Cold Weather Observations

[murphy]

I asked Ashley regarding the ICE coming on in cold weather.  I received the following reply.

 

The ICE will come on in extreme cold temps to help with maintaining the battery pack temp. Once the vehicle is out of the garage and moving with the wind chill it will cool off the entire vehicle quickly. Using the block heater will help some with this concern similar to preconditioning the vehicle.  It would then take longer before the ICE would have to engage.

 

The vehicle starting cold at work in EV Now mode is because the vehicle is near one of its normal stopping destinations. It will prioritize EV mode when you are near a normal stopping destination more than when not near one. So once the vehicle is driven far enough away it determines you are not stopping and then goes to a different strategy depending on the needs of the vehicle.

 

Unfortunately in very cold temperatures of 0 degrees Fahrenheit or colder the vehicle will need to use the ICE more.

Wind chill only affects skin.  It causes the moisture in the skin to evaporate which in turn reduces the temperature of the skin.  Cold air blowing over a metal surface, that is not wet, can't reduce its temperature any lower than the temperature of the air.  "Wind chill" has no meaning in this case.

Edited January 21, 2014 at 03:14 PM by murphy

[Russael]

Wind chill only affects skin.  It causes the moisture in the skin to evaporate which in turn reduces the temperature of the skin.  Cold air blowing over a metal surface, that is not wet, can't reduce its temperature any lower than the temperature of the air.  "Wind chill" has no meaning in this case.

 

I was wondering about this myself but forgot about it (after that -15F we had a couple weeks ago).  From what I've read about, this is correct... inanimate objects will not get colder than ambient, however, wind will bring the temperature of an inanimate object to ambient temp faster.

[larryh]

Yes, I think the engineers are referring to cooling the engine compartment.  The components in the engine compartment cool much faster when driving with the wind blowing through the grille.

[larryh]

I see in the owners manual regarding the left display:

 

Coolant Temp – Indicates engine coolant temperature. At normal operating temperature, the level indicator will be white and will be in the normal range (between “H” and “C”). If the engine coolant temperature exceeds the normal range, the level indicator will change to red to indicate that the engine is overheating. Stop the vehicle as soon as safely possible, turn off the vehicle and let the engine cool. The thermometer indicator next to the gauge will illuminate in blue or white to indicate the following:

• Blue thermometer - This indicates that the hybrid system is not warm enough to allow EV operation. The gasoline engine will run continuously when the indicator is blue. During silent key start mode, the thermometer indicator will be blue, but the gasoline engine will not run. This is the result of the vehicle computer allowing the engine to be cooler during the silent key start period. This is normal operation and does not indicate a problem with your vehicle. After the first engine start the indicator will turn white when the gasoline engine is warm enough to turn off.
• White thermometer - This indicates that the hybrid system is warm enough to allow EV operation. If the vehicle operates on battery power long enough, it is possible that the gasoline engine may need to run to keep the system warm. In this case, the thermometer indicator will revert back to blue.

On my return trip home this afternoon, the thermometer was always white, even when the EV icon was yellow, and later, after EV Now and EV Later modes of operation were disabled.  So this does not appear to be implemented correctly.  I wonder if silent key start mode is what they were referring to in the previous post regarding overriding normal priorities to run in EV mode when starting out from a frequent destination and the mode is set to EV Now.

Edited January 21, 2014 at 06:49 PM by larryh

[larryh]

I have only seen the charger continue to charge the 12 V battery after finishing charging the HVB once before now.  I look at the recordings for the power consumed for the past two months.   Every time, the charger shuts down shortly after the HVB finished charging.  So this is new charging behavior for me.  I have some hour long trips during the week, so that must have been keeping the 12 V fully charged.  But now the cold weather is putting more stress on the 12 V battery so it needs additional charging?

I observed the car continuing to draw about 67 watts of power today from the charger after charging the HVB completed.   I was able to verify that the 12 V voltage was 14.8 V.  So, sometimes, after charging is completed, the car continues to draw power from the charger to charge the 12 V battery.  This occur approximately every 2 weeks. 

