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Old 06-25-2010, 12:53 AM
nick_75au's Avatar
Join Date: Aug 2006
Location: BrisbaneQLD, AUSTRALIA
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Default RE: Help - New to brushless

Kv is RPM per volt, so a 1000 Kv motor will spin at 1000 RPM at 1 volt, 12000 Rpm at 12 volt, in general higher Kv means more power hungry the motor is as well.

A rough guide ~28mm diameter in or outrunner is fairly close to equivalent in power, a ~36 mm will be a better choice as it will run cooler. You can see in the table the Watts (power each motor can handle)

link has some specs on 750 motors

top one has a Kv of 415 bottom one has Kv of 1250 so that gives you an equivalent to look for.

you have a couple of ways top approach the selection of a motor as well, you could get a lower Kv motor and feed it with lots of voltage ie 2 to 3 8.4 volt batteries in series which is efficient.
or high Kv which will need a number of batteries in parallel to give reasonable runtime.