Gen II & Gen III in snow

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Toyota also swears that it is impossible on the GenII. And if by Toyota you mean Toyota dealers/dealership-technicians then be aware that they are rarely more than trained monkey wrenches. They will even charge you for an oil change with 5 quarts but the Prius takes less than 4 quarts, closer to 3.8q. ​

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I think you may have false preconceived notions about how the HSD works. ​

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Notice how there is no clutch or way to slip anything. It is directly coupled. When a force is applied to the wheel, it is immediately and directly applied to the outer ring gear which is one of the 2 electric motors in the Prius (MG2). MG1 is in the middle.​

The electric motors are always spinning, even when the ICE is not using gas. However with the design, above a certain speed (different between GenII and GenIII) MG1 will over-rev, so the ICE is spun with MG1 to slow it down. ​

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There are 2 potential problems with wheel spin. The major one is what happens when the wheels are spinning and going really fast then get a grip and slow down to almost nothing. MG2 is spinning fast, proportional to a wheel speed of 60mph or maybe 80mph or faster. Now it grips the road and has traction, so the wheel speed is now almost instantly the same speed as the actual vehicle speed. That change in rotation is a huge strain to the system. A side effect can be to induce a large voltage spike. In the Prius (and Camry) the DC-DC converter's output voltage is lower then in the Lexus (500VDC vs 600VDC to 650VDC). So a voltage spike on the regen system could possibly reach more than absolute maximum specifications of 500VDC but might be less then that of 650VDC. ​

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If you ever have the opportunity to drive a RX450h in the snow you will know what I mean in that it works like I think you are thinking it should work.​

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All engineering has design decisions. A larger boost converter from ~220VDC to 500VDC (230% boost) versus ~220VDC to 650VDC (295%) would be less efficient or cost more. The Lexus is 280VDC to 650VDC (again 230% boost, how interesting?!). Pack size and cost go up with a bigger pack, and the Prius is the baby on the low end of cost. Design decisions. You can choose to buy a CT200h which would be more expensive but have different design decisions with the same basic functionality.​

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No matter what vehicle it is good to toss it around and see what it can do. My only car not to do this in is my DMC12 because it doesn't touch snow or ice. ​

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P.S. What's the correct way to do quoting on this site? Standard bbcode doesn't seem to do it. And, I see no "reply with quote" button. What's the code here to attribute the quote to someone? (I'm a retired middleware geek, not a web designer.)​

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Use the "reply" button then copy and paste the [--quote-- "name", post: number, member:number"] tag (or a subset of it) and finish with the / quote like you have been.

 

It was their technical support phone line. I see your point.​

Perhaps, even probably. But, this didn't explain it. I can hear when the ICE is spinning in engine braking mode. I can hear that it is not when accelerating only with the electric motor.​

Regardless, this does not explain why any anti-wheel-spin-bot would not be able to simply reduce power to both engines thus maintaining traction and power rather than cutting all power.​

No interest. I'm not into driving fast cars or driving fast in any car any more. My young and stupid days are far behind me.

True enough, especially in this case where it appears my new(ish) car is far more different in handling than I had realized.

Regarding quoting text, I use the noscript plugin for firefox. It helps to first enable javascript for contextweb.com. Else, you don't get the quoted text in your reply at all. Once javascript is enabled for contextweb, yes, it is easy, just as it is on another forum I frequent. I was not aware that I had scripts turned off for anything other than google-analytics and twitter.

 

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Their technical support is no better than calling up Dell or Microsoft consumer help lines. "Is there a problem? Yes? Did you reboot it? Well then I have no idea, lets replace it at your cost."​

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This is what works for my GenII. I am not sure if it works in the GenIII. To disable TC:​

1) Car off
2) If not on flat surface, apply parking brake
3) Turn on, (Not READY) -- Press Power button twice, with no foot on brake
4) Pump gas pedal, pedal to the metal, 3 times
5) Shift to neutral (note: this requires you to press down the brake pedal then hold the shifter over for a second or two. Release brake pedal after in neutral)
6) Pump the gas pedal, pedal to the metal, 3 times
7) Face towards Japan and sacrifice a small woodland creature to the Toyoda empire
8) Put back in park
9) Pump gas pedal 3 times again, same deal
10) Car will beep, MFD will display "Problem!" and have a car with an '!' in it.
11) Step on the brake, press the power button.

