Volt Sales Figures

The concept Volt’s shape is also modified to achieve better aerodynamics and platform constraints. IMHO, the essence of the concept is still preserved. I would support the modification of EREV’s minor applications during various driving conditions to achieve better efficiency.
As for the well to wheel figures, there are so many calculations already.
I supported Bush administration’s decision going into Iraq in the past. Knowing what I know now, I can’t in good conscious to say the 10 years of costly war and almost 5000 troop’s lives has nothing to do with oil. If we included the cost of secure oil supply, the costs of oil extraction, refining as well as transport (and ignore environmental costs,) the cost of oil really can’t be exceeded by other sources. As we know currently there is no 100% coal generated electricity in the world, so the dirtiest electrons are still cheaper/healthier and coming from domestic source. As far as I am concern, I would pay more in my renewable source electricity bill to support the development of technology than paying unstable regions’ people who most likely are trying to destroy United States.

 

That's not really a definition. I've been following the Volt from its announcement and I've never interpreted it as you have. We have infered different things from the statement.

FYI. when the Volt was first introduced it was not even called an EREV (it was called E-Flex then). At the time (Jan 2007, see Green Car Congress: GM Introduces E-Flex Electric Vehicle System; Chevrolet Volt the First Application

First I saw of a GM definition of E-REV was in 2008 in a blog post.
The posting has disappeared but is cited at Driving the Volt)

That definition was made official in an April 2008 paper (At the SAE Advanced Hybrid Vehicle Powertrain meeting) by
Tate, Harpster and Savagian from the General Motors Corporation. See http://www.media.gm.com/content/dam/Media/microsites/product/volt/docs/paper.pdf)
In their paper they say there is no SAE definition and propose an EREV be defined as “A vehicle that functions as a full-performance battery electric vehicle when energy is available
from an onboard Rechargeable Energy Storage System (RESS) and having an auxiliary energy supply that is only
engaged when the RESS energy is not available."


Their definition is about the performance when battery is available, and explicitly prohibiting blending the RESS energy and the auxiliary energy supply. It does not say what level of battery can be held back in defining "available". So as I read it, neither mountain and Hold modes violate that definition. (And when you use MM or Hold mode, as designed, when one exists the mode, the car returns back to approximately the same battery state, thus they are not violating that definition, just changing the "minimum SOC" (And my understanding is both modes are litterly implemented by just changing the minimum SOC value).

Probably the most useful distinction from their paper is
"An E-REV does not need to start the engine for speed or
power demands from the driver and therefore does not
need to transition to a Blended operation strategy when
battery energy is available, unlike the Initial EV PHEV."

(Their definitions would classify the PiP as an Initial EV PHEV, because
you cannot get to all speed power.

The primary focus of the paper is showing that by allowing pure EV performance, they can reduce fule consumption and improve emissions.

I would agree that in their simulations they did presume all the battery is used first, but because of the way the EREV operates in the simulations, it would only improve the results if, on longer they cherry picked what miles to use for pure EV/CD mode, and which to use for CS mode. But such selective use of the battery (hold mode) would have muddled the result and were not necessary to prove their point.


You can make up your own definitions, but as I understand it, Tate et al. definition was the starting point for the definition being considered under the SAE standard effort J1715. I know there are people working on that, but I've heard nothing official on that standard definition.

 

Perhaps you missed the Figure 7. It specifically shows SOC 25% when CS mode is engaged. Turning on the gas engine before this threshold would violate the proposed EREV definition. Changing the threshold in MM would also violate as power is no longer "available" per the initial threshold.

Alternating between CD and CS mode should be considered blending as well. That's what PiP is capable of doing with the EV/HV button.

BTW, the "Initial PHEV" they used in the comparison is horrible! No wonder that Vue 2-mode plugin was killed.

For the record, PiP achieves eAT-PZEV with cold engine starts -besting Volt with ULEV so the premise of that paper only applies to GM hybrid and GM Initial PHEV.

 

Yes I've seen figure 7, but it is an example, not a definition.

Blending is when the ICE +EV must work together to provided the requested level of performance.

Saving Battery is not really different than having a smaller battery and then recharging somewhere. It may be operating a mixed-mode (mixing CD and CS, but that is not at all the same as blending). If the Volt drives 40miles EV, 10 gas. recharges, drive 40miles EV, 10 gas -- your definition would say that's blending. Its not. Again we can wait for the SAE standard definitions (which I'm hoping will define blended mode more formally).

The Volt is never blending -- which is using the plugin power to augment the primary drive train when the power demands. Its either in CD mode or CS mode. Hold and MM just impact when its in each one. (Though the EPAs stupid decision to not let US have Hold enforces more of the CD uses all battery power first).


