What do motor numbers mean (if anything)?

[Hugh Hemington]

When shopping for motors, I get the kv and obviously I understand what comes after the $, but I've noticed most motors have a four digit number that doesn't seem to correlate with anything -- not the kv, poles, max current or size.

I've also seen people on YouTube refer to their motors by these numbers as if it communicates something meaningful. After doing a fruitless search on the internet, I thought I'd pass the question along.

Is there a standard meaning to these numbers? If so, is there some reference to them somewhere?

Thanks

 

[Mike]

Someone asked a similar question over here. I provided the best answer I could, but the bottom line is that the numbers mean different stuff depending on the manufacturer. Technically, it relates to size (usually), but the size of what parts of the motor vary between manufacturers. I think it's only a valuable spec when you're comparing motors from the same manufacturer and line.

http://quadcopterforum.com/threads/question-about-motor.1123/#post-2379

 

[Hugh Hemington]

The other confusing thing is that sites and people quote watts achieved that are higher than the max current times the max voltage, so either the watt fairy is meddling with things, or the variable frequency provided by the ESC comes into play somehow.
I wish I could just download a spreadsheet of every motor on HobbyKing's site and do my own sort and filter! They could leave off the pricing. It would be so nice to be able to limit my search to the kv, max current, and max thrust range I want, then go see what they cost and the stock status.

 

[Mike]

Honestly - I think the info on at least Hobby King is wrong sometimes. For some lines, the datasheets are great, but for others, they are kind of sloppy with posting the data. Also, the max current & voltage is just the safe operating max for the motors. Anything above that, you're likely to burn them up or wear them out much more quickly. I'm sure the number is very conservative, so going over is definitely possible.