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    Mike500 Interessen-Gemeinschaft Prius

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    Apparently applying over 600 volts to the unit results in overheating and possible damage to the power transistors.

    Semiconductors are very sensitive to overheating.

    Basically, and apparently, the reprogramming of the algorithm will prevent the high voltage paradigm that would lead to overheating and damaging the power transistors.
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    BardManY2k Junior Member

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    Mine happened to be going in for routine maintenance today also and they let me know that they would do any/all recalls today to avoid a return trip... they were unspecific at the time, but now I know what prompted the sudden attention to the recalls. I will post back also when I know more.

    My biggest concern is that for the last 4 years the car has been running with software that allows the car to potentially shorten the life of a seemingly critical component. I don't want to be an alarmist, but does anyone more knowledgeable than me know of a way to measure the degradation of these transistors? Or is it possible that we will potentially start getting some nasty surprises as the mileage creeps up there. I am at 80,000 now and certainly hope to go twice that with no major repair expenses.
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    pfjmarina Junior Member

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    Just checked the Toyota's owners web site. The recall shows up for our 2011 Hatchback, but not for out 2013 Prius v (bought in October 2013)
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    dhanson865 Expert and Devil's advocate

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    That behavior is by design. It might seem weird to you but it protects the car from potential damage.
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    Skateruk Junior Member

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    Hi Kermit can you direct me to the site/thread etc from where you got the following from "Additionally, if the vehicle has the condition present the inverter assembly will be replaced prior to the software updates."
    I've got a feeling that I might need to refer to this as a back up...... just in case the dealer tries to stitch me up!
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    BardManY2k Junior Member

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    https://techinfo.toyota.com/techInfoPortal/staticcontent/en/techinfo/html/prelogin/docs/cp/e0etofaq.pdf

    I am concerned that they will only deal with a potentially damaged inverter unit if it has experienced complete failure as outlined in the document. Ours has been making a funny high-pitched noise (more than usual... been driving the car for the last 60,000 miles so we are familiar with the noises) - now I am worried that it is related to this recall/inverter and that they won't fix it if it breaks after the recall has been performed.
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    bedrock8x Senior Member

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    It the electronic industry, this is call a software fix for hardware defect.
    The fix is likely to restrict the boosted voltage much less than 600V to save the drive transistors from overheating.
    It may have a undesirable effect for reduce performance under full acceleration.
    BTW, this is a cheap fix than replacement of the booster inverter.
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    The Electric Me Go Speed Go!

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    Algorithm and Paradigm? Them there are big fancy college words. But I think what you just said is that Toyota is going to update some software to keep some transistors from potentially overheating.

    Cuz I don't take too kindly to folks changing my algorithm even if it does relax my paradigm.


    Check out post 39 of this thread. It appears Toyota will evaluate the condition of the unit and replace before doing software update if necessary.

    I think your concerns are very valid, especially in an "older" Gen 3. Of course the worry issue then would become is the dealership/technician REALLY evaluating the condition of the transistors. Or are they simply doing the software update and "telling you" it looks great?

    I would think overheating leading to deformation of a transistor could be a long term process. I would also wonder how hard it would be to get to those transistors and actually evaluate any potential damage.
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    inferno Junior Member

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    I wonder. Will the Horsepower of the Gen III be downgraded to that of a Gen II? lol...all this time we were riding inflated "power horse prii"?
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    jdcollins5 Senior Member

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    My thoughts exactly. If they lower the Boost Converter voltage to something less than the current 650V, or limit the current to protect the IGBT's, then we are not going to have as much "umph" when high power demand is needed or as much regen current when braking. The Gen III has more acceleration ability at highway speeds than the Gen II because of this additional boost. I was impressed with how much acceleration was available at 60+ mph when needing to pass.

    I have the Boost Voltage on my SGII so will be able to see this pretty quickly after the recall.

    Like TEM I think I will wait a while before taking mine in for the recall and see what others have to say about the affects of the recall.
    Last edited by jdcollins5, Thursday at 8:27 AM
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    GrumpyCabbie Senior Member

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    I guess it depends on how they program it. When my inverter blew I had been driving erm, enthusiastically over a distance of 20 miles overtaking cars one or two at a time, went down a 2 mile long hill whilst still in Power mode, accelerated to overtake a long truck, got half way past when pop and the inverter blew.

    Now perhaps it was the on off on off boosting that caused the problem. If they limit it to just a couple of occasions within a certain time limit and that way allow the boost for overtaking or joining a motorway, but restrict the voltage for the sort of driving I was doing?

    But I suppose you need to know how the car is going to react? Presently I know when I floor it at 60 the car is going to shift.
    cwerdna and jdcollins5 like this.
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    BardManY2k Junior Member

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    I think the most concerning part is that it simply refers to "the condition", without specifying if "the condition" = compromised transistors or limp mode. I'm not writing it well, but as I read it (glass half full?) it says that they will replace the inverter if it has failed and the car is in limp mode. I think it would be wonderful if they are actually inspecting the components and replacing accordingly - in addition to the software fix also. I will certainly confirm all of this later today with the dealer.
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    Eclipse1701d Prius Enthusiast

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    Hello all. Just had the update installed. No parts are needed, like other dealerships have told their customers. The tech connected his computer to perform the update. The hood was open and there was something connected near the inverter. I couldn't see very well from the customer area... He also had what looked like a battery charger connected in the 12Volt Battery area... The whole thing took about an hour. I could not notice any difference in the drive home other than when using the cruise control, the car tended to go 1MPH above the setting for a longer period of time then I am accustomed to before coming back down to the set MPH... (Had it set at 66 and it would drift to 67 for about 30 to 40 seconds, then come back down.)

