larryh

The capacity of the HVB degrades at a much greater rate with increasing temperature, and also, to a lesser extent, with increasing SOC and greater depth of charge/discharge during each charge/discharge cycle. The warmer the temperature and the greater the SOC, the faster the rate undesirable chemical reactions occur that degrade the HVB. People who live in the South might experience battery degradation at a rate of 1.6 times the rest of the nation. People who live in the North might see a degradation at a rate of 0.7 times the rest of the nation. The difference is due to the average temperature differences throughout the nation. To preserve the life of the battery for as long as possible, you want to keep it at a low temperature and to maintain a low average SOC, maybe between 20% to 30%. If you are a fanatic, you would only charge the HVB right before you leave and only charge it with sufficient energy to get you to your destination. If you are going to let the car sit for a while, it would be better not to leave the HVB fully charged.

I measured the speed of the car, coasting in neutral starting from 55 mph until stopped at about two second intervals, going both directions on a relatively level road. It took 200 seconds to stop in one direction and 150 seconds going the other way. Each time, I plotted the force slowing the car down (due to aerodynamic drag, rolling resistance, internal frictions of the car, etc.) vs. speed. The plots were fitted to two degree polynomials with R^2 = 0.9994, meaning a very good correlation. Averaging the two results to account for the calm wind and the road not being perfectly level, I get: F =0.1997*v^2 -14.975*v -143.02, where F is the force from aerodynamic drag, rolling resistance, etc. in Newtons and v is speed of the car in meters/second. The constant force at all speeds, -143.02 N, should be due mainly to the rolling resistance of the tires. The force due to the rolling resistance of the tires is approximately F = Rmg, where F = 143.02 N is the force on the car slowing it down due to rolling resistance, R is the rolling resistance, m is the mass of the car (about 1870 kg with everything in it), and g is the gravitational constant. Solving for R, I get: 143.02/(1870*9.902) = 0.0077. I doubt this is a very accurate way to measure the rolling resistance of the tires since there are other factors slowing down the car. But at least it provides an upper bound. You can find the rolling resistance for various tires here: http://en.wikipedia.org/wiki/Low_rolling_resistance_tire

Congratulations and welcome. I have been very happy with the Fusion Energi I purchased in April of 2013. During the first year of ownership, I spent a total of $600 on gas, electricity, and service to drive 12,000 miles. That includes a lot of electricity used to precondition the car with a 240 V charger during one of our coldest MN winters on record. I am constantly trying to understand how the PHEV technology in the Energi works and to optimize mileage. You should look around the forum to see other people's and my observations regarding the Energi, and feel free to jump in on any of the discussions.

I would enter Engineering Test mode and see if there are any DTCs stored to indicate any problems. But the dealer should have checked that. Hopefully, they checked the 12 V battery.

From the OBD II data I have logged, it looks likes the motor/generator is between 75% - 85% efficient in converting electrical to mechanical power. It is more efficient when producing greater power. The motor/generator is about 97% efficient in converting mechanical power to electrical power. In the negative split mode of operation, where the ICE consumes mechanical power from the ICE and converts it to electric power, which is then recycled back to the generator and reconverted back to mechanical power (to provide the reaction torque for the ICE to power the planetary gearset), the generator outputs about 78% of the mechanical power consumed by the motor. So if the generator is 80% efficient (converting electrical to mechanical power) and the motor is 97% efficient (converting mechanical to electrical power), this matches the 78% efficiency observation in negative split mode, i.e. 80%*97% = 78%. Also, I observe that the HVB seems to be about 97% efficient in storing energy and 97% efficient in retrieving it. That makes the efficiency of the portion of the indirect path above in red about 97%*97%*97%*80% = 73%. Power from the ICE is converted to electricity (97% efficiency), the electricity is stored in the HVB (97% efficiency), it is later retrieved from the HVB in EV mode (97% efficiency), and that electricity is used to power the motor (80% efficiency). That makes the indirect path between 73% - 78% the efficiency of the direct path. There is approximately a 22% - 27% energy loss. I think about 80% of the mechanical power generated by the ICE makes it to the wheels in the direct path. That means about 60% of the power makes it to the wheels in the indirect path.

I can't detect much difference in MPGe at 55 mph with the windows up vs. the windows down (at most 3%). You will definitely detect a difference with the A/C on. After it has cooled the car down, it consumes about 0.6 kW of power (only about 4% of the total power consumed). However, until then, it consumes up to 5 kW of power. That is more than the central AC for my house. You will definitely see lower MPGe. All you have to do is reset a trip odometer and monitor MPGe for AC vs. windows down.

