REEV concerns

OK, Don... My main beef was with those who initially claimed that ~25hp would be enough ICE power when they saw charts that said that is all that is needed to maintain highway speeds.

GM ended up using a more Prius sized ICE, and 53kWh is probably enough nearly all of the time with that healthy battery assist for occasional passing requirements. I am content to wait and see if any Volt owners complain about long hill climbs or not. It might be acceptable, but time will tell.

donauker said:

I assume you are aware that the "CVT" in the Prius is not actually a CVT.

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Yes, I have a Synergy drive vehicle myself.
Toyota does call it a CVT.
Prius Glossary

CVT is a type of transmission with an infinite number of gear ratios that are always changing depending upon the relative speed of the vehicle and the engine rpm. There are several types of CVTs. Hybrid Synergy Drive® uses an electronically controlled CVT (ECVT) which integrates a planetary gear set into the drivetrain.

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By the way, for whatever reason, Toyota has decided to increase ICE size for the 2010 model:
Toyota's 2010 Prius breaks cover

...The move from 1.5 liter to a larger and more powerful 1.8 liter Atkinson-cycle, four-cylinder engine should significantly improve the power to weight ratio and the performance of the Prius. The current 1.5l Prius has always scored well in city driving due to its regenerative braking but it has been noticeably lacking in highway performance due to its small engine capacity and the additional weight of a battery pack compared to vehicles with similar engine capacity. Contrary to conventional wisdom, the larger engine actually helps improve highway mileage. By making more torque, the new engine can run at lower average rpm on the highway. When operating at lower rpm, the new engine uses less fuel.

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The 4 cyl VVT-I puts out 98 hp (72 Kw) @ 5,200 rpm with 105 lb/ft (142 Nm) @ 4,000 rpm compared to 76hp (57 Kw) and 82 ft/lb (111 Nm) in the current model.

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Slightly related discussion:
High revs uphill - GreenHybrid - Hybrid Cars

Prius and steep inclines - PriusChat Forums

I must say, my experience on the grapevine was slightly different. It was one of the only two times that I felt my car wasn't quite powerful enough. Don't get me wrong, the Prius is a great car and handles everything nicely. It's just occasionally you might wish it had a little more oomph.

Anyway, onto the story.
I was headed southbound and all was fine. There was enough power, I had enough to noticeably accelerate with, too. That is, until the the last couple miles or so on the final uphill stretch. I was slowly falling behind traffic (which was cruising around 72 mph...but increasing!) and I found myself pressing the accelerator lower and lower. Finally, with the pedal floored I was going 76 mph with cars continuing to pass me. Even highway patrol decided to go around me. Needless to say, I was a little disappointed -- for the first time -- not because I couldn't keep up (I could, just barely) but rather I had no margin for safety. I was literally maxed out.

If you're wondering when the only other time was, it was southbound on highway 5 (ironic that it's the same freeway) somewhere near the Oregon-California border. Although this time the car was loaded with people and luggage. Again, it wasn't that I couldn't keep up, it was just the fact that I didn't have anymore room for a "just-in-case boost."...

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...I'm beginning to think that some running algorithms were changed
around '06 to manage the pack charge a little differently when
moderate to heavy power is asked of the engine and a larger
throttle opening is necessary at higher altitudes. My '04 took the
SOC down to one pink bar [from only 3 or 4 blue!] on the way over
Vail and Loveland in CO this summer [11000 feet or so] and with
nothing left in the battery, I was on the engine alone and having
to push it right up to 4000 or 5000 RPM to match "normal" traffic.
At 78 HP or less that is a bit anemic for the weight of the car, but
I was perfectly fine with climbing more slowly and waiting it out
like any loaded semi would.

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Avoid

Do You Regularly Drive in Mountains?

