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Ex-Tesla Spokesman: EPA's Electric-Vehicle Range Figures Are Grossly Inaccurate (1y old but useful article) « Open Forum « News, Reviews & Misc
 
Fri, 30 Apr 2010, 1:51am #1
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Edmunds.com article:

Ex-Tesla Spokesman: EPA's Electric-Vehicle Range Figures Are Grossly Inaccurate
http://blogs.edmunds.com/greencaradvisor/2009/05/assets/images/darryl-siry.jpg
Darryl Siry (left ), Tesla Motors' former chief marketing officer, blogs that he sees a troubling pattern emerging in how the most critical aspect of electric vehicles - range - is discussed by companies and the media alike.

"These are problems that could have a significant negative effect on the way the public responds to electric vehicles if manufacturers don't change the way they communicate expectations about range," wrote Siry, who is now a senior analyst for clean technology at Peppercom, a strategic communications firm.

The basic problem is that when an EV is described, it usually has a single "range" number associated with it, Siry wrote.

For example, the Tesla Roadster has a range of 244 miles. When people talk about the range of a car that is planned in the future, they also offer a single number. For instance, the media has reported that several car companies plan to come to market with EVs that have "a 100-mile range."

"Every time a single range figure is given, it should have about three asterisks next to it," he wrote.

'Your Mileage May Vary'

The biggest of the asterisks is the EV equivalent of "your mileage may vary." Using the Tesla Roadster as an example, Siry wrote, the car can indeed achieve a range of 244 miles (which is the Environmental Protection Agency's "combined number".)

In fact, one Roadster was driven as far as 275 miles before it was fully depleted, he noted. But under aggressive driving the actual range from a full charge to completely dead can be dramatically lower.

That is all well and good, but the problem is that the EPA driving cycle numbers systematically overstate what the typical driver is going to see in their daily driving.

It wouldn't be so bad if the EPA number was close to the average and depending on your driving you might see less or you might see more, wrote Siry, but it doesn't work that way. In reality, the EPA number is essentially an upper-limit number.

"The actual range you will get from a complete charge depends on a lot of factors, but I would say that as a general rule of thumb, if a company quotes an EPA range, you should apply a factor of 70 percent to that to get a realistic average range for a full charge."

'Full Charge'

The second asterisk relates to how "full charge" is defined. You'd think that should be straightforward, but it's not, he writes. In general, a battery pack should not always be charged to it's peak nor should it be drained to completely (or even nearly) empty.

"This is generally bad for the longevity of the pack. However, when the EPA test is done, the battery can be charged to its absolute maximum and the car is run until the wheels literally stop moving. This is not how a typical customer will experience a 'full charge,' " he wrote.

The typical charge settings for a car will charge a battery when it's still 10-15 percent energized. It may even limit performance or go into limp-home mode at some level above that, perhaps with 20 percent charge remaining.

These are all important factors to consider when you assess the realistic range of an EV, Siry wrote. "Depending on how the manufacturer has designed the battery management system, and depending on how the EPA test was conducted, you may have to apply another 70-80 percent factor to the range that the manufacturer states.

"Combine factors one and two above, and you are talking about average usable range of the car potentially being half of what is quoted as the EPA range. That is a very big gap in expectations that will come home to roost with consumers. If you think 'range anxiety' is a big issue, wait until the average consumer buys the car and on day 1 the average usable range is about 50-75 percent of what they were told in the marketing material (depending, of course, on how aggressive the marketing claims are)."

The Two Ranges

The third asterisk relates to the EPA's "beginning of life" range. The problem with it, as Siry wrote, is that the maximum capacity of a battery pack dwindles over time.

There are a lot of factors that affect how rapidly this reduction in capacity occurs, including number of cycles (roughly this can be expressed as miles driven/total miles per full charge), absolute temperature, variability of temperature over the life of the pack, average depth of discharge.

"This can also be a complicated discussion, but suffice it to say that the effects can be significant," Siry wrote. "It isn't an exaggeration to say that you should expect that the range of your EV could be 20 percent less after five years of use. In fact, that's being charitable."

Siry wrote that this is especially true for certain chemistries or cell types, such as the high-energy cobalt oxide cells used in laptops and cell phones. The end-of-life range of these types of packs could be significantly lower and the reduction much more dramatic. This is one reason that almost all manufacturers are moving toward chemistries that exhibit better cycle-life qualities.

So building on the example above, the realistic end-of-life range of an EV may be well below half of what was advertised.