If the ICE is not warmed up, it doesn't matter when you switch to EV later. The car essentially runs the ICE at idle speed until it is warmed up. Until the ICE is warmed up, the motor is going to do most of the work no matter what mode you are in. If the ICE is warmed up, you want the ICE to supply the acceleration to get up to highway speeds.

Yes. You want to reserve EV mode for slower speeds and when less power is required. The ICE operates much more efficiently at higher speeds, when more power is required, than at low speeds. EV mode tends to be less efficient at higher speeds.

Many people have wondered whether it is more efficient for the ICE to cycle on and off, alternating with EV mode, or to simply let the ICE power the wheels directly (without charging the HVB) when driving at high speeds. The following is my answer to that question. At speeds of 60 mph or more, driving on a level grade, you want to avoid running in EV mode or charging the HVB. You do not want the ICE to cycle on and off, alternating with EV mode, at high speeds. You only want this to occur at slower speeds. Power Flow Paths from the ICE to the Wheels There are two main paths for power to flow from the ICE to the wheels, the direct path, where the ICE transmits power directly to the wheels, and the indirect path, where the ICE charges the HVB, which then later in EV mode, powers the motor, which in turn powers the wheels. These paths are illustrated below: Direct Path: ICE => Planetary Gearset => Countershaft => Wheels Indirect Path: ICE => Planetary Gearset => Countershaft => Motor/Generator => HVB => Motor => Countershaft => Wheels The black arrows indicate flow of mechanical power. The red arrows indicate flow of electrical power. The indirect path is far less efficient than the direct path for transmitting power from the ICE to the wheels. My best guess is about 80% of the power from the ICE is transmitted to the wheels via the direct path, and at most 70% for the indirect path. This would suggest that we would never want to use the indirect path at all, i.e. EV mode, since it requires more energy, and consequently more gas, than the direct path. But there are additional factors that come into play. ICE Combustion Efficiency The ICE is more efficient when producing between 15 – 35 kW of power than when producing less than 15 kW of power. My best guess is that the ICE is about 37% efficient when producing 15 – 35 kW of power, i.e. 37% of the energy released from the combustion of gas is converted to mechanical power by the ICE. At lower power, the ICE may only be 25% efficient or less. So we would like to operate the ICE where it is most efficient, between 15 – 35 kW of power. And that is basically what the car does. You will rarely see the ICE producing less than 15 kW of power. Overall Efficiency of Power Flow Paths For the indirect path, the ICE will always be operating at power levels of 15 kW of power or more when charging the HVB, even at slower speeds. So for this path, about 37%*70% = 26% of the energy released from the combustion of gas will make it to the wheels. For the direct path, the ICE will be operating at power levels of 15 kW or more for speeds greater than about 55 mph, and about 37%*80% = 30% of the energy released by the combustion of gas will make it to the wheels. For slow speeds, if the ICE is not also charging the HVB and the ICE power is less than 15 kW, only about 25%*80% = 20% of the energy makes it to the wheels. If the ICE is also charging the HVB, then the power from the ICE will exceed 15 kW, and again the efficiency of the direct path will be 30%. When charging the HVB, we get a bonus. The ICE is now at a more efficient operating point and the portion of the gas being consumed to power the wheels is less than what it would be if we did not charge the HVB. Low Speed Efficiency At low speeds, we have: Efficiency of Direct Path when charging HVB: 30% Efficiency of Indirect Path: 26% Efficiency of Direct Path when not charging HVB: 20% For best mileage at low speeds, we would never want to use the direct path without also charging the HVB (the least efficient path). That means we want to alternate between the direct path and charging the HVB, and the indirect path to use up the accumulated energy stored in the HVB. We want the ICE to cycle on and off, charging the HVB, alternating with EV mode. The overall efficiency will then be between 30% and 26%, but it will be higher than the 20% associated with the direct path when not also charging the HVB. High Speed Efficiency At high speeds, we have: Efficiency of Direct Path when not charging HVB: 30% Efficiency of Direct Path when charging HVB: 30% Efficiency of Indirect Path: 26% For best mileage at high speeds, we would never want to use the indirect path (the least efficient path). We also don’t want to use the direct path and charge the HVB. We would have to use up the accumulated energy stored in the HVB at a later time using the indirect path. We certainly don’t want to do at higher speeds. We would have been better off simply not charging the HVB to begin with. So we would have to use up the accumulated energy stored in the HVB when driving at slower speeds. But that means spending more time using the less efficient indirect path when driving at slower speeds to use up the accumulated energy in the HVB. The conclusion is that we only want to use the direct path without charging the HVB at higher speeds. About 30% of the energy released from the combustion of gas will make it to the wheels at high speed via the direct path without charging the HVB.

