I had posted last night regarding a boat lift that i was going to take a look at today.1/2hp single phase motor SF1.15 wired at 120V. Nameplate is 8.5A, obviousley there is a gear reduction unit attached to it. Lowering the boat I get a reading of 8.2A on my meter, no problem the boat lowers about 40" and is in the water. Lifting is attempted, amperage is at 14 to start and remains fairly constant for about 30", at this point the load starts increasing progressively 15,17,20 etc. all the way up to 30 and the motor simply stalls no trip on the 20A CB.I notice that the steel cable at this point does not look like it is wrapping around the drum in a even manner(crossing over and laying atop the cable not next to it).Would the way the cable wraps on the drum cause an excessive strain on the motor? Also, with the proper gear reduction for the weight being lifted isn't the 14A load that is occurring on most of the lift already quite high?Owner states that in the 4 years he's owned it it has never worked what he would say was right(used unit with no manual or lift rating).I checked VD and found it to be running at about 112V while it was lifting the first 30" or so. Owner had a portable generator that he set about 120' from the lift and used a #10 cord, the motor still pegged at 30A and simply stalled. Any thoughts? Thanks.
excessive amperage on motor
- Thread starter nizak
- Start date
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texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Be aware that the ratio is is changing as the cable winds up. It is critical that the correct diameter cable is used as it has a great deal of influence on the overall ratio. I mentioned this in my post to you on the other thread. Also many of these have electric brakes on the back end of the motor that go bad in the hostile marine evironment and cause a lot of drag. Is this a 2 or 4 motor lift or a single davit?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
How blaming the gear reduction unit instead of the motor? Maybe the lift is binding due to an uneven lift. A properly operating drum should not have the cable overlapping.
What happens when the lift is operated without the boat on it?
What happens when the lift is operated without the boat on it?
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Jim has a point about the posibilty of the gear red. unit being bad. Not as common in my experience though. Another obvious thing that I failed to mention-is the lift rated for the weight of the boat? We used to do hundreds of these things years ago. In fact, years ago we were brought in to a sad, fatal electrocution of a 12 year old child on one of these. There are a lot of electrical and mechanical safety issues with these.
It's a single motor lift. Motor and gear reducer had just been rebuilt, the whole unit was upended in a storm last fall and tipped over submerging the motor and gear box for a few days.My thought was that maybe the structure had gotten distorted when it went over, the owner tells me that it was not damaged.
GUNNING
Senior Member
- Location
- Gainesville, Florida
My first take is it is a mechanical problem since the motor was within limits , be it high, on start up.
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
Is it not possible to call the manufacturer of the boat lift and ask them what the designed weight capacity is?
kwired
Electron manager
- Location
- NE Nebraska
A few things come to mind. First the thing is drawing heavy when lowering the boat. That tells me there is either motor problem or gearbox problem. The weight of the boat should help this motor to a certain degree and it will draw same or even a little less than with no load. Is it a capacitor motor? Likely so. Are the capacitors good? Do starting capacitors get switched out when motor reaches speed? Is motor connected properly? There is likely a reversing switch, mistakes can be made that may still allow it to run. Dual voltage motor running on low voltage places two segments of winding parallel to each other. If one winding is open the other one will still try to do all the work.
Have you run it with no load?
Have you run it with no load?
GUNNING
Senior Member
- Location
- Gainesville, Florida
Is there a missing counter weight or is it rigged wrong?
Ive never had any experience with boat winches but it does sound like it is binding or fighting itself. Gear box sounds like a good culprit.
Ive never had any experience with boat winches but it does sound like it is binding or fighting itself. Gear box sounds like a good culprit.
kwired
Electron manager
- Location
- NE Nebraska
It is likely just a worm gear drive and drum to wrap cable on like many other cable lifting applications. Low speed high torque.
Which reminds me another question for OP. You said this was rebuilt after being damaged, is it original motor and gearbox? If either was replaced and you have different speed motor or different ratio gearbox that will be a problem, different size cable drum will also be a problem.
Owner has no knowledge of the hoist manufacturer or of the lifting capacity. Bought as a used unit 5 years ago, says it "never seems to have been right". I am going to leave it up to him to figure out, I suggested calling a local marina and having someone come over that is familiar with this type of set up. Looking down the shoreline I could probably see 50 lifts, someone around there must have more knowledge about them than I do. Thanks all.
ceb58
Senior Member
- Location
- Raeford, NC
Sounds like he got what he paid for.
He got a good deal on it. Now, how deep of a hole is he going to dig in his attempt to make it right.
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