Max Range Charge Option

[dmen]

Reading about the Tesla road trip article in New York Times got me thinking about Ford's decision to limit a driver's access to the full 23kWh of the FFE battery pack. While I still don't see any documentation of this on Ford's websites, my experience concurs with other users here, in that my battery's effective capacity is 19.5 kWh or 85% of true capacity. A recent longer trip I took used 16.1 kWh and left 19% of capacity remaining. That gave me a total capacity of 19.8kWh. I figure a few hundred Wh were regenerated by braking, resulting in the slight discrepancy. So, I would really like to see Ford update the charging system to allow the option to charge to 100% of the 23kWh capacity.

My understanding is that LEAF can be charged to 100%, though it is recommended drivers do not routinely charge above 80%. Tesla's Model S apparently has a "Max Range" charge setting- with it turned off, the battery charges to 90%, but turning on the feature allows one to charge to the full 85 kWh. It appears Tesla also discourages routine Max Range charging to preserve battery life.
I understand Ford took an approach of more hand-holding to keep our batteries alive as long as possible- top speed limited to 84, no DC Fast Charging option, and preventing charge to 100% of capacity. But I also understand that occasional full charges should not significantly affect battery life, especially if the car is driven right away so it doesn't sit for an extended time with 100% full batteries.

Besides, it seems to me that the EPA efficiency/range calculations for FFE are based on 23kWh- The EPA testing cycle's average efficiency of 320Wh/mi gets you 72 miles based on a 23kWh battery, but only 60 miles based on 19.5kWh battery. I know from gas car experience that EPA efficiency ratings are very rough estimates, but if Ford allowed EPA to base their ratings on 23kWh, and post those numbers on the vehicle sticker, we owners should at least have the potential to access that capacity, right? It seems like false advertisement otherwise.

 

[user 3729]

It seems to me like FFE drivers are getting about the same range LEAF drivers get on a 100% charge, and maybe more in cold weather.

While I agree with the premise that more range is better with EV's, I think Ford's goal here was to make an EV where drivers didn't really have to worry about range degradation. Just spend a few minutes on the LEAF forum and you'll see how upset many drivers are about how well their batteries are holding up, particularly in hotter climates. Ford anticipates little to no range loss in these cars over time. Perhaps the BMS will extend the usable portion of the battery to compensate for range loss?

In my climate, the way I see the LEAF is ... I have about 80 miles of range * .8 (80% charge limit) * .8 (degraded battery) ... That's about 51 miles of range I can count on, at most, in a few years, and maybe 45 miles or less in cold weather. As a buyer, that's a huge turn-off. I realize that many owners will experience a better outcome, but when evaluating the purchase I don't want to be overly optimistic.

I think the FFE charge limit was a good decision based on the small pack size. I have a much greater confidence in the FFE battery based on that, and its active thermal management.

My personal feeling is that with a Tesla, you have a lot more to range start with, and a little degradation does not have as much potential to harm the usability of the vehicle. There would be a lot less temptation with a Tesla to do a max charge in the first place.

I don't know how the EPA does their math, but the numbers don't add up on the Model S or LEAF, either.

 

[dmen]

It seems to me like FFE drivers are getting about the same range LEAF drivers get on a 100% charge, and maybe more in cold weather.

The LEAF ranges I've seen posted on forums are generally higher than what I see with FFE, but then again I haven't looked at LEAF forums recently. I'll say forum posts should be taken for what they are- there are people who inflate their numbers because they like the brand, and people who drop numbers to make it look bad. Not sure if there are any objective data for LEAF owners, but FFE owners do. Most if not all FFE owners will sign up with MyFordMobile, and most of those will not opt out of features. Features include these nerdy challenges. MyFordMobile's "EV Stretcher challenge" records top 10 distances traveled in a single charge for owners split into 15 regions over the past month. It's not range exactly, but an approximation. It's actually better than range to me, because it's more like effective range. Who ever actually takes their vehicle to 0? It's like a gas car, you learn to put in gas before you ever get that warning light. With FFE, the "warning light" is 10 miles left in budget. The visual then turns yellow and the car warns one to turn off any accessories. After seeing it once or twice, I've been trained not to go that low.
Anyway, in my Midwest region, if you ignore the Ford test vehicles, the top distance is 100 mi. Good, but not really impressive. I'm at 7th with a 66 mile trip. I'll tell you that trip was without passengers, 1/2 highway driving at 65, and without cabin heating. Ambient temp was 35-40. In general, temps below that demand at least occasional cabin heating to defrost fingers/toes and windshield, and that results in no more than 50 miles to a charge for me. So I believe there are at least 20 FFE's in Illinois, and this region includes MI, OH, WI, IN as well- that means the average driver in this area is not even seeing 66 miles to a charge, or doesn't feel comfortable driving that far before plugging in. I am sure distances will increase in the spring/summer. But not by too much- #8 in the region that includes CA, where ther must be 3-400 FFEs on the road, is 95 miles. I read that to mean it is VERY hard to get 100 miles to a charge.
Well, 66 miles is just fine for my day-to-day needs. I can make 3 daily commutes before plugging in. But If I want to go to Milwaukee for summerfest, or MI harbor country, I'm gonna have to drive extra carefully. With those missing 4 kWh, I'd have a peace of mind several times a year, or avoid having to rent a car.