Look at the My Ford Touch EV info screen in the car. Does it say the battery is 100% charged? If not, then charging is stopping prematurely. You will have to then check your Go times and Value Charging Profile to make sure they are set up correctly.

I have had my car for over a year now and have been wondering how to determine how much capacity has been lost from the HVB during the first year of ownership, i.e. the state of health (SOH) of the HVB. In the C-Max Energi forum, a member from Texas has been experiencing decreased range from their HVB. The HVB battery charges normally, i.e. takes two hours using a 240 V charger, and the display shows 100% SOC after it is fully charged. However, when doing a comparison with another fully charged Energi, the plug-in energy used reported by the car's display was 4.4 kWh after entering hybrid mode, whereas the other Energi, after several more miles, reported 5.5 kWh before entering hybrid mode. The dealer measured the SOC and voltage of the HVB after it was fully charged and depleted. The values were normal. There is a PID named Energy To Empty (ETE) that measures the current energy stored in the HVB. When the bad HVB was fully charged to 100% SOC, ETE for was only 6.39 kWh. My car reports ETE is 7.14 kWh. If 7.14 kWh is the capacity for a HVB, that is SOH is 100%, then the SOH of the bad HVB was only 6.39/7.14 = 89%. So it appears you can track SOH of the HVB from ETE and SOC. Compute ETE/SOC, this is the capacity of the HVB. Then divide the capacity by 7.14 (assuming 7.14 is the capacity of a HVB that has 100% SOH), you can determine the SOH. For example, this morning, ETE was 7.05 and SOC was 98.70%. So the capacity of the HVB was 7.05/.9870 = 7.14 kWh. The SOH is then 7.14/7.14 = 100%. I don't know the actual capacity of a HVB with 100% SOH, so I'm not sure what the true SOH of my battery is.

I made the following posts in the Fusion Hybrid forum which explain the operation of hybrid mode during city and highway driving: http://fordfusionhybridforum.com/topic/8723-efficiency-on-longer-highway-trips/?p=84199http://fordfusionhybridforum.com/topic/8723-efficiency-on-longer-highway-trips/?p=84289http://fordfusionhybridforum.com/topic/8723-efficiency-on-longer-highway-trips/?p=84307

The driving coach is properly coaching you to accelerate moderately. If you limit acceleration to two bars, you will get a good acceleration score. Limiting acceleration to 2 bars results in near minimal energy consumption from the HVB. Fast acceleration wastes energy.

The following is a plot I made showing the energy consumed from the HVB (kWh) vs. distance for three different accelerations: about 1.5 bars (slow), 2 bars (medium), and 3 bars (fast). The total distance traveled is about 0.25 miles and the final speed is 40 mph. The x-axis shows GPS longitude traveling straight East. The y-axis shows the amount of energy consumed from the HVB by the motor. (I have subtracted out the power consumed by accessories.) The curves are not smooth due to errors in GPS longitude measurement. With 1.5 bar acceleration, I reach 40 mph at the end of 0.25 miles. With the faster accelerations, I reach 40 mph sooner and then used cruise control to maintain 40 mph. The faster the acceleration, the more energy that is consumed. However, the differences are small. Fast acceleration consumes about 0.012 kWh more energy than slow acceleration. With fast acceleration, you initially use a lot of energy to get up to speed and then the rate of energy usage drops to what is required to maintain constant speed (the purple curve). With slow acceleration, you will have a constant rate of energy usage until reaching the final speed (the blue curve). The faster the acceleration, the more the curve shifts to the left and up. It looks like the optimal acceleration is to apply constant power until reaching the final speed. The resulting curve will be a straight line from the start to the terminal point. Any faster acceleration will result in a curve bowed outward shifting up and to the left. The observed efficiency of the motor for slow acceleration was 79.6%, moderate acceleration was 80.7% and 79.2%, and fast acceleration was 78.6%--there was no significant difference.

