Cold Weather Observations

[rbort]

My answer to this:

 

In EV now the car uses the electric element to heat a small section of the coolant to give you heat.  

 

IF you switch to EV later and the engine starts, as soon as the engine starts even for 10 seconds it circulates ALL the coolant and the "hot" coolant that was heated up via the electric element is mixed in with the cold coolant and now the power draw from the electric element rises to try to reheat cold coolant.  The engine will heat the coolant at the same time and you're using dual power (engine and electric) to heat the coolant the fastest.

 

If you don't want to use electric to heat the car and are running the ICE you MUST wait until the coolant is up to operating temperature (FULL hot not partial) meaning 1/2 way on the temp gage and only then you can turn on the heat.  If you turn on the heat before hand it will use electric assist to help the engine heat the coolant faster.

 

Once you are up to 1/2 on the temperature gage, turn on the heat, if it draws any power on the climate screen (would be small) just select a directional for the air (up or down) and the draw will go away.  This is a bug in the system doesn't always happen and I believe their might be a fix for it in one of the patches.

 

Hope this helps,

 

-=>Raja.

Edited December 5, 2014 at 05:23 AM by rbort

[larryh]

I have observed that the car tries to maintain the heater core coolant loop at 140 F or above when the heat is on.   If the ICE coolant is between 140 F and 160 F and I turn on the heat, the car will use the electric heater initially for about a minute.  The heater core coolant loop takes a while to warm up.  If the ICE coolant temperature is above about 160 F, the heater doesn't come on. 

Edited December 6, 2014 at 12:09 PM by larryh

[rbort]

 

 

If the ICE coolant temperature is above above 160 F

 

What does that equate to on the temp gage in the car?  50%, 40%, what percentage?

 

-=>Raja.

[larryh]

The temperature gauge display in the car shows the heater core coolant temperature.  It does not show the ICE coolant temperature. 50% is about 190 F.   So 160 F might be around 40%.  You can use Engineering Test mode to observe the coolant temperature.  I don't remember which temperature it is displaying. 

Edited December 6, 2014 at 12:15 PM by larryh

[Hybridbear]

My answer to this:

 

In EV now the car uses the electric element to heat a small section of the coolant to give you heat.  

 

IF you switch to EV later and the engine starts, as soon as the engine starts even for 10 seconds it circulates ALL the coolant and the "hot" coolant that was heated up via the electric element is mixed in with the cold coolant and now the power draw from the electric element rises to try to reheat cold coolant.  The engine will heat the coolant at the same time and you're using dual power (engine and electric) to heat the coolant the fastest.

 

If you don't want to use electric to heat the car and are running the ICE you MUST wait until the coolant is up to operating temperature (FULL hot not partial) meaning 1/2 way on the temp gage and only then you can turn on the heat.  If you turn on the heat before hand it will use electric assist to help the engine heat the coolant faster.

 

Once you are up to 1/2 on the temperature gage, turn on the heat, if it draws any power on the climate screen (would be small) just select a directional for the air (up or down) and the draw will go away.  This is a bug in the system doesn't always happen and I believe their might be a fix for it in one of the patches.

 

Hope this helps,

 

-=>Raja.

This is what I already said I'm doing. Even though the coolant in both loops is at 180+, the car decides to isolate the small loop & use electric heat.

[rbort]

That doesn't happen to me in the Cmax, if the engine is hot I can get heat without using electric heat.  Didn't the Fusion have some issues of not being able to turn on the vent without the AC or something like that?  Maybe this is a similar bug I don't know as I'm not driving the Fusion?

 

-=>Raja.

Edited December 7, 2014 at 03:55 PM by rbort

[stevedebi]

The temperature gauge display in the car shows the heater core coolant temperature.  It does not show the ICE coolant temperature. 50% is about 190 F.   So 160 F might be around 40%.  You can use Engineering Test mode to observe the coolant temperature.  I don't remember which temperature it is displaying. 