While I agree with the premise that more range is better with EV's, I think Ford's goal here was to make an EV where drivers didn't really have to worry about range degradation. Just spend a few minutes on the LEAF forum and you'll see how upset many drivers are about how well their batteries are holding up, particularly in hotter climates. Ford anticipates little to no range loss in these cars over time. Perhaps the BMS will extend the usable portion of the battery to compensate for range loss?

Yeah, I stayed away from LEAF because I had the benefit of those early battery concerns when I was in the market. I understand the blame is primarily put on the poor temp management and the high mileage some drivers are putting on their cars. I've heard a bit about quick charing causing some of the problem too. I guess I haven't heard actual evidence relating to "full charging", or how often full charging needs to happen before it causes problems. Armchair physicists seem to say if it's less than once a week and especially if the vehicle is promptly driven, ie the battery isn't stored for days at 100% charge, the impact is not significant.
I'll say it would be genius if Ford gradually increases the available capacity of the battery over time to compensate for normal degradation. I seriously doubt Ford has done this. Wouldn't they have told us? It seems like something that can be updated though...

In my climate, the way I see the LEAF is ... I have about 80 miles of range * .8 (80% charge limit) * .8 (degraded battery) ... That's about 51 miles of range I can count on, at most, in a few years, and maybe 45 miles or less in cold weather. As a buyer, that's a huge turn-off. I realize that many owners will experience a better outcome, but when evaluating the purchase I don't want to be overly optimistic.

Then I would see the FFE as 80 mi * 0.85 (85% charge limit) * 0.9 (FFE's battery will degrade too, though ? how much)... to get 61 miles of range you can count on in a few years. If you get more, which you probably will, then great. But you really should be ok with this possibility if you are planning to buy this car. On the plus side, if your local temps don't get below ~45 degrees, you won't see a winter range drop.

Anyway, I think you're looking at this in a different way than I. You are comparing two vehicles, and you have the benefit of knowing if not from Ford then from users on this forum what FFE's battery system actually lets you use. I own this vehicle, and when I researched it, and when I purchased it, I was led to believe that I had 23kWh of energy available to me. I was led to believe that if I drive with an efficency of 320 Wh/mile, I could go 76 miles. Unfortuately that is simply not true. I care less about whether the vehicle can travel farther than another vehicle I don't own. I care about whether I can drive the vehicle that was sold to me, or a limited version of that vehicle. And whether or not there is good reason for the limitation, there is no communication from Ford acknowledging or explaining it.

 

[user 3729]

Ford definitely needs more community involvement, and maybe even some marketing. It is hard to find anything about this car... I'm not sure how they expect to reach their sales goals, but that's another topic, I suppose.

 

[jeffand]

Laboratory testing has shown after 100,000 miles or 8 years of simulated use, the battery used in Ford focus had over 90% of its capacity left. Now this is not real world testing but a simulation. In the real world the battery packs are subjected to extreme heat and cold ( -30 to 110F ). Only time will tell how well the batteries will do. :ugeek:
Two primary things decrease the range of any electric vehicle, using the climate control and speed.
Driving at 65 mph no climate may give you a range of 60 to 70 miles. Now driving at 45 mph should increase the range to just over 100 miles.

 

[user 3729]

That's about in line with what Tesla is projecting for the Model S.

 

[Arthur]

Here's a suggestion for Ford: Don't lie to your customers!

In a recent comment, "jeffand" said: "...driving at 45 mph should increase the range to just over 100 miles." That WOULD be true, if the car's EPA range rating (76 miles) were correct. It is not. The correct number should be 61 miles! That means that driving at 45 will result in a range of just over 85 miles. Try it! That's what you get: just over 85 miles! For me, that's the difference between just barely being able to get from Corning, NY to Rochester, NY ...and NOT being able to make it to Rochester!

Do the math: The combined (city/hwy) rating of "miles per gallon-equivalent" is 105. So far, so good. I believe that 105 is a good estimate of what kind of MPGe you will get, if you drive this car like a typical driver, in typical driving situations.

First, you should know that the electric equivalent of 1 gallon of gasoline is defined, by the EPA, to be 33.7 kWh.

