Dear Ford...

[dmen]

I don't mean to beat a dead horse. I like my FFE plenty, but I can't believe I'm the only one who feels misled by Ford on the range issue. Unlike other posters, I don't see it as neat that if I use 250 Wh/mi-- 22% less than Ford did on EPA's test course-- I arrive exactly at the EPA-listed range of 76 miles. I would see it as neat (and logical) if driving like that got me 22% further than the listed range!
I posted my wish for a Tesla- or Nissan-like "full charge" option in FFE a while back, and no one else seemed to share my opinion. So I'll leave it at that.

 

[WattsUp]

The EPA's info on the vehicle sticker says they think you'll get 320Wh/mi. Their 76 miles doesn't exactly make sense b/c you'd need 24.32kWh to go that far at that efficiency, but those are the numbers on the sticker.

No, that EPA number shows "how much electricity you will need to buy in order to drive 100 miles". The number represents a "normalized" unit of comparison (based on a standard distance of 100 miles). It allows the costs to operate different vehicles to be compared uniformly, regardless of each vehicle's actual maximum range. The EPA's number for the FFE actually does make sense if you keep in mind that the transmission of electricity from your wall socket into the battery isn't 100% efficient. Significant losses occur during the charging process which, of course, you will be paying for too. The EPA number takes this into account.

As we know, the battery in the FFE needs to be charged until it holds 19kWh of usable stored energy in order for the car to drive its maximum rated range of 76 miles. This charging, however, will actually require around 24kWh of electricity (coming out of your wall socket, and wallet). The difference (about 20%) is the electrical energy that is converted to heat and then lost. What heat? The battery in the FFE will heat up during charging, just like the batteries in your laptop and phone do... they get really hot, right? Same thing in your FFE. (And same thing in a Boeing Dreamliner, which apparently didn't have as good a cooling system as the FFE.) :lol:

So, although the FFE consumes electricity stored in its battery at the rate of about 19kWh per 76 miles, it "costs" about 24kWh to charge the battery to that level. Hence, the EPA rating of 32kWh per 100 miles (or about 24kWh per 76 miles in FFE terms). In other words, to go 76 miles in an FFE, you should drive at about 250wH/mile, with each mile of charge adding 320wH to your electricity bill.

You should not feel mislead by the EPA numbers. The EPA has accurately informed us how much electricity we will need to go 100 miles in the FFE... just like the gas needed by an ICE. With an EV, though, we actually need to buy more electricity than the car consumes as it drives... we also need to buy the electricity lost as heat while charging it. With an ICE, it would be as if the process of adding gas to the tank also consumed some additional gas. The MPG rating for the engine would still be important, but so would the "losses" from fueling. The final MPG figure would include that additional gas, and would represent the "real" cost. That's what the "32kWh per 100 miles" number is for the FFE.

Welcome to the EV learning curve.

 

[dmen]

Welcome to the EV learning curve.

Hope this wasn't meant to be as condescending as it reads... how long have you owned an EV? Welcome yourself

Your explanation of the EPA numbers taking into account "wall to wheels" electric efficiency sounds nice. If it's true, then sure I have no reason to feel misled by Ford. But I don't see anything on my vehicle's window sticker nor on fueleconomy.gov to support your explanation.

 

[WattsUp]

Welcome to the EV learning curve.

Hope this wasn't meant to be as condescending as it reads... how long have you owned an EV? Welcome yourself

Certainly didn't mean to sound condescending. :shock: Meant to imply that this is a lot of stuff to learn "for all of us".

It's all how you hear it in your head, which may not be the way it was intended. You should imagine me as a friendly Marty McFly saying, "wow, Doc, that's amazing... welcome to the EV learning curve", and not Biff knocking on your head saying, "hello McFly, hello... welcome to the EV learning curve". I intended the former, not the latter.

Your explanation of the EPA numbers taking into account "wall to wheels" electric efficiency sounds nice. If it's true, then sure I have no reason to feel misled by Ford. But I don't see anything on my vehicle's window sticker nor on fueleconomy.gov to support your explanation.

But, what else would the EPA number show? They charge the car, observing how much electricity is consumed to fully charge it. Then, they drive the car as far as it will go. At the end, they compute "watt hours / miles" (which is shown normalized to 100 miles on the sticker).

It's exactly the same methodology used for an ICE, substituting electricity for gas. Fill the car with gas, observing how much it takes to fill the tank. Then, drive the car until it stops. At the end, compute "miles / gallons".

