12 volt motor help, please!!! 2

[mmccrory]

Ok I am new here, but I have come to the experts to find the answers I need. I am planning on using a 1.2 hp geared 12 volt elec motor. It turns at 40 rpm and has 836 in.-lbs of torque. which is roughly 70 ft-lbs of torque. it uses 33amps.(not sure about if this is under a load or if it even matters)

I am using the motor as a drive motor witch will use belts and idler pulleys. there will be almost 200 feet of flat belt being used. the belt will be made of an elastic urethane, having a cross sectional measurement of 1/16" thick x 1/2" tall.

so here is my question, will the motor be big enough to do what i am wanting? Will it be ok to use continuously(24-48hrs)? And how fast will it draw down a 12 volt battery.

any help would be greatly appreciated. below is a link to the type of motor that i am possibly think about using.

 

[MikeHalloran]

What are you hoping to drive?


Mike Halloran
Pembroke Pines, FL, USA

 

[mmccrory]

i may have not worded that right. it will be the only motor that runs the entire belt assemply.

 

[MikeHalloran]

So, what does the entire belt assembly do?

Mike Halloran
Pembroke Pines, FL, USA

 

[Skogsgurra]

Mike (and anyone involved) needs to know what work the belt is supposed to do. You are not running it just for fun? Are you?

So, if you tell us what load the belt carries, the inclination, length of belt (you say 200 ft, does that mean a 100 ft conveyor?) and the linear speed of the belt, we (or you) can calculate the work and from there, we (or you) can decide if the motor is OK for this job.

Anyhow, with full load amperage 33 A, you will run a standard 12 V lead battery down in a couple of hours.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[Brad1979]

Something isn't adding up with those numbers. 40 RPM and 836 in-lbs of torque is about .53 hp. Not 1.2 hp. And to draw 33 A at 12 V the gearmotor would have to be between 95-100% efficient. Very unlikely. With a gearmotor like that, I'm guessing you'll draw closer to 50 A at rated speed/torque.

 

[FreddyZ]

"TruckStar Tarp Gear Motor — For 5-Bolt Mounts, Model# 5541095" implies intermittent short run duty cycle, not 48 hrs continuous duty at load. Perhaps you can have the vendor read a label for you and/or contact the manufacturer directly for application- specific info like the duty cycle it can tolerate at various loads.

That motor appears to be a worm drive, which provides high output torque at slow speed, but be aware that these may or may not backdrive [cause/allow the motor to spin if a load is left on the output shaft].

Again, a clue what your end function is would help. Speeds involved, loads, torque actually required.

 

[mmccrory]

ok maybe this will help clear the air. I am a duck hunter at heart and i am trying to make a swimming decoy system that will pull decoys in the water. kind of like something in the link below but on a much larger scale. but this may give you more of an idea of what the project is like.

so as far as the inclination, there should be none because it will be on a horizontal plane.

length of belt would be 200 linear feet (idealy, could be shorter if needed to be)

and linear speed would be however fast a duck can swim i guess. not sure about the speed but i would guess at maybe 60 feet per second would be a good starting point.

the 33 A answer is good. i figured at least 4 -6 hours hopefully. i just wanted to make sure it wouldnt draw it down in less than an hour of run time.

 

[mmccrory]

they may not be the right motor for the project. that is only what i had found searching the internet. maybe yall have a better idea or better motor i could use. like i said thanks for all the help and ideas on this project.

 

[MikeHalloran]

I don't think a duck can _fly_ at 60 fps.


Mike Halloran
Pembroke Pines, FL, USA

 

[MiketheEngineer]

I think he meant 60 fpm - or 1 fps - still seems like a duck paddling pretty hard. Most ducks seem to just waddle here and there.

I am a structural - so not really well versed in this area - but if you are pulling 33 amps - check the amp rating of your battery and subtract about 20% and you might be close.

 

[KllrWolf]

How long the battery will last is dependent on its Amp-Hour (Ah) rating. This rating gives how many amps the battery can discharge for one hour before it dies (roughly). Just divide the rating by the current draw and you will get an estimate of how long the system will run on the battery. Of course, you never want to fully discharge a battery to often as it will shorten its life greatly. The battery manufacturer can give what they consider a nominal discharge amount (percent of full charge) before the battery is affected.

 

[itsmoked]

You should build your decoy setup with the pulleys and everything else you need. Stick it in the water and then, using a spring fish scale, you hook to a loop in your cable (or use a prusik knot) and tow the thing around using the scale. I suggest you go about half as fast as the ones in that movie since that will look good, instead of ridiculous(movie). Read the scale.

Also bring a stopwatch and time yourself as you trudge thru the water over a measured distance, like 20ft. Be accurate. Be up to speed when you enter the timing zone.

Those two numbers will give you exactly the torque and motor speed you will be needing. You should not be guessing these fundamental values of your system.

Once you have those numbers everything else will fall out for you. Motor size, gear ratio, motor type, current draw, battery size, solar panel size, safety items, wire size, switch ratings, etc etc.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mmccrory]

thanks itsmoked i get it now. the fish scale will tell me the amount of torque i need and the speed at which i pull it is how fast it will need to move.

this will sure beat just guessing at a motor and not getting the right one.

and thanks for the info on the battery Amps/hour too.

 

[itsmoked]

Thanks.

To be a little more accurate in my description, the scale gives you the force. Torque is the twist a motor needs to supply, times the radius of the drive pulley that will be converting the motor's torque into that linear force.

So: The scale reading times pulley radius = motor's torque requirement.

Of course you need all the units to be correct and you need to multiply the experimentally measured result by a reasonable fudge factor to make sure it still works in an old or poorly installed situation.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[rmw]

MMc,

Are you going to be driving the motor or shooting the shotgun?

rmw

 

[waross]

33 Amps is probably the current that the motor will draw fully loaded. When you compare the torque needed to wind a tarp on a truck (I believe that is the normal application of this motor.) with the torque needed to pull wooded ducks you may find that the no-load losses predominate on your more. That means much less than 33 amps and much longer battery life. You can cut the motor speed in half by using a 6 Volt battery instead of a 12 Volt battery.

Bill
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"Why not the best?"
Jimmy Carter