So, that means that 105 miles per gallon-equivalent is the same as 105 miles / 33.7 kWh. Since 105 / 33.7 = 3.116, that means that 105 MPGe is equivalent to 3.116 miles/kWh. Multiply that by the 19.55 kWh (85% of the total 23 kWh) of battery energy that is available for use, and you get: 3.116 X 19.55 = 60.92, which means that the actual range, that corresponds to an MPGe of 105, is 61 miles!!! ...NOT 76 MILES!!!

Is "lie" too strong of a word? Is this just a simple arithmetic error, by the crack team of electric-vehicle engineers at Ford? Sh*t, I hope not, ...because, if it is, I can just imagine all of the other errors that they made, during the design of this car. It should fall apart, any day, now!

Frankly, I LOVE my Focus Electric. It's a great car! It doesn't really need all of the worthless software gimmicks. In fact, I would prefer a car where there were fewer gimmicks and more adjustable parameters. Call me silly, but I'd like to make my own decisions about some aspects of how my car functions.

Unfortunately, Ford can't give us that kind of user control of our own car. In fact, they don't even want us to know how our car works. It's called "proprietary information" or "intellectual property." Yeah, that's right, the detailed information about how this car works is NOT the property of the OWNERS of the car. If they told the OWNERS how it works, then Ford's competitors would find out, too, and that's just bad for business.

Well, guess what?!?! Having p**sed-off customers is bad for business, too!

Ford fails to realize where their real advantage lies. Many people (myself included) bought the Focus Electric, because it is the only fully-electric car being made BY UNION WORKERS! That wasn't the only reason that I bought a Focus Electric, of course, but, it was an important one.

Two thirds of Nissan's workers are "temps," who are not allowed to work enough hours to qualify for health benefits. Nissan also engages in some pretty aggressive "union-busting" tactics, to intimidate their workers and scare them into choosing not to meet with workers from the rest of the auto industry (the United Auto Workers Union), to begin the process of organizing a local UAW union, at the Nissan plant, in Tennessee, where the Nissan Leaf is now built, or at any of Nissan's other plants, in Tennessee, Mississippi, or Georgia.

Now, back to talking about the Focus Electric: I would like to be able to decide how much of my car's battery to use, both at the top and at the bottom. I'd like to do everything possible to maximize my battery's lifetime, but I'd also like to avoid being stranded, just because I couldn't use a tiny bit more battery energy to get to my driveway. My understanding is that the C-Max Energi is programmed to learn your route, and, if you keep running out of battery energy, just before getting home from work, it is capable of learning that, and allowing just enough extra energy to be used, to avoid running out. However, that route-learning program does not seem to have been included with the Focus Electric.

At the top end of the battery charging process, there is also a problem. I live at the top of a 600-foot hill. If my Focus Electric's battery is 100% fully charged, when I leave home, to go to work, then, it won't be able to capture the braking energy, from going down the hill. I have been watching this, and, sure enough, if my battery in NOT full, the battery accepts much more charge than it does when it is "full." Who knows! Maybe the battery is not REALLY full. Maybe Ford has just set some charging limit that they won't let us know about, much less have any control over. However, even if the battery really IS 100% full, then, Ford could have had the foresight to include an option that would allow me to set my car to stop charging, when the battery reaches 98% of "full." That would be just enough to make room for the energy that I could capture while braking, as I go down my hill. As is, I have 3 options: 1) Waste my time, monitoring the charging process, so I can stop it at the right time, 2) Stop charging much earlier (and risk running out of energy, if my driving plans change, the next day), or 3) lose efficiency by not being able to recover as much of the energy that I used going UP the hill.

That was one of the selling points of this car: that it had such a high efficiency of braking regen. It is very frustrating that Ford didn't anticipate that any Focus Electric owners would live on hills. Actually, I think they DID anticipate it, but they just decided that it was more important to keep the car's control options as SIMPLE as possible, out of fear of scaring away customers who are afraid of cars that have too many options that they don't understand. All I can say is, Ford should be less concerned about making ONE EXTRA SALE, and more concerned about satisfying their more savvy customers! ...because, guess what?!?! Their more savvy customers are probably also their more literate customers and are probably also the least fearful about making Ford look bad, and the most dedicated to fighting for better support and service!

So, give me a break, here, Ford! I sat on the phone, today, patiently trying to explain some of these things to a very "rote-trained" service representative, at your Customer Relationship Center (the name of which is a pathetic JOKE). Then, I got "disconnected," before I managed to get them to understand my questions, much less give me any answers! I'm sure it was an accident. ...bad cell phone signal, or something. ...or are your representatives instructed to get rid of the customers who are taking up too much of their time?!?!

In my life, I have bought the following cars:
1966 Ford Fairlane (used)
1976 Ford Pinto (used)
1983 Ford Escort (new)
1990 Ford Escort (new)
1994 Ford Escort (new)
2000 Ford Focus (new)
2008 Toyota Prius (new)
2006 Toyota Highlander (used)
2013 Ford Focus Electric (new)

Notice a trend?