Car will now be READY with the "Problem!" error. The engine will always run and not shut off regardless of stage. Traction control and stability control is disabled. ​

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In "B" mode, the engine not only spins, it spins at high RPMs so it is more audible.​

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But you can move without spinning the ICE in pure electric, but only so fast. Anything below 42mph MG2 can spin the wheels while MG1 spins the ICE counter to MG2 cancelling it out and making the ICE spin 0rpm. The 42mph magic number is when MG1 goes into 6500rpm range which is its "red line". The other scenario is if you are going 0mph (MG2 is static) you can rev the ICE up to about 1800rpm before MG1 redlines again around 6500rpm in the other direction. ​

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I don't think I get it, or you get it. Can you explain how such a system would work? ​

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t = 0, driving normally, everything ok​

t = 1 , the front wheels have struck a patch of ice, the driver does not yet realize it and the requested throttle position would cause the TC to kick in. The computer has not noticed because the wheels are still going the same speed​

t = 2, now the wheels are on the ice, the accelerator is still asking for more power but when applying to the wheels the wheels spin causing different speeds to be detected by the sensors, the Prius' traction control system now knows there is a problem and needs to regain traction​

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This is where the decision on what to do next comes into play.​

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Now that the computer knows the wheel is spinning, it is already going faster than vehicle speed. If it were to regain traction milliseconds later that sudden torque would be bad mojo for the drivetrain and a possible converter spike. So what to do? ​

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In a non-TC car, you can equate this to when you finally got off that patch of ice with wheels spinning and the car went "ca-chUNK" throwing the front end into the ground, your head forwards then as it gripped your head back into your headrest.​

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It's a "soccer mom" type hyrbid SUV with AWD. It is fast, but useful. More comfortable than anything else. But my point is mostly the same components with a boosted dc-dc output can be made to reduce power instead of cut power. If you drive one, then you will know what real traction control feels like. Not nanny drivetrain control that the Prius has.

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Ah. I don't care about what scripts run and actively encourage them. I enjoy AJAX pages and most of my personal sites employ a PHP backend with an AJAX front to get things done. I find it cleaner then constantly changing the address or refreshing when you need new content. But that is a completely different discussion that FHOP would probably enjoy.

 

Momentum really is key. The only time TC has stopped me dead was when I was trying to back over a muddy berm, from a muddy road, to park the car at a Christmas tree farm last year. Stopped me dead and I was doing about half a mph. I had to pull farther ahead and gun it so I had some momentum to pop over the berm without the TC shutting me down.

I've been very impressed with the TC and ABS on snowy/icy roads, including an impressive assent of my buddy's steep, paved... and ice covered driveway just last weekend. But again.. momentum. If I had every come to a complete stop halfway up the driveway I doubt I would have been able to get going again. TC would have shut me down cold.

 

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I have tried this. It does not work on a Gen 3. In fact, step 5 is not even possible in Gen 3 Prii. One cannot take the car out of park if the car is not READY.​

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As for the whole thing about not applying power to the electric motor, if that is a problem, all I can do is explain what happens on a significant downhill. If the downhill is just the right slope, neither too steep nor too flat for the current wind, friction, and rolling resistance, you can see (in a Gen 3 display) that no power is being produced by either motor. The car is just rolling. In my vision of an anti-spin system, if the electric motor truly is a problem, which I don't really believe, I would have the ICE producing the power that the downhill produces in the above coasting example and have the electric motor coast. I don't think this should be necessary. I think the anti-spin system would be able to apply less force.​

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I'll try. First though, remember that if you "hulk smash" your brake pedal with ABS, you do not produce any skid marks. Somehow, and you're the engineer so you tell me how, the ABS detects impending skid and reduces the force on the brakes.

