113 replies to this topic

[larryh]

The efficiency the motor/generator in generating electricity is probably around 90%, i.e. 90% of the mechanical energy provided to the motor/generator is converted to electrical energy.  The efficiency of the motor/generator in providing mechanical power is about 80%, i.e. 80% of the electrical energy provided to the motor/generator is converted to mechanical energy.   This means about 90%*80% = 72% of the mechanical power provided by the ICE to charge the HVB is actually recovered in EV mode.

 

From my previous post, I mentioned that perhaps only 72% of the energy provided by the ICE to charge the HVB is actually recovered during EV operation.  That is a big loss in efficiency.  However, it is not really as bad as it may seem.  The electric motor uses significantly less power to propel the car than the ICE. 

 

For my 65 mph commute, the ICE needs to provide about 17.6 kW of power just to propel the car.   The electric motor is consuming 6.9 kW of this power to generate electricity and recycling that electricity back to the generator which then supplies 4.9 kW power that sums with the 17.6 kW from the ICE via the planetary gear system.  So 6.9 - 4.9 = 2 kW of power produced by the ICE is being used to control the planetary gear system.  The ICE has to produce at least 2 kW more power than the motor.  Actually, it has to produce more power than that to overcome additional transmission losses (1.4 kW of additional power).

 

The motor requires 14.2 kW of power to maintain the same 65 mph speed on the freeway.  That is 14.2 / 17.6 = 81% of the power required from the ICE.  So even though only about 72% of the energy supplied by the ICE to charge the HVB is recovered in EV mode, EV mode requires significantly less power.  Effectively, we are recovering 72%/81% = 89% of the energy provided by the ICE to charge the HVB.  That is a lot better than 72%.  Having the ICE charge the HVB is not quite a free lunch (100% efficiency), but 89% is not all that bad. 

 

Note that the power drawn from the HVB to power the motor at 65 mph is 17.0 kW, which includes 0.3 kW of power to run the car's accessories, i.e. fans, radio, lights, etc.  The motor is thus 14.2 / (17.0 - 0.3) = 85% efficient at 65 mph.

Edited by larryh, 19 July 2014 - 09:19 PM.

[larryh]

From the data I have collected, the estimated average efficiency of the ICE producing different power output levels is:

 

Power     Efficiency

10           28%

15           32%

20           35%

25           36%

30           35%

35           35%

40           35%

45           34%

 

Since the ICE does not generally operate at low power levels, it is difficult to get good estimates at 15 kW of power and below.  For the 65 mph freeway commute when the ICE was producing 17.6 - 23 kW of power, the efficiency was 34.6%. 

 

If 89% in the previous post is correct, then the car should run in EV mode when the ICE efficiency falls below 0.89*0.36 = 32%, which is around 15 kW and is consistent with what I observe in the plots in the previous posts. 

Edited by larryh, 20 July 2014 - 06:15 AM.

[md13ffhguy]

I don't have all the technical knowledge that some of you possess about how this all works, so I'll just add one of my actual observations to this thread.

Friday night, I completed a 160 mile trip from central MD to the eastern shore. Over the first 60 miles, my MPG reached 55.1. Then, upon crossing the Chesapeake Bay Bridge, the terrain considerably flattens out. I thought about giving the technique described in this thread a try - forcing the HVB to fully charge and cruising on ICE alone, but after a couple of attempts, I quit. I just couldn't find the right position in the throttle to keep the car from automatically going into EV mode, so I just decided to let the car do its thing on eco-cruise.

Interestingly, on three occasions over the last 100 miles on flat terrain, I noticed the car seemed to go into the described mode all on its own. The HVB battery charge was nearly full, and the car cruised with the ICE running and an instantaneous MPG of 50+, which was interesting to observe. Sadly, however, my overall economy dropped over this stretch, as I arrived at my destination with an overall trip MPG of 53.0 (still, nothing to complain about).

[acdii]

It isn't easy, it took me weeks to develop it, and I drive 100 miles a day 5 days a week. Now it comes second nature.

[md13ffhguy]

I guess what I'm really wondering is, if I'm content driving at 55 MPH max, and currently experiencing 53 (summertime) MPG, is there really any benefit to mastering this?

[Texasota]

I guess what I'm really wondering is, if I'm content driving at 55 MPH max, and currently experiencing 53 (summertime) MPG, is there really any benefit to mastering this?

Only if you enjoy doing it. If mastering this technique is agravating, tiresome, frustrating, distracting, or seems contrary to the way the Ford engineers designed the FFH to operate, then let the FFH operate the way it was designed and enjoy the drive.