Are you certain of that? I thought it shows the calculated water temperature. There is no sensor for ICE coolant temperature, so Ford generally takes the cylinder head temperature (Cwt) and interpolates the estimated water temperature.

[larryh]

You can easily see for yourself.  Precondition the car or turn on the electric heater when it is cold.  The display will show that the coolant temperature is warm even when the ICE is cold. 

Edited December 8, 2014 at 09:26 PM by larryh

[stevedebi]

You can easily see for yourself.  Precondition the car or turn on the electric heater when it is cold.  The display will show that the coolant temperature is warm even when the ICE is cold. 

Thanks for the suggestion, but I'm on L1, can't precondition efficiently. Very interesting though, and I can't imagine why they would put coolant temperature there when it doesn't reflect the engine temperature. Unless they switch the guages when the engine is in use.

[rbort]

Without looking at any data, logic dictates that there is a heating element inside the heater core coolant loop that the EV portion of the car uses to heat the coolant in that section to put heat into the car.  That section is tied to the coolant temperature gage in the car.

 

IF you start the engine, it circulates all the coolant and immediately the warm air coming out of the register from EV heating is gone and the temp gage in the car shows an instant drop to cold on the coolant.  At that point EV heating is back to 5+kwh trying to reheat cold coolant and the engine is assisting as it warms up.

 

By the way Larry, if I remember right the ET screen coolant temp is the same as the temp gage in the car, I remember playing with it in the garage a while back and seeing it rise by turning on the heat in EV mode.  I'll have to try that again to confirm this.

 

-=>Raja.

Edited December 9, 2014 at 09:07 PM by rbort

[stevedebi]

Without looking at any data, logic dictates that there is a heating element inside the heater core coolant loop that the EV portion of the car uses to heat the coolant in that section to put heat into the car.  That section is tied to the coolant temperature gage in the car.

 

IF you start the engine, it circulates all the coolant and immediately the warm air coming out of the register from EV heating is gone and the temp gage in the car shows an instant drop to cold on the coolant.  At that point EV heating is back to 5+kwh trying to reheat cold coolant and the engine is assisting as it warms up.

 

By the way Larry, if I remember right the ET screen coolant temp is the same as the temp gage in the car, I remember playing with it in the garage a while back and seeing it rise by turning on the heat in EV mode.  I'll have to try that again to confirm this.

 

-=>Raja.

Raja,

OK, I looked it up. There is a coolant sensor in the electric loop, and when the ICE is running the Engine Coolant Temperature is inferred from the Cylinder Head Temperature.

Edited December 9, 2014 at 10:52 PM by stevedebi

[rbort]

I did the test tonight.  It was 47 degrees when I got back to the car plugged into a remote charger.  I powered on in ET mode.  Scrolled to coolant temperature, it was 9C.  I turned on the heat at 68 degrees and waited.  Battery icon draining, coolant temp started to rise slowly.  Once it reached 54C, the blower started blowing warm air into the cabin below my feet, at the temperature reached 56C, the blower speed had increased to the max it seemed to want to run at.  The temp continued to rise until 64C, and then started dropping off back down to 62F.  I assumed (cannot see climate draw) that the power draw had dropped from 5kwh+ to less now that the temp is getting warmer in the car.  I increased the temp to 85F on the climate control.  The blower fan increased and the temp started to rise again.  This time it peaked at 66C before trailing back off to 64C.  I powered off and ended the test.  I remembered correctly, temp gage in car is the same as coolant temp in ET mode.

 

66C is 150F so apparently the EV mode heat does not bring the temp to 1/2 way on the temp gage in the car, and in remembering what I've seen before, I'd agree that is correct it only comes up about 1/3 of the way or so.

 

Steve, if you start the engine then maybe its switching to a different temp sensor is what you're saying?

 

-=>Raja.

[stevedebi]

...

 

Steve, if you start the engine then maybe its switching to a different temp sensor is what you're saying?

 

-=>Raja.