This is a serious issue because the general public is not going to easily understand all the mental gymnastics that go into having a good understanding of what to expect from an EV, Siry wrote. This is also an issue that gets more serious as EVs go mainstream and are no longer purchased mostly by wealthy early adopters willing to forgive these quirks and inconveniences.

Solutions 1 & 2

He wrote that there are two solutions to this problem - and mass adoption of EVs by the mainstream public depends on them.

The first is that manufacturers need to communicate honestly and transparently about the realities of range. The second, he wrote, is that the EPA must establish new guidelines and standards specifically for EVs that address the issues outlined above.

Most importantly, the EPA should develop a standard that includes both the beginning-of-life range and the end-of-life range with a common definition of the expected life of the vehicle.

"If both of these things happen, we can avoid the consumer backlash I fear we are headed for with regard to range expectations," Siry wrote. "With so much progress being made on the EV front, I would hate to see the momentum slowed by false promises and disappointed consumers."

Posted by Scott Doggett May 18, 2009, 9:42 AM Link

Last edited Fri, 30 Apr 2010, 11:43am by student


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Fri, 30 Apr 2010, 2:03am #2
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Where he was while at tesla? :)


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Fri, 30 Apr 2010, 2:10am #3
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I think he was in charge of the people that put this graphic on the website:

http://www.teslamotors.com/images/content/well_to_wheel_energy.gif


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Fri, 30 Apr 2010, 2:33am #4
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The EPA range rating for the Tesla Roadster should be treated like the EPA rating for MPG: for comparison purposes only, and don't expect yours to be that good. As I've noted before, the real-world driving range for the Roadster is reported at 160-200 miles, or 65-82% of the EPA range rating.

But the EPA number seems to be nonsense for PHEVs. 230 MPG for the GM Volt? Please, that's just silly-- it has *no* relation to the MPG anyone will actually get when driving.

I actually do agree with the bashers ("Student" and Y_Po) on this point; the numbers are misleading, and a buyer who expects to get the range listed on the sticker on the window of his new car is in for a very rude shock.

I hope the EPA revises its method of rating EVs, and revises it soon. And car companies should offer realistic range numbers to would-be customers, unless they want to have a *lot* of very unhappy customers.


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Fri, 30 Apr 2010, 3:07am #5
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So what it boils down to that this car has a practical range of less than half what is advertised. Its no great surprise of course, but considering it will only carry two people with no luggage and costs $100,000 it sounds to me like only a total numpty would be tempted to buy one.

I'm amused by Lensman's sudden conversion. Not long ago he was brandishing the same page displayed by Student as being gospel truth! Lets not be too hard on him however. He is making progress.

Presumably we have to apply this sort of degredation to the Leaf too. So its practical range is perhaps fifty miles?? In other words unless you can charge the thing up at your destination and afford the time to do so, you can only visit places 25 miles from home?

Again, it would seem to be a car designed for idiots to buy.

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Fri, 30 Apr 2010, 3:15am #6
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The difference is that MPG is not an upper limit. Some people, including myself, experience much better mileage when driving a ICEV than advertised.

With EVs, however, the EPA is not an average - it is more like an upper limit you will hardly ever see.

"It wouldn't be so bad if the [EV] EPA number was close to the average [as with ICEV EPA mpg] and depending on your driving you might see less or you might see more, wrote Siry, but it doesn't work that way [for EVs]."


Bill Nye says limits for a dielectric are simply what have been demonstrated to date.


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Fri, 30 Apr 2010, 3:51am #7
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Lensman wrote:

I hope the EPA revises its method of rating EVs, ...

That method was never official, and they've already said they won't use it.


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Fri, 30 Apr 2010, 4:48am #8
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Here is Darryl Siry's original blog post:

The Problem With Electric Car Range Figures
May. 14, 2009, 8:40 PM

I see a troubling pattern emerging in how the most critical aspect of EVs – range – is discussed by companies and the media alike. These are problems that could have a significant negative effect on the way the public responds to electric vehicles if manufacturers don’t change the way they communicate expectations about range.

The basic problem is that when an EV is described, it usually has a single “range” number associated with it. For example, the Tesla Roadster has a range of 244 miles. When people talk about the range of a car that is planned in the future, they also offer a single number. For example, the media has reported that several car companies plan to come to market with EVs that have “100 mile range.”

Every time a single range figure is given, it should have about 3 asterisks next to it.

The biggest one is fairly well known, and is the EV equivalent of “your mileage may vary.” Using the Tesla Roadster as an example, the car can indeed achieve a range of 244 miles (which is the “EPA combined” number.) In fact, one Roadster was driven as far as 275 miles before it was fully depleted. But under aggressive driving the actual range from a full charge to completely dead can be dramatically lower.

