larryh

When the HVB temperature falls below 0 F, the Energi also disables regenerative braking. Aerodynamic drag increases about 15% when the temperature falls from 70 F to 0 F. Thus I would expect the energy required for the 8 mile commute to work to increase from 1.8 kWh to 1.15*1.8 = 2.1 kWh. So there is an another source of friction causing the 2.5 - 2.1 = 0.4 kWh of energy loss. The commute takes about 15 minutes, so there is roughly (probably not very accurate) 60/15*0.4 = 1.6 kW of power loss due additional frictional losses above what I would expect.

The following plot shows kWh/mile vs. outside temperature for my 8 mile city commute to and from work in EV mode. Climate is off. At 70 F, it requires 0.230 kWh/mile of energy from the HVB for the commute (or a total of 8*0.230 = 1.8 kWh). At 0 F, it requires 0.317 kWh/mile (or a total of 8*0.317 = 2.5 kWh). So it requires 0.317/0.230 = 1.38 times as much energy for the commute at 0 F vs. 70 F. It I go to Tesla's web site, they have a calculator for estimated range vs. temperature. For city driving with climate turned off, the estimated range is 347 miles at 70 F and 337 miles at 0 F. They show very little reduction in range. You get 97% of the range at 0 F vs. 70 F. That seems strange since I would expect aerodynamic drag alone to cause a greater reduction in range than that. Even on the highway at 70 miles per hour, they show the range at 0 F to be 93% of the range at 70 F. For the Fusion Energi, the energy capacity of the HVB is reduced 15% at 0 F. So rather than about 5.7 kWh of usable energy, the usable energy is 0.85 * 5.7 = 4.9 kWh. The Tesla must have a heater for the HVB so they do not lose range in cold weather. The range of the Energi at 0 F, is thus 4.9 / 0.317 = 16 miles. The range at 70 F is 5.7 / 0.23 = 25 miles. So the range at 0 F is 65% of the range at 70 F. Tesla does significantly bettery with 97% of the range at 0 F vs 70 F. 15% of the difference (97% - 65% = 32%) can be attributed to the Energi lacking a heater for the HVB. The remaining 17% must be due to significantly higher friction with the Energi vs. the Tesla in cold weather. So the question is why does the Tesla do so much better in colder weather? The 1.38 addtional energy factor required for the Energi at 0 F vs. 70 F causes a significant reduction in range. Being a hybrid, the Energi has the additional overhead of the eCVT. I wonder how much impact that has on performance in cold weather. It must add a significant amount of additional friction in cold weather over pure electric cars. If that is the case, the eCVT is the big hit to MPGe in cold weather. I wonder how other purely electric cars do in the winter? Other than the eCVT, I have no other explanation why the Energi requires so much more energy at 0 F vs 70 F. I suspect the increased friction contributions from greater aerodynamic drag and greater tire rolling resistance at 0 F are responsible for less than half of the increased energy demand.

Now if only the Energi had a larger battery and on-board charger to take full advantage of what a Level 2 charger could provide.

This plot shows the Interior Cabin Temp vs. Garage Temp for the past winter with the preconditioning temperature set to 72 F using a Level 2 Charger. I generally leave before the Go Time, so the interior temperature might be a little warmer if I waited until the Go Time to leave. Even on the coldest days this winter (below -10 F outside), the cabin temperature is generally in the 50's. I don't bother to precondition the car when the garage temperature is above 50 F. I don't want the cabin to be above 60 F in the summer when I leave--I would just have to open the windows to cool it down. Preconditioning with the Level 2 Charger works well enough that I don't use heat during my 12 minute commute to work. A Level 1 Charger is inadequate for preconditioning. I would be forced to use heat and the ICE for my commute to work.

With the level 2 charger, preconditioning consumed 2.72 kWh. With the level 1 charger, it consumed 1.18 kWh. The EBH requires 440 watts, so if you run it for 2 hours, that is an additional 0.88 kWh. If the charger on-board the car were large enough to supply the full 5 kW of power to the heating element (it currently can only supply about 3 kW), preconditioning would have raised the temperature approximately 40*5/3 = 67 F degrees. If it could supply the full 7.2 kW power provided by a level 2 charger and the heating element were larger, then there would be no problem preconditioning the car to the desired temperature.

