Max Range Charge Option

[Arthur]

It doesn't take 24.4 kWh to charge the car. Buy a "Kill-A-Watt" meter, and check it out. Besides, even if it did take 24.4 kWh to charge the car, that would never have any effect on the RANGE of the car. The range is determined only by driving behaviors, by driving conditions (e.g., hills, or lack thereof), by vehicle efficiency (motor, tires, battery, etc.), and by the number of kWh that are actually available to be used to drive the car. These are the 4 categories of criteria that combine to determine your fuel economy (MPGe). In other words, the efficiency, with which the 19.5 kWh can be used, is already factored into the fuel economy number (105 MPGe). So, you don't need to fudge that number, to take that efficiency into account (like you were doing, when you multiplied 320 Watt-hours/mile by the ratio of 19.5 kWh/24.4 kWh (which, as you mentioned, is 0.8, or 80%), to get 256 Watt-hours per mile). The efficiency with which the batteries energy is discharged, and used by the car, is already factored into the fuel economy number.

In fact, that ratio (80%) has nothing to do with battery efficiency. Instead, it a measure of how far MISMATCHED the fuel economy and range values (that the EPA has listed, for this car) are. If they were being completely honest and using numbers that actually represented the same test trip, that ratio would be 100%. So, it is totally incorrect to say that that ratio has anything to do with efficiency.

Again, either our car gets 105 MPGe and 61 miles of range, OR it gets 131 MPGe and 76 miles of range. In fact, those 2 scenarios could both be accurate, on separate trips, with two different sets of driving behaviors. You just can't "mix and match" the numbers, like Ford and the EPA want to do.

Last weekend, I drove very carefully (gentle braking and accelerating, and never exceeding 45 mph) and got 160 MPGe and the corresponding range of 92.6 miles. (Actually, I had about 5% of my available battery capacity left, at the end of the trip. So, my distance for the trip was actually only 87 miles.

The reason that I am upset is this: If the set of numbers that the EPA reports (105 MPGe and 76 miles of range) were actually true (in other words, if they actually corresponded to each other, for the same trip), then my driving style, last weekend should have gotten me 160 MPGe (the same as 209 Watt-hours/mile) and a range of 116 miles. That is the kind of performance I expected from my Focus Electric, based on the range claims of Ford and the EPA.

Here is the calculation: (160 miles/gallon-equivalent) X (24.4 kWh) / (33.7 kWh/gallon-equivalent) = 116 miles.

In reality, I would have to achieve 200 MPGe (the same as 168 Watt-hours/mile), in order to get a range of 116 miles from a battery that only allows 19.5 kWh to be used. Of course, ANYTHING is possible, under extreme enough conditions, but beware of anyone who claims to have accomplished this. Such an accomplishment will only happen, if the trip involves an extremely large elevation change (downhill, of course) AND/OR if a large fraction of the trip is spent driving at speeds below 20 mph (possibly on a car-sized treadmill).

Here is the calculation: (200 miles/gallon-equivalent) X (19.5 kWh) / (33.7 kWh/gallon-equivalent) = 116 miles.

I guess I should have checked the numbers more carefully, before buying the car. Naïve, trusting person that I am, I didn't imagine that Ford OR the EPA could get away with that level of dishonesty (or that they would even want to try to).

Now, OUR job is to hold their feet to the fire and demand recompense for the inferior vehicle/battery that we have ended up with. If WE lied about our credit, THEY would repossess the f**king car! So, it is our obligation, as "diligent consumers," to correct this situation.

 

[WattsUp]

It doesn't take 24.4 kWh to charge the car. Buy a "Kill-A-Watt" meter, and check it out. Besides, even if it did take 24.4 kWh to charge the car, that would never have any effect on the RANGE of the car.

Yes, it does take, on average, about 24.3 kWh to fully charge the car, and I have checked it out (as have others; see dmen's post in this thread). You can measure it yourself, and it is what the EPA measured as well. And, that measurement is the basis of the other numbers the EPA gives for the FFE. They are all just alternate expressions of the ratio "24.3 kWh to 76 miles". All of them.

What's the more likely scenario here? That you've discovered an auto-industry/EPA conspiracy to disseminate inaccurate EV information, or that you've used an incorrect assumption in your calculations that throws off all the numbers in precisely the way that you're upset they are all off?

If you fix your broken assumption, all the numbers will make sense. I've shown this to be true using your own equations. Everything works out if you assume that EPA's methodology is relative to the energy required to charge the car, and that the amount is 24.3 kWh.

I and others have measured that this is indeed true, and the estimate from the government study (of 80% charging efficiency) correlates very well with the observed ratio of required energy (24.3 kWh) to stored energy (19.5 kWh) when charging the FFE.

And, the fact that driving along in the FFE at 50-60 mph (more or less equivalent to the EPA test scenario) consumes about 250 Wh/mile (which is sufficient to go 76 miles on 19.5 kWh), also supports this line of reasoning.

 

[WattsUp]

@Authur: So is the fundamental blockage here is that you simply don't "believe" that charging the FFE battery is only 80% efficient?

I ask, because I can see how you would then conclude that the 320 Wh/mile figure from the EPA could somehow be related to the usable battery capacity, and the rate at which the car consumes from it (also in units of Wh/mile). As dmen was saying, this can be confusing; the numbers are in the same units, but they are not related to each other.

But, if you are going to insist that charging is 100% efficient, or even just very close to it, then we'll never make any progress here. It simply is not. I don't know what else to tell you. All I can do is direct you to the government info again, and suggest you measure the energy required to complete a full charge yourself.

 

[Fluke]

I don't want to get in the middle of the current discussion, but will add some data from my charging experience over the last year (OK, 10.5 months) with the FFE. I track similar data on the charger for my Chevy Volt, too.

I track the circuit feeding a GE Wattstation 240V EVSE with a TED 5000 and also note the kWh usage reported by the FFE's trip meter for every trip taken. Comparing the wall-to-car kWh required versus the FFE reported charge values has shown that I have averaged 83% efficient (kWh reported by car / kWh reported by TED 5000) in the charging process over the last year. The individual charge sessions range from about 79% to 90%, depending (apparently) mainly on ambient temperature.

 

[WattsUp]

Comparing the wall-to-car kWh required versus the FFE reported charge values has shown that I have averaged 83% efficient

Thanks Fluke. This is similar to my experience. My average is about 81%.

I use (strangely enough) a Fluke clamp meter to measure the wattage flowing "from the wall" to my EVSE. I charge using a ClipperCreek LCS-25, which provides about 4.8kW and takes about 5 hours to charge my FFE. Sometimes shorter, sometimes longer. My external temperatures are pretty ideal, I would think, right now; consistent range of 60-80 degrees in the garage where my FFE is parked.

So, my total energy used to charge: 4.8 kW * 5 hours = 24 kWh

And, my charging efficiency: 19.5 kWh / 24 kWh = 0.81