That is all well and good, but the problem is that the EPA driving cycle numbers systematically overstate what the typical driver is going to see in their daily driving. It wouldn’t be so bad if the EPA number was close to the average and depending on your driving you might see less or you might see more. But it doesn’t work that way. In reality, the EPA number is essentially an upper limit number. The actual range you will get from a complete charge depends on a lot of factors, but I would say that as a general rule of thumb, if a company quotes an EPA range, you should apply a factor of 70% to that to get a realistic average range for a full charge.

Which brings us to asterisk #2, which is how “full charge” is defined. Seems like it should be straightforward but it’s not. Nothing in the land of EV marketing and communications is. In general, a battery pack should not always be charged to it’s peak nor should it be drained to completely (or even nearly) empty. This is generally bad for the longevity of the pack. However, when the EPA test is done, the battery can be charged to its absolute maximum and the car is run until the wheels literally stop moving. This is not how a typical customer will experience a “full charge.” The typical charge settings for a car will charge a battery to some point, perhaps 85 or 90%, and will consider the pack “depleted” somewhere above 0%. Lets call it 10%. It may even limit performance or go into “limp home mode” at some level above it, perhaps with 20% charge remaining. These are all important factors to consider when you assess the realistic range of an EV. Depending on how the manufacturer has designed the battery management system, and depending on how the EPA test was conducted, you may have to apply another 70-80% factor to the range that the manufacturer states.

Combine factors one and two above, and you are talking about average usable range of the car potentially being half of what is quoted as the EPA range. That is a very big gap in expectations that will come home to roost with consumers. If you think “range anxiety” is a big issue, wait until the average consumer buys the car and on day 1 the average usable range is about 50-75% of what they were told in the marketing material (depending, of course, on how aggressive the marketing claims are.)

But wait! We aren’t done yet. Asterisk # 3: The EPA range that is quoted to you is the “beginning of life” range, or “BOL”. The problem is that the maximum capacity of a battery pack gets lower over time. There are a lot of factors that affect how rapidly this reduction in capacity occurs, including number of cycles (roughly this can be expressed as miles driven/total miles per full charge), absolute temperature, variability of temperature over the life of the pack, average depth of discharge. This can also be a complicated discussion, but suffice it to say that the effects can be significant. It isn’t an exaggeration to say that you should expect that the range of your EV could be 20% less after 5 years of use. In fact, that’s being charitable.

This is especially true for certain chemistries or cell types, like high-energy cobalt oxide cells used in laptops or cellphones. The “End of Life” (EOL) range of these types of packs could be significantly lower and the reduction much more dramatic. This is one reason that almost all manufacturers are moving toward chemistries that exhibit better cycle life qualities, like NMC, Iron Phosphate, and Manganese.

So building on the example above, the realistic EOL range of the EV you will buy may be well below half of what was advertised when you bought it. The good news is it will charge to full in less than half the time!

This is a serious issue because the general public is not going to easily understand all the mental gymnastics that go into having a good understanding of what to expect from your EV. This is also an issue that gets more serious as EVs go mainstream and are no longer purchased mostly by wealthy early adopters willing to forgive these quirks and inconveniences.

There are two solutions to this problem, and I propose that both begin immediately. The mass adoption of EVs by the mainstream public depends on it.

First, manufacturers need to communicate honestly and transparently about the realities of range. This may be hard to do because of the complexity of the issue and the fact that it is tempting to just hide behind to rosy EPA figures. In the long run, however, people who actually drive these cars are going to share their real world experience and if expectations aren’t set appropriately up front there is going to be a lot of disappointment.

Second, the EPA must establish new guidelines and standards specifically for EVs that address the issues outlined above. Most importantly, the EPA should develop a standard that includes both BOL range and EOL range with a common definition of the expected life of the vehicle.

If both of these things happen, we can avoid the consumer backlash I fear we are headed for with regard to range expectations. With so much progress being made on the EV front, I would hate to see the momentum slowed by false promises and disappointed consumers.
This post originally appeared on Darryl Siry's blog.

Site I grabbed it from.


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Fri, 30 Apr 2010, 12:53pm #9
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If I had a Volt I'd definitely get better than 250 mpg. More like 1000 mpg.