This is what I want the anti-spin system to do. It must detect impending wheel spin in whatever small time frame works for ABS in exactly the same way. Then, it can "feather the gas pedal" electronically at the amount of forward force that keeps the wheels just on the verge of spinning, but not spinning.

Just as there are no skid marks from ABS, I would expect no ca-chunk from anti-spin. It's in the spec, my version of the spec. If the engineers can't produce it, perhaps we're not ready to have the system.

There have been many examples of people thinking of great things for which the level of technology was not available for years or even decades. The SQL database language was developed many years before anyone had fast enough computers to make relational databases a reality. Now, they're on the way out. But, they are still huge 45 years after the first production version.

(geeky tangent)

I started using noscript because of cross-scripting taking control of email and sending spam from my account. I love that I can disable google-analytics and other crap. Noscript is a pain because you enable scripts on a per site basis. So, for things like yahoo mail that uses AJAX, it works perfectly after enabling scripts once. The other really great add on that I highly recommend is Adblock Plus. Unlike noscript, adblock has no downside at all. It simply clears your screen of advertising and frees your available bandwidth from the task of loading ads.
(/geeky tangent)

 

BTW, we've now ordered these tires (Continental ProContact with EcoPlus) that we hope will not be too bad on mileage and also hope will last. Consumer Reports rated them just below the Michelin Defender that some have said is a huge hit on gas mileage. They actually get higher marks than the Michelin in some areas. Unfortunately, people are complaining both about puncture risk and about short tread life. We decided to give them a try anyway since they're better on snow and should be much better on mileage. It seemed worth the risk. The Michelin EnergySaver A/S gets terrible write-ups for snow as well as some complaints about tread life. Else, that would have been a no-brainer.

Continental USA Car / Light Truck / SUV -ProContact™ with EcoPlus Technology

 

As I said in my first post, I need to learn some new technique for keeping momentum. It used to be easy. I used to keep my foot partly on the gas and not worry if the tires spun just a bit. With front wheel drive, cars don't fishtail. In fact, the spinning tires actively pull the car in the right direction. So, a bit of spin? Who cares??!!?

Now, the car stops me dead in my tracks if I spin. So, I'm buying tires I hope will be better and will try not to spin at all. When TC kicks in, I'm dead. So, I need to learn to avoid it at all costs. I had been going 30+ MPH when TC killed all of my momentum. A bit of wheel spin would have been an utter non-event and would have kept my momentum with no trouble, regardless of 2k1Toaster's disbelief. I was there. I could have kept going for miles with that much momentum.

 

Not sure I agree with you about the Subaru without snow tires, I had a forester that went up steep snowy inclines, on the beach etc etc. Michelin x-radials. Felt like you could go anywhere.

 

The Michelin X is/was among the grippiest all season tires around. I think they'd be bad for mileage on a Prius. But, if you're going to compare a Forester with crappy tires, these are not the tires to use as a comparison. True, no all-weather tire will beat a snow tire in snow. But, the X is a good tire nonetheless. I've gotten through a lot of snow with camrys and other front wheel drive cars with tires that were no match for those.

Just playing devil's advocate, for my part. I don't think comparisons between Prii and AWD or 4WD vehicles are really all that relevant. IMHO, it always makes sense to buy the most fuel efficient vehicle that meets one's needs. If those needs are driving on real 4WD tracks on a regular basis (as opposed to well-maintained gravel roads), the diesel Prado (not available in the U.S.) might be a good choice. At an estimated 29 MPG with the ability to lock the diffs and plenty of ground clearance, it should get through almost anything. In Australia's top end, I did drive 4WD tracks and never even needed to switch to 4 low, let alone engage the diffs. And the fuel efficiency is better than most U.S. passenger cars. Actually, it beats our national average for our fleet of cars.

Toyota Land Cruiser Prado - Wikipedia, the free encyclopedia

Here in the NE of the U.S., it is rare to even find a poorly maintained gravel road. So, most of our SUVs are laughably overqualified or overpowered or even more often, just plain stupid. I always have to laugh at the morons with Lincoln Naggravators and low profile racing tires. Those things aren't good for anything. Neither are most of the "sport" versions of SUVs that have all sorts of suspension bits hanging down and reducing their ground clearance to only a bit more, or sometimes not even more, than a normal passenger car.