Does that count for anything?!? I might've stayed with Toyota, except for the fact that they've made it very clear that they're not going to invest any more than they have to in electric cars, anymore. They see electric cars as a dead end.

I thought Ford had the opposite attitude. If so, they need to start acting like it!

 

[WattsUp]

First, you should know that the electric equivalent of 1 gallon of gasoline is defined, by the EPA, to be 33.7 kWh.

So, that means that 105 miles per gallon-equivalent is the same as 105 miles / 33.7 kWh. Since 105 / 33.7 = 3.116, that means that 105 MPGe is equivalent to 3.116 miles/kWh. Multiply that by the 19.55 kWh (85% of the total 23 kWh) of battery energy that is available for use, and you get: 3.116 X 19.55 = 60.92, which means that the actual range, that corresponds to an MPGe of 105, is 61 miles!!! ...NOT 76 MILES!!!

I'm afraid you've made an error. You have incorrectly included the charging overhead in your range computation.

Charging the FFE, and typically any EV, is only about 80% efficient. The remaining 20% of the electricity used during the charging process is lost as heat. In other words, you must supply 20% more energy than the car will actually end up storing in its battery. This is the charging overhead. The figures from the EPA are based solely on the energy required to charge the car, which necessarily includes this overhead, and then drive the car until it stops moving. How much energy the car stored, or exactly how it used the energy to propel itself, is irrelevant to the EPA's measurements. (Besides, what other figure would make sense for the EPA to report? The energy needed to fully charge any given car, and then go X miles, is the only one that represents the true "cost" per mile. And this is exactly what the EPA has reported about the FFE.)

Anyway, above, you divided the FFE's usable stored energy (19.5 kWh) by the amount of energy (per mile) that it took, according to the EPA, to fully charge the battery (namely, 320 Wh/mile; from 33700 / 105 = 320) and then drive 76 miles (when, presumably, their FFE stopped moving). But, in doing so, you effectively included the charging overhead when computing how much energy you expected the car to then use (per mile) propelling itself. This was your error, and naturally yielded a result (61 miles) that is 20% lower than it should be.

Instead, to exclude the charging overhead, you should have used 80% of 320 Wh/mile, or 256 Wh/mile, when dividing the usable energy. Doing this, we get:

19.5 kWh / 256 Wh/mile = 76 miles

And this result is rooted in the reality of the FFE. Driving an FFE at speeds 55-65 mph requires an average energy usage of about 250 Wh/mile. Anyone who has spent enough time with the car knows this to be true. If the average usage is kept around 250, the FFE can indeed achieve 76 miles per charge easily. I see no evidence that Ford has lied about its range... something which is tested and reported by the EPA, in any case, not Ford.

Personally, I achieve 70-80 miles regularly in my FFE, often with partial freeway time at 65 mph. Just so long as my overall average stays around 250 Wh/mile. I also sometimes do long stretches of slower 40-50 mph driving, when the average energy usage drops to more like 200 Wh/mile. During these times, the car estimates high 80s, 90s, and sometimes 100 miles of range on a full charge, which is indeed accurate:

19.5 kWh / 200 Wh/mile = 97 miles

 

[Arthur]

Your statements are very deceptive, "WattsUp!" What's up with that? Are you purposely trying to mislead others, or do you really not understand how to calculate this stuff?

The only time I have heard the term, "charging overhead" used, in association with electric cars, is when referring to the "charging overhead costs" of for-profit charging stations that require you to pay for charging your car.

So, first of all, you've "made up" a term and introduced it into the discussion, in a way that necessarily confuses things.

The reality is that NEITHER the battery charging process NOR the discharging of the battery (to power the car) is 100% efficient. There is energy lost to heat, in both processes. In fact, there is energy lost to heat, in any process that converts energy from one form to another.

That said, those energy losses are already accounted for, elsewhere. When people say that their car is fully-charged, after receiving 19.5 kWh of energy, they are correct. It acually took a little more than that (nowhere near the 20% that you claim), but that extra energy will not show up on MyFordMobile, where it shows the summary of a charging event. Granted, their summary is somewhat useless for this discussion, because it rounds off to the nearest kWh, but even if it didn't round off, it is still only reporting the amount of energy (kWh) RECEIVED by the car's battery. The energy lost to heat will only show up on your electric bill or on a Kill-A-Watt meter, if you have one attached, between the car and the outlet you are plugged into. And, again, for the charging-up process, I think you would find that the energy lost to heat is much less than 20%.

 

[WattsUp]

Your statements are very deceptive, "WattsUp!" What's up with that? Are you purposely trying to mislead others, or do you really not understand how to calculate this stuff?

