Cold Weather Observations

[rbort]

Nice graphs Larry!  I saw this behaviour when I was driving home through CT from NY.  I took the country road as I didn't have much gas left and was trying to make it home without having to refuel.  On the country road speeds were 45 mph or there abouts and the engine cycled on and off often.  At 12F I found out that the engine didn't run enough for me to keep the cabin heat on, I was looking at the climate screen and I could see the draw from the electric heater coming on.  I also looked at the coolant temperature and noticed that the engine couldn't keep it up at 1/2 way on the gage.  Too slow of a speed on country roads to build up heat and/or too many on'off cycles as well.  I think even if it continued to run at slow speeds (1500 rpms or there abouts) at 12F using cabin heat the engine had a hard time reaching the temp to 1/2 on the gage.  That's when I started thinking about blocking the grill but its rare that I hit this situation I'm not commuting every day like this.

 

To solve the issue then I just turned off the heat when the climate wanted to use EV power to warm the cabin and turned it back on when I was on a longer stretch with the engine running.  Recirculate might be a very good idea, as instead of 12F coming through the heater core it would be closer to 60F or there abouts.

 

-=>Raja.

Edited February 27, 2015 at 03:31 PM by rbort

[larryh]

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. 

[rbort]

Definitely because you're robbing heat from the engine by blowing frigid air right through the coolant in the heater core.  In the summer time you can use this trick while climbing mountains (like Haleakala or Mr. Washington for example).  In this situation I turn on the heat at 85F in the summertime and roll down the windows to rob all the heat from the engine while its working hard climbing steep grades.  Helps to keep the coolant temp down and better for the engine in general.  This trick worked very well in the older cars, nowadays modern cars are probably better suited to handle the situation better without having to use the heater.

 

When I drive somewhere now with my Cmax, once I get on the highway and fire up the engine I roll up the windows (the front two are cracked 1/4 inch all the time) and wait for the coolant temp to rise to 1/2 way and then I turn on the heat so no EV power is lost.  Turning it on before its at 1/2 way means the engine and EV power heating element are going to work together to warm the coolant.  I'd lose some EV range that way so instead I just wait a few minutes until everything is warmed up by the engine and then turn on the heater.  I found that sometimes I have to push the directionals (to the feet and to the face) right away after turning on the heater to clear a low power draw (about 300w) on the climate from the battery.  That's probably a bug in the system but its my work around.  Pushing the air directionals to the feet and face (once each) seems to clear it right away.

 

Once I get off the highway and the engine shuts off I have to turn the heat off within 1 minute after that, as the coolant in the heater core  gets cold quick and you see EV power heat coming in.  I didn't think before to use recirculate, I should probably try that next time I might triple my heat time to 3 minutes instead of 1 for example (depending on the outside temperature) before I have to turn the heat off due to the residual heat from the engine gone.  You would wish that the car would be smart enough to continue to circulate ALL the coolant from the engine to give you heat (as an option) instead of just the small loop in the heater core but Ford engineers probably thought you might need to use the engine again so keeping it warm is better than cooling the whole thing down.  Only the driver would know if he needed it any more or not, for me coming home from the south I have a 10 mile trip on country roads after getting off 295 highway it would be ideal to just use all the coolant for the heater core so I can continue to get heat 1/2 way home with no engine but in reality I've learned to live without heat so its not an issue any more.

 

-=>Raja.

[larryh]

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. 

 

Edited February 27, 2015 at 05:01 PM by larryh

[larryh]

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.

 

 

Edited March 1, 2015 at 05:49 PM by larryh

[larryh]

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.

 

Edited March 1, 2015 at 05:49 PM by larryh

[rbort]

That is very interesting about the grill blocking Larry, thanks for the info.  I wonder if the situation is the same with the Cmax.   People think that grill blocking helps keep the engine warmer, looks like you've done some myth busting here.  Just to be sure, your grill blocking was complete (i.e. no leaks).  Maybe to be sure you should tape some saran wrap over the whole grill to insure no leaks?

 

In any case your tests prove what I saw as far as the heat is concerned.  If you turn off the engine by switching to EV now or Auto from EV later for that last few miles home on the battery, you must turn of the heat within 1 minute or so (depending on outside air temp) as in short time the coolant will be cold enough that EV heat will kick in. 

 

-=>Raja.

[larryh]

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.

 

 

Edited March 1, 2015 at 05:55 PM by larryh

[Russael]

This is exactly what I do in the morning when it's stupidly cold.  I use a Go Time, then when beginning my commute, I run recirculate up until the windows start fogging, and usually by the time it starts doing that, the car has reached 72 degrees.  At that point, I can turn off recirculate and the car will maintain temperature, but I know it starts eating more energy to keep the coolant warmer.

