Motor magnets exploding
 

I have two motors that the magnets have exploded
It looks like someone took a chisel to the end of the magnet
They are both can type brushless run on three li-po and both 5400 speed
One is an Eflite and the other is a Himax, unless they are both made by the same company I would doubt if it is a manufacturing flaw
Could it be over rev?
The windings look fine
Only a few runs on each motor
Any ideas?

RE: Motor magnets exploding
 

Definitely overspeed. 5400Kv on 12.6 Volts is 68,040 RPM. I've never met a motor that could take more than about 30,000 RPM. Even under load, you're still going to be well over 30,000 RPM.

I'm pretty sure the specifications for these motors limit cell count to 8 NiCd/NiMH. That's 2S LiPoly.