I'm not being deceptive. As I've tried to explain, you made an error in one of the key assumptions for your range calculations. The energy used the charge the car (what the EPA's 320 Wh/mile number is based on) and the energy stored in the car are two different things. That problem is that you mixed the two in your calculations, and have come out off by the exact factor we would expect, 0.8. (61 / 76 = 0.8)

It is incorrect to divide the energy stored in the battery (19.5 kWh) by the amount per mile used to charge it (320 kWh/mile, according to the EPA). You have to divide the stored energy by the rate at which the car will consume it. If we say this rate of consumption is 256 Wh/mile, we get 76 miles, the car's advertised range. From my and others experience, 256 Wh/mile is a very realistic rate to consume energy from the battery driving around at 50-60 mph.

I didn't make any of this up. It is fairly common knowledge that charging a lithium-ion battery is only about 80% efficient. There is a 20% loss, or overhead. I called this the "charging overhead" for the purposes of my explanation, and I don't think this term was unreasonable. We could also call it the "charging loss". The point is, these losses are significant, and if you include them in your battery-relative range calculations (which you did), your result will be incorrect.

Re: 20% losses from charging. In the bottom section of http://www.fueleconomy.gov/feg/evtech.shtml, you will find the following:

Battery and battery charger efficiency are assumed to total 81% (roughly 90% each) based in part on estimates from published studies

You will also find links there to the studies.

Personally, I have measured around 24 kWh coming "out of the wall" to fully charge my FFE. As we know, this results in only 19.5 kWh stored in the battery. So, we get 19.5 / 24 = 0.81, and this corroborates the government's estimates for charging efficiency. In other words, there is an overhead, or loss, of about 20%. Much of the loss comes from the heat generated during the charging process; the battery gets hot. Surely you've noticed this with your phone or laptop... same thing with the FFE. (And this is why the FFE's cooling fans sometimes come on while charging.)

Further, if we multiply the EPA's measurement of 320 Wh/mile by 76 miles, we get 24.3 kWh as the amount of energy required to achieve a full charge, which matches my personal "out of the wall" observations.

To summarize: Your computation divided 19.5 kWh (the stored energy) by the wrong rate. You used the externally-observed "charge rate" of 320 Wh/mile (which includes the charging losses), giving 61 miles, which is incorrect. Instead, you should have used the car's internal "discharge rate", which is known to be around 256 Wh/mile at 50-60 mph, which gives 76 miles.

-----

Lastly, we are all here to help and support each other. It doesn't help anybody to be accusatory or insulting. If you take a moment to go over your calculations again, rather than assume that I'm wantonly attempting to mislead, I think you will see your error.

I'm willing to be shown that there is a mistake in my assumptions or computations, but I currently stand by them. My results match the observations of the EPA, the claims made by Ford, and my own experience and understanding, as well as that of many others whose related discussions you will find here.

 

[Arthur]

So, what you're saying is that inefficiencies in the charging process cause the car to use 20% more electrical energy (0.2*19.5=3.9 => 19.5+3.9=23.4 => 23.4 kWh is used to add 19.5 kWh of energy to the car's battery).

Then, you are further saying that this increase in the total energy used to achieve a full charge of the car's battery, will actually cause the car to consume battery energy at a slower rate (than it would if the charging process were 100% efficient), when it is being driven.

So, you're saying that a DECREASE in charging efficiency leads to an INCREASE in discharging rate??? In other words, you're saying that it leads to an decrease in the number of Watt-hours consumed (per mile?). Furthermore, you're saying that the only way we can be getting this decreased number of Watts consumed per mile, despite having the same total number of kWh stored in our battery and using the same driving techniques (and speed), on the same route, is that the decrease in charging efficiency must have CAUSED the range to increase, thus CAUSING the same number of Watt-hours to be consumed over a longer distance, which, in turn CAUSES the reduced number of Watt-hours consumed PER MILE...

...thus PROVING that we have a greater range than we thought we did!!!

Wow! That's amazing! I think you've invented a new kind of... ...I'm not sure what you've invented. A new kind of math? A new kind of logic?

...or just a new kind of bullsh*t!

Am I being impolite to call it what it is?

...fertilizer! I'll call it fertilizer! You've invented a new kind fertilizer, for the mind.

It is true that the human mind can often be a very "fertile" place, for this kind of thinking to grow and spread.

Am I allowed to say "no thank you" to the offer of "brain fertilizer?"

It was kind of you to offer, though.

 

[WattsUp]

So, what you're saying is that inefficiencies in the charging process cause the car to use 20% more electrical energy (0.2*19.5=3.9 => 19.5+3.9=23.4 => 23.4 kWh is used to add 19.5 kWh of energy to the car's battery).

Not quite. I said the charging process uses 20% more energy than that which is stored in the battery. The car doesn't ever "use" the lost energy, the charging process does (generating wasted heat). When charging is complete, the car has 19.5 kWh in its battery that it can actually use to propel itself.

As you more or less calculate above, adding 19.5 kWh to the FFE battery requires about 24 kWh, which represents a ratio of 0.8. This ratio very closely reflects the efficiency of the charging process as estimated by http://www.fueleconomy.gov, which is 81%.

