How to tell when FPs fry?

[Alex1072]

How do the FPs burn out? Do they give out lots of smoke and make it obvious, or do they sometimes just slowly lose torque. I'm asking because I suspect we partially burned ours out before ship.

[Biff]

Both, If they are really fried they smell back long after. They also just don't put out the power of a new one if they are partly cooked. We are going to Buckeye with four spares.

[Greg Marra]

They smell really really bad.

[Ken Patton]

In my experience they actually start to smell before they are fried.

In some cases the plastic fans melt. Once the fan melts you are in trouble because thats what was cooling the motor.

We have had the 2003-style motor smoke, but then still be usable afterwards.

What we use as the F-P test, and what has worked so far this year where we are running the "6V" motors in our drive system - is to touch the motor: if it is almost too hot to touch, then you should stop running it and let it cool. Don't let the motor get too hot to touch - and of course don't stall the darn thing - and you might be able to make it last.

I don't recommend "thermal-shock-in-a-can" either .

Ken

[sanddrag]

Do yourself a favor and get some of the heat sinks mentioned in this thread

[Mike33]

they smell bad and/or the famous magic smoke is seen

[Al Skierkiewicz]

The FP motors have a few failure signs, some of those are mentioned above. It is possible when the motor is in stall to only burn one winding. This will give you some false indications in that the motor smells bad but still seems to function. The FP motors have three windings, so one burning reduces the output power by almost a third but since the winding is invariably shorted, the current consumption skyrockets and the heat goes up. You will ask "how you will know if you smell a bad motor?" A burned motor leaves no doubt, it is vastly different than the mechanical, hot oil and brush, smell the motor normally has. A simple visual inspection with a flashlight will show one or more of the following...
1. Loose or cracked fan.
2. A discolored winding compared to the others.
3. Discoloration of the commutator (the copper contacts on the armature)
4. Smoke damage
5. Completely burned commutator and windings.
Arcing is not a sign that the motor is defective, all DC motors will arc at the brushes as part of their operation.