Can someone explain electric motor "numbers"?

[warpspeed]

Sorry if this is in the wrong spot but as we don't have a dedicated motor forum I'm hoping I can get away with it. :mrgreen:

Brushless motors have a numbering system that confuses me. (happens easily)
For example, Wangtronic 30-65-08. Or Electrowang 10-17-3.

Certain esc's have the same sort of numbering system. Wangometric 45-80-12.

Do you guys have any clue what these numbers mean?

Thanks!

[spork]

I asked that same question a long time back. The word I got was that there is no consistent meaning to those numbers. Perhaps they mean something to a particular manufacturer.

As far as I know the three numbers that matter are the KV (RPM/volt), wattage capacity, and efficiency. KV alone evectively only tells us the "gearing" of the motor (i.e. high-speed low-torque or high-torque low-speed). It tells us nothing about how much power it can put out.

[peterob]

As Spork said the manufacturer decides how to label their product. Two cases which come to mind from your question are Medusa motors and Kontronic ESC's.

A Medusa 28-32-2800 means the motor is 28mm in diameter, 32mm long and has a KV rating of 2800.

A Jazz 40-6-18 ESC means it has a 40A output, and the BEC operates with an input of between 6 to 18 NiCad cells in series (7.2V to 21.6V, although it's actually rated at 25V for some reason).

Can't think of any others that use the x-y-z numbering, but there's no set standard.

[Pinecone]

Axi uses stator diameter - staor length - number of turns, so a 2212/34 is a 22mm diameter stator, 12 mm thick with 34 turns of wire.

Himax uses case diameter - stator length/thickness - KV, so a 2808-980 is a 28 mm motor, with a 8 mm thick stor with a kv of 980. A 2015-4200 (inrunner) is 20mm diameter case, 15mm long stator, kV of 4200.

E-flite uses size equivalent and kV for smaller motors, so a 450-920 is equal to a brused 450 with a kV of 920. Their larger motors are nitro equivalent size, so a Park 46 would be used in an airplane that used a nitro .46.

Originally Graupner came up with a naming scheme for brushed motors that was based on their power, with each Xyy series bine a given diameter of motor, with the yy telling length/power. Soa 400 motor is larger and more powerful than a 300 motor, but smaller and less powerful than a 500 motor. A 450 motor is the same diameter as a 400 motor, but longer and more powerful. Since this naming is common, many use it (Trex 450 is a 450 sized motor heli) even though it doesn't actually relate to brushless motors.

[warpspeed]

Yikes! Almost wish I hadn't asked! A little standardization would go a long way here, wouldn't it? Reminds me of when r/c car motor manufacturers listed the actual rpm on the package-apparently that was too easy so they switched to "turns", thereby confusing half the planet but effectively concealing their respective secret sauces!

The Medusa scheme makes sense to me. Outer dimensions and kv rating-everything you need to know at first glance. Graupner's is not so bad either.
Either way, they've all sure gone to a lot of trouble in trying to be different while describing the same thing!

I'm not sure I understand the kv=gearing thing though. I thought kv was simply a number multiplied by the amount of voltage to obtain max. rpm figures? In other words an 1150kv motor running at 22.2 volts would top out @ 25530 rpm. I understand how you'd use this information to determine the correct gearing, but not sure what it has to do with either high or low torque?

Thanks again gents-as always your insight is greatly appreciated!

[spork]

I'm not sure I understand the kv=gearing thing though. I thought kv was simply a number multiplied by the amount of voltage to obtain max. rpm figures? In other words an 1150kv motor running at 22.2 volts would top out @ 25530 rpm. I understand how you'd use this information to determine the correct gearing, but not sure what it has to do with either high or low torque?

KV is the electronic equivalent of gearing in this sense:

You could have a 200 watt 4000 kv motor and a 20 watt 4000 kv motor. Both would turn 40K rpm at 10 volts with no load. But the 200 watt motor is 10 times more powerful. It could lift 10 times as much heli.

Similarly you could have two 200 watt motors. One is 1000 kv and the other is 4000 kv. They both put out the same power - but one spins 4 times as fast for the same input voltage (but with only 1/4th the torque). All you have to do is change the mechanical gearing by 4:1 and the two motors will perform identically.

So the KV will tell you what mechanical gearing will be required to get the desired RPM for your setup. But it won't tell you a thing about how powerful the motor is. Make sense?

[Pinecone]

And turns will tell you about the motor also. More turns means lower max current (thinner wire) higher Rm (thinner wire) and lower kV.

So with an outrunner on a plank an Axi 2212/34 will turn a bigger prop slower than a 2212/20. Putting the bit prop on the /20 will draw too much power overheating the motor.

But I agree, some standardization would be nice.