MG1 & 2 Motor and inverter temps

The motors can obviously tolerate much higher temperatures, but the inverters are much more senstive to heat.. If I recall in "The Prius That Shook the World", they were struggling to keep the IGBT temperatures down to ensure reliability and also because of thermal expansion issues (the IGBT is a large device to handle all that current, and it expands at a different rate than the heat sink it is bonded to, so high temperatures could crack the chip,, Even when they changed heat sink material to a ceramic, the cooling of the inverter was still a big concern and they had to go with 3 separate radiators in the first gen Japanese Prius.. Although I can't find the reference in my quick leafing through the book, the target of keeping the inverter temp below 65 C (150F) seems to stick out in my mind for some reason..

Now obviously, they have improved the IGBT and inverter in both the Classic and the HSD Prius and the components are likely much higher reliability, but I would still try to keep the temperatures as low as possible..

On my Classic, I've got two levels of intake blocking: a sheet of aluminum bubble wrap insulation right in front of the ICE radiator and behind the inverter radiator (remember that the Classic still has separate ICE/AC and inverter radiators- this is IMO a great design that they should go back to vs a completely integrated rad as in the HSD as it allows you to block off the ICE while maintaining cooling of the inverter), and then corrugated plastic shields inserted in the very front (these do not seal completely- there are various gaps, etc where the mountin struts are, etc, but the second stage of blocking helps the warm-up by at least a couple of minutes).. The bubble wrap radiator insulator goes in in late fall/early winter and then I add the front shields in one at a time as the temperature gets colder, I'll take one or both out for long highway drives.. What I've found is that temperatures below -10 C, with things completely blocked off, the inverters never get above 45 C no matter what.. As external temperatures rise, I have to ensure that I take out the front shields to get adequate inverter cooling- it's not a big deal for single trips where the car has at least a couple of hours to cool back down between trips, but if I have to do a milk-run and make lots of stops and starts, the temperature can build up and I've reached 61F on the MG1 inverter. When the ICE temperatures consistently reach the high 90s, then the bubble wrap layer comes out as well and we're in "summer mode"..

Basically, I think the conclusion that you can draw is that in the middle of winter the risk is much less than people have made it out to be, but as weather gets warmer, you should ensure that you get the blocks out.. I would suggest 0C as the threshold when you install/remove intake blocks.

 

I run "winter lips" on my Classic and leave the upper grill slots open. Last weekend I ran out to see eflier (Norm) to have him add the OBD11 chip to the wifes module ( I took it out of her car ) and on the way home we were on the cell and monitoring the Inverter temps which were quite low 40's C and then I stopped and pulled the lips and the inverter temps climbed up to the mid 60's C. So now tell me why pulling the lips caused the temp to rise. Is the air flow pattern changed that drastically thru the inverter rad to cause it to rise up? when the air flow should be straight on to it and thru it vs. the changed angle from the top down thru it from only the opening at the upper grill? this is a head scratcher for me at this time. One other thing that I do notice with the lips is that the OAT rises up, meaning that the air is flowing to the front of the car, inside the front bumper cover that is. OAT 7C, OAT on MFD is showing 20-24C

Edit: Evan the MG1 temps are always higher on mine. I can only assume that it works harder and thus generates more heat.

 

I have monitored these temperatures in 2001 Prius with the Graham Davies miniscanner. In heavy load summer driving (long hill climb) the MG1 temp rises well above MG2 and the inverters. The highest I recall was about 105 oC. Assuming that I understand the placement of the temp sensors, it seems that MG1 either cannot transfer its heat as well to the coolant, or possibly it is receiving a bit too much heat from the ICE (whose coolant was about 95 oC at the time).

I am also interested in knowing what a critical temp for MG1 would be.

 

have any of the Classic owners seen a coolant schematic for the Inverter and the MG's on a Classic. I'm wondering if MG1 is the last on the circuit before the rad?
Edit: for grammar and spelling, sorry.

 

Well I have had my first two runs with the CAN View OBDII watching the inverter and MG temps. My radiator blocker is attached to the Bra and is of the same material. It also has zippers installed so I can open and close the blocker a bit and it is Velcroed on so I can remove it for the summer. Here are my results. Max temp from the formatted screen at the end of the trip. 15 Min drive over rolling hills pulse and glide max speed is 40 mph. M1 inverter 129 F, M2 Inverter 134 F, MG1 114 F, MG2 107 F. The trip back same route same speeds but with the lower radiator opening unzipped to permit air flow, upper closed. M1 inverter 125, M2 inverter 129, MG1 121, MG2 112.

