Motor Temp - How Hot is Too Hot for an Outrunner?
 

Ran a Himax 6330-210 on a Vanquish over 500 flights starting last August and never noticed a heating problem. Replaced that motor with a new 6330-210 about 100 flights ago (why- long irrelevant story) and noticed last week it was coming down 140F in 80deg ambient air. Yesterday was 93F outside and it was coming down 150F. Reading temps with an IR thermometer gun pointed at the mounting base of the motor which holds the rear bearing. The can is cooler. Flying Intermediate. Batteries come down about 110F max measured with same IR gun. Running a Tru-Turn turbo cool spinner (same as on previous motor) and PT 21-13.

As summer heats up, I'm wondering if this motor is going to over-heat and fail. What do you guys think- how hot is too hot?

Generally the magnets are the lowest rating, usually they should be good for 90-100C (sorry I use metric) range before they will start to fail. Windings should be good for much higher temperatures. So measuring the temperature of the can will be the best point to get an idea of the magnet temps, I wouldn't be too concerned until you start seeing 75-80C on the can on your normal ambient days. If you are normally 60-70C on the can, and on a hot day you get up to 75-80C that wouldn't bother me too much at all. Any hotter than that and it would be a good idea to start looking for ways to try and move more air through the motor bay.

Ah- so I've been measuring/concerned with the wrong part. That's good to know. Don't remember temp values off the can, but I do remember they were significantly less than the mounting base. Looks like 150F is ~65c so the can should be in fine shape. Will check when I get to fly again in a few days. Thanks for your help

The weak point is usually the glue used to secure the magnets. Some of the cheaper chinese things start to throw magnets at about 200F, the good ones (Himax, Scorpion) and "Name" brands like Hacker are good for much higher temps (i.e. Scorpion rates theirs to 180C/356F). And, of course, if the magnets aren't designed for high temps they start to demagnetize, but, again, the better brands are designed to handle high temps.

Peter+