Who has done their recall?

What I meant is what you were saying about being aggressive in maintaining speed setpoint, increasing speed rapidly to reach setpoint. It would also hold speed setpoint to within +/- 1 mph when going up or down hills.

Others have indicated that after the update the cruise control is less aggressive and the speed can wander up to 2 mph or better.

You are also verifying this. I will try tomorrow and see if I see a difference.

 

My cruise strayed +/- 2 mph before the recall and after the recall. My Civic hybrid did the same thing. I always figured this was normal for cruise control. I've never had really fancy cars, so maybe I am just used to accepting this as normal behavior.

 

I had an unexpected opportunity this morning to perform a 0-60 trial when I was stopped at a traffic light with no traffic in sight in front of me.

Prior to the update my 0-60 trials resulted in an average time of 10.2 seconds and a fairly consistent 153A HV battery amps.

After the update my 0-60 trial this morning resulted in a time of 10.4 seconds and a constant 120A. The 10.4 seconds agrees with crabbyman's results after the update.

So, it appears that Toyota has limited the rate of rise of the Boost Converter voltage and limited the battery amps as kbeck expected. This is what you would expect in trying to limit current and current spikes to the IGBT's in order to limit heat.

In order to limit the electric motor contribution and still maintain the 0-60 accel rate this tells me that the ICE has to be contributing more than before. This goes along with others indicating that the sound of the ICE has increased after the update as the ICE has taken more of the load than before.

 

Finally got my recall notice. Guess I'll be taking the Prius in to have that .2 seconds added to my 0-60 mph time. Oh, well.

We've driven this car in very hot southeastern weather several times with no problem. One trip, a return from Florida had to be done in a hurry, so we blended with the fastest moving crazy traffic. If component meltdown is possible, I would imagine that particular trip would have cooked it. Especially as loaded down as we were for that month long excursion. We don't do that to this car on a normal basis... it is driven as gently as possible for maximum MPG.

 

From what I understand, it is not the constant loading on the Inverter/Converter that is overheating the unit but the current peaks when accelerating to pass at WOT and heavy regen when going down mountains, etc. That appears to be what Toyota is trying to limit.

GrumpyCabbie has indicated that he was driving at high rates of speed and passing multiple vehicles when his inverter failed.

 

The battery amps in crabbyman's case actually increased from 135.9A to 148.1A, different from yours. So does it mean the update does not necessary limit the battery amps?

I believe the restriction of load factor only kicks in after certain threshold temperature has reached. Under normal operating temperature, the inverter still operates at its full capacity. Here is a link to a patent describing Inverter overheating protection control apparatus and inverter overheating protection control method and may be related to this recall.

Vincent

 

Hi Vincent,

I can only compare the before and after of my car under similar 0-60 trials. Also this was my first trial after the update.

When I did the trial this morning I had just left the house and had been driving moderately and long enough for the ICE coolant to get up to temperature. I would not expect the Inverter temp to have had time to reach any temperature threshold but I was not monitoring Inverter temps at the time.

On other trials prior to the update the car had been driven for some 25 miles back home from work and I would suspect the Inverter temp was somewhat higher than a morning trial. I need to try another trial after the drive home from work to compare.

We obviously need to perform additional trials under different conditions to gather more data before making any further assumptions. It would be nice if others would perform trials so that we could have more data input other than crabbyman and I.

Thanks for the paper.

Dwight

 

jdcollins,

Well, I did predict the rate of rise decrease, but not the battery amp decrease. There seems to be some questions about that later on in the thread. More data from varying participants will help in that regard.

What's also interesting about all this is that people are reporting better gas mileage after the update. Now, that might simply be due to the warmer weather since Spring finally struck, but it might also be real.

The problem with the better gas mileage idea is that if the ICE is providing more energy during acceleration, one would expect worse gas mileage, not better.

Given this and the reports of better gas mileage, then it's possible that Something Else is in play. I now put up my hands and start waving them.

I think it highly likely that extensive computer modeling of car dynamics were performed in Gen I, Gen II, and Gen III. Highway driving, stop and go, data taken from (volunteer) commuters and Toyota employees driving about, and so on. That would be one input into such a tool. The other input would be ICE performance, gearing ratios, transistor performance, electronic characteristics of inductors, capacitors, batteries, and, without a doubt, the algorithms in the engine and inverter controllers. Complex, you betcha. Such multivariate systems can be optimized for whatever characteristics the manufacturer has in mind, with optimization touching things like how much power, how much efficiency, and so on. Results of this tool would go into firmware changes into a car; the car would then be driven around, data taken, then that data plugged back into the tool for correction/more optimization. Note that any driving around would probably be on a set course that would be repeated for each go-around.. But what the course actually consisted of would also be a matter of modeling. Lots of fun.

This would have all started on Gen I, back in the day, with improvements and algorithm changes as Time Moveth On from Gen II to Gen III. Gen III started shipping in 2009, so the Toyota people would have had their arrays of computers cranking away from 2007 through late 2008, freezing the code as production got started. People have noted that there's been occasional updates (bug fixes?) from time to time, but I suspect nothing major.

