Question about degraded range due to heat, longer charge

[Jasper7821]

I just bought my Focus last night and fully charged it left to work this morning with the range of 75 miles. I drive 12 miles city and 20 miles freeway.
After the 11 miles to the freeway enterance the range said 73 miles and 9 surplus from regeneration. It was about 75 degrees.

When I got to work with cruise control set to 75 and AC off the range said 51 and I was all happy thinking that I have no problem at all making it home and should have close to 20 miles left when I got home.

I work in the middle of the desert and it was 100 degrees today. After work the range still said 51. I starting driving and kept the AC on for the entire time. As soon as I was driving the range went down to 47 and I only went about a mile.
After I got home the status was I think -9 miles and I had 9 miles left on range.

The trip to work avg was 221wh/mile but the drive home was 337wh/mile,or something close to that.
Does the heat really effect the battery that much to make that much of a difference from the same drive at 75 v/s 100 degrees.

And when I plugged the charger (5.5kw) the start and finish time was 7hr and 30 something minutes. Does that mean with a hot battery it wasn't allowing the full 5.5kw into the battery.
Is still charging and the total time now says about 6hrs.

Anyways, just looking for answers.
thanks.

 

[WattsUp]

Regarding your drive, I don't think heat had anything to do with difference in energy usage. It sounds more like the elevation between your home and work decreases. Does it?

On level ground, you simply can't drive at 75 mph in the FFE and use only 220 Wh/mile. 220 Wh/mile is more like what you need for about 45 mph, on level ground. Sustaining 75 mph takes somewhere between 350-400 Wh/mile. And, of course, somewhat more if running the climate control.

So, based on your report alone of doing 75 @ 220, I suggest that your drive to work is actually slightly downhill, which effectively assists the motor, allowing the car to sustain higher speeds using less energy. Consequently, your drive home must be uphill, which will use more energy.

That said, perhaps you were reporting the overall average Wh/mile for your entire trip (in each direction) which will thus include the stretches at slower speeds and account for regen? (Which the trip meter does reflect, btw.) Still, my comments about an elevation change would apply.

---------------

Regarding the charging time, I've never experienced them yet (I live in CA), but I suppose very high external temperatures might cause the on-board FFE charger to "take things slower", seeing as the battery may need more cooling. It may deal with this by charging at a lower rate (slower charging) or simply needing to allocate more power to cooling (leaving less for actual charging).

 

[WattsUp]

Also, when using the trip meter, be sure to reset it separately at the beginning of your trip to work or back home. Otherwise, the average Wh/mile displayed on the way back home will reflect the energy usage from both legs of the trip so far, instead of keeping them independent.

In other words, if you don't reset the trip meter before the drive home, the low energy usage of your trip to work will "pull down" the average displayed during your trip back home, which will be misleading.

Another "trip meter trick" is to reset it while you're at a steady speed. Give it a moment to stabilize and you can get a good idea of the "immediate" energy usage at your current speed on the current terrain. And keep in mind there are actually two trip meters, so you use one to track the average for your entire trip and the other to reset mid-trip in order to experiment with "immediate" Wh/mile measurements.

 

[Jasper7821]

Regarding your drive, I don't think heat had anything to do with difference in energy usage. It sounds more like the elevation between your home and work decreases. Does it?

On level ground, you simply can't drive at 75 mph in the FFE and use only 220 Wh/mile. 220 Wh/mile is more like what you need for about 45 mph, on level ground. Sustaining 75 mph takes somewhere between 350-400 Wh/mile. And, of course, somewhat more if running the climate control.

So, based on your report alone of doing 75 @ 220, I suggest that your drive to work is actually slightly downhill, which effectively assists the motor, allowing the car to sustain higher speeds using less energy. Consequently, your drive home must be uphill, which will use more energy.

That said, perhaps you were reporting the overall average Wh/mile for your entire trip (in each direction) which will thus include the stretches at slower speeds and account for regen? (Which the trip meter does reflect, btw.) Still, my comments about an elevation change would apply.