    It was 24 miles to home and when I shut it down it reported 51.7mpg for the trip.
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    Dark_matter_doesn't Prius Tinkerer

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    Solid state electronics loose ultimate lifetime by overheating, but it's generally not obvious that a thermal-based failure is imminent. So I'd expect that Toyota won't replace inverters unless they've already failed. They won't proactively replace the units because they might have overheated and lost significant lifetime. Toyota is just too cheap.

    On the other hand, this recall should be the basis for forcing Toyota to replace inverters that fail "prematurely" after the recall is completed (in Toyota's opinion).
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    GrumpyCabbie Senior Member

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    So it might be prudent for me with my new inverter not to get the recall done? That way I'll have the extra performance as well as lots of life left in the inverter (y)
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    squeakywipers New Member

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    My Prius had been at my local toyota the last two weeks - I was rear-ended and had left my car there for repairs/insurance to get their act together. I'm hoping to get it back by this Friday, with the recall service done in time for the long weekend. I like driving long distance for road trips, and this glitch is unsettling....
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    Skateruk Junior Member

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    Hey Grumpy, have a second inverter fitted and double the performance!! :D
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    Mike500 Interessen-Gemeinschaft Prius

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    'Lectric, I guess today's college was equivalent to high school 40 years, ago.:(

    I learned those words in high school Physics 45 years, ago.

    Then again, there was one President who got elected twice for his mediocrity and ignorance.

    In the new employment market, persons with college degrees are working as waiters and barristers at Starbucks.o_O
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    jdcollins5 Senior Member

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    I like your idea better. If they only limit the amount of time allowed at 650V Boost mode that should be fine for most. I know the times that I am passing cars or accelerating hard are few and not very long.

    I haven't had a reason yet to drive quite as "enthusiastically" as you describe above !
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    The Electric Me Go Speed Go!

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    If I'm slowly getting an understanding of what the overheating transistors controlled I wouldn't expect a performance difference except perhaps if driving the vehicle aggressively. I'd wonder about acceleration times or differences. Slower? Less electric boost, more reliance on engine power? Those type of things.

    The "IF" I'm slowly getting an understanding part....is very valid. Toyota hasn't really been very forthcoming with what the software update exactly does....or exactly what changes will happen to the operation of the Power Boost Module.
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    KiwiAl Junior Member

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    A Boost Converter increases a DC voltage to a higher DC voltage. So, the 260V battery voltage gets increased to about 500V DC by the Boost Converter in the Gen2 (and 3, I think). Other (newer) models have higher voltages still.

    Wikipedia - Boost Converter
    Prius mentioned here

    Regarding concerns that the software patch will only fudge over a hardware design problem, it really depends on how it works. I suspect that the software will be the cause of this problem, rather than the hardware itself, because of the way hardware and software are designed these days. (Make the hardware simple, and do all the logic and clever stuff in the software.) Certainly, the inverters that power the motors (MGs) will have to be software controlled because of the complexity of what they are doing, moment to moment, but the Boost Converter?? I can't see the need to have it software driven (i.e. switching the individual transistors at high speed), but maybe it is anyway.
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    bwilson4web 03 and 10 Prius

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    When the weather clears up, I'll run a benchmark test; get the patch; and re-run the benchmark.

    Bob Wilson
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    KiwiAl Junior Member

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    Hi TEM,


    Can't quite agree with you there. Toyota didn't tell you how it worked before this recall (lots of Patents, Trade Secrets and so on, for sure), so why would they tell you how they are changing it now?

    Be Happy that the ultra-proud Japanese are willing to lose face once again by admitting yet again that the product isn't perfect, and are doing something to fix it. Having dealt with the Japanese over product issues, I know how hard it is to get them to actually admit there is a problem. For example, Model "X" exhibits are certain problem. Complain and they admit nothing. But then, when Model "Y" appears, the problem isn't there any more.

    Seems to me that no one here knew about this problem 'til now, so I reckon it wasn't that big a problem, and maybe Grumpy Cabbie is one of the few who had the misfortune to encounter it when pushing the car to its limits. And they are fixing it anyway. Maybe he ought to try to claim damages from that failure and get a refund on his inverter?

    But here's a thought - maybe the Toyota design is really not that good. The modern 3-phase Inverter / Variable Speed Drive is fully able to detect over current - usually using I2T to determine the amount of heat being generated - and trip out the drive. Of course, this is not desirable in an automotive situation - Pop - the Inverter Safety Trips out, mid-overtaking... Pull over to the side, wait for cool down and push the reset button... Yeah, not the best.

    But there is absolutely no reason that the drive can't detect over-power, and throw up a warning light to get the driver to back off, and/or simply derate the output to prevent a failure - just like a rev limiter or a diesel engine top speed governor does. Derating the output under overheating conditions is very common in Power Supplies, but in most power supplies, a constant output voltage is required. If it starts to drop, it's usually all over and the supply shuts down, but it is also possible to reduce the pulse frequency and/or duration to cause the output voltage to drop, thereby reducing the available power. I wonder if the Toyota HSD system does this.

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