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KV of a motor

how do you tell?

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Gaz Elliott11/08/2010 00:02:45
665 forum posts
30 photos
Hi all,
is there a way of determining the KV of a motor.
I bought 2 motors from giant cod about a year a go. the purple can motor bruhless type. These do not come with info on the can DOOOOOH. how to tell what the KV etc is as they both look exactly the same on the outside.
Gaz non electrohead but trying!!!!
David Ashby - Moderator11/08/2010 08:16:23
10953 forum posts
1684 photos
615 articles
I know Robotbirds sell a Kv meter for approx £30 Gaz, not used one myself though. 
Sparks11/08/2010 08:18:47
265 forum posts
55 photos
You can use the 'drill press' method, which involves driving motor via a bench drill and measuring generated voltage with 'scope or multimeter.
See this post thread  for fuller explanation:
Bruce Richards11/08/2010 08:21:41
1849 forum posts
Power up the motor and measure the voltage and RPM. Them divide the RPM by the voltage and this will give you the RPM per volt (KV). Well it will give you a reasonable approximation.
Erfolg11/08/2010 12:36:18
11659 forum posts
1297 photos
I have seen an advert for an electronic device which gave a Kv value for a motor.
I have looked at BRC, GiantCod, Robotbirds, HobbyKing even my BFMA News and have been unable to find the device.
I remain convinced it exists, as I thought when I saw the advert, Mhhh, do I really need one. Then thought, how would it help me.
I guess it must produce an approx. value, probably doing Bruces calc.
The good news is I found an electronic Rev meter for $15 or approx £10 plus p&p at Hobby King
David Ashby - Moderator11/08/2010 12:44:21
10953 forum posts
1684 photos
615 articles

"I remain convinced it exists"
 Here's the link  
Thanks for your faith Erfolg.  


Erfolg11/08/2010 13:14:28
11659 forum posts
1297 photos
Thanks David
I have subsequently found it hear also Meter link at $ for £.

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