The X-Gauge Codes are listed here: "http://fordfusionhybridforum.com/topic/6503-scangauge-ii-x-gauge-codes/" You can translate them using this document: "http://www.scangauge.com/wp-content/uploads/XGaugeCoding.pdf"

On my commute home yesterday, I allowed the car to operate normally in Hybrid Mode, turning the ICE on and off, to observe the HVB cell voltage variation when the SOC of the HVB is low. The HVB cell variation generally remained less than 10 mV. It is only at the end that it started rising close to 20 mV when I tried to prevent the ICE from coming on and use up the remaining charge in the HVB, forcing the HVB to provide slightly more power to propel the car. So low SOC, i.e. Hybrid Mode, does not seem to cause any undo stress on the battery if you allow the car turn on and off the ICE as it is programmed to do. The problem seems to occur when you try to override its programming and prevent the ICE from coming on, discharging the battery for a long period of time without allowing the ICE to share the load or allowing the HVB to recover by running the ICE to recharge the battery and rebalance the cells. The HVB seems to be in a more weakened state, it cannot recover as easily from the stress of providing high power output. That's probably one of the reasons why the power output of the HVB is limited to 2 bars in the Empower screen while in hybrid mode. Hybrid mode begins when the SOC falls below 21.5% at about time 4:38. The purple line shows the ICE power output. The ICE is on when the power is non-zero. The green line shows the power output of the HVB. Negative power means regen or the ICE is running the motor/generator to generate electricity. Most of the time the HVB was assisting the ICE in propelling the car. However, at times, the ICE was generating electricity for the HVB.

The following is a plot of SOC vs. Cell Voltage for the HVB made from the data collected during my commute on Friday. The HVB has 84 cells in series. In order to make this plot, I had to assume the HVB had an internal resistance of 0.11 Ohms. If I just plotted the data and assumed it had no internal resistance, the dots would be scattered all over the chart. Ideally, the voltage measurement should be made with no load on the HVB. But that is not practical when driving--I'm not about to pull over to the side of the road every mile and turn off the car so I can make a measurement. The lowest voltage observed of any cell during the trip was 3.38 V. When there was no load on the HVB, the lowest cell voltage observed was 3.44 Volts. The maximum cell voltage at that time was 3.48 V.

For further discussion of this and analysis of the HVB, see the following thread: "http://fordcmaxenergiforum.com/topic/2794-video-explaining-what-happens-to-mpge-and-soc-charging-while-powered-on/?p=21685"

The 120 V charger supplies the car with about 1.06 kW of power. The heater and AC can initially consume up to 5 kW of power. During remote start, most likely the AC and the heater will consume at least 2 kW of power, so the 120 V charger cannot supply sufficient power to prevent draining the HVB. You need a 240 V charger. It can supply the car with 3 kW of power.

I tried the same experiment again. This time I increased the time resolution of the data, i.e. logged data faster to get more accurate results. I also removed the power being consumed by accessories. Acceleration Energy (kWh) slow 0.134 moderate 0.134 fast 0.137 I get similar results except for moderate acceleration--something was wrong the first time I did it. There is very little difference between the measurements. I'm not sure how to control all the variables to get more accurate results. But I suspect fast acceleration is wasteful as indicated by the data and the analysis in my previous post.

I accelerated from a stop to a maximum speed of around 40 mph. I measured the total energy consumed after traveling about 0.25 miles. The slow acceleration took the entire distance to reach 40 mph. Acceleration Speed Energy (kWh) Slow 0.136 Medium 0.143 Fast 0.137 There are too many different ways to accelerate to 40 mph over a distance of 0.25 miles. There is not much difference in the energy used to determine which is the best way.

The following is a plot of the voltage variation between the HVB cells for my 60 mile commute this morning. The plot on the left shows the variation vs. SOC of the HVB. The right plot shows the variation vs. power output of the HVB, where negative power results from regen. I'm not sure how correct this is, but I suspect that large voltage variation is bad and is indicative of stress on the battery. You want all the cells to be balanced with less than 0.01 volt variation. According to the graphs below, large voltage variation occurs when the SOC is low and during high power output of the HVB. I'm not sure how long it takes the cells to recover and become rebalanced after the balance is perturbed. The worst thing you can do for the balance is to run the HVB at a low SOC. It increases significantly below 17% SOC. That is about 50% charge for the hybrid battery icon. Perhaps we should stay in EV later mode and maintain the charge level above 20% until the end of the trip. At the end, then let it enter hybrid mode and use up the remaining charge of the battery. Try to stay out of hybrid mode as long as possible. This may help preserve HVB life.

You should contact Ashley from Ford and ask her assistance to help with diagnosing the problem. See the following thread: "http://www.fordfusionenergiforum.com/topic/1605-official-ford-service-out-of-office-thread/"

Others have posted that they have received the low voltage battery email after the fact. It appears that sometimes the battery is to weak to send out the message when the condition is detected and it is sent out later once the battery recovers.