This plot is the same as the one in post 316 except I am using a Level 1 EVSE. The outside temperature is 14 F. The EBH is plugged in. I set the GoTime to 7:45 am with a temperature of 85 F. Preconditioning begins at 6:55:12 am and stops at 7:46:14 am. So it again takes 51 minutes. It warms the cabin temperature from 14 F to 30 F, or 16 F degrees which is in line with the prediction in post 319. Note this time, however, the engine temperature never exceeded 90 F. Hence, the car never grabbed any coolant from the engine to warm up the heater core. The coolant in the heater core never exceeded 55 F. The EBH did not help with preconditioning the car this time.

In Post 316 above, the HVB provided an average of 3.12 kW of power during preconditioning. The EBH provided about 0.44 kW of power. When using a Level 1 (120 V) EVSE, I estimate that the HVB would provide an average of 0.95 kW of power. So when temperatures outside the car are in the teens, preconditioning will raise the interior compartment temperature by the following Fahrenheit degrees: Level 2 Charger + EBH supplies 3.12 kW + 0.44 kW = 3.56 kW of power will heat cabin by 40 F degrees. Level 2 Charger supplies 3.12 kW of power will heat cabin by 3.12/3.56 * 40 = 35 F degrees. Level 1 Charger + EBH supplies 0.95 kW + 0.44 kW = 1.39 kW will heat cabin by 1.39/3.56 * 40 = 16 F degrees. Level 1 Charger supplies 0.95 kW will heat cabin by 0.95/3.56 *40 = 11 F degrees. Since the temperature in the heater core is not constant during preconditioning and the car is not well insulated, the Level 1 Charger estimates may not be accurate. I will have to actually try it to determine a more accurate estimate. Using the EBH provides about 5 F degrees of additional heating for the cabin. I only use preconditioning when it is cold out, so I don't know at what outside temperature preconditioning will heat the cabin to the actual temperature specified. I haven't seen any interior temperatures much above 63 F so far this year (when the exterior temperature was in the mid 30's). A plot of interior temperature vs exterior temperature does not increase monitonically--the length of time preconditioning takes varies depending on temperature. So sometimes at a higher outside temperature preconditioning takes less time than at a lower temperature and as a result the interior cabin is not warmed as much at the higher outside temperature.

It appears that using the EBH has an impact on preconditioning. You can see that when preconditioning begins, the car appears to turn on the coolant pump to draw some of the warm coolant from the engine into the heater core. When this happens, the engine temperature plummets (the green line) and the coolant temperature in the heater core jumps (the red line). You can see the engine temperature fall from 99 F to 79 F when preconditioning starts. It then turns off the pump, after the engine temperature and coolant temperature in the heater core equalize, allowing the EBH to warm up the engine again. Then, periodically, each time the engine temperature reaches 90 F, it turns on the coolant pump again to steal some more heat from the engine. Again, the pump is turned off when the engine temperature and coolant temperature in the heater core are equalized. It repeats this cycle seven times. Each time, the coolant temperature in the heater core plateaus at a new higher temperature. The net result is that preconditioning with the EBH plugged will result in the passenger compartment being heated a few degrees warmer than without using the EBH. If you use the EBH and precondition the car, the engine temperature will be limited to at most 90 F. If you don't precondition the car, the engine temperature will get warmer. I need to get the engine temperature to 100 F in order to prevent the ICE from starting when it is below -10 F. Preconditioning prevents that from happening. The engine temperature is usually around 85 F. But I wouldn't want to drive to work when it is -10 F in a very cold car which has not been preconditioned.

The following chart shows the car being preconditioned in the garage. The garage temperature is 14 F. The outside temperature is -8 F. I plugged in the EBH on a timer to start at around 2:00 am. I set the GoTime to 5:30 am with a temperature of 85 F. Preconditioning begins at 4:40:49 am and stops at 5:31:43 am. So it takes 51 minutes. It warms the cabin temperature from 17 F to 57 F. Preconditioning consumes 2.72 kWh of electricity. From the beginning of the recording at 3:30:16 am until 3:51:25 am, the car is finishing charging the HVB. Between 3:51:25 am and 4:40:49 am, it is waiting to precondition the car (and charging the LVB). The green line is the Engine Temperature. From about 2:00 am until preconditioning starts at 4:40:49 am, the EBH heater warms the ICE to 99 F. Some of the heat from the EBH makes its way to the heater core and warms up the coolant in the core to 43 F. The red line shows the temperature of the coolant in the heater core. The blue line is the interior cabin temperature. You can see the temperature rise from 17 F to 57 F during preconditioning. The purple line is the power being drawn from the HVB. It is negative at the beginning when the HVB is being charged. You can see spikes in the power drawn from the HVB by the electric heater during preconditioning. It apparently draws momentary bursts of energy from the HVB. Between these bursts, the HVB is allowed to recharge. The lighter blue line at the bottom of the chart is the power being supplied by the 240 V EVSE to the car's on-board charger. The charger is about 89% efficient, so at the beginning of the chart, while charging the HVB, the on-board charger is consuming 3.31 kW of power and applying 2.93 kW of power to the HVB. While preconditioning, the on-board charger is consuming 3.11 kW of power. Additional power is consumed from the EVSE for the on-board electronics and fans.