Edited by Texasota, 20 July 2014 - 03:10 PM.

[larryh]

 

For my 65 mph commute, the ICE needs to provide about 17.6 kW of power just to propel the car.   The electric motor is consuming 6.9 kW of this power to generate electricity and recycling that electricity back to the generator which then supplies 4.9 kW power that sums with the 17.6 kW from the ICE via the planetary gear system.  So 6.9 - 4.9 = 2 kW of power produced by the ICE is being used to control the planetary gear system.  The ICE has to produce at least 2 kW more power than the motor.  Actually, it has to produce more power than that to overcome additional transmission losses (1.4 kW of additional power).

 

The motor requires 14.2 kW of power to maintain the same 65 mph speed on the freeway.  That is 14.2 / 17.6 = 81% of the power required from the ICE.  So even though only about 72% of the energy supplied by the ICE to charge the HVB is recovered in EV mode, EV mode requires significantly less power.  Effectively, we are recovering 72%/81% = 89% of the energy provided by the ICE to charge the HVB.  That is a lot better than 72%.  Having the ICE charge the HVB is not quite a free lunch (100% efficiency), but 89% is not all that bad. 

 

Note that the power drawn from the HVB to power the motor at 65 mph is 17.0 kW, which includes 0.3 kW of power to run the car's accessories, i.e. fans, radio, lights, etc.  The motor is thus 14.2 / (17.0 - 0.3) = 85% efficient at 65 mph.

 

For my commute home, I recorded more data to verify the previous results.  This time, the temperature was 86 F and there was a headwind.  Previously it was 62 F and the wind was calm.  I did not use AC nor have the windows open.  The ICE output 19.6 kW of power this time to maintain 65 mph.  The net power to the HVB was approximately 0 kW.    The electric motor was consuming 7.7 kW of power to generate electricity and recycling that electricity back to the generator which then supplied 5.4 kW of power that sums with the 19.6 kW of ICE power by the planetary gear system.  So this time 7.7 - 5.4 = 2.3 kW of power was being used to control the planetary gear system.  That represents a 2.3/19.6 = 12% loss of power used to control the planetary gear system.  The efficiency of the ICE was 34.5%. 

 

In EV mode, the motor required 16.2 kW of power to maintain 65 mph.  Again, using the motor to power the car is more efficient than using the ICE.  The motor only needs to generate 16.2/19.6 = 82% of the power required by the ICE to propel the car.  Previously, the percentage was 81%.  So I am getting consistent results.  Apparently there is a total loss of 19.6 - 16.2 = 3.4 kW from the planetary gear system, or 3.4/19.6 = 17% when the ICE transmits its power through the planetary gear system. 

 

The power drawn from the HVB was 19.6 kW.  Accessories used 0.6 kW of power.  So the efficiency of the motor was 16.2/(19.6-0.6) = 85%--the same as before.

 

I will have to see if I can determine the power at the wheels to determine the loss of power being transmitted from the motor to the wheels. 

Edited by larryh, 20 July 2014 - 05:38 PM.

[acdii]

What is the fuel consumed to recharge the HVB after depleting it running in EV?  This has the largest impact that can be seen on the instant.   For me when the ice is doing a consistent 45+MPG at 60 MPG, and not 20 to recharge the HVB after going a mile in EV seems more efficient.

 

At lower speeds where you can also recapture energy by braking, running EV does seem to be the best solution.  Just for tests next week I will use the cruise set at 60 for my daily drives and compare the results to what I have been getting. Hopefully mornings wont be very hot, but the afternoons are supposed to be upper 80's+ this week, so hard to do an honest comparison due to the temp differences.

[larryh]

Since I have the Fusion Energi, my car does not work quite the same as the Fusion Hybrid.  On a level freeway at constant 65 mph, the car does not normally run in EV mode.  I switched from EV Later to EV Auto to turn off the ICE and run in EV mode so I could compare the operation of the ICE and the electric motor.   The plot below details what happened when I switched back from EV Auto to EV Later to discontinue EV operation.

 

The switch occurs at time 6:57:14.  The top light blue line shows instantaneous MPG.  It rises from 30 MPG when starting to charge the HVB to about 45.6 MPG after charging has completed.  The next darker blue line shows the power output from the ICE.  It starts at about 30 kW when charging begins and drops to about 17.6 kW after charging has completed.   The third blue line from the top is the power output from the generator.  It is a relatively constant 5.0 kW.

