[Fivedoor]

Hey guys,

I am doing and OCD analysis of my daily commute. My daily drive is 27.35 miles to work, and then the same route home, most of the drive is at 55 mph with around 2 miles at slower speeds (mix of 35 and 45 mph). I am not a hypermile type of guy, but I don't hammer the accelerator and brake either.

I will leave the climate control on the same setting year round and I am making charts that are based on total energy use, and charts for energy use if I were to drive with climate control off. I am also separating out bad weather days into their own charts vs good weather days.

I may get board before a full year worth of data is collected, but I did something similar with my old Volt before I changed jobs, I had around 6 months of data... so I have hopes that I can stick it out for a year. At that point I can start varying my driving speed to see it's effect on my range. I can probably extrapolate lots of information from only a few data points after I compile a year of baseline data.

Later,

Keith

PS: Also charting the charging efficiency of my charging sessions based on kwh used and kwh provided by my charge-point EVSE... not sure if the temperature in my non-climate controlled garage will effect efficiency enough to notice, but we will see!

 

[Fivedoor]

Hey guys,

Here are my charts for June. You will notice that with higher temperatures the car becomes more efficient if you are willing to sweat, but if you run the AC it becomes noticeably less efficient at high ambient temperatures. Climate control is set on 73F Auto.

This is the chart showing total energy use with climate control and battery conditioning.

This is the chart with just energy use for propulsion.

Later,

Keith

 

[LooseBolt]

Do you have any sort of data for solar gain? I'm thinking that accounting for sunny vs cloudy days may reduce your variance.

 

[Fivedoor]

Do you have any sort of data for solar gain? I'm thinking that accounting for sunny vs cloudy days may reduce your variance.

My "good weather" charts will include, day sunny, day partly cloudy, day cloudy, and night driving... I wasn't planning on a "night vs day" set of charts, but I may do them in the future if I get bored, and definitely not going to differentiate based on solar loading. My charts that are for propulsion energy only should not be affected by sun.

Keith

 

[GJETSON]

You will notice that with higher temperatures the car becomes more efficient if you are willing to sweat

Yup, hot air is lower density, as is more humid air. Also, the battery's impedance goes down. A win, win, win...if you don't mind sweating.

From 23 years driving without AC in hot, humid Virginia...tee shirt, shorts, flip flops, iced tea. Sponge off and change at work.

 

[Fivedoor]

Yup, hot air is lower density, as is more humid air. Also, the battery's impedance goes down. A win, win, win...if you don't mind sweating.

From 23 years driving without AC in hot, humid Virginia...tee shirt, shorts, flip flops, iced tea. Sponge off and change at work.

On most days with the AC blasting I use less than 14 kWh out of 60 on my commute... so no need to sweat If I still had my 2016 Volt with 14 kWh available, I would probably sweat in an attempt to never use gasoline.

Keith

 

[Eriamjh1138]

The vertical axis is miles/kWh, right?

Are those numbers from the car or calculated based on actual energy in divided by miles driven?

 

[Sean Nelson]

Yup, hot air is lower density, as is more humid air.

Air with more H2O is less dense than air without???

 

[XJ12]

Air with more H2O is less dense than air without???

Because of those two hydrogens in water. Nitrogen and Oxygen are diatomic making them heavier.

 

[Sean Nelson]

Because of those two hydrogens in water. Nitrogen and Oxygen are diatomic making them heavier.

Huh. You learn something new every day.

So I guess that means moist air rises even if it's not warmer than the surrounding air...

 

[GJETSON]

Air with more H2O is less dense than air without???

Yup.

http://www.theweatherprediction.com/habyhints/260/

 

[XJ12]

Huh. You learn something new every day.

So I guess that means moist air rises even if it's not warmer than the surrounding air...

switching to other physical phenomena with that question. diffusion means it will mix and not completely stratify

 

[redpoint5]

So I guess that means moist air rises even if it's not warmer than the surrounding air...