I think that may be the case. I was using the illustrations in the Ford OBD documentation for the C-Max, which shows the two sensors. But that document only tells what settings will cause the OBD2 errors to come out. It lists coolant temp as an input to several codes, and the diagram shows two different methods of obtaining ECT, but they don't explicitly say it is measured differently when the ICE is running.

 

However, it makes sense to me that they would use the inferred ECT when in EV Later, because the heat is coming from the other loop, where as in EV mode it is coming from the electric loop. At least I hope that is what they do - when I'm running in the desert and have the Temp MyView up, I want to know the engine temperature, not the temperature of the electric heating loop!

Edited December 10, 2014 at 04:50 PM by stevedebi

[Hybridbear]

One proof that Cyl Head Temp is used is the fact that the PID for it and for coolant temp poll the same sensor in Torque Pro.

[Hybridbear]

I think that may be the case. I was using the illustrations in the Ford OBD documentation for the C-Max, which shows the two sensors. But that document only tells what settings will cause the OBD2 errors to come out. It lists coolant temp as an input to several codes, and the diagram shows two different methods of obtaining ECT, but they don't explicitly say it is measured differently when the ICE is running.

 

However, it makes sense to me that they would use the inferred ECT when in EV Later, because the heat is coming from the other loop, where as in EV mode it is coming from the electric loop. At least I hope that is what they do - when I'm running in the desert and have the Temp MyView up, I want to know the engine temperature, not the temperature of the electric heating loop!

When the heat is off the loop is all one. When the ICE is on and hot and the heat is on the loop is all one. The loop is only isolated when using electric heat only. If I preheat the car without having plugged in the EBH, only the small loop has hot coolant. If I plug in the EBH but don't precondition the coolant is warm in both loops.

[stevedebi]

When the heat is off the loop is all one. When the ICE is on and hot and the heat is on the loop is all one. The loop is only isolated when using electric heat only. If I preheat the car without having plugged in the EBH, only the small loop has hot coolant. If I plug in the EBH but don't precondition the coolant is warm in both loops.

Uh, OK, but I'm still not sure why they would have two ways to measure ECT if it is all the same.

[larryh]

This morning, after two miles, rather than disabling EV Mode and showing a yellow EV icon (Locked Electric Mode Override by Driver), the car changed the mode to EV Auto and disabled the EV Now and EV Later modes completely.  The display showed the three icons EV Auto, EV Now, and EV Later with EV Now and EV Later crossed out.  The car would not allow me enter EV Now or EV Later modes.  The outside temperature was -11 F.   I had used the EBH, so the ICE temperature ranged from 82 F to 72 F during the first two miles.  The HVB temperature ranged from 32 F to 36 F.  So I am guessing that this occurs when the outside temperature is below 0 F.  The ICE eventually turned on when the ICE temperature fell below 60 F. 

 

For the commute home, the outside temperature was -2 F.  The car immediately turned on the ICE and displayed the yellow EV icon.  The engine temperature was 0 F and the HVB temperature was 10 F.  So the outside temperature threshold that determines whether the EV modes are completely disabled must be between -2 F and -11 F.  The internal car temperatures were much colder during the commute home, so I would have expected that it would be much more likely for the car to completely disable the EV modes. 

Edited January 5, 2015 at 10:39 PM by larryh

[larryh]

This morning my commute to work was very similar to yesterday, except it was -7 F.  The car remained in EV Auto mode for the entire commute.  Based on my observations, the following table is my best guess for the car's behavior in cold weather:

 

Outside Temp  ICE Temp   Mode at Startup  Mode Change            ICE Starts

< -10 F       < unknown  EV Auto          N/A                    Immediately

< -10 F       > 60 F     EV Now           EV Auto after 2 miles  After 2 miles when ICE temp falls

                                                                 below 60 F

> -10 F       < unknown  EV Override      N/A                    Immediately

                (0 F?)