The engine block heater is not going help much with heating the cabin. It heats the engine and coolant up to around 85 F when it is cold. That is not enough to make much of an impact on heating the cabin. It takes a lot more energy than that when it is cold--the engine block heater provides much less than 1% of the energy required to warm the cabin. The most effective way to heat the cabin is to use preconditioning with a 240 V Charger. I am able to warm the cabin up to around 50 F when it is cold using the energy from an electrical outlet (you need to park the car in a garage for best results). That is adequate to allow me to drive my 8 mile commute to work in the morning without using much heat. My EV range in the winter is around 18 miles. I use the engine block heater to prevent the engine from coming on. In EV mode, the engine will start if the engine temperature falls below 15 F. I can heat up the engine using the engine block heater to prevent the engine temperature from falling below that threshold when the outside temperature is below 0 F.

This chart is for my commute today when the outside temperature was 28 F. Compare it with the chart in post 300 when the outside temperature was -2 F. This time the heater core coolant temperature remains close to the ICE temperature when the ICE turns off. I parked the car in the Sun so the interior temperature started out at 54 F. Sometimes I had the recirculate option on and sometimes off. It didn't seem to make much difference when the outside temperature is 28 F. Most likely, because the climate fan was at its lowest setting. If it were on high, I would probably see a difference. When it was -2 F, it took 70 seconds for the ICE temperature to drop 23 degrees. At 28 F, it takes 2 minutes at 15 seconds, i.e. twice as long. The electric heater never came on.

Many years ago, cars had slider controls to control the amount of outside air being drawn in. Now they just have a recirculate button which seems to be an all or nothing control. With all the automated climate control functions, we have lost the ability to assist climate control to help it operate more efficiently. Efficiency of the car could be significantly increased if they had more intelligent climate control programming. Do they really need to draw in 100% cold outside air to control humidity in the car? Do they really need to run the electric heater so often to maintain the heater core temperature above 140 F or so when the ICE is off?

I repeated the experiment of post 308 with the climate control recirculate air option enabled. The outside temperature was 14 F. The interior temperature was 18 F, about 4 F degrees warmer than yesterday. This time, the heater consumed 1.88 kWh of energy, less than 2/3 the amount that was required when the recirculate air option was disabled. So using the recirculate air option greatly increases the efficiency of cabin heating. Not using the recirculate option incurs 50% more energy to heat cold outside air. In the plot below, with the recirculate option, the temperature of the coolant in the heater core was able to stay above 140 F after the cabin temperature reached 65 F, and, unlike without the recirculate option, was able to warm up the cabin to 72 F. After the cabin reached 65 F, the electric heater turned on and off perodically and no longer maxed out at 5 kW. Without the recirculate option, the heater consumed maximum power for the entire time it took to heat the cabin. Recirculating interior air also significantly slows the cooling of the coolant in the heater core after the ICE turns off, extending the amount of time before the electric heater needs to come back on to warm the coolant back up.

The following plot illustrates the electric heater efficiency. The car is parked in a building. The outside temperature is 13 F. The cabin temperature starts at 14 F. I turn on climate control set to 72 F to heat the car using only the electric heater. After 36 minutes, the cabin temperature finally reaches about 72 F. The heater consumes 3.00 kWh of energy. That amounts to about 10 miles of EV range. The red line shows the engine coolant temperature (ECT2). The green line shows the cabin temperature. The blue line shows the power being consumed by the electric heater. The climate fan starts at minimum speed and the ECT rapidly reaches 147 F. I turn up the fan to medium speed and the ECT2 falls to 120 F. The electric heater is only able to warm the car up to about 65 F after 30 minutes and is unable to warm it up any further. After 33 minutes, I push the recirculate air button. The ECT2 rapidly climbs back up to 147 F and the interior cabin temperature finally reaches 72 F. The electric heater cannot supply enough heat to keep the cabin warm when it is below 20 F. If I were driving the car on a road, the electric heater could never keep up. The electric heater does significantly better when you recirculate the interior air. It will use significantly less energy and keep the cabin much warmer.

