Cold Weather Observations

[Mike B]

Thanks, makes sense now!!!

[stevedebi]

I noticed something interesting this morning. Here in LA it hit a surprising low of 52 degrees, and I turned on the low level defrosters, and then the vents, and set the temperature to 66 or so. The energy went to the max of 5. It gradually went back down to 1.5 - 2.

 

After a while I decided it was enough and set it back to low and shut off all but the vent. To my surprised, it was still showing a small discharge for climate, maybe .25 or so. I had to turn the power off to get it to clear. Turning the system back on resulted in the same small draw.

 

I eventually killed the draw by turning the A/C ON, and then back OFF. Then the climate went to zero. So evidently the system can get a bit "stuck" at a small discharge rate if the low level defrost is on, and then turned off.

[larryh]

The following chart plots the maximum amount of Energy stored in the HVB vs. HVB Temperature.  I have kept a record each morning of the ETE (Energy To Empty) at 100% SOC and HVB temperature.  At 30 F the energy capacity is down about 0.15 kWh vs 90 F.  That is not much loss.  We'll have to see what happens when it gets below 0 F. 

 

Edited November 13, 2014 at 10:09 PM by larryh

[openair]

Note that when it is below 0 F, generally after the first couple of miles, the EV mode selection menu pops up with the EV Now and EV later icons crossed out.  I can no longer select EV Now or EV Later modes.  The car now gives preference to using energy from the battery over using the ICE.  That is fine for my 8 mile commutes when I have adequate EV range from the battery for  the trip to work and home.  However, it is not fine for my 60 mile commute on the freeway.  Normally, I reserve the battery for EV mode later when I get off the freeway.  But when it is below 0 F, EV Later (as well as EV Now) is disabled.  I am forced to use up the HVB energy on the freeway.  The car wanted to run entirely in EV mode on the freeway with the ICE coming on periodically just to warm the coolant backup up.  It is generally more efficient to use the ICE on the freeway and reserve EV mode for slower speeds.  It did warm up the HVB from about 23 F to 57 F.  Even after the HVB temperature warmed up to 57 F and the ICE warmed the coolant to 120 F, I was still not able to select EV Now or EV Later.   The HVB was depleted after 21 miles.  The first six were on city streets.

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.

Edited November 13, 2014 at 11:51 PM by openair

[larryh]

I don't think the mode that you are in influences this behavior.  It has not been much below 20 F yet this year, so I haven't experienced this recently. 

Edited November 14, 2014 at 12:06 AM by larryh

[larryh]

Here is my question to and response from Ford regarding this issue.

 

Question:

 

How do I reserve the high voltage battery power (HVB) for later use when it is below 0 F.  After a short time, the EV mode selection screen pops up informing me that EV Now and EV Later are no longer available--the icons are crossed out.  Now I am stuck in EV Auto mode and can't select EV Later.  I am forced to use the entire high voltage energy on the freeway going 65-70 mph.  The battery quickly depletes at these speeds when it is -5 F.  I want to reserve the HVB to use after I get off the freeway.

 

Response:

 

I checked with my technical adviser and there isn't a real way to override HVB power, because the vehicle is programmed to use HVB and engine power as necessary to provide heat for the battery and engine compartment.

[openair]

If it were "necessary" to drain the HVB during the first ~30km of driving when it was below 0f, to maintain "heat for the battery and engine compartment," the vehicle would be pretty much out of luck for the rest of the gas tank.  Unless the battery somehow deals with cold weather better, requiring less heating, when ev range has been depleted.

Edited November 14, 2014 at 03:55 AM by openair

[Rexracer]

As a future Fusion Energi owner, I found this thread very informative. I do have to ask though, What is the ICE, and what does it do?

Mike B. The problem with every forum is that certain terms get created and used, and new people don't know what they are. If there isn't a glossary of abbreviations at the top intro section there should be.

So don't be afraid to ask what can feel like stupid questions.

[stevedebi]

If it were "necessary" to drain the HVB during the first ~30km of driving when it was below 0f, to maintain "heat for the battery and engine compartment," the vehicle would be pretty much out of luck for the rest of the gas tank.  Unless the battery somehow deals with cold weather better, requiring less heating, when ev range has been depleted.

Excellent point, at the very least one would think Ford would only use the HVB until the ICE warmed up sufficiently.

 

And while they are at it, allow EV Later, but put up an alert indicating "Main Battery In Use for Engine Heating".

