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Author Topic: Dc motor current draw  (Read 4513 times)

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Offline sillydipstixs21Topic starter

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Dc motor current draw
« on: May 24, 2007, 11:59:23 PM »
I found a bunch of 12v lift motors (Harmar Mobility) and they look pretty good?  They're 12v and use a draw of 3amps or so at no load, with 270 rpm.  how can i find out what it max draw will be when designing it? in other words it 'stall current'?  For a nice size i was thinking four in a tank drive.

here's the link to the motors: http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=1290

any advice or whatnot is encouraged.

Offline Eco19R

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Re: Dc motor current draw
« Reply #1 on: May 25, 2007, 01:36:44 AM »
This is going to sound stupid but - you could always stall the motor while the amp-meter is hooked up  ???

Offline dunk

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Re: Dc motor current draw
« Reply #2 on: May 25, 2007, 03:00:49 AM »
obviously Eco19R's suggestion will be the best way to find out but if you want to know before you order the motors and you can't find a data sheet then you are a bit out of luck.
the stall current will vary from one model of motor to another but you could get an approximate fugue by searching for specs of other motors with a draw of 3amps at no load.

the other tactic you could use is make sure your motor controllers have a maximum current protection circuit so they switch off when too much current is drawn.
that way even if it turns out your motors draw more current than you expected your components will still work together without burning out your motor controllers.

dunk.

Offline Admin

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Re: Dc motor current draw
« Reply #3 on: May 25, 2007, 07:14:49 AM »
3A at 12V is a lot of power at no load!

I can easily see this thing drawing 80W+ when doing actual work . . . you will be hard pressed to find an affordable motor driver with that power rating . . .

Offline sillydipstixs21Topic starter

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Re: Dc motor current draw
« Reply #4 on: May 25, 2007, 12:51:44 PM »
Forgive my first post, it was late and half my brain was off.  I was trying to figure it out before i bought it and was only able to find out what was listed on that website in my previous post.  it has what looks like an automotive connector and the guy at the shop said thEY most-likely were used in car mounted wheelchair lifts(the ones that slide in your trailer reciever) so i thought they would be somewhat of a nice start to a design.  the wire gauge is rated to 75amps.  but it seems not worth picking up.  thanks for the responces guys!

Offline sillydipstixs21Topic starter

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Re: Dc motor current draw
« Reply #5 on: May 26, 2007, 02:55:17 AM »
the design in my head is similiar to this: http://www.roboteq.com/roboviadesign.html
but with treads and suchs. 

 


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