> -10 F       unknown    EV Now           EV Override after 2    After 2 miles

              (0 F?) to                   miles

              15 F

> -10 F       > 15 F     EV Now           EV Override if ICE     When ICE temp falls below 15 F

                                                                         temp falls below 15 F 

 

EV Override refers to the mode in this post:  http://www.fordfusionenergiforum.com/topic/1446-cold-weather-observations/?p=17751.

 

So when it is below -10 F and the ICE temperature is above 60 F, the car will remain in EV Now mode for the first two miles.  After that, it will switch to EV Auto mode.  The ICE will then come on as soon as the ICE temperature falls below 60 F.

 

It is desirable to keep the car in EV Now or EV Override mode.  When in this mode, the ICE generally does not come on until the ICE temp falls below 15 F.  In EV Auto mode, the ICE comes on when the ICE temp falls below 60 F, so it comes on sooner. 

Edited January 6, 2015 at 08:41 PM by larryh

[flyingcheesehead]

The temperature gauge display in the car shows the heater core coolant temperature.  It does not show the ICE coolant temperature. 50% is about 190 F.   So 160 F might be around 40%.  You can use Engineering Test mode to observe the coolant temperature.  I don't remember which temperature it is displaying. 

 

How do you get into Engineering Test mode?

[flyingcheesehead]

Have you had anymore experience with this phenomenon?  A later poster, Marc, said it was related to starting in EV now and doesn't occure in auto or ev later? Were you in EV now when this occured?

 

Anyone else experienced the vehicle allowing only auto operation below 0f and ev later disabled?

 

This is very concerning to me as every other weekend I am unable to charge the battery after i drive 75km one way to visit my gf.  Currently i use ev later to keep charge for driving around the city when i get there and battery health.  I imagine the cold weather preventing me from doing that, the cold itself and no charging for 1.5 days will be less healthy for the battery than if i could use ev later.

 

I've had it happen a few times in the last couple of weeks (super-cold weather) when starting in Auto mode too.

 

Drives me nuts, because I'm usually trying to switch to EV Later as well. I can see why they'd turn off EV Now, but I don't know why they'd turn off EV Later!

[larryh]

The best advice for winter is to keep the ICE warm.  Using the EBH in the morning allows me to make the commute to work in the morning entirely in EV using EV now mode (as long as the outside temperature is not much below -7 F).  Even parking the car in an open garage is significantly better than leaving it outside.  The HVB temperature drops much more quickly when the car is left unprotected outside in the cold.

Edited January 12, 2015 at 10:21 PM by larryh

[rbort]

Larry here is a question for you.

 

I went to Worcester and back on EV power this past Saturday.  On the way there the temp was around 20F, I recharged the car when I got there while at the theater.

 

When I left the temp was somewhere between 1F and 10F the whole trip.  Some pockets as low as 1F, average about 5F and warm spots at 10F.

 

I never started the engine the entire trip and the car never forced the engine to start.  In the above table, are you assuming that the climate is on and that the cabin heat is active?  I'm asking because I would expect that the engine temperature was less than 15F and the outside temperature was greater than -10F but the engine didn't start.  I assume its because I had no heat on.  Correct?

 

FWIW, I drove practically the entire EV battery and got a range of about 22 miles at those extreme temps (extreme for us here, for you I know it can be much worse).

 

-=>Raja.

Edited January 13, 2015 at 05:48 AM by rbort

[larryh]

It is assumed climate is off in the above table.  The table only provides a rough estimate of when the ICE will start.  There are other factors that come into play.  If the ICE did not start, then the ICE temperature was most likely above the turn-on threshold which is about 15 F.  It takes several hours for the ICE to cool down.  You would have to monitor the ICE temperature.  The car does not provide that temperature. 

Edited January 13, 2015 at 09:40 AM by larryh

[larryh]

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. 

 

Edited February 27, 2015 at 03:27 PM by larryh

[larryh]

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.

 

Edited February 27, 2015 at 03:21 PM by larryh