Edited November 14, 2014 at 05:15 PM by stevedebi

[Mike B]

Mike B. The problem with every forum is that certain terms get created and used, and new people don't know what they are. If there isn't a glossary of abbreviations at the top intro section there should be.

 

So don't be afraid to ask what can feel like stupid questions.

I've been able to figure a few things out by reading the threads. Figured out HVB was the high voltage battery, which the car runs on until it's depleted. GO sounds like either heating or cooling the car so it will be a comfortable temp before you get in it.

[stevedebi]

I've been able to figure a few things out by reading the threads. Figured out HVB was the high voltage battery, which the car runs on until it's depleted. GO sounds like either heating or cooling the car so it will be a comfortable temp before you get in it.

GO times are the official Ford terms for preconditioning the cabin. It can be found in the owner's manual, and at either the My Ford Mobile (MFM) site, where you register your car, or the mobile MFM app.

 

Basically, you set the times you want your car to be ready in the morning. If you have a level 2 charger, the cabin can be cooled or heated to one of three temperatures.

 

EDIT: Theoretically, GO times work with the 120V charger that comes with the car, but in practice there just isn't enough juice - it won't be able to charge and still condition the cabin in most circumstances.

Edited November 15, 2014 at 12:27 AM by stevedebi

[larryh]

The following plot shows how much more energy is required to drive in EV mode in cold weather when the car is not warmed up.  Two ratios are plotted, one for mechanical energy (energy output by the motor) and one for electrical energy (energy output from the HVB).  As an example, at 40 mph, it takes about 1.8 times more mechanical energy to propel the car when the temperature is 0 F vs. 75 F.  The motor has to produce 1.8 times as much power at 0 F vs 75 F to go 40 mph.  The HVB has to output about 1.6 times as much power.  The electric motor is more efficient at higher power output so the electrical energy ratio will always be less than the mechanical energy ratio. 

 

These ratios are computed after about a mile of EV driving from a cold start, i.e. the car has not been warmed up.  The ratios are much worse for the first mile or so (1.5 times or more higher).  If the car were warmed up, the ratios would be much less.

 

The ratios are significantly higher at slower speeds when internal friction vs. aerodynamic drag dominates.  This suggests that when the car is cold, internal friction is the main source of the extra power required to drive in cold weather.  I suspect the cold makes the transmission fluid and other lubricants very stiff.  It takes a lot of energy to overcome this additional stiffness.  Once the car has warmed up, the ratios will be much less. Unfortunately, it will take several miles of EV driving to warm up the transmission.  Running the ICE will warm it up much quicker.

 

Edited November 20, 2014 at 08:27 PM by larryh

[larryh]

Right after starting the cold car, it took 3 times as much mechanical energy to go 30 mph at 0 F vs. 75 F.  After driving 16 miles in EV mode, the ratio dropped to 1.7 times as much.   This translates to about 1.5 times as much energy from the HVB as it did at 75 F.  I tried warming up the car using the ICE first, the mechanical energy ratio was still high at 2.7.  Apparently, warming up the ICE doesn't help all that much warming up the transmission and other lubricants.  You just have to drive the car.  But by the time you warm everything up, the HVB will be empty.  However, if you have a long enough trip, it might be advantageous to use EV later for the first part of the trip so you can use the HVB later after the car has had a chance to warm up. 

Edited November 15, 2014 at 08:00 PM by larryh

[larryh]

The following shows the amount of energy consumed from the HVB per mile for my 8 mile commute to work in EV mode over the past year.  Each marker indicates the kWh/mile vs. outside temperature for a trip.  The markers well above the solid line are probably due to using the heater or a/c.   For the trips near the solid line, little or no a/c or heat was used.   About 50% more energy is required at 0 F vs. 80 F.  The commute is on city streets with a speed limit of 55 mph.

 

Note that I park in an attached garage at home.  So the car is significantly warmer than the outside temperature.  The car is parked outside all day at work and will be near the ambient temperature for the return trip.  The trips below 10 F are all trips where I started from the home.  The ICE usually starts when it is cold for the return trip when it is extremely cold.  I excluded trips that are not entirely in EV mode.  Thus the chart may be a little biased.  The actual energy per mile may be significantly higher at colder temperatures if the car were parked outside at home.