I think most everyone is happy with the L2 chargers that they have purchased. I would choose one based on price and features that are important to you.

The following plot shows the results of Grille Blocking driving 60 mph on the Freeway at -2 F. The plot shows the same commute traveling South on two different days. In one case, the Grille was blocked with foam pipe insulation. In the other case, the Grille was not blocked. In both cases, the wind is from the NW at 15 mph. Grille blocking doesn't seem to have any significant impact on the ICE temperature. The red line is the ICE temperature with no Grille Blocking after the ICE has stopped. The purple line is the ICE temperature with Grille Blocking after the ICE has stopped. Without Grille Blocking, the ICE temperature falls 18 F degrees after 70 seconds. With Grille Blocking, it fell 23 F degrees after 70 seconds. It fell more with Grille Blocking. The blue line is the coolant temperature in the heater core with no Grille Blocking. The green line is the coolant temperature in the heater core with Grille Blocking. Without Grille Blocking, the temperature fell 18 F degrees after 70 seconds. With Grille Blocking, it fell 25 F degrees after 70 seconds. Again, it fell more with Grille Blocking. I can't guarantee all variables have been taken into account. But I don't see any significant improvement using Grille Blocking.

It has now been 36 hours. The ICE temperature is still 5 F and transmission fluid temperature is still 1 F. The outside temperature this morning is -3 F. The outside temperature warmed up into the teens yesterday. The ICE temperature is going to be several degrees warmer than the outside temperature in the morning (unless the outside temperature warms up during the night or it is very windy). As I have stated before, it takes a long time for the ICE to cool down to the outside temperature.

This plot is for the same commute as the one above. The outside temperature is similar at -12 F (a couple of degrees warmer). The difference is that the Grille is blocked with foam pipe insulation. There doesn't appear to be much difference between the two charts. The HVB temperature started out a few degrees warmer in this chart (simply because the garage was a few degrees warmer)--that's about all. The ICE temperature without grille blocking fell 25 F degrees in 9 minutes and 40 seconds. With grille blocking, it fell 23 F degrees in 9 minutes 50 seconds. I don't see any significant difference. It doesn't appear to help prevent the ICE from starting when it is below -10 F. In order to prevent the ICE from starting during the commute, I would need to warm the ICE to at least 100 F. The engine block heater only warms it to about 85 F after three hours when the garage temperature is in the teens.

This plot shows temperatures for my 8 mile commute to work at -14 F. I used the engine block heater before I left. It warmed the ICE to 85 F. I also preconditioned the car. That warmed the cabin to about 53 F. The coolant temperature in the heater core was 88 F. The garage temperature was 10 F. After two miles, EV Now mode was disabled and I am stuck in EV Now mode. When the ICE temperature fell below 60 F, the ICE came on. You can see this via the blue line showing the ICE power at time 5:36:40. It remained on until the ICE temperature rose above 100 F at 5:39:15. The ICE rotated at 1500 rpms the entire time. The ICE was only used to propel the car. It was not used to charge the HVB. When no power was required from the ICE to propel the car, the ICE continued to rotate and provided zero torque (no power was output by the ICE). You can see the ICE temperature fall several degrees when the ICE started and the coolant pump turned on pumping cold coolant from the radiator to the ICE. Since I did not use climate control, the cabin temperature fell from 53 F to 43 F. Even with the climate control off, the coolant temperature in the heater core fell very rapidly after the ICE turned off. When the ICE turned off, it was 92 F. Two minutes, 20 seconds later, it was 64 F. Since I did not have climate control on, it was probably cooled by the cold air blowing through the radiator. The HVB temperature rose from 30 F to 40 F. The Transmission Fluid Temperature rose from 30 F to 56 F.

You can see in the graph in post 300 how much the car struggles to warm the coolant (even on the freeway) when I first turn climate control on at around 2:25 pm and the cabin temperature starts rising rapidly. From 2:25 pm to 2:40 pm, the coolant temperature rises slowly as the cabin temperature rapidly increases. When the cabin temperature approaches 72 F and rises less slowly, the coolant temperature rises more rapidly and eventually peaks at 190 F. It must take a lot of energy to heat the cabin.