Not necessarily. Fog lingers along the ground, but usually humid air rises and forms clouds.

Counter-intuitive that driving through fog is less dense than driving through dry air.

 

[Fivedoor]

The vertical axis is miles/kWh, right?

Are those numbers from the car or calculated based on actual energy in divided by miles driven?

These numbers are calculated based on the kWh used and the percentages (driving, climate, and battery conditioning) with the vertical axis being miles per kwh and the horizontal axis being ambient temperature.

Air with more H2O is less dense than air without???

Because of those two hydrogens in water. Nitrogen and Oxygen are diatomic making them heavier.

This is correct for water vapor, when the water changes state from gas to liquid it becomes much more dense than dry air.

I suspect that Fog is much denser than dry air of the same temperature, and that if you raise the temperature of the same air 5 deg and it becomes much less dense then dry air of that same temperature. If you try and look it up on line you get dozens of conflicting opinions on weather fog raises or lowers the density of air...

Rain of course is horrible for air density, as well as hugely increased drag on the tires for a wet road vs dry pavement.

Later,

Keith

 

[Eriamjh1138]

You didn’t answer my question, but based on your response you used he numbers the car gave you, not a metered measurement from an energy measuring device on the wall. Without the energy meter, you do not account for charging losses and inefficiencies of the OBC.

 

[Fivedoor]

You didn’t answer my question, but based on your response you used he numbers the car gave you, not a metered measurement from an energy measuring device on the wall. Without the energy meter, you do not account for charging losses and inefficiencies of the OBC.

From my very first post in this thread:

PS: Also charting the charging efficiency of my charging sessions based on kwh used and kwh provided by my charge-point EVSE... not sure if the temperature in my non-climate controlled garage will effect efficiency enough to notice, but we will see!

These numbers are calculated based on the kWh used and the percentages (driving, climate, and battery conditioning) with the vertical axis being miles per kwh and the horizontal axis being ambient temperature.

So, the numbers in the charts are the cars displayed energy used and split up according to the percentages provided by the car. As stated in the title, this is a temperature vs range (as measured in miles per kWh), not a total wall to ground energy efficiency study. As noted in my "PS" on my first post, I am gathering the kWh from the wall vs kWh used to show charging efficiency... I may chart those results at some future date.

Keith

 

[GregBrew]

Huh. You learn something new every day.

So I guess that means moist air rises even if it's not warmer than the surrounding air...

Talk to a pilot about "density-altitude".


There are some days in Reno, NV that you simply can't fly out: High-ish altitude, hot air, high humidity. They all conspire to reduce air density to the point that you can't generate enough lift to get out of the bowl that contains the airport.

 

[Sean Nelson]

Talk to a pilot about "density-altitude".

My worst experience with density altitude was flying out of the Grand Canyon airport one hot afternoon. The airport elevation is around 6,500 feet, but the density altitude was close to 9,000. Boy, was that ever a shallow climb out over the rim of the canyon in my Cessna Cardinal...

I don't recall learning about humidity affecting density altitude, though, all I remember is temperature.

 

[XJ12]

I don't recall learning about humidity affecting density altitude, though, all I remember is temperature.

I also was trained to just use temperature in calculating the density altitude.

quoting this source: https://www.aopa.org/news-and-media/all-news/2016/september/08/density-altitude

(Air density also is affected by humidity, but humidity’s effect on density altitude is much less dramatic than temperature’s.)

 

[GregBrew]

My worst experience with density altitude was flying out of the Grand Canyon airport one hot afternoon. The airport elevation is around 6,500 feet, but the density altitude was close to 9,000. Boy, was that ever a shallow climb out over the rim of the canyon in my Cessna Cardinal...

I don't recall learning about humidity affecting density altitude, though, all I remember is temperature.

It's not nearly as impactful as temperature and altitude, but high humidity can add several hundred feet to effective altitude. If other conditions make things marginal, humidity can easily make flight a no-go.


http://www.boldmethod.com/learn-to-fly/performance/density-altitude/