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Difference between "6V" and "7.2V" speed 400 motors

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Difference between "6V" and "7.2V" speed 400 motors

Old 02-05-2004, 11:55 AM
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Heartland
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Default Difference between "6V" and "7.2V" speed 400 motors

I'm looking to get a speed 400 motor. Several are advertised as "6V Speed 400" and "7.2V Speed 400". What's the difference? The voltage range and current figures are the same for both motors (according to the Tower Hobbies website, maybe that's wrong). Are those numbers the maximum voltage you can use without damaging the motor? Is one more efficient than another at it's "rated voltage"? Thanks ahead of time for the help.

-Aaron
Old 02-05-2004, 01:12 PM
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Jim Finn
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Default RE: Difference between "6V" and "7.2V" speed 400 motors

Get the 6 volt motor unless you plan to use a gear box. I use a speed 400... 6 volt on 7 cells with a 6.3X3 prop. (terry prop) THe 6 volt is much more powerful than the 7.2 volt when run direct drive. FMA has the 7.2 motors for $5.
Old 02-05-2004, 01:58 PM
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Heartland
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Default RE: Difference between "6V" and "7.2V" speed 400 motors

I plan on using it in a glider, so I think a geared setup would work best. I'm still not quite sure on the reason for the different classification. Would the 6V motor make more power for a specified voltage than the 7.2V? Which would draw more current in order to make a the same amount of power in a geared setup? I've only messed around with glow power so far, so I'm pretty dumb when it comes to electrics. I figure I'll just jump in with something inexpensive and learn as I go. Thanks again for the help.

-Aaron
Old 02-05-2004, 03:31 PM
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Matt Kirsch
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Default RE: Difference between "6V" and "7.2V" speed 400 motors

Yes, the 6V motor will output more power on a given voltage, with a given prop. It will spin the same size propeller at a higher RPM, drawing more current to do it. Power is voltage times current, Volts times Amps.

Change any one element in the system (besides the motor), and the comparison goes right out the window.

Both motors are capable of handling about the same amount of current. The 7.2V motor is capable of handling more overall power because you can run a higher cell count (voltage) without causing the motor to spin itself into oblivion.
Old 02-05-2004, 05:05 PM
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Default RE: Difference between "6V" and "7.2V" speed 400 motors

That's exactly the info I was looking for. Thank you both for your replies.

-Aaron

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