---------------

Regarding the charging time, I've never experienced them yet (I live in CA), but I suppose very high external temperatures might cause the on-board FFE charger to "take things slower", seeing as the battery may need more cooling. It may deal with this by charging at a lower rate (slower charging) or simply needing to allocate more power to cooling (leaving less for actual charging).

Wow, thanks. I never thought of the elevation change.
My work is downhill but its only a 547ft reduction and over the 32 miles I wouldn't think that would make a difference.
The 221 and 337 numbers came from what the car told me at the end of the trip on the trip summary so that's what I based it on.
I'll reset both trip meters and use the second one as an instant gauge during the trip to see where I'm at on energy usage, thanks for the tip.
I keep the information screen on that has the meter with the blue lines that stop just under the 3 and that's how I was viewing my instant wh/mile usage.
I was wondering why at 75mph I was able to keep the bar under the 3 and I was happy but then freaking out on the drive home and even when I slowed to 65 it was well over 3. I guess elevation must be a factor.
I'm going to buy a car cover and try to keep the car cooler while its sitting at work all day.

Also, both times since charging the car the range says 75 and not 76. Can that be the battery degrading from the car sitting at the dealer for 7 months?

 

[v_traveller]

My commute has a 1200ft elevation loss/gain, a little more than twice of yours. about 38 miles each way. Takes 6.6-9 kWh to get to work, 9.5-12kWh coming home. High #s are when there's no traffic on the freeway on a cold day, avg over 70mph.

Observation: A/C at 90F-102F ambient doesn't seem to suck as much juice as the heater at 40-55F.

 

[Jasper7821]

OK, got to work and trip summary was 31.8 miles and used 6.4kw and 203wh/mile and range said 56 miles left. I had the cruise set to 70mph and windows down and it was 81 degrees outside.
Started with 75 miles range and I drove 10.2 miles until I got to the freeway and I still had 73 mile range and the trip meter showed 10.2 miles, 167 wh/mile and 1.7 kw used.

So I think the 547ft decrease in elevation made a difference.
I'll have to get the summary when I get home in the 100 degree temp and using the AC and see what it took for the days commute.

So I got 4.96875 miles per kw (round to 5) and my electricity is about 8 cents per kw so does that mean my commute to work cost only 51 cents?

 

[WattsUp]

So I got 4.96875 miles per kw (round to 5) and my electricity is about 8 cents per kw so does that mean my commute to work cost only 51 cents?

Yes, something like that, pretty cool eh?

And your $0.51 number seems like you correctly accounted for the typical 80% charging efficiency, correct? (Since $0.51 / 5 = $0.10) Though, high ambient temps during charging might reduce your actual charging efficiency. At some point, would be interesting to measure the power required for full charge under those conditions, if you have the equipment.

So, right on. Almost makes you giggle, doesn't it?

 

[Jasper7821]

So I got 4.96875 miles per kw (round to 5) and my electricity is about 8 cents per kw so does that mean my commute to work cost only 51 cents?

Yes, something like that, pretty cool eh?

And your $0.51 number seems like you correctly accounted for the typical 80% charging efficiency, correct? (Since $0.51 / 5 = $0.10) Though, high ambient temps during charging might reduce your actual charging efficiency. At some point, would be interesting to measure the power required for full charge under those conditions, if you have the equipment.

So, right on. Almost makes you giggle, doesn't it?

No, I didn't count for charging efficiency. What is that?
I just rounded my number and maybe they came out correct all said and done.
I would like to measure the actual power but I don't have anything that could measure it.

it took 5hrs and 40 minutes to charge and I had 8 miles range left. it was 90 degrees in the garage last night while charging.
So with the LCS-25 power output at 4.8kw I think the car didn't let all the juice in as it could have because the battery was hot when I got home in the 100 degree temp and immediately plugged it in.

I fly electric helicopters and use up to 10,000mah batteries and always had to wait for the battery to cool down for about 30 minutes until I could charge them again. I wonder if I should be waiting to plug the car in since it seems to have charged at a slower rate then 4.8kw.
If that's the case then there was no reason at all to buy the more expensive station that could charge at 6.6.