Edited January 22, 2014 at 09:39 AM by larryh

[larryh]

I tried remote start for 10 minutes with the car plugged in this morning to see if that affected the HVB battery temperature.  The temperature of the HVB remained at 30.2 F.  Preconditioning warmed up the HVB the usual 4 degrees F. 

[Russael]

Temperature this morning for me was -3F.  I preconditioned as usual, hopped in the car, hit the recirculate button, and started making my way to the office.  About 1 mile from the house, the ICE kicked on.  It sort of seems like the threshold for that is 0F, at least for my morning commute with preconditioning.  The cabin was plenty warm already.  Status of the car on the EV screen said the engine was on for system performance for a quick second, and then switched to 'heater settings'.  Engine stayed on until I was about a mile from the office (before EV+ kicked in).  Even though I was back in EV mode and the heater had spun down the fan, EV Now and EV Later were both still locked out and I was stuck in EV Auto.  My MPGe for the commute was 29.  Ouch. :)  Still, that's better than 9 MPG with my Expo when it's this cold.

[larryh]

You have a short commute, so if the ICE turns on, it is going to be on for most of the commute.  How much gas did it consume?  I am usually able to get by with about 0.07 gallons. 

[larryh]

I suspect that the engine coolant temperature determines when the ICE comes on.   This is what I have observed for the past two days using EV Now mode and no heat.

 

Yesterday morning, I drove in EV mode until the coolant temperature fell below 10 F.  As soon as that happened, the ICE turned on.

This morning, the coolant temperature only fell to 15.8 F and the ICE remained off.

 

Yesterday afternoon, the coolant temperature was just below 0 F when I left work.  The ICE turned on immediately.

This afternoon, the coolant temperature was 3.2 F when I left work.  The ICE turned on at exactly 2.0 miles from work.

 

My conjecture so far is as follows:

 

When you start out from a frequent destination, the ICE starts immediately when the coolant is below 0 F.  When it is between 0 F and 10 F, you get to drive 2.0 miles in EV mode before the ICE turns on.  If it stays above 10 F, you can run in EV mode.   However, as soon as the coolant temperature falls below 0 F, the ICE turns on.

 

Once the ICE turns on, it remains on until the engine coolant temperature exceeds around 100 F.  If the engine coolant temperature falls below about 70 F, it comes on again.

 

This all assumes the heater is off.  I'm not sure how it works with that turned on yet.

 

So, to stay in EV mode, I think you want to keep the ICE as warm as possible.  A heated garage or an EBH.

Edited January 22, 2014 at 09:55 PM by larryh

[Russael]

You have a short commute, so if the ICE turns on, it is going to be on for most of the commute.  How much gas did it consume?  I am usually able to get by with about 0.07 gallons. 

 

It says 0.1 gallons... EV ratio to and from work today was 47%.  It's been lower than that before.

 

Funny... I feel cheated getting 30MPGe with this car and I was happy with 26MPG that I used to get with my Focus... and would be happy to see 19MPG with my Expedition.  Heh.  Go figure.

 

Your observation of 10F to get the ICE to kick on sounds plausible.  I have driven in 8F without heat and the ICE stayed off, but I admit I wasn't watching the coolant temperature either.  My ICE seems to kick on (if it's going to) within 1.5 to 2 miles as you've observed as well. 

 

When it enables the engine, it seems to use both battery and ICE to propel the car.  My battery still drains while the ICE is on, but doesn't go down as quickly.

Edited January 23, 2014 at 12:24 AM by Russael

[larryh]

If you are looking at the trip summary, the display truncates the gallons of gas to one decimal point.  I use the trip odometer to provide a more accurate measurement.  The actual amount could be 0.19 and the trip summary would show 0.1.  You would have to have used about 2.8 kWh of electricity for your 5.3 mile commute to get 29 MPGe with 0.1 gallons of gas.  I don't use that much electricity for my 8 mile commute, but then I don't need much heat on the way to work after preconditioning. 

Edited January 22, 2014 at 11:37 PM by larryh

[Russael]

I used 2.2kwh on the way to work with 29MPGe and I used 2.0kwh on the way back with 31MPGe.  Nice that the system truncates instead of rounding.