Btw, your percentage computations above are not entirely correct. The actual total where 19.5 constitutes 80% would be 24.375, not 23.4. (The mistake: Adding 20% of 19.5 to itself is not equivalent to 80% of 24.375.)

Then, you are further saying that this increase in the total energy used to achieve a full charge of the car's battery, will actually cause the car to consume battery energy at a slower rate (than it would if the charging process were 100% efficient), when it is being driven.

I didn't say that the charging process somehow caused the car to consume at a particular rate. I just pointed out that the in fact car does consume 256 Wh/mile when driven around at 50-60 mph. The car has displays which show this, and which you can verify yourself.

The "normal driving" consumption rate of 256 Wh/mile exactly fits the EPA estimate of 76 miles, 320 Wh/mile charging rate, and 105 MPGe, when you take the charging efficiency (80%) into account. It also matches the estimate of "32 kWh per 100 miles" (a figure that appears on the FFE window sticker) which is just another way of saying "320 Wh/mile".

At any rate (pun intended) , the rate of consumption is totally unrelated to the charging rate. If you drive such that your consumption rate will be different, say, more slowly at 30-40 mph, which you can verify consumes 200 Wh/mile or less, you will get a range of perhaps even 100 miles. But, of course, doing so won't affect the charging process in any way. It will still take about 24 kWh to fully charge the car.

So, you're saying that a DECREASE in charging efficiency leads to an INCREASE in discharging rate??? In other words, you're saying that it leads to an decrease in the number of Watt-hours consumed (per mile?). Furthermore, you're saying that the only way we can be getting this decreased number of Watts consumed per mile, despite having the same total number of kWh stored in our battery and using the same driving techniques (and speed), on the same route, is that the decrease in charging efficiency must have CAUSED the range to increase, thus CAUSING the same number of Watt-hours to be consumed over a longer distance, which, in turn CAUSES the reduced number of Watt-hours consumed PER MILE...

...thus PROVING that we have a greater range than we thought we did!!!

Wow! That's amazing! I think you've invented a new kind of... ...I'm not sure what you've invented. A new kind of math? A new kind of logic?

...or just a new kind of bullsh*t!

Am I being impolite to call it what it is?

...fertilizer! I'll call it fertilizer! You've invented a new kind fertilizer, for the mind.

It is true that the human mind can often be a very "fertile" place, for this kind of thinking to grow and spread.

Am I allowed to say "no thank you" to the offer of "brain fertilizer?"

It was kind of you to offer, though.

Well, I don't know what to say. I think you've misunderstood practically everything I've attempted to explain. I hope that you'll eventually go back and make sense of the numbers yourself, instead of merely insisting that they're wrong.

I've offered to you what I strongly believe to be correct math and knowledge, and which has yielded results that match every other piece of documented information. I'm sure others here will back me up.

You've chosen only to be dismissive and bizarrely rude. I'm sorry you feel that way.

 

[jmueller065]

Keep in mind that the EPA calculations are black box testing: They are done the same for every vehicle (standardized) so that comparisons can be made.

Thus when calculating mpge the EPA does NOT use the 19.xx kWhr "usable" in the battery figure. The EPA simply measures the amount of electricity used to charge the car (input to the EVSE) and then runs the car over a simulated course on a dyno.

Basically:
- Charge to full
- Run course
- Charge to full measuring how much electricity used
- Calculate mpge
- Repeat and average

Note that since the measurements are taken externally the efficiencies of the charger are included in these calculations (e.g. it takes more than 1 kWhr to put 1 kWhr into the battery).

 

[WattsUp]

jmueller is right, the EPA testing consists simply of:

1) fully charging the car (observing the total energy, E, passing through their EVSE) and,
2) driving the car until it stops (observing the total distance, D).

The EPA says the observed distance D for the FFE was 76 miles. They also say the energy required per mile, M, is 320 Wh. From simple arithmetic, we know that M must equal E / D.

We can agree on these facts? If not, please explain.

-------

So, working backwards with the following formula:

M = E / D

we can compute E, the total energy required to fully charge the FFE.

First, multiply both sides by D, and then cancel out:

M * D = (E / D) * D
M * D = E

Then, flip it around, and substitute in the known values for M and D:

E = M * D
E = 320 wH/mile * 76

Therefore, the total energy E is 24.32 kWh. In other words, the EPA needed just over 24 kWh to fully charge the FFE, after which it then was able to drive 76 miles.

We can agree on this logic? If not, please explain.

-------

Seeing as the EPA says that the FFE will "get" 320 Wh/mile, then next thing we (Authur) tried to do is divide the usable battery capacity of 19.5 kWh by 320 Wh/mile, yielding only 61 miles, which didn't match the EPA estimate of 76 miles.

