. If we can blame the electrician, why not the hoist installer?

The amp readings with and without the boat would be nice.
 
20 volt drop is to much in my opinion even if the motor stalls out..I would guess that the boat lift is not rated for the weight of the boat..even changing the pulleys which is only few dollars is going to take the lift out of specs and void the warrenty..If the centrifugal switch was not working it would not start at all..My guess if the lift is rated correctly we have an assembly problem something is binding..I would also think there is a feed problem as well..I would start by inspecting the lift for mechanical correctness..even if it came preassembled does not make it correct or eliminate damage in moving or installation..My bet is couple of issue at hand..
 
crossman said:
My take is that trying to diagnose the issue based on limited voltage drop information and assuming it is an electrical problem is less likely than it being a mechanical issue with the lift.

Hopefully we get more info back from the OP so we can see what the actual problem was.
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True enough. Done got my curiosity up.
 
cschmid said:
20 volt drop is to much in my opinion even if the motor stalls out..I would guess that the boat lift is not rated for the weight of the boat..even changing the pulleys which is only few dollars is going to take the lift out of specs and void the warrenty..If the centrifugal switch was not working it would not start at all..My guess if the lift is rated correctly we have an assembly problem something is binding..I would also think there is a feed problem as well..I would start by inspecting the lift for mechanical correctness..even if it came preassembled does not make it correct or eliminate damage in moving or installation..My bet is couple of issue at hand..
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If you had 5x full load, a 20 volt drop might be close to what you get.
 
mivey said:
Could be a bad gearbox, but I would think there is a chance the installer botched up the cabeling, pulleys, etc. If we can blame the electrician, why not the hoist installer?
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I am with you. The binding could be anywhere from the gear box/drive to the pulleys for the cables, anything in the entire install.

I didn't catch whether this was a brand new hoist or a used one.

Anyway, just as in industrial maintenance -- boss, this isn't an electrical problem, it is a mechanical problem!:D
 
quogueelectric said:
Use a superhawg to drive the gear you will know if it has mechanical problems right away. My money is on the superhawg not even hicupping.
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If I'm correct that the problem is electrical and not mechanical, as the majority seems to feel, the Hawg would have the same problem if it's powered from the same circuit.

Brant, another question: at what point is the change from two to one ungrounded conductor? I'm thinking of substitution as the next troubleshooting step, after my last question.
 
LarryFine said:
If I'm correct that the problem is electrical and not mechanical, as the majority seems to feel, the Hawg would have the same problem if it's powered from the same circuit.

Brant, another question: at what point is the change from two to one ungrounded conductor? I'm thinking of substitution as the next troubleshooting step, after my last question.
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Without the amperage I am guessing the problem to be mechanical The gear reduction and the motor torque are not enough to lift 2 tons is what I am officially going with. The motor is going into locked rotor currents causing the voltage drop but we still cant get the amperage until the op gives it to us we are best guessing.:wink::smile:
 
mivey said:
If you had 5x full load, a 20 volt drop might be close to what you get.
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I can buy into the five x's arena but if the motor is unprotected then it would get really hot and after couple of tries you would start to smell the windings as they cook..I believe we have a double fold problem here..I believe there is a mechanical issue as well as a electrical problem..I believe you need to put a draw on the circuit and test every point until you find the start of the voltage drop..All you would need to cause a voltage drop is hook up a couple of milk house heaters and slap them on 2000 watts that should cause a drop..but not not a five x's drop which would be about 58 amps if I am correct..any other ideas on how to cause a large drop at an affordable cost..
 
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