 

I'm pretty sure a Go Time also uses recirculate while it heats.

 

Interesting results though. :)  I love your continuing analysis of this car.

[larryh]

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.  

 

 

Edited March 1, 2015 at 05:48 PM by larryh

[rbort]

Good stuff Larry!  We sort of figured that when you mentioned it and data is fun to see!

 

What does it mean to me?  Well, maybe coming home from a long trip that last 10 miles when I go EV only and shut off the engine I should push recirculate and maybe the car can still get home in EV power and keep the heat on.  I would have to experiment to see how many "extra" miles I need besides "10" to get there with heat than without.  I know I need about 40% battery to do it without heat (not in severe cold).

 

-=>Raja.

[larryh]

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?

Edited March 1, 2015 at 03:05 PM by larryh

[Hybridbear]

Definitely because you're robbing heat from the engine by blowing frigid air right through the coolant in the heater core.  In the summer time you can use this trick while climbing mountains (like Haleakala or Mr. Washington for example).  In this situation I turn on the heat at 85F in the summertime and roll down the windows to rob all the heat from the engine while its working hard climbing steep grades.  Helps to keep the coolant temp down and better for the engine in general.  This trick worked very well in the older cars, nowadays modern cars are probably better suited to handle the situation better without having to use the heater.

If you want to cool the ICE you should turn on the AC. Turning on the AC opens the grille shutters which cools the ICE. See this post: http://fordfusionhybridforum.com/topic/9689-road-trip-observations-with-torque-pro/?p=92301

[larryh]

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. 

 

Edited March 1, 2015 at 11:53 PM by larryh

[Hybridbear]

On Saturday I was parked away from home from about 9:00-9:00. I had access to a 120V outlet to charge the Energi in the parking ramp where I parked, but I didn't plug in the block heater because I didn't want to trip any circuits. The outlets in this parking ramp are spaced about every 20 parking spaces so there's no way to plug in using two different circuits. I had used the block heater before leaving home in the morning so the coolant was about 145 F when leaving home and about 95 F when I arrived at my destination 18 miles away. The ambient temps on Saturday ranged from single digits to high teens. It was about 8 F when I arrived in the morning and 12 F when I was driving home. While sitting outside for almost 12 hours the car cooled almost down to ambient.

 

The coolant cooled from 95 F to 15.8 F.

 

The tranny fluid started at 99 F leaving home, peaked at 101 F while driving on the freeway and dropped to about 93 F after driving through the city to my destination. It cooled to 13 F while parked.

 

The HVB cooled from 78 F to 26 F. It heated back up to 55 F while driving home. It had started out the morning at about 68 F and only rose to 78 F while driving in the morning.

 

Considering that the coolant showed 15.8 F when I got in the car to go home I was very concerned about the ICE coming on. The ambient temp was 12 F for my 18 mile drive home. However, as I drove and the other underhood components warmed up the ICE coolant actually increased in temperature. The tranny fluid got up to about 70 F by the time I was near home and the electric motor coils and inverters were all slightly warmer than 100 F. This caused the ICE coolant temp to rise to 17.6 F midway through my drive and stay there until I got home.

 

I was also concerned about arriving home without running out of battery. I left home in the morning with the Energy to Empty (ETE) showing 7.1 kWh. When I started driving in the evening with a cold HVB the ETE was only 6.2 kWh even though the car was fully charged. I arrived home with 0 miles of range remaining and an ETE of 1.506 kWh.

[larryh]

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.

 

Edited March 5, 2015 at 11:14 PM by larryh

[larryh]

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.

Edited March 5, 2015 at 11:36 PM by larryh

[rbort]

I noticed this before, mentioned it to you Larry that when preheating the air coming into the car is not "hot"  May be warm at best...

 

So, what is the minimum temperature that the garage needs to be at before your preheat can actually warm the car to 85 degrees?  How about 72 degrees?

 

Looks like at 14F the car went from 17 to 57.

 

Do you have data with warmer temps to see when the preheat can actually reach its goal?

 

-=>Raja.

[larryh]

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. 

Edited March 6, 2015 at 09:29 AM by larryh

[larryh]

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. 

 

Edited March 6, 2015 at 02:47 PM by larryh

[rbort]

Interesting to see that level 1 still does "something".  So how many KWH does it take every morning to preheat the car, is it around 3 including the EBH? 

 

-=>Raja.

[larryh]

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. 

Edited March 7, 2015 at 12:30 PM by larryh

[murphy]

My level 2 charger is capable of supplying 9.6 kW.  (240 volts x 40 amps).

:)

[larryh]

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.

 

Edited March 7, 2015 at 07:25 PM by larryh

[larryh]

My level 2 charger is capable of supplying 9.6 kW.  (240 volts x 40 amps).

:)

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.