The Prius will not climb very steep hills indefinitely. One aspect of the vehicle's design that drastically improves economy and reduces emissions is that the engine is not sized for the peak power demand. When heavy acceleration or steep hill climbs are called for, MG2 provides a boost to meet the performance needs using power from the battery. Although heavy acceleration can't go on for very long and the battery gets a chance to recharge, in some parts of the world you can find steep hills long enough to drain the battery to its lower limit. At this time, you have only the ICE power to run with and you'll be forced to slow down. You'll still make it to the top. People have driven to the top of Mount Washington, which averages a 12% grade for more than seven miles. But, after the battery power is gone, the maximum speed (according to my calculations) will be about 40 m.p.h. Not being able to climb Mount Washington at 60 m.p.h. is, of course, no reason not to choose a Prius. But, if your daily commute happens to be over the California coastal range or some other long steep hill, joining the trucks in the extra slow lane might wear a bit thin after a while.

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Nice explanation of Toyota's Synergy Drive "power split" device.
(yes, eCVT is a bit of a misnomer, but Toyota does use it too).

How much power to maintain speed?

...
22 HP to maintain 55 MPH
...
50 HP will maintain 55 MPH up a 6-7% grade.
...

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...Also going up even a 1% incline will change the results as well...
rolling resistance will be reduced by 1% as the normal force against the road is no longer the whole weight...
so ~6.57 Watts less rolling resistance... but you traded it for gravitational force acting against you... which means ~1% of the gravitation force of the car becomes a counter force... or about 834*9.8*0.01= ~81.732 N * 13.411 = ~1,096 Watts = ~1.1kW of gravitational resistance to even a 1% incline...

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...Gravity:
as you go up an incline your normal force for the rolling resistance will be decreased.
So a 1% incline will reduce your rolling resistance to 99% of the 0% incline rolling resistance.
while at the same time adding 1% of the vehicle weight as a pull against you... 834 * 9.8 = 8,173.2 * 0.01 = 81.732 N
...

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TEG said:

Nice explanation of Toyota's Synergy Drive "power split" device.
(yes, eCVT is a bit of a misnomer, but Toyota does use it too).

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Yes, this is the single best source of information on the Synergy Drive I have ever seen. Oddly enough it was this site that several years back started me down the road to electric.

Being a techno geek all of my life and a computer programmer most of it, I was intrigued by the complexity/simplicity of the Synergy Drive. After studying all of Graham's writing's in depth I just had to have it and purchased my Lexus 400h. The brief periods of electric only drive lead me to trying to maximize electric mode which of course became frustrating in how limited it was. After a few months with the Lexus I decided any new personal vehicles I would purchase would need to have a plug and a substantial electric only range.

Same story for me basically.

My wife's Highlander Hybrid (same drivetrain as the 400h) sits in the driveway next to my RangerEV, which was the most I could afford to get myself a plug in vehicle with decent range, and batteries that will last more than a few years.
The Highlander will be our long trip car, and hopefully the RangerEV gets replaced by a "BlueStar", SmartEV, MiEV, or some such affordable EV once the Ranger eventually wears out. Perhaps "Model S" if something miraculous happens, but I am not holding my breath on that right now.

donauker said:

After studying all of Graham's writing's in depth I just had to have it and purchased my Lexus 400h.

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He is a different and much more knowledgeable Graham, just in case there was any confusion! :smile:

Just a quick (probably uninformed) question .... but it seems like the issue with the Prius on hills/mountains is primarily due to the relatively small battery that drains too quickly to provide any useful impulse on a hill. With the Volt, the battery is substantially longer and should be able to provide full power on a hill ... provided that the hill is not too long (many miles of mountain/hill driving) or the battery is not too fully depleted when starting.

Question: Couldn't the problem be substantially addressed by a toggle switch for the driver to let the car know to keep the battery nearly fully charged. i.e. if you know you are driving up to Mammoth Mtn, then tell the car, and it will maintain the battery at full charge state. A fully charged battery plus the engine should be able to last quite a while -- 40 miles of mountain, minimum, by definition.

Similarly for a range-extender on the Tesla: if you turn on the range extender when you start driving, then even a small range extender should be able to get you quite a distance. i.e. 250 miles nominal electric mode + (3 charging hours while you're depleting your electric range * 25HP) + (whatever time that buys you * 25HP). I expect the result would extend the range out to ~500 miles...

Dan.