This is another plot of the same 60 mile commute at -2 F. The green line shows the power being consumed by the electric heater. The red line is the ICE temperature, which is actually called the cylinder head temperature (CHT). The blue line is the coolant temperature in the heater core, which is called the engine coolant temperature 2 (ECT2). The purple line is the temperature inside the cabin. The car only displays the ECT2 temperature. You can't view the CHT. I didn't turn on climate control much until the CHT reached around 160 F to prevent the car from using power from the HVB to power the electric heating element. You can see that when CHT drops below 160 F, the electric heater comes on occasionally. The cabin temperature was set to 72 F. I tend to turn climate off when the CHT falls below 160 F to prevent the electric heater from coming on. You can see the difference between CHT and ECT2 via the red and blue lines. The ECT2 is usually cooler than the CHT. Since the coolant is warmed by the ICE, that is to be expected. You can also see that the ECT2 temp falls much more rapidly than the CHT when the ICE is off and the coolant pump turns off. The coolant is then isolated in the heater core and no longer warmed by the ICE--the electric heater is then the only source of heat. I assume the car is warming outside air to heat the cabin. That will quickly cool the coolant isolated in the heater core loop. I wonder if the coolant outside the heater core loop is warmer than what is in the heater core loop and if continuing to bring that in to warm the cabin wouldn't be better than running the electric heater to warm the rapidly cooling coolant in the heater core. I should try recirculated air to see if that prevents the ECT2 from falling so rapidly.

The following plot shows the ICE and Transmission Fluid Temperatures (TFT) for a 60 mile commute at -2 F. The blue line is the ICE power in kW. This indicates when the ICE was running. The red line is the ICE temperature and the green line is the TFT. The max ICE temperature was 190 F. The max TFT was 103 F. When the ICE turns off, the ICE temperature falls rapidly. For example, at about 3:00 pm, it fell from 180 F to 150 F in 1:41 minutes (one minute and 41 seconds) going 55 mph. After 1:30 minutes of elapsed time, the coolant pump turned off and the ICE temperature began to rise again. It rose to 162 F and then quickly fell back to 150 F when the ICE and coolant pump started again. When the ICE is off, you can see the small humps in the red line when the coolant pump turns off and the ICE temperature begins to climb again. When the ICE turns on again, you can see dips in the red line when the coolant pump is started again and the ICE temperature initially falls before rising. If you don't keep the ICE running, the heating element is going to have to come on to provide heat to the cabin. It generally starts to come on when the ICE temperature falls below 160 F. At lower temperatures, the ICE temperature falls more slowly. At 3:05 pm it took 9 minutes to fall from 165 F to 135 F. However, I was traveling slower through several towns during that time. You want to keep the ICE on when driving on a freeway when it is cold to prevent the car from using energy from the HVB to heat the cabin.

I have been tracking the estimated SOC of the 12 V battery as reported by the car each morning for the past several months. The plot below shows the results. I applied TSB 14-0020 in June 2014, which changed the programming used by the car to charge the 12 V battery. So the SOC rose significantly after that date. The estimate seems to be very noisy. The average SOC seems to be around 90%. I'm not sure what the expected SOC for the 12 V battery should be.

The garage temperature was in the upper 20's during the day. It was only in the early morning that the garage temperature fell to 15 F as the outside temperature fell well below 0 F. An attached garage is significantly warmer than outside so the ICE temperature is going to be well above the outside temperature. Last night at 7:30 pm, the ICE temperature was 160 F, Transmission Fluid Temp was 94 F, and the HVB temperature was 68 F. The outside temperature was below 0 F. This morning it is -8 F. The car was left outside all night. There was very little wind. The temperatures 11 hours later were: ICE temperature was 5 F, Transmission Fluid Temperature was 1 F, and the HVB temperature was 16 F. So you see how long it takes for things to cool down even outside.

It takes a long time for the engine to cool down to ambient temperatures as I have previously stated, especially if you park in an enclosed area out of the wind. When I park at work, outside in the wind, then usually by the time I leave, after 9 hours, it has cooled down to the outside temperature. But that is only because the morning temperature was 20-30 F cooler than the afternoon temperature and it was windy. If you park in a garage, it is going to take a lot longer than 9 hours to cool down to the temperature in the garage. Driving 55 mph does cool the ICE down quickly when it is cold. I see the temperature fall from 180 F to less than 140 F within five minutes. Preheating the car does not warm the ICE at all, not even one degree. Only the coolant isolated in the heater core is heated by the heating element during preconditioning. The only way to warm the ICE is to use the engine block heater. I don't use climate control during my commute to work. The cabin is already warm via preconditioning and heat is not necessary.