 

I prefer to stay warmer on the way to work, and I usually consume 2.2 to 2.4kwh.  On the way home, I usually will return with no climate, unless the ICE decides it wants to come on.  Then I turn climate on and figure I may as well roll back in warmth. :)

[larryh]

The ICE used about 0.12 gallons of gas.  You can get the ICE to turn off sooner if you temporarily turn off climate control and reduce speed when the coolant temperature is above 100 F.  You might be able to reduce it to about 0.08 gallons.  But if it won't let you back into EV Now mode, then you might be stuck.  I will have to figure out where that is on the temperature gauge on the left display.

[Russael]

If the ICE does decide to come on, I'd rather it get to a regular operating temperature... in hopes that oil maintenance mode won't activate on me.  I dislike using gas, but at the rate I'm going, I'm using gas at a rate of about 1 tank a year.  I can live with that. :)

 

I'll be rolling to the Detroit Auto Show this Saturday, so I'm sure my ICE will finally get a bit of a workout. 

[larryh]

The criteria in my previous post that determines when the ICE starts is incomplete.  Today it was -15 F outside.  It was 3 F in the garage.  I used the EBH.  It warmed the coolant to 82.4 F after 3.5 hours. 

 

After driving 2 miles in EV Now, the car disabled EV Now and EV Later.  I could no longer select them.  The engine coolant temperature was 71.6 F at that point.  When the coolant temperature dropped below 10 F the other day, the EV icon turned yellow to temporarily disable EV operation.  After the coolant temperature rose above 100 F, EV operation was re-enabled.  The EV Now and EV Later modes were still available to be selected.  This time, I could no longer select EV Now or EV Later.  There must be some other criteria that is used to completely disable EV Now and EV Later operation.    I was now in EV Auto mode.   I continued in EV until the ICE turned on when the coolant temperature was 57 F.  This occurred at about the same point in my commute as the other day.  The ICE ran about 3 minutes until the coolant temperature exceeded 105 F.   Because the coolant was warmer, it ran about one minute less.   It consumed fuel at the same rate as the other day.

Edited January 23, 2014 at 10:43 PM by larryh

[Russael]

The car must be looking at ambient outside temperature as well to determine how the vehicle should drive.  I'd love to see their flowchart of cold weather driving.

 

Today, it was 6F outside.  I preconditioned as usual, left the house with heat at 70 and recirculate on as usual, and about 2 1/2 miles in, my HVAC fan slowed down so I turned off recirculate to let in outside air since my windows were fogging.  The ICE stayed off.  I made my 5.3 mile commute using 2.8kwh of energy with 64MPGe.

[larryh]

I asked the author why cold weather performance of tires has a much greater impact on EVs than gasoline powered vehicles, i.e. -13% vs -4% loss in range.  I received the following response:

 

It's the same resistance applied on less energy available, so the impact is much more noticeable.

 

So there are no differences regarding performance of tires used on EVs vs gasoline cars.  But if the effect of increased rolling resistance on tires has more impact on EVs, then I would expect the increased aerodynamic drag to have a similar impact on EVs.  But according it the article the impact is -6% vs -5% loss in range.  So I am still confused by the author's response. 

I received further clarification from the authors of the article at http://insideevs.com/infographic-fleetcarma-cold-weather-fuel-efficiency-electric-versus-gasoline-showdown/:

 

The main reason is that aero represents a larger fraction of the load on an EV. Setting aside powertrain losses and auxiliaries, the loads can be put into three main buckets: aero, rolling, braking. In an EV you recoup a portion of the braking through regenerative braking. So the effects of aero and rolling have a larger share of the "load pie" in an EV. So denser air increasing aero losses will have a disproportionately bigger impact on an EV than on an ICE. So you may not have expected it, but the answer to why EVs are proportionally more impacted by aero drag in cold weather is: ...because of regen

Edited January 24, 2014 at 06:07 PM by larryh

[larryh]

In order to observe the HVB sensor data, I have to turn the car on so that the scanner can connect to the ECU.  When the car is turned, it generally uses about 1 amp of current from the HVB.  So I assume that 3 amps were going into the HVB and 1 amp was being diverted to power the car.  So that accounts for the all the power:  4 amps * 341.5 V = 1366 Watts, which is what I observe on the Kill-A-Watt meter. 