I'm not making up that battery charging is not 100% efficient, it simply isn't. We've all experienced this with our phones and laptops. It is self-evident to me that the EPA number will necessarily reflect all these efficiencies (and/or inefficiencies) -- "wall to wheels" as you put it, which is a great phrase. The EPA doesn't care how much the car consumes from its battery, or how efficient the charging process is... the EPA only cares about how much electricity must ultimately be "supplied to" the car to make it go X miles. Their methodology is independent of all other factors, as it should be.

You can also measure for yourself, with something like a Kill-O-Watt device, that filling your FFE requires that you supply it with about 24kWh. Your FFE will show that 19kWh was stored in the battery (but this is irrelevant to the EPA). The rest heated up your garage (also irrelevant). Some of the supplied electricity eventually goes towards moving the car, some doesn't. But, whatever those proportions, if you then took the car out and drove it until it stopped, how much electricity would you consider it had "cost" you to do so? Your electricity bill would consider it 24kWh, which is what the EPA number is meant to inform us about.

Even if you didn't personally believe anything that Ford, the EPA, or I said, once you got hold of an FFE, isn't this how you would compute its "watt hours per mile" yourself? It's exactly what everyone does when "manually" computing the MPG of their ICE (observe how much the gas pump says it took to fill the tank and then check the odometer later).

 

[jmueller065]

This page:
http://www.fueleconomy.gov/feg/evtech.shtml

Energy efficient. Electric vehicles convert about 59–62% of the electrical energy from the grid to power at the wheels—conventional gasoline vehicles only convert about 17–21% of the energy stored in gasoline to power at the wheels.*

Note the text "From the grid".

Electric motor efficiency—including inverter and gear reduction losses—assumed to be 76.4–80.2%, using estimates from Miller et. al. (SAE 2011-01-0887) and adjusting downward by 4% for parasitic losses.
Battery and battery charger efficiency are assumed to total 81% (roughly 90% each) based in part on estimates from published studies (Chae et. al., 2011; Gautam et. al., 2011).

This data from the fuel economy .gov website kind of supports what WattsUp is saying.

 

[dmen]

Right on. Pardon my mis-read on the comment, wattsup.

You and jmueller have convinced me. I didn't see the wording on the EPA site jmueller quoted first as referring to how they come up with specific EV efficiency ratings... I read it as simply highlighting how much more efficient EV are compared to ICEV for people thinking of going electric, and your numbers don't work with only 62% efficiency. I didn't pay attention to the footnote explaining where the first quote's numbers come from, but the battery charging efficiency assumption detailed works with your numbers. Anyway, the piece that hit it home for me is the $600 a year fueling estimate on the sticker. The math works out to $576 using the listed $0.12/kWh, 15000 mi/year and 32kWh/100mi assumptions. I guess they round up. When they list dollars, I know they are counting at my wallet, not my motor.
So, thanks for the education! I have to say I still consider the EPA data misleading, but in the sense of confusing and not adequately explained rather than flawed.
Now if I can just get my stop safely now warning issue fixed promptly, I will be all set!

 

[WattsUp]

Right on. Pardon my mis-read on the comment, wattsup.

Understandable... I see how it could have sounded bad. I always tend to assume we are all on friendly terms here and that smiley faces help clarify the comments/jokes. But, apologies for (temporarily) making you feel bad.

Now if I can just get my stop safely now warning issue fixed promptly, I will be all set!

Hope it works out. As always, let us know what happens.

I'm crossing my fingers that I won't be "next" for some nightmare scenario as it seems other have experienced. I've had a couple yellow wrenches, though they have seem to have stopped. Other than that, my FFE has been nothing but joy.

----

Edit: And thanks jmueller for pulling up those stats.

 

[mdfocus]

Please add option to turn off light ring. It is an attractive nuisance that invites trouble when parked outside overnight. I use a black garbage bag to cover it up.

I tried a couple of layers of blue easy release painter's tape, which only dulls the glow. Totally agree--the ring light should be a customizable option.

If you have not got charging ring light turned off goto YouTube and search. It gives a detailed video from Ford.

 

[Pearl]

Please add option to turn off light ring. It is an attractive nuisance that invites trouble when parked outside overnight. I use a black garbage bag to cover it up.

I tried a couple of layers of blue easy release painter's tape, which only dulls the glow. Totally agree--the ring light should be a customizable option.

If you have not got charging ring light turned off goto YouTube and search. It gives a detailed video from Ford.

https://www.youtube.com/watch?v=sjHakQgXb2Y