Reported Trip Energy Used vs Energy required to recharge car

[Rhyalus]

Ha! The wiki page explained MPGe fairly well, but there is some math involved. I am not a fan of this reported metric... There is talk about introducing something better, which I am hoping for.

 

MPGe does not tell the whole story.

 

R

(Note: this post is not in response to Larry...it was in response to person commenting about how it is like school.)

Edited July 7, 2013 at 12:41 PM by Rhyalus

[larryh]

Note that the range estimates posted above are based on the assumption that the same amount of energy can be withdrawn from a fully charged battery regardless of the rate power is drawn from the battery.  That may not be correct.  I've seen the reported plug-in energy used when the battery is depleted vary from 5.5 to 5.8 kWh.  Part of the variation could be explained by the average speed of the trips.

Edited July 7, 2013 at 03:02 PM by larryh

[Russael]

Very cool.  My lifetime MPGe is around 163, and most of my travel is between 35MPH and 50, so that fits.  Interesting that it's so linear.  Perhaps when I go to the Ren Cen in Detroit for another nerdfest, that I'll try traveling around 55MPH on the freeway (minimum is 45).  Besides, once I'm in Detroit city limits, the actual expressway speed limit does become 55, even though everybody ignores it (and still do 75 - 80... crazy people).  If I can get 23 miles out of the battery, I'll be pretty happy since the place is surrounded in charging stations.

 

I did find a surface street route that reduces travel to 18 miles... but I'm hearing that particular route is... not pleasant (nor all that safe).  So expressway it is.

[larryh]

Driving on highways/freeways with max speeds ranging between 55 and 60, I generally get around 24.5 miles in EV mode before switching to hybrid mode.  However, I do have to slow down at a couple of stop signs and for traffic when entering the downtown area, and there is a mile long moderate downhill segment.

 

But of course, you can't normally achieve the ranges shown above in real driving since you cannot travel at constant speed and level roads with calm winds.  (I think you might have a bunch of pretty irate drivers following you going 20 mph on a highway for 43 miles :rant2: ).  When you slow down or stop, the regenerative braking system can only capture 75% of the lost kinetic energy.   I'm not sure how efficient the generator is in capturing energy while coasting. 

Edited July 7, 2013 at 07:30 PM by larryh

[larryh]

Using the MPGe measurements in the post above for constant speed, you can estimate the kW of power required to maintain constant speed as follows:  power = mph /

(MPGe / (33.705 kW/equivalent gallon)).  This yields:

 

speed (mph) power (kW)

20                  2.7

30                  4.6

40                  7.1

50                10.8

60                15.3

70                22.6

 

When going between 40 or 50, I notice the power indicator in the Empower screen is around the first mark.  And when going around 60 to 70, it is at the second mark.   I would guess that the marks on this screen each denote 10 kW of power.  This is further confirmed by an experiment I did this morning.  I maintained a constant power with the indicator on the Empower display up to the first mark.  After 2 minutes and 35 seconds, the trip odometer display indicated I had used 0.4 kWh of energy.  So the power was then 0.4 kWh / (2.58 min / 60 min/hour) = 9.3 kW.  Which is not exactly 10 kW most likely from measurement errors and difficulty maintaining constant power.

Edited July 13, 2013 at 03:54 PM by larryh

[larryh]

If I plot kWh consumed per mile. vs. speed for the data above, I get the expected response curve:  energy consumption increases with the square of speed.  So, theoretically, going 75 mph vs. 60 mph uses almost 60% more energy.  Well, maybe not quite due to other factors.  Based on my data, it is around 40%.

 

Edited July 14, 2013 at 12:56 PM by larryh

[Russael]

What you show with relation to speed vs energy consumed also applies to gasoline vehicles (it's not linear, its curved as you show).  Reducing your speed by 5MPH on the freeway can save you a good chunk of gas and increase your MPG rating.  Depending on the length of your trip, 5MPH doesn't cost you as much time as you might think either.  If you drive at 65MPH for 1 hour, you cover that distance during that time... but if you take that 65 mile trip and drive it at 60MPH, it'd only cost you an extra 5 minutes of time to cover the same distance, a difference of about 8.3%.  And the faster you go, the smaller the cost (eg. 75 vs 70 costs you about an extra 4.3 minutes or a difference of about 7% to cover the same distance).