So, what happened? What happened is the computation itself is completely wrong. 19.5 kWh cannot be divided by M. M is computed from E and D, which are independent of whatever the car's usable battery capacity happens to be. (As jmueller says, the EPA knows nothing of the usable battery capacity... it could by anything, depending on the design of the car.)

I mean, it would be possible for the FFE to receive exactly the same EPA rating (of 320 Wh/mile) if its usable battery capacity happened to be a little smaller, but its motor slightly more efficient (in the exact opposite proportion). Or, the usable capacity larger, but the motor less efficient. In both scenarios, an M of 320 Wh/mile could still be true of the FFE, but the usable battery capacity would be something other than 19.5 kWh.

This is why you can't divide 19.5 kWh by 320 Wh/mile. The two numbers are not directly related and dividing one by the other has no meaning. It is an invalid computation and gives you a wrong answer.

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But, finally, the actual reason dividing 19.5 kWh by M gives you the wrong answer is because the energy required by the EVSE to charge the battery and the energy later consumed from the battery are not equal. They are not even close to equal because the charging process has significant inefficiencies (or "overhead", or "loss"). It is, in fact, only 80% efficient, and this ratio is naturally reflected in all the numbers we've been talking about, including the (incorrect) range of 61 miles that Authur computed:

256 Wh / 320 Wh = 0.8
19.5 kWh / 24.32 kWh = 0.8
61 / 76 = 0.8

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Final point: It occurs to me that Authur may be thinking a little to much "in ICE terms", where dividing the capacity of the gas tank by the MPG rating from the EPA directly yields the car's range in miles. With an ICE, this works because the amount of gas required to "fill the tank" exactly matches the amount later available for use by the engine. But, this doesn't work with an EV. With an EV, the amount of energy required to "fill the tank" is greater than the amount later available for use by the motor. Filling a gas tank is "perfectly" efficient (gas out = gas in). Filling a battery is only 80% efficient (electricity out < electricity in).

 

[Arthur]

The bottom line is that both the EPA and the auto companies are trying to convince us that they have two, separate, empirical tests that they do on electric cars. Supposedly, one of those tests determines a typical value that we should expect for the car's fuel economy, and the other test determines a typical value that we should expect for the car's range.

This is a fiction. If you know the number of kWh that the car is programmed to allow you to use, and if you know the result of an empirical test for MPGe, then you can CALCULATE the value of range that corresponds with that value of MPGe, and vice versa.

For the Focus Electric, they claim that the EPA did a test that resulted in a fuel economy value of 105 MPGe (which is the same as 321 Wh/mi or 32.1 kWh/100 mi). If they got 105 MPGe and if 19.5 kWh of the battery capacity is actually usable, then the car must have gotten a range of approximately 60.8 mi, during that MPGe test.

If they claim that they did a test that resulted in a range value of 76 miles, then the car must have gotten an fuel economy of approximately 131 MPGe, during THAT test.

Obviously, they would like to have the best of both numbers (an MPGe that is low enough that Ford won't get sued for lying about the fuel economy that typical drivers can achieve with the car and a range that is high enough to NOT scare away customers, due to range anxiety.

Well, they can't have it that way. Either you drive at 105 MPGe and get a range of 61 miles, or you drive at 131 MPGe and get a range of 76 miles. Both are possible to achieve but, you can't "mix and match."

 

[WattsUp]

Again, the EPA's numbers have nothing to do with 19.5 kWh. Trying to fit 19.5 kWh into your computations is where you are going wrong.

The EPA's measurements are relative only to the total energy required to charge the car, which is 24.3 kWh, and the distance it can then travel.

From there, the math is simple:

24.3 kWh / 76 miles = 320 wH/mile

33.7 kWh / 320 Wh/mile = 105 MPGe

The number 19.5 kWh has nothing to do with anything the EPA measured or says about the FFE.

 

[Arthur]

It's simple arithmetic:
(105 miles/gallon-equivalent) X (1 gallon-equivalent/33.7 kWh) X (19.5 kWh) = 60.8 miles
or
(76 miles) X (33.7 kWh/gallon-equivalent) / (19.5 kWh) = 131 miles/gallon-equivalent

There is only ONE way that both EPA estimates could both be valid, at the same time: The battery would actually have to have a usable capacity of 24.4 kWh.
(76 miles) X (33.7 kWh/gallon-equivalent) / (105 miles/gallon-equivalent) = 24.4 kWh

Any of us who have run our battery down as far as possible, and, then charged it all the way up, again, know that we are not being allowed to use anywhere near 24.4 kWh.

So, Ford and the EPA are lying. They're convinced that it's the only way to sell these cars. Unfortunately, when there are known mathematical relationships between the quantities that someone is lying about, their lies can easily be exposed (unless, of course, the majority of their customers don't BELIEVE in mathematical relationships).