And from everything I've read the PiP EV button will not magically allow it to do 75mph (let alone 100), or very high demand driving, so the EV/HV button cannot stop blending except by limiting the driver's ability to access the full range of performance.

eAT-PZEV means each cost start is better. My wife's outback is PZEV too. Big whoopie. If one considers that the EREV will have less than 1/4 as many starts at all, and that 60% of the population can use Volt with 0 starts on almost all trips, the eAT-PZEV is not really better. Divide the volt emissions by 4 and its cleaner than a Prius. But CARB/EPA's testing methodology is antiquated and does not actually account for either start frequency or AER range. If the Volt had 300 or 3000miles of battery range, it would still only be a ULEV as its based only on data when started, not how often it will actual start. But clearly a 3000mile range EREV would produce less emissions.

 

PiP's EV mode is a vast improvement from regular Prius's EV mode usability to pseudo-highway speed, IMHO. I really wish PiP to sell well. Even though I had hoped that it will be priced lower to facilitate mass adoption. There are more powerful forces to wish the whole movement away from oil monopoly fail. We can split hair all day with different efficiency numbers under different scenarios, but at the end of day PiP and Volt are both much better than gas guzzlers that sell so well this year. Hybrids merely account to 2.6% of total vehicle sold in November. We need to get general public used to the idea that using plugs are not as scary as all the nay sayers lead them to believe. More than ten years ago there are a lot of headlines about how Prius is going to be a failure and the battery replacement cost is going to make used Prius utterly unusable. We now know the opposite are true. We can continually hold grudges that part of the funding for the headlines were from US automakers and oppose to anything coming out of those makers. That will only strengthen those powerful forces’ goal to limit hybrid and EVs to a niche market. To move hybrids and EVs to broader acceptance we need competition to drive down price. Even though Mitsubishi i is too cute of a jellybean for me, I really hope it will sell like hotcakes too. J

 

Let's use that example then. 85% is full and 25% as empty (plug electricity no longer available). If you use gasoline at 65% SOC, that violates EREV definition.

Perhaps you misunderstood. It is not blending because you exhausted the battery first.

If you go 20 miles on battery and 10 miles on gas and another 5 miles on battery until it runs out, then you are blending two fuels. You could have went the entire 35 miles on battery. You have a hybrid that alternates between two fuels. EREV must exhaust the battery first before tapping into gasoline to extend the range.

How about when the gas engine is running for the cabin heat? Does all the generated power only go into the battery? How can you tell it does not get routed back to the motor?

In CS mode, Volt blends with a clutch to PSD to turn the wheels.

I only need to provide one example to prove that Volt is not an EREV. I provided three.

 

Considering the strength of the oil lobby in America, it is surprising that American car companies even have hybrid/electric cars. As long as gas is plentiful and below $4 a gallon, the electric car market here will be miniscule.

 

I can tell you the experience that I saw. The gas engine won't just run anytime when it needs heat. It only happens when temp goes under 25 F. In Texas, my friend’s Volt went through whole winter last year never experienced engine running just for heat. When the engine does run for heat, the power doesn't go to the motor because by default system favored EV operation (just like when in service mode to burn stale gas, so engine load is as low as possible.) From other Volt owner's experiences are engine shut off quickly (less than ten minutes) once the heat is sufficient.
In CS mode the clutch only engages PSD under the situation that speed is more than 75mph, in favor of efficiency. I won't hold this against them because I would hope under this demanding situation I would get most efficiency available. CS operation under highest speed limit in Texas would theoretically never calls for clutch engagement , thus no turning of wheels. Of course drivers can do whatever they want.

 

Since a 'pure' EREV is a stupid design, I imagine most Volt owners are breathing a sigh of relief and trying to forget the years of GM misinformation. I will say though that the present Volt implementation is mostly EREV, and therefore inefficient.

 

First, the concept of "winter" in Texas is hard to take seriously, here in Minnesota.

Second, we know for a fact that direct-drive can be engaged with speeds as low as 30 mph. Where did the 75 come from? And why wouldn't the system take advantage of efficiency from blending as long as the engine is running anyway?
.

Blending can offer the best of both worlds, intentionally avoiding it never made any sense. It was pretty much just a marketing gimmick to appear more advanced.

In reality, advancement comes from tweaks to the components & software. There's optimization & cost-reduction Toyota has embraced that GM hasn't even addressed yet. For example, Toyota's use of sub-packs is likely a big contributing factor to how the battery can be air-cooled rather than requiring a fluid. To accomplish that, there's the obvious need to monitor individual temperatures and adjust draw on-the-fly. That sophistication takes time to develop & refine. Simply using one big pack instead is effective, but crude & expensive.