 

It's food for thought the next time you take a trip and mash the pedal, thinking you're saving yourself a ton of time. :)

 

My trip to Baltimore is 514 miles one way, mostly tollway travel, and the speed limit varies a lot.  It's now 70 in Ohio, 65 in PA, and once I go through Breezewood and get on I-70, I think the speed limit there is only around 55.  I could spend 20 minutes figuring out the differences, but doing time calculations sucks. :)  I think it only adds about an hour to my whole trip (about 9 hour total) by traveling 65 on the turnpike and doing 55 - 60 on I-70, traffic and hunger stops contingent. :)  Fuel savings driving my beast adds up.

[larryh]

I measured the MPG in hybrid mode at different speeds on the same 12 mile section of Freeway:

 

speed (mph)  MPG

70                  41.0

65                  44.4

60                  47.1

 

In this speed range, the relationship between speed and MPG also seems to be linear.  I doubt this holds true at significantly slower speeds.  So, I would estimate at 75, you would get about 38 MPG and at 55 you would get around 50 MPG.

 

If I divide the MPGe for EV mode by the MPG for hybrid mode at the various speeds I get:

 

speed (mph)   ratio

60                   2.81

65                   2.67

70                   2.55

 

This is telling me that at 60 mph, EV mode is 2.81 times more efficient than hybrid mode, i.e. I can go 2.81 times further with a given amount of plug-in energy, i.e. electricity, vs. the equivalent amount of energy from the combustion of gas.  Note that the efficiency ratio increases with decreasing speed.  That suggests if you cannot complete the entire trip in EV mode, it is best to reserve the plug-in energy for the lowest speed portions of the trip, or equivalently, the portions of the trip that use the least power.  I estimate that from this optimization you could save at most about 0.1 gallons of gas.

 

Ford should offer an option in the EV Auto mode to set a threshold for turning on the ICE.  At the moment, it appears to be fixed at 40 kW.  If one could adjust the threshold, you could have the car automatically select EV mode for the lowest speed portions of the trip and reserve the ICE for the higher speed portions, thereby optimizing EV range.  For example, tell the car to use the ICE when going over 60 mph; or as another example, when the power exceeds 30 kW.

Edited July 19, 2013 at 01:58 PM by larryh

[larryh]

I measured a couple of additional data points (40 mph and 50 mph) for MPG vs. speed in hybrid mode this morning.  Actually, the relationship looks quite linear from 40 mph to 70 mph.  This is what I also observed for MPGe vs speed in EV mode.  So with every 10 mph increase in speed, you loose 7.5 MPG.

 

Edited July 20, 2013 at 01:28 PM by larryh

[Eric4539]

Thank you for your calculations, larryh. I'm going to see how I can apply your lessons to my driving although I don't like to use that much brain power while in my car!

 

I leave my car in Eco + mode hoping it's learning my driving style. Problem is that my initial drive home from the dealer was 500 miles or so of atypical driving and I also had a 240 mile round trip after that. But the remainder of the time the car sits plugged in for 2 days or more before being driven.

 

Yesterday I did 7 short drives totaling 19 miles but a couple of those segments were under 2 miles each so they didn't register. I never exceeded 45 mph and the car ran 100% EV, and the car is set on Auto.

 

I'm doing another 240 mile drive on Friday and I plan to be in Auto mode until I get on the highway. I'll do EV Later until I exit the highway at my destination and then go to Auto again. Cannot recharge at my destination. I'll do the same Auto, EV Later, Auto on the return drive. The last time I did that drive I got 42.8 mpg getting there and 42.9 mpg an the return.

 

This time I'm going to see how my speed affects my mpg, but I really don't like driving less than 75 mph.

[larryh]

Note that MPG will vary depending on head/cross/tail winds, atltitude changes, climate control, temperature, and other factors. 

 

You can easily observe the affect of speed on MPG.  Set Eco Cruise to the desired speed and reset a trip odometer.  After about 15 miles, the MPG should start settling down to a consistent value.  Set Eco Cruise to the next desired speed and reset the trip odometer and wait another 15 miles.  The two segments of roads should hopefully be level and have similar conditions.

 

I'm not sure that the car learns your driving style.  I think it is preprogrammed.  The only thing I am aware of that is "learns" is where you park the car to charge, i.e. EV+ mode.  It would be nice if the car would actually learn your routes and automatically optimize the use of EV mode over the route.  But I think you have to do that yourself.  Just reserve EV mode for the slower portions of your route.

 

I prefer a more leisurely drive than racing to keep up with everyone else.  I have enough stress in life without driving adding any more.  So I observe the speed limits.  Driving 70 vs 75 mph will save you 14 minutes for a 240 mile drive.  It will cost you about 0.6 gallons of gas.

