Elec. motor heat - and longevity

[bonaire]

In another thread - a reply mentioned motor heat.

>> The motors run hot….. motor A was 230 the other day. Motor A and Motor B typically run hot (A always more than B if it is being used such as with highway speeds) usually close to 200 degrees.
<<

I'm "so close" to buying a Volt and may do paperwork tomorrow with Stingray. But this has me at a pause. Maybe WOT or someone can chime in.

In my days of RC car racing, we used to try to keep electric motors (brushless) down below 180*F or risk what some would call de-magnetizing of the motor magnets. This leads to power-loss and of course, less competitiveness of a car's motor.

Now, does running the types of motors in the Volt equate to the same issues - where permanent magnets in a Volt motor are susceptible to heat-fade and loss of their overall power down the road if they reach 200*F+ during normal driving? RC boats actually have water-cooling piping in them since they are enclosed in the hull and would heat faster than an exposed one. petefoss has experience with RC planes and may know what I'm talking about here. An electric motor without magnets becomes basically, a toaster.

[Fulgerite]

You are assuming that motor temp reading is the PM magnet. It might be the coil temp. I am quite certain this is well within the designed operating range for the Volt's motors. With over 20,000 Volts on the road... I have not heard one single complaint about a loss of power... Or motors overheating.

I think your concerns are un-supported by any real issue here.

[bonaire]

Thanks - that's really what I need to hear. I know everyone is doing well on the road but the number just jumped out at me based on my other non-EV experience and thought I'd ask. I guess the motor heating wouldn't be felt at the time of one or two hot days but I'm more thinking daily temps hitting 200*F or higher ongoing and the effects on the permanent magnets.

I wonder if induction motors would have any heat issues at all (versus perm magnet)?

[Steverino]

I recall reading somewhere on this site that the electric motors are oil bathed for cooling.

[scottf200]

I recall reading somewhere on this site that the electric motors are oil bathed for cooling.

See red about the motor oil cooling. I think this is in the FAQ in my sig too.

The Volt uses regular GM "Dextron VI" transmission oil to pressurize the clutches and cool all three electric motors (Motor A, Motor B, and the auxiliary pump motor C). The oil is carried through dedicated passages at all times for a base level of circulation, but it can be increased in flow to Motor A or Motor B as needed if the temperatures begin to climb toward their material limits. The oil is sprayed on all parts of the windings and rotors and was enhanced through years of development. It is very rare that this active cooling is needed. If there's any issues with motors and temperatures, it is that the motors generally do not create enough heat compared to a traditional transmission. The Volt has a thermostat for the transmission oil cooler so that it will warm up more quickly for better efficiency.

I hope this answers your question and helps in your purchase decision!

[Fulgerite]

Thanks - that's really what I need to hear. I know everyone is doing well on the road but the number just jumped out at me based on my other non-EV experience and thought I'd ask. I guess the motor heating wouldn't be felt at the time of one or two hot days but I'm more thinking daily temps hitting 200*F or higher ongoing and the effects on the permanent magnets.

I wonder if induction motors would have any heat issues at all (versus perm magnet)?

As I recall one of the motors is all induction. The other one has magnets. And I believe the motors are oil cooled. As I said before... When you get a temperature reading of 200 it matters WHERE that sensor reading is taken from. Is the temperature probe attached to the permanent magnets? Is the temperature probe attached to the field coils? Is the temperature probe measuring the coolant?

If you are looking for a confirmation from GM on this ... They did test this car extensively in all driving conditions for at leas two years before selling a single car.

I suppose you can hold off buying a Volt and miss out on the best driving experience of your life... Based on what?

[DonC]

I suppose you can hold off buying a Volt and miss out on the best driving experience of your life... Based on what?

Better to ask before than after the purchase! Most product information is read after the purchase. That's not the best timing though I've been guilty of this myself.

[Fulgerite]

Better to ask before than after the purchase! Most product information is read after the purchase. That's not the best timing though I've been guilty of this myself.

Don... Normally I would agree. But in this case he is suggesting that a hobby model toy motor overheated: Therefore the Volt motor will fail too.

There is no credible information to suggest that the Chevorlet Volt motors overheat. (Or have any sort of issue whatsoever.) The Volt is a REAL automobile backed by a 5 year 100,000 mile powertrain warranty. The Volt has millions of hours of extensive testing behind it. The Volt does not use RC toy motors for locomotion. There is absolutely no correlation whatsoever between the way a hobby toy motor behaves versus a modern electric automobile.

There ARE about 10,000 OTHER things to worry about on a Volt: Battery degradation, Inverters failing, Computers failing... Many many, more... I suppose if you have a phobia of melting motor magnets you might want to consider a LEASE. With a lease you don't have to worry about the magnets in your Volt failing. It's ALL under warranty until the day you turn it in and walk away.

[bonaire]

No - what I was saying was motors with magnets that get too hot can have the magnets lose some of their effectiveness lowering AER by drawing more wattage to then output the same power. I want to understand the Volt better in this area. Scottf's reply was what I was looking for.

Little harsh on the reply, there. Plus, the RC models I'm talking about are $1K or higher racing cars (1/8 scale, pro-level) not toys. Motors are in the $200 range and the ESCs are highly programmable (not just Normal and Sport mode but actual acceleration and braking curve programmable). Please understand that in this case, you don't understand enough about this hobby and are being quite critical of it - similar to how you're replying to me. The hobby lead me to be an enthusiast of and proponent of the Volt. I've been following Lyle's forum here for 4 years now.

What I want to determine is after say 3-4 years, if AER is dropping, is it due to motor magnetic strength fatigue or Li-Ion battery life diminishing. Could be both down the road. GM offers warranty-replacement terms of 70% or lower AER during 100K/150K miles as meeting warranty parameters. Would someone driving up Mt. Washington every day get the same warranty-support as someone cruising 30 mph through Michigan countrysides?

[Henry_FL]

The material in magnets goes well into the 150-200C range before you have permanent losses depending on the mix

http://www.micrometals.com/materials_index.html

I don't know where RC motors come from, but I would guess its magnet composition isn't based on longevity or thermal property's, there is a huge range of materials and hence the characteristics of the finished cores

GM's Phd know way more than any of us will ever dream to know, and its proven they got it right with active thermal management of many aspects of the car.

My kind advice, quit finding reasons to get cold feet and just get the damn car ...