In fact, driving cross-country in the U.S., we didn't come across much that we couldn't get through in a Prius. After 7.5 miles on a moderately maintained gravel road that we knew to be 8 miles long, when we hit a sign that said "Stream Crossing Ahead", we even made it through the 3 stream crossings that followed. I believe that was near Olympic National Park, if I remember correctly. Or, perhaps a bit farther south along the west coast.

 

I drove a Generation 2 Touring Edition (2007) for 3 years, it was no problem in snow, but performs, as all cars do, better, and safer, with a good set of winter tires. I drive 2010 Generation 3 in the 5 model configuration with the low profile 17" wheels and tires, In winter they have P215/45-R17 Michelin Primacy Alpin PA 3 Winter Tires and the car drives well on everything so far.

 

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You sure? I can do it on my RX450h and I have seen reports of others doing it too...

Turn the car on with 2 power button presses but not using the brake, then hold the shift lever in the neutral position for a few seconds. It should be possible. I have seen the most mention of it from people who do this to shift the car into neutral without READYing it to roll it places. Like in/out of a garage.

 

I didn't try holding it in neutral, just tapped it. I'll try holding it next time we drive somewhere and will let you know how it goes. Thanks.

 

The Prius and no HSD should go to neutral by just tapping it. You must hold it there. READY or not, the neutral position takes time to register. The only way to get to neutral instantly is while READY and while going at a speed above parking pawl speeds (~7mph). Then if you press the park button or shift to R the car will beep and be in N.

 

To drive ANY vehicle in snow, the largest benefit will always be gained by two things: a set of nice steel wheels from the Tire Rack, and a set of actual snow tires (Blizzaks or equivalent). These tires really are different, you will not believe how much better your car does with dedicated snow tires. And their own wheels means that you (or any shop) can throw them on in less than a half hour, and you're good to go.

Note 1: I live at 40 degrees North Latitude, in the heart of the heart of the country.....here, snow tires are a tossup.

Note 2: When the snow gets much deeper than the lowest part of your undercarriage, you're not going much of anywhere, no matter the state of TCS, or whether you've got 2,4, or 16 wheels driven. As someone alluded to earlier, if you want to plow snow, buy a snowplow.

 

rico567,

This may be true. However, as I said above, I'm not going to stack a spare set of wheels and tires or even just tires on my coffee table in the living room. Living in an apartment means there is no space for an extra set of tires. I've never needed dedicated snow tires on any other car to get through a northeast winter. And, snow tires would shred in a week on summer pavement. So, I need all season tires that work well enough, even if they're not as good as dedicated snows. I hope that the tires I've ordered and plan to have on Friday will be good enough. I can't say when my next snow test will be. I'll be sure to post the non-scientific, empirical results when I have them.

 

I could be mistaken, but I believe I read that only battery power is available to a Prius when in reverse. I guess that would preclude any TC at all.

 

I had hoped to have more information for an update. However, I have not hit really difficult driving conditions since this discussion. I have tried the Aztec Two-Step again and the gen-3 does go into "Maintenance Mode". So, I'm keeping those instructions in the glovebox in case they become necessary.

I'm also finding the new tires far better than the old. What snow we have hit with them has been much easier to deal with. Traction control has not engaged. That said, we have not yet had a case of driving up a steep back road covered with snow and ice. So, only time will tell.

The new tires also provide a smoother ride on irregular and imperfect pavement. And, the car feels significantly better in turns. I liked the handling in corners before. I like it more now. Gas mileage is suffering a bit. For the first 1,000 miles, it was significantly worse, maybe 2-3 MPG lower in the worst gas mileage conditions. Now it seems to be getting better again. It may not really be back to our prior 51.4 average yet. But, we haven't hit warm conditions yet either. The car was always worse on MPG in winter. I expect it always will be. If nothing else, the ICE must be kept warm enough for both heating the car and responsive re-starting of the engine.

I'll post another update if we get worse driving conditions for a better test or as the MPG of the tires stabilizes.