Edited July 20, 2013 at 03:47 PM by larryh

[Energized]

I measured the MPG in hybrid mode at different speeds on the same 12 mile section of Freeway:

 

speed (mph)  MPG

70                  41.0

65                  44.4

60                  47.1

 

In this speed range, the relationship between speed and MPG also seems to be linear.  I doubt this holds true at significantly slower speeds.  So, I would estimate at 75, you would get about 38 MPG and at 55 you would get around 50 MPG.

 

 

 

At 75 mph I get 38 mpg with the A/C on.   At 80 mph I get 34 mpg.

[larryh]

Thank you, Energized, for these two data points.  The A/C generally uses about 0.5 kW of power.  At 75 mph, the power to the wheels is around 28 kW.  So A/C uses less than 2% of the energy.  It won't have much impact on MPG.  The measurement errors for MPG are probably more than 2%.  I updated the chart to include these measurements.  They align quite well with what I have measured.

 

 

So every 10 mph increase in speed reduces MPG by about 7 MPG.

Edited July 21, 2013 at 11:09 AM by larryh

[Griff]

It can be all dependent on the length of your trip as well. I travel 34 miles one way, daily. 28 miles of that is, generally, 55-70 miles per hour. I  use Auto until it runs out. At that point, I do the rest of the drive between 30-45mph. I get 95MPGe. If I save the battery for the slow parts, I only get 60 MPGe. I think I get the better numbers because when my big battery runs out, I'm in that slower traffic. There is a lot more Regen from coasting and braking as well as an easier drive because of the slower speeds.

[larryh]

The electric motor is about 3 times more efficient than the engine at 40 mph.  At 70 mph, the electric motor is only 2.5 times more efficient.  You should get better overall MPGe if you reserve EV for slower speeds.  I find that for my 56.5 mile commute, if I switch to EV later in the 60 mph and faster zones, I get much better results.  If I simply choose auto EV and run in EV mode until the battery is depleted, I get about 63 MPGe for the trip.  If I reserve EV for the slower portions, I get about 70 MPGe.  

 

Since I switched, the estimated range in EV mode with a full charge has now increased to 27 miles rather than 23 miles before.

 

You could try switching to EV later in the 70 mph zones and use auto EV the rest of the time.  Of course, just make sure that you deplete the battery.  The most gas you could ever save by optimizing using EV mode is probably less than 0.1 gallons.

Edited July 25, 2013 at 09:56 PM by larryh

[larryh]

Note that my 56.5 mile commute is mostly freeway/highway.   The mileage at the different speeds in the charts above are applicable for highway/freeway driving.   I don't know what results you would get for city driving.  I haven't tried to determine hybrid MPG vs. EV MPGe for city driving.  All my commutes in the city are in EV mode.

 

If you were really ambitious, you could reset one of the trip odometers at the start of each of the various segments of your commute and determine the MPGe you get for that segment in EV mode vs. hybrid mode.  You would, of course, have to drive each segment at least once in EV mode and then in hybrid mode.  Use EV later on the segment(s) with the lowest EV MPGe / Hybrid MPGe ratio, where the electric motor is least efficient vs the engine.

Edited July 26, 2013 at 10:34 AM by larryh

[Eric4539]

Not sure if I'm posting this question in the right place....

 

Several of you are experts on this subject.

 

I installed a 240V charger and at first I was getting 23 miles in the HVB per charge.  Now the number of miles per charge seem to be decreasing.  The last 2 times MFM showed 21 miles in the battery but when I started the car it showed 18 miles in the battery.  I think this morning when I started the car it showed 16 miles in the battery.  MFM shows that I drove 21.9 miles round trip and I depleted the battery just as I returned home.  It took 2 hours, 9 mins to fully charge the car and now MFM shows only 20 miles in the battery.  So steadily I'm "losing" miles per charge: 23, then 21, and now 20...

 

Is this decrease in miles per recharge indicative of my driving style?  Thanks my friends!

[murphy]

It's driving style and use of climate control.

What do the three lines on the coach display look like?

[larryh]

Are you driving any different lately than before?  If you are completely frustrated with MFM, you could always do a master reset of MyFord Touch/Sync and erase all the previous data so it has to compute your EV range from scratch, on the remote possibility there could ever be bugs in the Sync software ;) and it is now confused by the transition from a 120 V to a 240 V charger.  What charger voltage did you specify in MFM in the charge profiles?  If you do a master reset, then you are going to have restore all of the settings that you modified back into MyFord Touch, re-pair your phone, and reconnect to MFM. 