 

The orange line shows the change in energy of the HVB.  I arbitrarily chose 0 kWh as the starting energy in the HVB (it actually had 2.91 kWh of energy left).  ETE stands for Energy to Empty, i.e. the amount of energy in the HVB.  The car added 0.122 kWh of energy to the HVB.   That is an increase in SOC of 1.7%--the capacity of the Energi HVB is 7.14 kWh.  That corresponds to a change in SOC of 20% on the 2D hybrid battery icon. 

 

The green line shows the power applied to the HVB (when negative) or drawn from the HVB (when positive).   When switching to EV later mode and charging begins, the car initially applies 10 kW of power to the HVB. 

 

The red line shows the power being consumed by the motor to generate electricity.  It starts consuming 15 kW of power to charge the HVB and reduces to 7.1 kW after charging completes. 

 

I don't have a good way of determining how much of the gas consumed went to charge the HVB.  By computing the area under the power curve for the ICE, I estimate that it output about 0.12 kWh of energy to charge the HVB.  But that is not very accurate.  0.12 kWh was the amount of energy that was stored in the HVB so I get 100% efficiency which is not right.

 

I'll just assume that the ICE is 90% efficient in generation of electricity, so 0.122/0.9 = 0.136 kWh of energy was required.  Assuming the ICE is 37% efficient, that is 0.011 gallons of gas.

 

Note that the ICE efficiencies that I reported in my previous posts are probably a bit low.  The fuel data that is recorded is always overly pessimistic.  For this trip, the logged data showed I had used 0.67 gallons of gas.  The car reported that I had only used 0.62 gallons of gas.  So the efficiencies reported above should probably be multiplied by 1.08 to get the correct value.  The ICE efficiency for the portion of the trip plotted below was 37%. 

 

 

Edited by larryh, 20 July 2014 - 08:26 PM.

[larryh]

Actually, I think only about 87% of of the ICE energy applied to the motor to generate electricity is converted into electricity.   I already determined that 17 - 12% = 5% of the power from the ICE is lost by the planetary gear system, so that power does not even make it to the motor (see post 87).   I believe the motor is at least 92% efficient in converting mechanical power to electrical power from the data plotted above (and maybe as high as 94%).  So that means at least 95%*92% = 87% of the ICE power applied to the motor to generate electricity is converted to electricity.   That would imply the effective efficiency of the recovered energy when driving in EV mode is about 87% rather than 89% (see post 81).

Edited by larryh, 21 July 2014 - 05:10 AM.

[larryh]

I think the efficiency of the motor in generating electricity is in the upper 90% range.   I can estimate this as follows.
 
At around 15 kW, from the previous posts, the efficiency of the motor in producing power to propel the car was 85%.  When I drove to work today, I verified that the motor was 85% efficient at this power level.    However, efficiency decreases with power output.  At about 5 kW, the efficiency fell to about 72%, i.e. 72% of the electrical power from the HVB was converted to mechanical power by the motor. 
 
Let’s assume the generator is equally efficient at generating power.  From the previous posts, during steady state when no power was being supplied to the HVB, the generator was providing 5.4 kW of mechanical power and the motor was consuming 7.7 kW of mechanical power on Sunday’s commute—there was a power loss of 7.7 – 5.4 = 2.3 kW.  For Fridays’ commute, the generator was providing 4.9 kW of mechanical power and the motor was consuming 6.9 kW of mechanical power—there was a power loss of 6.9 – 4.9 = 2 kW.
 
Assume that all the power loss is associated with the conversion between mechanical and electrical power by the motor and generator (I don’t know how valid this is).   Since the generator is 72% efficient, on Sunday, it must have been consuming 5.4/0.72 = 7.5 kW of electrical power.  On Friday, it was consuming 4.9/0.72 = 6.8 kW of electrical power.  The electrical power was provided by the motor, so on Sunday, the motor was 7.5 / 7.7 = 97% efficient in generating electricity.  On Friday, it was 6.8 / 6.9 = 99% efficient.  Due to measurement error, I can’t be certain of the exact values.  So I’ll assume the efficiency of the motor in generating power is approximately 97%.  This is consistent with the observed efficiency of the motor in generating electricity during regenerative braking.
 
That means the that 95%*97% = 92% of the power from the ICE used to charge the HVB is converted to electrical power (there is a 5% loss in power when transmitting power from the ICE through the planetary gear system).   This also means that the efficiency ratio in post 81, could be as high as 92%*80%/81% = 91%. 
 
