What IS the maximum acceptable inverter temp??

[JimboK]

With temperatures now starting to dip and the AC hopefully turned off for the season, I put the grill block back in yesterday with all the but the bottom-most slit in the lower grill covered. With that slit open and Can-View monitoring temperatures of the ICE, MGs, and inverter, I'm not worried about overheating. But as I consider when to block that last slit, I'd like to know the maximum acceptable inverter temperature. A PC search turned up comments such as, "My inverter gets to [x] degrees [with a grill block]," or "I don't know what the maximum temperature is." But I can't find anyone citing a maximum safe temperature. Does anyone know one, preferably supported by Toyota documentation or other reliable source?

[efusco]

Somewhere in the bowels of PC there was some pretty extensive discussion of this. It's believed that the Inverter can tolerate some pretty incredible temps...230F range. But it's also clear that Toyota tries pretty darn hard to prevent it from getting anywhere near there.
I started getting nervous when temps started getting up to 120 on a regular basis...it never seems to get anywhere near that, summer or winter, without grill blocking and I figured that was probably by design.
Light on data, heavy on speculation I know, but that's all I got for ya.

[hobbit]

From the "operation history data" part of the repair manual, which
details various recorded out-of-bounds measurements [for '04] ...
.
_ MG2 (NO 1) TEMP HI -- motor temp above 174C (345F)
_ MG2 (NO 2) TEMP HI -- trans. fluid temp above 162C (324F)
_ MG2 INV TEMP HI -- motor inverter rose above 111C (232F)
_ MG1 INV TEMP HI -- generator inverter rose above 111C (232F)
_ CONVERTER HEAT -- boost converter temp rose above 111C (232F)
_ COOLANT HEAT -- inverter coolant forecast temp above 65C (149F)
.
I have no idea what "forecast temperature" is, but it looks like
the inverter's coolant loop is expected to stay on the cool side.
.
This is supposedly data that the ECU would store long-term so a tech
could hook up a scantool and make judgements about your driving
style. Some of the items are a bit big-brotherish or just don't
make any sense, such as if you pressed the accelerator while in
Neutral [bfd] or my favorite,
_ PREVENT STAYING -- engine speed stays in resonance frequency band
which I've *never* gotten an answer on what the F it means.
.
anyways, hth. It's all in the TIS stuff.
.
_H*

[tochatihu]

On the electricals side, I stongly suggest 'the lower the better'. In nhw11 Prius I don't think I ever saw inverter temperatures above low-90s oC. Note that this is not a pressurized coolant system and it you ever got above 105 oC, you would be pressure-testing it. Probably a bad hobby.

All that is separate from what the inverter semiconductors can tolerate safely, and uninformative on when the computers might act to put you into some sort of limp home mode.

Max noted for MG1 (which ran hotter in mine) was 105 oC or so, and rare. An MG2 failure recently reported here was concurrent with 160 oC recorded. So don't do that!

[efusco]

Thanks Hobbit, my memory was right on w/ the 230F mark. In any case, I still stand by the keep it lower philosophy, I'd guess that at 230F there's probably been damage or is very near the damaging range.

[dmckinstry]

<div class='quotetop'>QUOTE(tochatihu @ Sep 16 2007, 08:20 PM) [snapback]513502[/snapback]</div>

On the electricals side, I stongly suggest 'the lower the better'. In nhw11 Prius I don't think I ever saw inverter temperatures above low-90s oC. Note that this is not a pressurized coolant system and it you ever got above 105 oC, you would be pressure-testing it. Probably a bad hobby.

All that is separate from what the inverter semiconductors can tolerate safely, and uninformative on when the computers might act to put you into some sort of limp home mode.

Max noted for MG1 (which ran hotter in mine) was 105 oC or so, and rare. An MG2 failure recently reported here was concurrent with 160 oC recorded. So don't do that!
[/b]

I was worried last summer when driving at freeway speeds (70-75 mph) in external temperatures arround 100F for an extended period of time the higher of the 2 (I don't remember whether it was MG1 or MG2) reached 184F. This was between Winnemucca and Reno. I don't know whether the altitude was relevant or not. That's the only times I've seen either inverter temperature above 160F. Usually, it's much lower than that.

This was according to CAN-View, and I never noticed a problem with performance or any lights on the dash indicating a problem.
Is the fluid in the motor generators and the transaxle the same? I'm approaching 60k miles, and thinking about replacing the tranaxle fluid.

Dave M.

[statultra]

thanks for the info!!i needed it for a while

[Devil's Advocate]

Is there a way to check the mig I & II temperatures through any of the MFD screens.

If not where can I get the CAn-View tool?
I have found the Scan-Gauge II, but cannot tell if the ScanGauge tells me Mig temps.

[efusco]

<div class='quotetop'>QUOTE(Devil's Advocate @ Sep 17 2007, 03:29 PM) [snapback]513883[/snapback]</div>

Is there a way to check the mig I & II temperatures through any of the MFD screens.

If not where can I get the CAn-View tool?
I have found the Scan-Gauge II, but cannot tell if the ScanGauge tells me Mig temps. [/b]

1)No
2)hybridinterfaces.ca may still have some available, but he's discontinued making new ones. Someone was selling theirs here recently too...check the private sales area.
3)There's a thread active today about the new SGII and it's capabilities. It's going to have most of the data that CAN-View does with the new upgrade.

[JimboK]

I'm resurrecting this thread because sometime in the near future I want to do some grille block testing, looking at (among other things) heat buildup under the hood. I've spent an hour or two searching the PC archives and chasing external links. From what I can gather, it seems we don't know much more now than we did when I first posted this.

First, it seems pretty clear to me based on Hobbit's post here, discussions elsewhere, and my own observations, that overheating of MG2 is extremely unlikely. (Can I assume MG1 has the same "out-of-bounds" thresholds?) I've never seen MG temps come close to 100C, much less 162C+. I should qualify that by saying I don't do continuous monitoring of MG temperatures, only spot-checks. My testing will include continuous monitoring.

To the original point of the thread: Of eyewitness accounts of inverter temps in day-to-day driving, the highest I could find are Tochatihu's report of 90C-ish from his NHW11 (post 4 above) and Frank Hudon's report of 87C on a steady high speed climb up an 11% grade. I have seen them as high as 150F-ish in sustained summer highway driving -- again, via spot checks. Many of the more-learned-than-I around here suggest something around 150F as a maximum. That seems a bit arbitrary (not implying that's a bad thing), but it also seems to offer a wide margin of safety and will keep the electronics happier within their thermal comfort zone.

So for my grille blocking, for both testing and continuous use in cooler weather, I propose to keep inverter temps at the same (semi-arbitrary) 150F or below on a sustained basis, but to allow occasional spikes to 170F-180F. Any higher than that and some of the block comes out.

What say ye members of the PC brain trust?