Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: jamort on March 12, 2009, 07:15:53 PM
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I'm try to find the mah of this so I know what smah battery to get... any ideas I looked on the website but didn't see anything....
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I'm try to find the mah of this so I know what smah battery to get... any ideas I looked on the website but didn't see anything....
probably be good to mention what you are specifically talking about
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mAH I was wondering about how many amps it would take to run this motor for however long.... on say 12 volts cause I'm trying to get the amount of Mah my motor needs
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Hi,
mAH I was wondering about how many amps it would take to run this motor for however long.... on say 12 volts cause I'm trying to get the amount of Mah my motor needs
First off, it's mAh (m=milli, A=Ampere, h=hours).
Second, mAh is a measure of capacity, A is a measure of instantaneous current. You're comparing apples and pears here.
Third, you didn't mention which motor you are talking about, nor its parameters?
Btw. the capacity is only valid for a certain current draw. Higher currents means less capacity and v.v.
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this
http://www.trossenrobotics.com/store/p/4927-16-1-36mm-Planetary-Gearmotor-RS-540-Motor.aspx (http://www.trossenrobotics.com/store/p/4927-16-1-36mm-Planetary-Gearmotor-RS-540-Motor.aspx)
I ws planning running it on 12v and need to know how many it draws so I can make calculations for the battery I saw A but that was it
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Hi,
Well, unloaded it takes 1A, but you get no (payload) work from it.
Stalled it takes 42A, but since it's stalled, all the work goes into heat.
Useable work is in between these two extremes, but where depends on the weight, velocity, acceleration and friction of your vehicle
The parameters you need:
Operating v : 4.5v - 12v
Nominal v : 12v
No Load RPM : 1050
No Load A : 1A
Stall Current : 42A
Stall Torque : 632 oz-in 4461 mN-m
Kt : 15 oz-in/A 106 mN-m/A
Kv : 88 rpm/v
You need to find out how many mN-m (milli Newton meters) or oz-in (ounce inches) you need for the assembled vehicle (w. batteries, motor(s) and all) to go at the velocity you want and then divide this number with Kt (torque constant) to see how many volts (V, not v as they write).
Not knowing the vehicle, its run-ability, its loaded weigth etc. I could only guess (and would probably be wrong), so I better not.
Your driver should be able to handle more than the stall current, lets say 50A+ but the average may be as low as a 2..5A, depending again on the factors mentioned.
The Kv (Velocity factor) of 88 means, that when you've found the needed RPM of the wheel, you can divide that with 88 to find out how many V you need.
Since you're using 12V, you need to use PWM to reduce speed.
One thing's for certain, it will get hot if put to real work, since it has a high stall current, which means low winding impedance (to compare, I have a few, quite heavy, 12V motors about 15..18cm in diameter and around 10 cm in thickness and their stall current is "only" ~80A).
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ok I'm justt trying to get this right its my first lare robot.... built 5 small ones and thought I'd give this a go...
my intentions are
for it to have about an 18" by 12" body weigh about 15-20 pounds and be tracked... similap to a pack bot