 

[WattsUp]

And your $0.51 number seems like you correctly accounted for the typical 80% charging efficiency, correct? (Since $0.51 / 5 = $0.10)
So, right on. Almost makes you giggle, doesn't it?

No, I didn't count for charging efficiency. What is that?

Typical charging efficiency (of the entire chain: wall socket -> EVSE -> on-board car charger -> battery) is about 80%. In other words, when you charge your car, the car ends up storing 80% of what you supply to it "from the wall". For example, if 10 kWh passes through your ESVE from your electric utility, only 8 kWh will actually end up stored in the battery. Obviously, you will pay for 20% more electricity than you will be able to actually use for driving. But, no worries, this is still way more efficient than the ICE energy equation.

Fortunately, the EPA numbers reflect charging efficiency, since they are trying to inform you about the "true cost" per mile for any given car. When the EPA computes the Wh/mile for an EV, they are referring to electricity "from the wall" versus miles driven. Keep in mind the Wh/mile rate reported by the EPA is a different measurement from the Wh/mile reported by the car, which is just the car's internal measurement of how much electricity is being discharged from the battery relative the current speed. In other words, the EPA's Wh/mile is based on the total energy supplied to the car, whereas the Wh/mile reported by the car is based on the energy stored in the battery (about 20% less than the total supplied). So, although the units are the same, the numbers cannot be directly compared (others have gotten very confused by this).

So, when I saw the difference between 8 cents and 10 cents in the numbers above, I thought you were accounting for the 80% ratio already.

----

By the way, the total usable energy that can be stored in the FFE battery is about 19.5 kWh. Assuming the typical charging efficiency of 80%, you will pay for about 24.4 kWh worth of electricity to fully charge an empty FFE:

19.5 kWh (storage capacity) / 0.8 (charging efficiency) = 24.4 kWh (total needed)

And this is why the LCS-25 charger should (normally) take about 5 hours to fully charge an empty FFE:

24.4 kWh (from the wall) / 4.8 kW (charging rate) = ~5 hours

And you end up with 19.5 kWh stored in your battery again.

 

[Fluke]

WattsUp,
Do you live in a part of the country that experiences very cold temperatures? Just curious, because this winter I was only able to utilize around 13 kWh of the battery in the January/February timeframe. My driving efficiency (mi/kWh) went down a bit, but not much when I didn't use heating. As a result, my winter range was degraded to 50 miles or a bit more at times. Since the temperatures have increased I'm back up to the full battery capacity available that I was seeing last summer and fall.

 

[Jasper7821]

And your $0.51 number seems like you correctly accounted for the typical 80% charging efficiency, correct? (Since $0.51 / 5 = $0.10)
So, right on. Almost makes you giggle, doesn't it?

No, I didn't count for charging efficiency. What is that?

Typical charging efficiency (of the entire chain: wall socket -> EVSE -> on-board car charger -> battery) is about 80%. In other words, when you charge your car, the car ends up storing 80% of what you supply to it "from the wall". For example, if 10 kWh passes through your ESVE from your electric utility, only 8 kWh will actually end up stored in the battery. Obviously, you will pay for 20% more electricity than you will be able to actually use for driving. But, no worries, this is still way more efficient than the ICE energy equation.

Fortunately, the EPA numbers reflect charging efficiency, since they are trying to inform you about the "true cost" per mile for any given car. When the EPA computes the Wh/mile for an EV, they are referring to electricity "from the wall" versus miles driven. Keep in mind the Wh/mile rate reported by the EPA is a different measurement from the Wh/mile reported by the car, which is just the car's internal measurement of how much electricity is being discharged from the battery relative the current speed. In other words, the EPA's Wh/mile is based on the total energy supplied to the car, whereas the Wh/mile reported by the car is based on the energy stored in the battery (about 20% less than the total supplied). So, although the units are the same, the numbers cannot be directly compared (others have gotten very confused by this).