 

Henry, i think you need to make your test runs at least a few hours apart. despite the VERY nice weather we had, i did a few runs around town. (bought a new LG 8100...very nice) and my temps barely moved. never really got much above 100º F.

granted, no long duration trips, mostly 35 mph and less.

ok, i admit i did a bit of aimless joyriding to play with the new CANVIEW stuff...(hate admitting to wasting gas...but you know how toys are plus, had to test my new phone to make sure the signal is ok....only have 15 days to find out if i wanna put up with it for the next 12 months)

but never saw high temps at all. now i will be making a 30 mile freeway trip today and will be hauling around a total of four people, so i will be checking out that info...probably wont be much record keeping (although everyone loves my car, they think i need help with my obsession. i agreed wholeheartedly and handed the notebook and pen to them but... they apparently meant something else)

 

The Classic NCF shows the coolant flow from inverter down to MG1, through to MG2 and then out to the radiator.. MG1 is right next to the ICE, so perhaps the increased temperature is heat conduction from the ICE?? MG1 is the smaller of the two motors, but it is also the e-CVT "control" motor so it's always working, which maybe also contributes to a higher temperature?

Frank- I've noticed that if I stop and then shortly restart my car, the hybrid temperatures immediately go higher.. Probably because the coolant flow stops and the heat is no longer being removed, so the devices residual heat drives the temperature readings up.. Did the temperatures go down as you drove around more or did they stay there?? I'd be interested to see what your readings are if you let the car cool off for a couple of hours first.. The significant OAT change is surprising.. With my Classic's front completely blocked (the aforementioned two-level blocking), and also a sheet of the foil bubble wrap insulation on the inside of the hood to keep the ICE as warm as possible, the OAT reading only changes 1 or 2 degrees, but the IAT that goes up as much as 5-10 degrees due to pulling warm air from inside the closed-up engine compartment. Where is the OAT sensor in the HSD Prius located?

 

isnt it on the front grill area??

 

C4, I drove about 35 miles with the lips out and the temp was consistantly higher than when I have them in. My thoughts are as the upper grill area is open that the airflow is in and then down, if you look just to the bottom of the inverter rad you can see holes thru the belly pan and what my thoughts are is that the air thru the grill would rather travel down thru those holes rather than go thru the A/C condenser and the rad, and that sets up a circular air flow that takes the Inverter cooler air flow down and then it slowly flows forward and heats the front of the bumper area where the OAT thermistor is located. It's in almost the same spot on the G2 Prius. Note that the ICE temp stayed at almost the same temperature. Lips in or out on this trip.

 

Drove today with both of the blockers unzipped and it was about 10 cooler inverter temp 101-104 MG1 &2 98. Going to butt it up again. I wonder what optimal and max temps are? If I was doing it I would take the highest recorded temperature recorded ever and pack on a good margin. I think that would make us safe in the PNW at any rate. I am going to consider anything under 150 as acceptable for now.

 

highest inverter temp I've seen is 87C. Hot day, A/C on and a hill of 11% for 3/4 of a km. floored and holding 85 km per hour. Ok so I was speeding but so was everybody else. If I had gone the speed limit that tanker truck would have run over me.

 

OK 188-187 for a top temp summer, radiator open, no DTC. That gives me a upper limit. Some how we need to establish norms for this car. Do you suppose if I wrote Toyota a nice letter they would tell me? I might just do that, could not hurt?! Dear Toyota what are the operating norms for the inverter temps, MG1 temps, and MG2 temps. Yours respectively Henry F Drygas Jr. How about that?

 

worth a try but steal a stamp from work so your not out anything when they don't reply.

 

Not even if I added Dr. Henry F Drygas Jr. ? It says on the diploma "and all the rights and privileges there unto" ? Maybe I could say it was a poison control issue, like a patient ate the inverter and MG1 and MG2? Kind of like that episode of MASH where Klinger stated to eat the Jeep?

 

took my trip today, top winding temps up to 121ºF. the inverters got to 109º but what was rather amazing, i got off the freeway, did about a 6 mile jog at city speeds and the inverters cooled right down to 75º right away. wild.

i have to guess that these temps will be at least 30-60º higher in the summer. i think, just as we see water temps flattening out, these temps will find their own plateau as well.

 

ok now I know your off your meds. As a layman take two of them and post here in the morning.

 

The nice nurse gave me a shot and I am feeling much better now! Still we should be able to work out some norms. It gets hot in Missouri in the summer. Efusco could help us this summer. Anyone else in hotter climes? It is fairly moderate in the PNW. I am not sure if we could get better summer lows than around here. We will need help with winter lows. A bit too late this year but it is only a few months till winter in the northland> :lol: I am sure those in that area do not want to here that with spring coming on, but this is data collection and we have to look to the future.