However, if Toyota is going to ship a Gen IV in 2015 or so, it's a gimmie that they've improved that software test platform: Algorithms, minimizations, driving sequences, and all. Now, they discover late last year/early this year that an Algorithm Change limiting temperature differences on a semi-emergency basis is now in the works. So, do you think they resurrect the old software, computers, driving routes, and all from 2008... Or do they dump it into the new system and give it a whirl?

I'm betting the latter. In which case algorithms may have been improved all over, to the extent possible, and both better (or at least the same) gas mileage and your observed reports about very similar 0-60 mph times, and the current draw, may both be right.

To tell the truth, it's probably going to take a year's worth of Fuelly data and statistical analysis to determine by how much, if any, the gas mileage has improved or decreased. It is nice to see that the driveability/gas mileage numbers haven't changed dramatically, unlike the software changes Honda put into their Insight Hybrid, where the gas mileage got a lot worse after the change.

KBeck

 

Do you ever see something that leaves you incredulous, scratching your head? Just trying to picture: an early morning stroller, witnessing a lone Toyota Prius at a red light, suddenly taking off across the intersection and tearing up the street with protesting tires.

 

Fast and Furious:Tokyo Glide

 

Not sure about the Insight, but our second gen Civic Hybrid had a software update with the expressed purpose of battery protection/preservation. I noticed a possible slight reduction in mpg. It was on the whole a decently done balancing act. Except: one widely suspected effect of that update was it became damn-near impossible for a failing battery to trigger warning lights, the prerequisite for Honda to acknowledge there was a problem.

 

My IMA battery was barely holding on for 30k miles, constantly getting worse and worse and it became rare to start the car without the starter. It literally didn't throw the IMA warning light until I was driving home one night and the battery completely went out.

 

on my understanding,
Toyota try to de-utilize inverter a bit not to push hard, it goes to peak -> ramp-down->flat.
before the recall. the power would go to peak and constantly stay , in acceleration or re-gen.

 

LOL ... there was a big black pickup truck beside me in the other lane at the light. I could not help but laugh at what he must have thought when I took off and left him in my mirror. As soon as I hit 60 I slowed back down to the 50 mph speed limit and he caught back up with me. I caught a glimpse of a grin on his face when he passed by

 

I agree. That is basically what I am seeing at first.

 

It does appear at first glance that Toyota has done a decent balancing act of limiting Inverter and electric motor usage with more ICE usage. I would expect to see a slightly lower mpg rather than an increase by doing this but I guess it would depend on the balancing act and other changes made by Toyota.

My concern now is that I have driven my car for 77,000 miles prior to this update with a 100,000 mile warranty. Living on the coast my car has lived a fairly sheltered life compared to others that live in the mountain areas. Other than my latest 0-60 mph testing I normally drive the car very conservatively .

My question is how close is my Inverter to the pass/fail line prior to the update? I guess it will take time before we see if Toyota continues to see Inverter failures after the update. What if my Inverter fails at 105,000 miles? Is this a patch job to get our Inverters beyond the warranty period? I guess time will tell.

 

We do know for a fact that raising spring temp will raise MPG. There is no need to speculate about additional impact from the recall. I follow my MPG very closely and didn't see any delta that was not explained by ambient temps.

 

Based upon Toyota's description on the problem and their description of the solution, I suspect that you'll be in good shape.

The problem description said, "Cracks under the transistors". Given the context, those would be horizontal cracks, culminating, in a failure case, with the transistor coming off the heat sink.

The problem solution said, amongst other things, "Inspect". Transistors of the type used often have on-board thermal sensors (diodes) and you can bet that the heat sink has something in there, too. A nickel says that during manufacture, either/and before assembly into the car and after, differences in temperature between the transistor and the heat sink under certain fixed loads are checked vs. current and so forth; at least, that's what I, as a EE, would have done. Any such cracks would be apparent since they would do Not Good Things to heat transfer and would therefore show up during factory testing. My guess at the "Inspect" bit is that the dealership update software checks for this since, frankly, nobody's going to open up the case to go look. Cracked transistor solder would get found that way and you'd end up with a loaner until the dealership manages to find a new inverter. Since some posters to the site have reported lengthy wait times for new inverters it's a good bet that this repair process has been going on and some percentage of inverters in the field are being replaced.

Hence, count yourself lucky. And it's a decent bet that your car is fine.

KBeck

 

I hope you are correct with your analysis of Toyota's "inspect" process. You apparently have a more positive opinion of the inspect process than I do.

 

There was some of the WOT and good hills involved in that rapid return to Maine (the one trip I described). Only time I've done that to the car. Generally, our long range travel is done close to speed limits with no WOT or terrible urgency. The fact that our commute is quite rural, allows us to maintain a gentle driving routine on a daily basis.