So, when I saw the difference between 8 cents and 10 cents in the numbers above, I thought you were accounting for the 80% ratio already.

----

By the way, the total usable energy that can be stored in the FFE battery is about 19.5 kWh. Assuming the typical charging efficiency of 80%, you will pay for about 24.4 kWh worth of electricity to fully charge an empty FFE:

19.5 kWh (storage capacity) / 0.8 (charging efficiency) = 24.4 kWh (total needed)

And this is why the LCS-25 charger should (normally) take about 5 hours to fully charge an empty FFE:

24.4 kWh (from the wall) / 4.8 kW (charging rate) = ~5 hours

And you end up with 19.5 kWh stored in your battery again.

Ahhh, ok I get it.
So my actual cost per kw on my bill is .078 cents per kw. so when charging the car its actually costing me .0936 per kw right?

 

[Jasper7821]

WattsUp,
Do you live in a part of the country that experiences very cold temperatures? Just curious, because this winter I was only able to utilize around 13 kWh of the battery in the January/February timeframe. My driving efficiency (mi/kWh) went down a bit, but not much when I didn't use heating. As a result, my winter range was degraded to 50 miles or a bit more at times. Since the temperatures have increased I'm back up to the full battery capacity available that I was seeing last summer and fall.

My garage last night when charging was 90 degrees and the car said 75 miles this morning. I thought the 1 lost mile was from the heat.
When I got to work this morning the car said 56 miles left. now 8hrs later it says 58. And I even played with the remote starter and ran the car with the AC for a minute. Plus it's 100 degrees now.
I don't get why the car says more when when it did this morning.

Yesterday it said 50 when I got in to leave, I drove about a mile on level ground and it lost 3 miles.

Also, yesterday I had the cruise set to 75 and had 50 after my 32 mile commute (21 freeway/11 streets).
Today it said 56 when I got to work and I had it set to 70. So that 5mph difference really made an impact on the range

 

[dmen]

Also, both times since charging the car the range says 75 and not 76. Can that be the battery degrading from the car sitting at the dealer for 7 months?

No, the starting range of 75 miles isn't reflecting battery degradation before you bought it. The range displayed after a full charge is estimated based on the energy efficiency in your last several trips, and modified by any difference in climate settings. It seems to take into account about 6 previous trips. So it's guessing you will have a range of 75 miles because your trips (and probably the test drive trips before you took the car) have averaged a bit over 250 Wh/mile. Since your commute was 64 miles and you had 9 miles left in range, 75 sounds like an accurate guess. If you set cruise control to 65 and set A/C to a higher temp for the next few commutes, you'll see the following morning's starting range guess step up. It takes some getting used to what the numbers mean, but don't try to think of the starting range as a very meaningful number unless your driving habits remain constant. If you take several 2-hour 45 mph drives then fully charge, your car will show a 90-100 mile range. But if you then do your very same 64 mile commute the same way you always do, you'll still be almost empty when you get home. Unfortunately the range prediction only knows what kind of driving you've done, not what kind of driving you're planning to do, even if you program a route in the nav system.
It would be great if dealers that are "EV Certified" had salesmen or techs who could explain this stuff to the interested shopper. Oh well. As long as you don't get stranded somewhere, at least it's kind of fun figuring it out!

 

[vetboy45]

"Also, yesterday I had the cruise set to 75 and had 50 after my 32 mile commute (21 freeway/11 streets).
Today it said 56 when I got to work and I had it set to 70. So that 5mph difference really made an impact on the range."

The 2 things that will affect range the most are how fast you drive and the climate control, with speed being the biggest drain. Everything else like radio and lights only account for a tiny fraction of the overall load on the battery. Remember that air resistance (drag) increases exponentially with increased speed so that going twice the speed takes way more than twice the energy. That's why if you get into trouble with range, turn off the climate control and slow down. As an example, a guy was able to drive the Tesla Model S 425 miles on a single charge when the EPA rating is 265 miles. He did it at 18 miles per hour for 24 hours.