Edited July 29, 2013 at 10:36 AM by larryh

[Eric4539]

It's driving style and use of climate control.

What do the three lines on the coach display look like?

I have the climate control set at 74 but I bump the temperature up to 76 at times.  After the car is sitting in the sun I need to decrease the temperature to 72 in order to be comfortable.  Summers where I live are brutal.

 

The coach display shows braking to be my worst driving behavior.  It was yellow for a while but move to blue; still far below my acceleration and cruising.  I am always in Eco mode and I use my Adaptive Cruise Control as much as possible.

 

 

[Eric4539]

I tried to post a photo of the Coaching screen but I think it is too large so I will try to make it smaller.  Acceleration is actually the worst, then Braking, and my best is Cruising.

 

larryh - I did not set up a Charging Profile since the address displayed as my home address is incorrect .  I do not know how it got the wrong address listed.

[Andre07]

I was just reading that the 12 Volt Lead Acid Battery for the ICE Starter and auto Accesories is chaged from the Plug-in Circuit, that if the Vehicle is left unplugged this Battery can go dead.

 

So if the 12 Volt Lead Acid Battery is charged during the HVB charging, it may account for the discrepency you are finding on how much Power your are using with the 120 Charging.  Not sure why using the L2 Chager would be any different.

 

I also read on this forum that this 12 Volt Lead Acid Battery is rated at 380 AHs, Amp Hours.

 

I tried to fin this info on the Ford Web Site to no avai.

 

Can someone go into to their Truck and check the Rating that is marked on the 12 Volt Lead Acid Battery please so we can try recheck some Calculations.

 

I have not purchased the Ford Fusion Hybrid Energi yet so I can not check anything on it.  Would be appreciated and helpful I believe to all reading this Thread if someone that has the L2 CHarger could let us know what the Voltage Potential is at the Plug end.

 

The Wall Plug Cable should Have 120 VAC Potential at the Plug.

 

Also wonder what Voltage the 7.6Kw LiOn Battery is rated at,  was ready that most Hybrid Battery Packs are rated at 300 VDC, but again have not found any info on this as of yet.

[TX NRG]

The 12V shows it has 390 Cold Cranking Amps. The HVB pack is said to have a peak voltage of 361 during regen braking.

[larryh]

I tried to post a photo of the Coaching screen but I think it is too large so I will try to make it smaller.  Acceleration is actually the worst, then Braking, and my best is Cruising.

 

larryh - I did not set up a Charging Profile since the address displayed as my home address is incorrect .  I do not know how it got the wrong address listed.

You can always delete incorrect charge locations.  You home address should show up in the charge locations when you charge from home.  You can then name it as your home charging profile. 

[larryh]

I was just reading that the 12 Volt Lead Acid Battery for the ICE Starter and auto Accesories is chaged from the Plug-in Circuit, that if the Vehicle is left unplugged this Battery can go dead.

 

So if the 12 Volt Lead Acid Battery is charged during the HVB charging, it may account for the discrepency you are finding on how much Power your are using with the 120 Charging.  Not sure why using the L2 Chager would be any different.

 

I also read on this forum that this 12 Volt Lead Acid Battery is rated at 380 AHs, Amp Hours.

 

I tried to fin this info on the Ford Web Site to no avai.

 

Can someone go into to their Truck and check the Rating that is marked on the 12 Volt Lead Acid Battery please so we can try recheck some Calculations.

 

I have not purchased the Ford Fusion Hybrid Energi yet so I can not check anything on it.  Would be appreciated and helpful I believe to all reading this Thread if someone that has the L2 CHarger could let us know what the Voltage Potential is at the Plug end.

 

The Wall Plug Cable should Have 120 VAC Potential at the Plug.

 

Also wonder what Voltage the 7.6Kw LiOn Battery is rated at,  was ready that most Hybrid Battery Packs are rated at 300 VDC, but again have not found any info on this as of yet.

For all batteries it takes more energy to charge the battery than you can get of the battery.  In addition, during the charging process, the on-board electronics must run to monitor and control charging along with the battery cooling fans.  This take additional 60 watts of power.  With a 240 volt charger, the charging time is reduced.  So you won't have to run the on-board electronics or fans as long. So you should use less electricity and hence get more efficient charging.  Note that there is no way to get any energy out of the HV battery unless you power the on-board battery control module.  The 12 V battery is the only means of providing this power.  The 12 V battery is supposed to be adequate to provide the power to start the car under normal conditions.  You're not supposed to have to worry about a dead 12 V battery.