DRM said:

...Couldn't the problem be substantially addressed by a toggle switch for the driver to let the car know to keep the battery nearly fully charged.

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Or include an inclinometer in the car and in a setup menu tell it what angle you want to kick in the ICE,

Couldn't the problem be substantially addressed by a toggle switch for the driver to let the car know to keep the battery nearly fully charge

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Yes! I had been saying that before. If you started on a drive from SF to Tahoe and flipped the "try to keep my battery at least 80% full" switch as you left, then the ICE would come on sooner, and you would start uphill past Sacramento with plenty of charge to 'make the grade' uphill without problem. The possible problem (as I see it) is the weak ICE coupled to a strategy of "drain the pack first" with no option to override.

Another option would be to have it GPS/Nav coupled and it calculates what you need based on the destination you programmed in at the start of your trip.

DRM said:

Couldn't the problem be substantially addressed by a toggle switch for the driver to let the car know to keep the battery nearly fully charged.

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I would think just integrated with GPS, which should have elevation and road speed data. Similarly you want the battery near empty when you return home for full benefit.

This thread is very similar to using the Roadster as a grocery/long distance vehicle. It should be used just as GM is intending it for. The range extender used only when one miscalculates one's travel distance for the day.

REEV concerns should be about the product not meeting the manufacturers stated performance. What I've read here so far is like the analogy of buying treadmill and then hanging clothes on it instead of exercising on it.

Use the Volt as it is intended. Plug it in nightly and pay the premium for the peace of mind that you can forget every now and then yet not get stranded when you need it most.

What I got from this thread, so far, is that if you are in the city (travel 40 miles or less) and in the market for a hybrid, buy the Volt. If you don't want to plug in, buy the Prius.

BTW, how far off do you think GM will be with the Volt launch? Will it launch with more or less bugs than the Roadster?

Takumi said:

BTW, how far off do you think GM will be with the Volt launch? Will it launch with more or less bugs than the Roadster?

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I think even with them rushing to get the car to market, it will have less bugs than the Roadster. After all, they are still a large automaker and they have fairly strict testing. I think they have already evaluated what potential bugs may pop up and have, for the most part, parts lined up and probably testing for at least the initial release.

The question is if the company survives long enough for the car to be released.

Don, something else I just noticed:
2010 Toyota Prius Sales Will Hit 100,000 in 2009, Toyota Says | Straightline Blog on Edmunds' Inside Line

Other efficiency improvements this year include a smaller, lighter front transaxle that's gear-driven rather than chain-driven to reduce friction. A new planetary reduction gear allows the front-drive electric motor to run at higher rpm -- a 13,500-rpm max compared to a 6,400-rpm max previously. The inverter is also smaller and lighter, thanks to improved cooling.

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Old vs New (2010) Prius transaxle:

The chain is gone!!! I always found it humorous that the Prius used a chain. (did the other toyota hybrids use a chain also?) I wonder why they got rid of it. To improve packaging? Efficiency?

On the whole "ev mountain climbing deal," none of matters. The EV market is tiny and production figures will be modest in the near future. Neither the market nor the problem is large enough to make mountain driving/speeding a limiting factor in the short-term success of EVs.

Joseph said:

The chain is gone!!! I always found it humorous that the Prius used a chain. I wonder why they got rid of it. To improve packaging? Efficiency?

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It was in the quote:

Other efficiency improvements this year include a smaller, lighter front transaxle that's gear-driven rather than chain-driven to reduce friction.

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TEG,

Thanks for that picture. The original design was amazing in its compactness and the new one is truly a work of art! Adding the gearing to MG2 thus allowing for a higher rpm / lower torque motor design saved a good bit of space.

Elon takes a swipe at REEVs, Jalopnik takes a swipe at Elon: Jalopnik - Tesla's Elon Musk Continues War Of Aggression Against Volt, REVs - elon musk

I don't think there is much here that hasn't been said before, just gawker et al raking up old stuff.

Ya know, I read that this morning from GM-Volt.com. I preferred the version without all the editorializing.

Tesla CEO Critical of the Chevy Volt | GM-VOLT : Chevy Volt Electric Car Site