 

[WattsUp]

Any of us who have run our battery down as far as possible, and, then charged it all the way up, again, know that we are not being allowed to use anywhere near 24.4 kWh.

I'm not saying that. What I am saying is that it will require 24.3 kWh to charge the battery. But, for that, only 19.5 kWh is stored in the battery for use, because the charging process is only 80% efficient. (But, this 19.5 kWh detail is irrelevant; you can't use it in your computations with the EPA's numbers.)

If we think about it, it truly does "cost" 24.3 kWh in electricity to fully charge the FFE. You can verify this with a Kill-A-Watt device on your EVSE. And that's what the EPA is telling us, the cost to drive the FFE. In doing so, they do not tell us anything about the usable capacity of the battery, or how it functions relative to other internal details of the car, nor do they need to.

So, forget that you know about the 19.5 kWh usable capacity of the FFE battery. The EPA doesn't know about it. All of the EPA's numbers are based solely on the externally observed 24.3 kWh required to charge and the externally-observed 76 miles distance covered. I have shown that all of the other numbers reflect exactly this.

 

[WattsUp]

There is only ONE way that both EPA estimates could both be valid, at the same time: The battery would actually have to have a usable capacity of 24.4 kWh.

No, there is another way: Assume the EPA's numbers are relative to the energy required to charge the battery, which is 24.3 kWh, not the usable energy stored in the battery, which for the FFE only happens to be 19.5 kWh. (It could have been 19 kWh, or 20 kWh. Doesn't matter.)

The arithmetic is simple, but your inputs are wrong. But, if we go with the above assumption, and plug 24.3 kWh into your equations (instead of 19.5 kWh), we find that 76 miles, 320 Wh/mile, and 105 MPGe all pop out.

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It's simple arithmetic:
(105 miles/gallon-equivalent) X (1 gallon-equivalent/33.7 kWh) X (24.3 kWh) = 76 miles
or
(76 miles) X (33.7 kWh/gallon-equivalent) / (24.3 kWh) = 105 miles/gallon-equivalent
and
(24.3 kWh) / (76 miles) = 320 Wh/mile

 

[dmen]

Wattsup is right in his explanation of the EPA vehicle sticker number assumptions. When the 320 Wh/mile figure is explained as representing the cost in energy to drive the car a mile, it makes sense. It will take about 320 Wh from your electric utility to put 250 Wh in your battery, which will move the car a mile, and at that rate you will go 76 miles on a full charge.

I initially saw it like Arthur did, and I am sure most people who buy this car will see it that way at least at first. Some reasons I personally think it's confusing and/or misleading:

1. If the sticker says 23 kWh battery, it is reasonable to think that is the amount of energy we can use. Maybe it's "common knowledge" that Li batteries shouldn't be fully charged and fully discharged to prolong their life, so the buyer should know 23 doesn't really mean anything... Well it's common sense to give a buyer a concrete number for the available capacity so he can plan trips more accurately. Knowledge is power.

2. If the sticker says the estimated efficiency will be 320 Wh/mile, and the car has a display showing Wh/mile, it is reasonable to think these numbers are comparable, and that if I get a "better" number when driving, I should get a better range.

3. Electricity is a steal compared to gasoline. I'm not looking at these numbers on the sticker to see how much I'm going to pay to charge the car. I know it's going to be a small fraction of what I'd be paying for gas, and I charge for "free" while shopping at the stores where free public chargers are located when possible. I'm not worried about my electric bill. I'm focused on the part that might cause worry, the range. And incorrectly, I interpreted the other numbers- efficiency and capacity- from a range point of view instead of the cost point of view from which they were generated.

4. That 80% EVSE efficiency is an average. I have measured between 65% and 85% with the level 1 alone, apparently depending on outside temp, starting charge level, who knows what else. I'm pretty sure the efficiency will vary from one EVSE to another, all other conditions being equal. Including this fudge factor in the vehicle's listed efficiency, when it's affected by something other than the vehicle itself, seems wrong.

To be clear, I understand WHY efficiency and therefore range are calculated the way they are, but I think it's fair to call it confusing. The sticker really should have disclaimers clarifying what the usable battery capacity is, what 320 Wh/mile represents, what the corresponding DRIVING efficiency is, which EVSE is used in testing (assume Ford/Leviton), and at what temperature. This might not all be relevant to EPA requirements but it would be honest and useful to a prospective buyer.

Like Arthur, I would prefer more customization or control over the FFE power management. I would like to have an eco mode so I can't waste energy accelerating and speeding, and make it to the beach house on one charge. I would like to be able to use 90% or 95% of capacity very rarely. I was responsible enough with my gas car to change the oil on time- I can be responsible with this car too, and can take the blame if I'm not. I would like to have a sport mode taking out the computer limit on accelerating from a start for those times I just want to have fun. I would like to decrease coast regen, while others would like to increase it.