So to calculate the amount of gas consumed by the ICE to charge the HVB, assume the ICE is 37% efficient and that 92% of the power from the ICE supplied to the motor to generate electricity is converted to electricity.  The capacity of the HVB in the Fusion Hybrid is 1.4 kWh.  Furthermore, I estimate that about 97% of the energy supplied to the HVB is stored in the HVB.  If the ICE charges the battery from 20% to 80%, then the amount of energy applied to the HVB must be around 1.4 * (80% - 20%) / 97% = 0.87 kWh.  If the ICE is 37% efficient, each gallon of gas provides the ICE with 0.37*33.705 = 12.47 kWh of mechanical energy.   So the ICE must consume about 0.87 / 12.47 = 0.07 gallons of gas to charge the HVB from 20% to 80%.
 

[acdii]

well I did a test this morning, Temps were about the same as last week, traffic about the same, took the same route I normally take, only difference was I used cruise control. Note I have the Adaptive cruise, so it adjusts speeds according to what is in front of me, otherwise its the same as all the rest.  There were two instances where the cruise applied braking,  where I would have been lifting and gliding instead, so other than that, everything is pretty much the same.

 

End result, 47.8 MPG.  Its roughly 1 MPG less than what I have been getting. For 1 MPG, I think I wont bother with trying to stay on ICE, and just use the dang cruise instead.  I will have more information by the end of the week as I will continue my test the entire week. 

[jeffo65]

My resluts from this weekend.

 

I drove from St Charles, MO to Chicago, IL on the most awe inspiring Interstae 55 and had these results

 

Drive from St Charles, MO to Chicago, IL

- Drove with ACC on

- Drafted behind semis for about 150 miles of the 312 miles at a speed of 73 mph

- I did not try to stay in or out of EV mode, just let the car decide what it wanted to do

- Mileage was 45.1 for northbound trip

 

Drive from Chicago, IL to St Charles, MO

- Drove with ACC on

- Drafted behind semis for a minimal amount of miles, maybe 10.

- Set cruise at 73 mph

- I did not try to stay in or out of EV mode, just let the car decide what it wanted to do

- Mileage was 43.1 for northbound trip

 

Can't complain about results.

Edited by jeffo65, 21 July 2014 - 01:25 PM.

[corncobs]

well I did a test this morning, Temps were about the same as last week, traffic about the same, took the same route I normally take, only difference was I used cruise control. Note I have the Adaptive cruise, so it adjusts speeds according to what is in front of me, otherwise its the same as all the rest.  There were two instances where the cruise applied braking,  where I would have been lifting and gliding instead, so other than that, everything is pretty much the same.
 
End result, 47.8 MPG.  Its roughly 1 MPG less than what I have been getting. For 1 MPG, I think I wont bother with trying to stay on ICE, and just use the dang cruise instead.  I will have more information by the end of the week as I will continue my test the entire week. 

I would say you have trained your girl well that's why the results are so close.
Mine isn't tuned for your kinda driving so the last time I drove towards Rockford with ECC it returned 45 MPG.

I still believe that if you spend the time and drive your daily drive conservative for a few weeks and do it manually (no ECC) the computer learns the driving pattern and the capabilities of its components maximizing the performance later of when the same route is driven with heavy use of ECC for example.

My ECC is pretty much doing the same things I would be doing so it works out perfect for me. Ok I admit something I'll force EV mode once and a while but overall it's a very relaxing drive. ( even more so without some morons you can't avoid)

[acdii]

My resluts from this weekend.

 

I drove from St Charles, MO to Chicago, IL on the most awe inspiring Interstae 55 and had these results

 

Drive from St Charles, MO to Chicago, IL

- Drove with ACC on

- Drafted behind semis for about 150 miles of the 312 miles at a speed of 73 mph

- I did not try to stay in or out of EV mode, just let the car decide what it wanted to do

- Mileage was 45.1 for northbound trip

 

Drive from Chicago, IL to St Charles, MO

- Drove with ACC on

- Drafted behind semis for a minimal amount of miles, maybe 10.

- Set cruise at 73 mph

- I did not try to stay in or out of EV mode, just let the car decide what it wanted to do

- Mileage was 43.1 for northbound trip

 

Can't complain about results.

The best I have found is being 2 bars on ACC behind a flatbed semi. Sets you back just the proper distance for safety(2 second rule) and still allows you to ride in the wake to take advantage of the draft. 

[Texasota]

well I did a test this morning, Temps were about the same as last week, traffic about the same, took the same route I normally take, only difference was I used cruise control.

 

End result, 47.8 MPG.  Its roughly 1 MPG less than what I have been getting. For 1 MPG, I think I wont bother with trying to stay on ICE, and just use the dang cruise instead.  I will have more information by the end of the week as I will continue my test the entire week. 