 

[WattsUp]

WattsUp,
Do you live in a part of the country that experiences very cold temperatures?

No, I'm in San Jose, CA. While at night some winters it can dip to freezing or below, it doesn't usually. More likely, "very cold" is somewhere in the 30s-40s.

In any case, my FFE is garaged at home and at work. I've only had my FFE since late January this year, so I suppose it saw some cold temperatures, but I didn't notice any range degradation.

 

[Fluke]

WattsUp,
Do you live in a part of the country that experiences very cold temperatures?

No, I'm in San Jose, CA. While at night some winters it can dip to freezing or below, it doesn't usually. More likely, "very cold" is somewhere in the 30s-40s.

In any case, my FFE is garaged at home and at work. I've only had my FFE since late January this year, so I suppose it saw some cold temperatures, but I didn't notice any range degradation.

We had a cold winter here and it was interesting because I was not able to utilize anywhere near the 19.5 kWh battery capacity that is available when the temperature is nice. If I had been pushing up against the battery capacity during the summer to make my commute there is no way it would have worked during the winter here. The battery just won't perform to its warm weather capability in winter temperatures.

 

[WattsUp]

:arrow: Edit: Oops, I made a tiny mistake in my numbers. Corrected now.

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Ahhh, ok I get it.
So my actual cost per kw on my bill is .078 cents per kw. so when charging the car its actually costing me .0936 per kw right?

Well, sort of. Your cost per kWh (you buy electricity in kilowatt-hours, not kilowatts) on your bill obviously stays the same. It's what you get for each kWh purchased that varies. I think what you were trying to say is that each kWh of energy stored in the car will cost you 0.0936 cents, right?

That's almost correct; the actual cost is 0.0975 cents. Here's why...

Purchasing one kWh "from the wall" will cost you 0.078 cents on your utility bill, but this will only yield 80% of a kWh (or 800 Wh) stored in the car (assuming typical charging efficiency of 80%; see posts above). Thus, to store an entire kWh in the car, you will need to buy another 250 Wh from the wall (of which 80%, or 200 Wh, will be stored in the car) for an additional 0.0195 cents. This adds up to a grand total of 0.0975 cents for 1000 Wh, or one kWh, stored in the car. (This seems like an SAT question.)

Even better, we can now compute some other meaningful costs. Such as...

Filling his FFE will cost Jasper a measly $1.90:

19.5 kWh * 0.0975 cents = $1.90

Normally, the FFE can go 76 miles on a full charge, so that's $0.025 per mile for Jasper to drive his FFE around:

$1.90 / 76 miles = $0.025

Contrast that with an ICE-mobile that gets, say, 25 mpg at $3.50/gallon. That nets out at $0.14 per mile. The FFE offers well over an 80% savings over gasoline for the same transportation value delivered! And that's not even factoring in the FFE's nearly non-existent maintenance costs (no oil changes, no smog checks, no tune-ups, etc.). :lol:

 

[Jasper7821]

Awesome, that's sounds about just right except it's probably even a little better since the 76 miles doesn't consider regeneration which driving around town will make the cost even less.
Also I was paying over $500 a year for tags on my BMW, now it's only $37 a year. And my insurance is $200 a year less.
So I'm totally benefiting from the FFE.

Yesterday I drove my 32 mile commute with 11 streets and 21 freeway (75mph speed limit) and used 203hw/mile and 6.4kw and I set the cruise to 70mph.
Today I set it to 65mph (with everyone blowing by me) and when I got to work I used 200wh/mile and 6.3kw. With only a penny difference I see no reason to drive 65mph. And the conditions were the same, 80 degrees and no wind.
Monday I'll drove 75 and see where it yields.

Also when I got in the car this morning the range was 78 instead of 75. So as time goes on getting away from all the people who test drove the car and the mellow way I drive, I'm hoping the range keeps going up a little.
The lifetime summary went from 344wh/mile yesterday to 329wh/mile when I got to work.