 

 

Edited November 15, 2014 at 05:08 PM by larryh

[Hybridbear]

Plugging in the block heater significantly warms up the transmission fluid. I've seen it start at around 100-120 F when using the block heater versus 65-70 F (the ambient temp underground at our apartment).

[larryh]

I have tried the EBH.  On Friday, the temperature in the garage was 30.2 F.  I ran the EBH for 3 hours.  The engine coolant temperature increased to 91.4 F and the transmission fluid temperature increased to 43.9 F.  It only warmed the transmission fluid temperature by 14 F. 

 

I tried warming the car using the ICE on Saturday.  The outside temperature was 3.2 F.  The engine coolant temperature increased to 120.2 and the transmission fluid temperature increased to 30.8.   The 18 F increase in transmission fluid temperature did very little to reduce the internal friction.  The mechanical power required to propel the car at 30 mph was 2.7 times higher than when the outside temperature was 75 F.  Without warming the car, it was 3.0 times higher.  Warming the transmission fluid temperature by 18 F did little good. 

 

However driving the car for 16 miles in EV mode raised the transmission fluid temperature to 72 F and reduced the ratio to 1.7 

 

A heated garage will do a much better job keeping the car warm. 

Edited November 16, 2014 at 11:45 AM by larryh

[larryh]

I don't think the mode that you are in influences this behavior.  It has not been much below 20 F yet this year, so I haven't experienced this recently. 

 

Today at 2.00 miles into my commute home from work in EV Now mode, the ICE started.  The car displayed the message "Engine Enabled for System Performance" and the EV now icon was displayed in yellow.    The outside temperature was 13 F.  The car entered an EV mode called Locked Electric Mode Override by Driver--one of the five possible EV modes.  The four other modes are: EV Now, EV Later, EV Auto, and Hybrid Mode.  The ICE ran until the coolant temperature reached 102 F.  The RPMs remained constant the entire time at 1500 rpm.  The car then returned to EV Now mode for the remainder of the trip.

 

If I had used EV Auto mode, the ICE would have probably started immediately after starting the car.  In EV Now mode, the ICE will stay off if you leave from a frequent destination for the first two miles.  All the EV modes remained available to me the entire time.  My guess that the purpose of this mode is to warm up the engine compartment. 

Edited November 17, 2014 at 10:44 PM by larryh

[stevedebi]

Today at 2.00 miles into my commute home from work in EV Now mode, the ICE started.  The car displayed the message "Engine Enabled for System Performance" and the EV now icon was displayed in yellow.    The outside temperature was 13 F.  The car entered an EV mode called Locked Electric Mode Override by Driver--one of the five possible EV modes.  The four other modes are: EV Now, EV Later, EV Auto, and Hybrid Mode.  The ICE ran until the coolant temperature reached 102 F.  The RPMs remained constant the entire time at 1500 rpm.  The car then returned to EV Now mode for the remainder of the trip.

 

If I had used EV Auto mode, the ICE would have probably started immediately after starting the car.  In EV Now mode, the ICE will stay off if you leave from a frequent destination for the first two miles.  All the EV modes remained available to me the entire time.  My guess that the purpose of this mode is to warm up the engine compartment. 

Larry,

I've not heard of the Locked Electric Mode Override by Driver mode, though I've seen the car do that several times. Is there a document or something that describes these modes?

[larryh]

That terminology is used by the Forscan app (at forscan.org).

[Hybridbear]

Today at 2.00 miles into my commute home from work in EV Now mode, the ICE started. The car displayed the message "Engine Enabled for System Performance" and the EV now icon was displayed in yellow. The outside temperature was 13 F. The car entered an EV mode called Locked Electric Mode Override by Driver--one of the five possible EV modes. The four other modes are: EV Now, EV Later, EV Auto, and Hybrid Mode. The ICE ran until the coolant temperature reached 102 F. The RPMs remained constant the entire time at 1500 rpm. The car then returned to EV Now mode for the remainder of the trip.

 

If I had used EV Auto mode, the ICE would have probably started immediately after starting the car. In EV Now mode, the ICE will stay off if you leave from a frequent destination for the first two miles. All the EV modes remained available to me the entire time. My guess that the purpose of this mode is to warm up the engine compartment.

Did you have the HVAC system on?

 

Tomorrow I'll be doing a trip from work to my parents' house in the evening. We'll see if the ICE comes on even with the car in EV Now.