With so much price spin and the omission of electricity usage from owner reports, it will take awhile still for consumers to realize the "superior" technology isn't what it first seems. The impression is that using electricity as much as possible is the best choice... which isn't always the case... hence the marketing approach for EREV losing effectiveness.
.

 

1)Hehe, yes Texas is mild in winter. The point is it won't turn on in every situation just for heat as a blanket statement.
2) I stand corrected it should be 70mph. When enigine turned on for heat they usually just run for few minutes at lowest load, why would tack on motor demand be more efficient?

I don't have any intention to be confrontational. It’s not in every situation that blending is the “only” way to go, even PiP still can’t complete 20 miles roundtrip commute without burning gas. PiP is a better choice if one needs to commute over 80 miles daily than Volt. Volt is better in daily commute of 40-60 miles than PiP IMHO since I don’t have to burn gas or burn very little.

 

We will just have to agree to disagree. As I previously stated in several of my earlier posts, electricity in my case is renewable at 14 cents per kW. I would pay to the development of energy research or upgrade of grid and in both cases domestic generated; rather than paying for continual oil monopoly and in more cases, unstable regions’ economical development. I like the choice of able to insulate myself from oil prices fluctuation if I work hard, but I also can’t fit 100 miles range into my life around Fort Worth metropolitan before sufficient level 3 charging are common sight in DFW. I can't do that with PiP, as I stated before I considered Leaf and Prius before I decided on Volt. Blending has it's place but doesn't "always" make sense. Same can be said avoiding blending doesn't "always" make sense either, but it's definitely not "never" making any sense.

 

I'm more inclined to accept BLutz's explanation: they wanted to offer an EV experience for as much driver time as they were able given the battery size constraints, and sacrificed efficiency as the required trade-off.

And yes, giving the marketing department a bullet point of "no oil" (some of the time) appealed to the simple-minded customers and the overarching message.

 

Same was said with first gen Prius by critics in regards to efficiency. I don't feel EREV is a stupid design but you are entitled to have your opinion. Which I find it to be more simple-minded than my rational of not using oil if I can.

 

I should be more accurate and say that a pure EREV design is inefficient compared to a blended, optimized HSD, and in that sense it is stupid.

GM obviously agrees somewhat, as you can see in the ways blended mode can be or must be used.

Huh ? Critics also said the traction battery would require replacement every 5k miles. Stick with facts. I use efficiency to mean wh/unit-distance when power-plant to wheels are compared.

 

For the record I don’t think those critics were right at the time but there was no way to prove them wrong then. The main point for you to attack first gen Volt's efficiency on using ICE as range extender. I just want to point out that efficiency number will improve in the subsequent generation of generator. But that doesn't necessary mean just because this application is not as well as it could be and that makes the concept stupid. Prius improves on each generation, there is no reason to believe Volt won’t do the same. If you still can’t see that then that’s OK
Pure efficiency number doesn’t mean anything to me if I have to burn gasoline during the day when I can avoid it.
I don’t want to get into an argument with you except you called people don’t share your view simple-minded. If you find me annoying to you can just ignore me.

 

It looks like the misconception is spreading.

Blending doesn't equate to an "always" absolute.

It simple means that sacrifices aren't made for EV purity.
.

 

First, it seems you are mixing the concept of a Blended PHEV, and a Blended Control strategy.

A Blended PHEV, like the PiP, is a vehicle which MUST use a blended strategy because it cannot provide the full range of performance with just the EV. That does not mean it cannot be operated in pure EV mode for some cycles, e.g. A PIP should be capable of doing UDDS in EV mode, but not US06. See IEEE Xplore - Sign In
for their definition.

An EREV has full EV performance and does not NEED to use the ICE (as long as their is sufficient battery available).

These are classes of vehicles. The PiP is a Blended PHEV. The Volt is an EREV.

You cannot prove the Volt is not an EREV, the Volt defined the EREV class. It may be the car has can operate in modes that don't fit neatly with the academic paper with an early definition, but the Volt is the definitive EREV.

PHEVs with weak electric engines need to blend, EREV's don't.


Operational modes for a PHEV can be Charge Depleting (which means the grid energy (battery), on average, is being depleted/used) and Charge Sustaining (which means the battery, on average, is maintaining its current level of charge). There can also be a Charge Adding mode where charge is, on average, being added to the battery from the onboard fuel source. The EPA procedures define how to measure when a vehicles reaches "charge sustaining", everything before that is considered Charge Depleting. (Current testing proceedures do not support Charge Adding modes. )


During Charge Depleting mode, a the car can use a blended control strategy, or a electric-first control strategy. In a blended control strategy the car supplements combines (blends) both power sources to meet the required operational demands (speed or power) or to improve emissions. A blended control strategy allows for a longer CD mode. Electric-first control strategy will use the electric power until its reached its minimum SOC, and then switches to CS mode.

