240 degrees!!!

At least with most transmissions you can downshift to keep the rpms up and maintain coolant flow. I don't see how that would work with a Prius. Towing uphill in an unprepared vehicle is a definite transmission killer.

 

I don't know why people tow clearly it's not design for that purpose! There are limitation thrushold which componets are design to withstand . I guess if you have too. Heat is cause of most componets breakdowns! Back off a little and rest it! Running 50/50 redline water wetter will bring down coolant temp 10-25 degress. Clean out debris from raditor, turn off a/c, running the heater will help too! Get ready to sweat! ,Driving at nights on hot day instead during day time!

 

First of all, it is unlikely that a comparison to German war criminals will surface here -- we are not discussing Volkswagen.

Secondly, with over 20 years of experience in engineering, I can safely say that engineers do know better. They know that what they write in owners' manuals must be tempered to protect the manufacturer. The true measure of a car's performance can only be measured by racing it or pushing its limits in other ways. There is lots of redundancy built in to all aspects of a car's capacity. Just don't be stupid, and always keep up the maintenance.

Thirdly, the Prius is rated for towing in other markets, so it is clear that the warnings in US manuals must be interpreted in light of the specifications in those markets. I don't see a significant design difference in those models (like heavier gears, larger shafts, more displacement, etc), do you?

 

Since the term "anti-towing Nazis" has already been used, I stand by my quote. The whole point for me is that you can justify about anything. But when the mg2 temps are at 240F, something is wrong. Don't start looking for reasons why it is OK to tow when the evidence supplied by the OP shows clearly that it is not.

 

First, I missed the reference to German domination early in the thread. The word, "Nazi," in this case was not properly capitalized (a comment from someone who has been accused of being a grammar Nazi). Come on folks! If you are going to post an insult, at least get the grammar right!

I guess I am confused. What is your authority that MG2 temperature at 240 degrees F is too high? Electric motors can be designed for a wide range of temperature conditions (-40C to +120C). For high temperature items like hardened steel shafts and special high temperature bearings are standard. Motors are also insulated (winding insulation and insulation of the winding from the iron core) depending on their intended use. An F rating would anticipate operation temperatures up to 311 degrees F. Class H ratings allow for up to 356 degrees F.

From the engineeringtoolbox.com I found the following lifespan effect of temp:

In general a motor should not operate with temperatures above the maximum. Each 10 degrees C rise above the rating may reduce the motor lifetime by one half. It is important to be aware that insulation classes are directly related to motor life.


Example - a motor operating at 180 degrees C will have an estimated life of:

• only 300 hours with Class A insulation
• 1800 hours with Class B insulation
• 8500 hours with Class F insulation
• tens of thousands of hours with Class H insulation

​

The Gen 3 Prius MG units are, unsurprisingly, insulated as Class F.

I don't think the OP has any issue, although another concern in electrical motor service life is temperature rate of rise. Rapid rise is very detrimental to the service life of any electrical device (except, perhaps, an oven or stove element).

I wonder at what MG temp the car starts throwing codes?

BTW, I worked for quite some time in the motor repair industry and worked on motors in very extreme environments, including smelter operations and deep well applications.

 

Post #18 in this thread has links to some real data.

The following snippet of info is from page 70 of the pdf...

According to the 2010 Prius repair manual, the stator temperature is generally kept below 100ºC. Figure 3.23 shows the motor temperatures measured during tests conducted at a power level of 50 kW and a rotor speed of 5,000 rpm. The motor is capable of operating at 50 kW for 4:34 (minutes:seconds) prior to reaching a stator temperature limit of 150ºC.

 

So, there you go.

There is no issue for concern at 240 F degrees. 150 C = 302 F. 240 F is 80 percent of the test data and 67% of Class F insulation rating.

The engineering in these cars rocks! That motor typically runs at 28% of its rated maximum temp.

 

Please.. I've read of Prii owners towing thousands of pounds (not even exaggerating) without problems. Who cares! Plus it's his car. I cheer you on for that! Electric motors are ok in high heat situations as long as the electric motor is rotating.

I also don't see how it could over stress the battery? Since the computer will only accept so much current back, and the battery will only change to 80 something %.

Side note the 2004-2009's did have larger more powerfully electric motors, but they were utilized at a lower current. Just a little fun fact

 

Our 2010 prius showed peak mg2 & mg1 temps of 258 & 268 F on a recent trip from vegas to laughlin. outside temps were 78 F
The average motor temps on level ground were probably 225 & 235 F . If memory serves me correctly prius motor overtemp codes are set at nearly twice those temperatures.

 

It appears to me that owning an OBD2 Fusion with a Bluetooth or WiFi link is just a tool that results in worry. That being said, I just ordered a link so I can worry more.

 

Again, a lack of careful reading on my part. I didn't notice the reference to the other thread that has the same information that I have provided, as well as a notation that the dashboard warnings will trigger at 162 degrees C. That's 323 degrees F, and is consistent with the class of motor insulation noted.