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Fri, 30 Apr 2010, 4:55pm #10
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Darryl Siry was at Tesla Motors in the early days, when they were very open and forthright about their progress-- and problems. Siry ran a blog and IIRC a private forum for Roadster owners on the Tesla Motors site. Later, after what Martin Eberhard called a "stealth bloodbath" in which about 10% of the employees were laid off or fired, Tesla Motors clamped down on the information flow, hiding their problems and what they were doing to fix them. This was the culmination of the process whereby money man Elon Musk "eased out" co-founder Martin Eberhard, who was first demoted and then fired, with Musk basically becoming an auteur, controlling *everything* at TM.

Of course, I have no idea exactly why Siry was terminated... whether he resigned or was fired. Clearly Siry favored the openness under which TM originally operated. I suppose he's not happy to see TM become as secretive as the average business; perhaps that's the main reason he is no longer working there, regardless of whether his leaving was his decision or Musk's.


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Fri, 30 Apr 2010, 5:11pm #11
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Tec wrote:

So what it boils down to that this car has a practical range of less than half what is advertised.

A practical range between 65-82% of advertised is "less than half"?

Tec... and I don't mean this unkindly... are you getting senile, buddy? If so, that would explain a *lot*.

Darryl Siry interview wrote:

"I would say that as a general rule of thumb, if a company quotes an EPA range, you should apply a factor of 70 percent to that to get a realistic average range for a full charge."

I'm glad to get the opinion of an expert on this! That sounds like a good rule of thumb.

Tec wrote:

I'm amused by Lensman's sudden conversion. Not long ago he was brandishing the same page displayed by Student as being gospel truth!

No "conversion" here, Mr. Diesel-Head. The chart is much better info than anyone on *this* forum has researched-- including me! Apparently you don't understand the meaning of "for comparison purposes only".

Last edited Fri, 30 Apr 2010, 5:20pm by Lensman


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Fri, 30 Apr 2010, 5:54pm #12
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95% of the time people drive less than 40 miles before they are back charging their EV.
Since my garage does not have a gas/diesel pump range matters because it is a hassle to get refueled. The only time I may consider the range limitations of my EV is for very rare long trips. I guess I would recharge during a lunch/leg stretch break.
hmmm, imagine a vehicle however where you never need to go to a gas station, get oil changes, and brake maintenence is rare. I hope they put that on the sticker!


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Fri, 30 Apr 2010, 6:02pm #13
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ricinro wrote:

hmmm, imagine a vehicle however where you never need to go to a gas station, get oil changes, and brake maintenence is rare. I hope they put that on the sticker!

The experience of EV owners, such as those who owned EV-1's, is that maintaining an EV can be done at only 1/10 the cost of maintaining a gas guzzler.

This is one reason why the popularity of EVs will snowball, once batteries/capacitors come down in price and up in ED. People don't generally consider the cost of maintenance when buying a car... but the word *will* get around once lots of people start buying EVs!


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Fri, 30 Apr 2010, 6:17pm #14
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Hmmmmm... There might be a business opportunity here. Drive a big honkin' diesel truck with a diesel powered emergency generator on the back to charge up all those stranded EVs that didn't make it back to their charging stations. (:->)


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Fri, 30 Apr 2010, 9:09pm #15
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EEpower wrote:

This thread is about Darryl Siry, didn't he basically quit to avoid being fired:

We just got word that the turmoil at Tesla Motors is continuing as SVP for Marketing and Sales Darryl Siry has tendered his resignation. According to the post on Siry's personal blog, he is leaving "due to some disagreements in strategy.

This would be perfectly in keeping with his above blog. Apparently he didn't want to lie to customers like his boss wanted him to. A man of integrity.


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Fri, 30 Apr 2010, 10:18pm #16
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student wrote:

Apparently he didn't want to lie to customers

He choose wrong profession then.


Q: What would happen if you give 12V battery and two 6V light bulbs to Weir/Nelson?

A: They will wait 8 years for 12V➜6V DC-DC converter.

http://theeestory.com/topics/3687
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Sat, 01 May 2010, 4:49am #17
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Is it important why he made these statements?

The point is that they make excellent sense. We all know that companies are likely to thrash a brand new battery to death, severely damaging it in an attempt to maximise 'range', we all know that you can't get the full advertised charge in and out of batteries, and we all know that they degrade with time.

The case he is making is entirely plausible, which is more than you can say for the advertising material produced by the manufacturers.

I've lost count of the number of times I've seen an ad for a flashy car dripping with whizz-bang features at a ludicrously low price, only to find that the model featured is the top of the range one costing 50% more than the accompanying price which turns out to be the price of the bottom of the range one and doesn't include tax!

I wonder whether Lensman has ever actually entered a car showroom with the intention of buying a car. He seems to be a car salesman's dream customer. Those of us who have, usually more often than we'd like, are a lot more sceptical and with excellent reason!

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