 

Only speculation on my part but I don't believe you can make any meaningful, reliable or useful conclusions concerning the 1 MPG difference between your two driving styles when you do not have a controlled environment for your tests. Wind speed and wind direction is a much larger variable than summer time temperature variations, minor differences in traffic conditions or driving style.

 

As an example, last Friday I took a 65 mile road trip to the north with a modest tail wind in my 2012 Focus. The trip computer indicated 44 MPG when I arrived at my destination. I spent 30 minutes at the destimation and then headed back home with the wind now a head wind and it appeared to have increased in speed. When I arrived back home the trip computer indicated 40 MPG for the entire trip. This implies I got 36 MPG on the return trip south.  That is an 8 MPG difference between the trip north and the return trip south and was likely due almost entirely to the wind. Even a very light wind can easily make a difference in MPG greater than 1 MPG.

[larryh]

There is a wide variation in the amount of energy required for a commute depending on temperature, wind speed and direction, traffic, and other factors.   The following table shows the variation in energy required and fuel consumed for a 60 mile commute.  There is linear correlation between the amount of fuel consumed and the energy output of the ICE.   Perhaps 90% of the variance in MPG for the same commute is from wind, temperature, traffic, and other factors that are beyond your control that affect how much energy is required.  The trip that consumed the most gas required 49% more energy than the trip with the least amount of gas consumed.  (Note each trip also consumed about 5.9 kWh of plug-in energy in addition to the gas). 

 

Energy Output of ICE (kWh)  Fuel (gallons)

6.531893327                 0.593525846
6.662831782                 0.591398591
6.769850679                 0.609514536
7.02045321                  0.616525337
7.348378985                 0.64225446
7.593411538                 0.671953975
7.655557735                 0.678221184
8.001970951                 0.697196885
8.331743778                 0.726306456
8.602420337                 0.707282661
9.710379355                 0.80417292
 

Edited by larryh, 22 July 2014 - 05:02 AM.

[acdii]

The winds in the morning have been pretty consistent, light, usually out of the north or south, which has little effect since I am driving mostly east. I didn't mention it since it wasn't a factor. Winds dont normally become an issue until later in the day.  The morning drive is between 6:30 and 7:30, and traffic is nearly always the same, so makes for a good consistent test. The only variable are the traffic lights, some I breeze through others tend to be spotty. Usually the ones that turn red are at the bottom of a valley, so slowing down requires more braking than Regen can capture, then have to climb up a hill from a dead stop.  The problem with two of these lights is you can never tell if they will turn red, or stay green, sometimes when I expect it to stay green, they turn red, with no cross traffic, other times with cross traffic I expect it to turn red and it stays green. Mucks with the brake score for sure.

 

My trip home on cruise, with AC on was not that good, I could have done much better manually, managed only to get 41.5,

[Texasota]

The morning drive is between 6:30 and 7:30, and traffic is nearly always the same, so makes for a good consistent test. The only variable are the traffic lights, some I breeze through others tend to be spotty.

Again, only speculation on my part, but this seems to be a large stretch for you to make this claim. Even very modest winds from any direction can have a surprisingly significant impact on MPG. You do not have a controlled environment and there are too many variables for you to attribute the 1 MPG difference to the driving style.

 

My anecdotal evidence and larryh's hard data above strongly suggests there are numerous variables coming into play that noone can accurately estimate, account for, or adjust for when you do not have a controlled environment.

[acdii]

Oh you mean like the controlled environment used by Ford to determine EPA?  

 

These are what are classified as Observations, nothing more, were they Opinions, then you could jump all over me.  They are only observations that I see in my particular car, on my particular daily drive, with my particular driving style. The majority of people who read what Larry posts will go right over their heads, eyes glazed over, and will be meaningless. 

 

The OP asked for best way to achieve high MPG on the highway. Based on my observations and a few others, we gave tips on how to do it. My particular style, where I maximize the use of ICE over EV at speed greater than 50 MPH vs. the use of Cruise control was what I was explaining. So far my observation is on the first test the end result going to work, where my MPG has been a very consistent 47-49 MPG every day when it is not raining when I do not use cruise, and the one day I did use cruise I found the MPG to be very close. However on my return trip where traffic is poor, and a lot of red lights, using cruise turned out to be 3-4 MPG below what I would normally see. Going home is usually a 44 MPG trip, and the trip last night was 41.5.

 

Again, this was just an observation in the real world where 2/3rds of my trip is at 55-60 MPH, with my driving style. No scientific data, or facts, just a simple, this is how I get 47 MPG driving the FFH on the highway.