In a Blended PHEV, the electric-first can either limit the operation performance to stay within its EV performance parameters, or it can switch to blended control when demand requires.

In an EREV the strategy for all testing will be Electric-first, which, since its not limited will consume all the battery.

For the EPA/CARB testing they only consider simple scenarios and simple strategies are sufficient. Real life is more complex and users may choose to do things EPA/CARB does not consider in testing. Does not change the definition of the vehicles control strategies .

If one defined 25% as the minimum SOC, then its the given chart.
With mountain mode one defines the minimum SOC to be 45%, so it would be a different chart. In EU, the Hold mode could define the minimum charge as 85%, if the user chose. So what? The operational control strategy of the Volt is EV-first until it reaches minimum SOC, then switch to CS mode. No blending control is ever used -- unlike a PiP, the Volt EV motor can do it all so it does not need to blend.

The Volt will never allows anyone to exhaust the battery. It only allows one to use the battery down to mode-specific minimum SOC.

The "exhausted" requirement was not part of your vauge definition of blended. You have yet to provide a citation to a definition that supports your claims.

Alternative between two control strategies using different fuels is clearly a "Mixed Mode". It is not blending because its not depleting the stored charge while using gas or supplement the EV motor with power from the ICE.

Blending will hopefully be formally defined as a vehicle control strategy blending grid-based (plug-in) energy form the RESS with onboard fuel-based energy. Blending is an an onboard engine control strategy and is defined so the EPA and and others can meaningful measure/separate milage that is benefiting from grid-based energy, and the onboard fuel-based energy.

A Volt is either using EV (and deleting its RESS), or in Charge-sustaining mode on gas. If it switches, e.g. to preserve added RESS needed for mountain travel, it simply enters CS mode sooner. If I stop the car or switch out of that mode, the human is choosing to say more battery is now available. This is the fundamental difference between mixed and blended modes. The car is not making a choice, the driver is. An EREV uses the "Available", but nothing in that definition says the driver cannot be selecting what is available.
EPA does not test any mixed strategies.

Actually none of the generated power when running for cabin heat goes into the battery, the car switches to Charge-sustaining mode and consumes the energy to drive. Once the engine is sufficiently hot, the car returns to charge-depleting mode with the same level of battery charge as when the engine-started due to temperature. One can tell by looking at the kWh before/after. (However, regen during CS mode will put charge back in the battery). I've not tested it enough to know that it will never charge the battery, but in the 6 times I've measured it, it has not.

I will grant you that engine-running-due-to-temperature is not consisten with a pure EV-first control strategy (as this is the car's choice, not mine). I wish they did not have this feature. But this is not related to the operational strategy of the car with respect driving. And even if I'm not driving the car but its on it will run the ICE for temp.

On the other hand, its not blending, it just switched back to CS mode (i.e. mixed modes).

Not sure what you mean there. In CS mode the Volt CAN operate as a parallel+serial hybrid, or as just a serial hybrid. Neither of those are blended operation as they are not blending the grid-provided energy with the gas energy. In CS mode its all gas-based energy.

You provided none, because you don't seem to understand the difference between vehicle classes and control strategies. It not clear you understand how the Volt actually operates nor what "blended PHEV control" means.

On the other hand this is all semantics and definitions. I don't want you confusing others with poor semantics, but I don't expect too many care about this level of semantics (if people do want it to tol continue to discuss it, but it really should be in its own thread).

 

Is it optimally efficient, probably not. But Volt owners are more likely breathing a sigh of relief that the volt is way more efficient than any other hybrid and comes without the range limitations of Leaf or iMeVs. I know I am.

A Pure EREV is only a "stupid design" if the person considering does nto really undertand it. Maybe you are projecting a personal unusual transportation constraint as if they were common. An EREV is not ideal for everyone, but it is for lots of Americans.

 

First one has to define how you want to measure efficiency. if one defines efficiency interms of oil usage, as quartzav already pointed out, he an EREV can generally be way ahead. If one measures it in terms of CO2 or pollution, and charges on Renewal power, an EREV is generally better. If one measures it on cost for fuel, an EREV is generally better. if you measure it on how efficiently it uses gas, presuming its using gas, then a HSD is better.

For any given "efficiency metric", the comparison of an optimized HSD versus an EREV depends very much on the expected travel patterns of the uses. If going long distances a blended plug-in HSD may be more efficient. If doing a commute more common in the US, the EREV is generally better.

And note you are comparing the first generation EREV with the 3rd generation Prius. The first gen "optimized HSD" only achieved 41MPG, so one would have to driving 100's of miles a day to make the first generation optimized HSD more efficient than the first generation EREV.

I've addressed Blended Mode above. I'd be interested to here you describe how and when a Volt is "blending".