[rbort]

My engine in my Cmax never comes on like that.  I've driven in as low as 9F in auto mode and the engine doesn't start.  Of course I don't have any climate control on.  Not sure why the engine wants to start to "warm up the engine compartment"...call it confusing...

 

-=>Raja.

[larryh]

Did you have the HVAC system on?

 

Tomorrow I'll be doing a trip from work to my parents' house in the evening. We'll see if the ICE comes on even with the car in EV Now.

No--climate control was off.  I think it has to sit out in the cold for quite some time before the ICE would come on.  In my case, it was 7 F in the morning and the car was at work for 9.5 hours.  It must be some combination of outside temperature, coolant temperature, and HVB temperature that causes this.  The temperatures at the beginning and end of the trip were:

 

Outside Temperature: 13 F

Coolant Temperature: 14 - 63 F

Transmission Fluid Temperature: 14 - 52 F

HVB Temperature: 26.6 - 39.2 F

HVB SOC: 57% - 31%

 

For the commute to work in the morning, the ICE did NOT come on even though it was colder outside.  The temperatures were:

 

Garage Temperature:  28 F

Outside Temperature: 7 F

Coolant Temperature: 84 - 63 F

Transmission Fluid Temperature: 44 - 67 F

HVB Temperature: 41 - 55.4 F

HVB SOC: 96% - 63%

 

So even though it was colder outside, the car was much warmer for the commute to work vs. the commute home.  If the car is too cold, the fastest way to warm it up is to run the ICE.  I believe the ICE runs in a special mode that generates heat faster than normal.

Edited November 18, 2014 at 11:48 PM by larryh

[Russael]

It was around 15 degrees F last night when I departed my cousin's abode from about 10 miles away.  For the trip there, I preconditioned, kept the hvac on (cycling recirculate on and off), and got there with 4 miles left on the battery.

 

Since I couldn't plug in, I set the car to Auto mode to let the ICE come on when it saw fit, still using cabin heat... too cold for me. :)  It did that at the foot of his driveway and hardly cycled at all... it stayed on for most of the duration home.  The display maintained discharge mode while moving, only going to put energy back in to the battery during regen.  Interestingly, that 4 mile charge seemed to had doubled to 8 miles (display did not indicate that), as I went in to hybrid mode a few miles from the house.

 

It took quite a long time for the cabin to get warm... I would've expected it to have been faster.  I can remote start the car in EV Now mode while plugged in and within 10 minutes, it's pretty comfortable at that temperature.  I think the car would warm up faster if it opened both cooling loops, using the electric heating element to assist the ICE in its warmup.  The generator could easily supply enough power for that to move the car and float the battery.

 

Turned in to my subdivision, EV+ mode kicked in, and I ran out of battery completely about 500 feet from the house.  ICE came on for about 10 seconds as I got to the driveway and nearly came on again just as I was parking in the garage.

 

Last year, I did everything I humanly could to keep the ICE off.  This year, I don't care as much.  :)

[rbort]

Its interesting to note battery figures are counter intuitive...

 

 

 

Outside Temperature: 13 F

Coolant Temperature: 14 - 63 F

Transmission Fluid Temperature: 14 - 52 F

HVB Temperature: 26.6 - 39.2 F

HVB SOC: 57% - 31%

 

For the commute to work in the morning, the ICE did NOT come on even though it was colder outside.  The temperatures were:

 

Garage Temperature:  28 F

Outside Temperature: 7 F

Coolant Temperature: 84 - 63 F

Transmission Fluid Temperature: 44 - 67 F

HVB Temperature: 41 - 55.4 F

HVB SOC: 96% - 63%

 

It took 33% battery to go 8 miles to work in the morning with a warmer car and transmission and only 26% to come back in colder conditions listed above.  Must be some other factor like the way to work is uphill and the way back is downhill.

 

I see the battery charge also dropped from 63% down to 57% sitting as the temp of the battery dropped from 55 to 27F which is something I also experience in my Cmax.

 

-=>Raja.

Edited November 18, 2014 at 02:18 PM by rbort

[larryh]

Its interesting to note battery figures are counter intuitive...

 

It took 33% battery to go 8 miles to work in the morning with a warmer car and transmission and only 26% to come back in colder conditions listed above. Must be some other factor like the way to work is uphill and the way back is downhill.

 

-=>Raja.

The ICE came on and provided the additional energy. Edited November 18, 2014 at 02:30 PM by larryh