This morning it is 3 F outside.  The HVB temperature is 14 F.  Using the 120 V charger, the Kill-A-Watt meter shows the charger only drawing 910 watts of power.  It usually draws 1365 watts when the HVB is warm.  The HVB SOC is 85%.  The power that makes it to the HVB is 660 watts.  So it looks like the charger in the car doesn't draw as much power when the HVB is cold. 

Edited January 25, 2014 at 03:55 PM by larryh

[larryh]

I am now recharging after a trip this afternoon that warmed the HVB to 55 F.  This time the Kill-A-Watt meter says the charger is consuming 1400 kW of power.  So power used to charge the battery varies with temperature.  I also notice the Service Engine Soon light came on.  I saw the following DTCs:

 

P04B5 - Fuel Fill Door Stuck Open

U0412 - Invalid Data Received From Battery Energy Control Module A

 

The description for the first one states:

 

P04B5: 1) Mechanically stuck (door open) or customer did not close fuel door. No indication to close FTIV after refueling. 
 

Well, we bumped the button on the console to open the fuel door.  So that explains that DTC.

 

But I don't know what the second one is about.  Some network communication error from the battery control module in the  Auxiliary Emission Controls System.  This DTC is applicable to most ford vehicles so it is not referring to the HVB control module. 

Edited January 25, 2014 at 11:26 PM by larryh

[murphy]

You raise a point that I have been wondering about for awhile.  There is a huge amount of communication on the CAN bus between the various modules in the car.  Does an OBD interface sending commands on the CAN bus cause conflicts in the operation of the car?  I already know that with a Davis CarChip connected it is impossible to run a Vehicle Health Report.  I discovered that on my 2010 Fusion Hybrid.  The same problem happens on my 2013 Energi.  I have to disconnect it from the OBD port to run a VHR or the car will say that the "report can't be run at this time" presumably because it found an unknown entity on the bus.

Edited January 25, 2014 at 11:37 PM by murphy

[larryh]

The scanner does collect quite a bit of information.   I don't know anything about the CAN bus or its bandwidth, and how much data and at what rate it is safe to collect from a scanner.  The snow drifted in around my car, so I had a hard time getting out.  I was suspecting that this might have had something to do with it.   I don't know what the difference is between a Pending fault (for the fuel door) vs. a History fault (for the comm error) is.  I wonder which one is causing the Service Engine Soon light. 

Edited January 26, 2014 at 12:14 AM by larryh

[larryh]

It was the fuel door fault that caused the Service Engine Soon light to come on.  The light is now off and I no longer see the DTC.  It showed some notification or other on the display when I was stuck in the snow.  I didn't catch what it was.  I am assuming that was what caused the other DTC.

Edited January 26, 2014 at 10:11 AM by larryh

[larryh]

Last night when I arrived home, the HVB temperature was 55.4 F and the SOC was 17.8%  This morning, when I started to charge it, the HVB temperature was 32 F and the SOC was 11.4%.  As the battery cooled, the SOC dropped significantly.  I suspect that low SOC shortens the life expectancy of the battery.  Maybe that is why Value Charge immediately charges the battery to increase the SOC by 10% if the battery is depleted when it is first plugged in and then waits until the Value Charge time to complete charging.  I probably don't want to leave my battery in a low SOC at night waiting to charge in the morning when it is cold.

Edited January 26, 2014 at 03:38 PM by larryh

[larryh]

Today, after sitting overnight in -15 F temperature, the HVB temperature is down to -2.2 F.  The estimated range is down to 15, from 25 in the summer.  As always, when it is -15 F, the Intelligent Access Key (IAK) loses its intelligence.  In order to start the car, I have to put the IAK in the backup slot.  It cannot be used to unlock the doors either.  It simply does not work when it is this cold.  Has anyone else that has left their car out in -15 F temperature overnight had this problem?

Edited February 2, 2014 at 02:41 PM by larryh

[murphy]

Today, after sitting overnight in -15 F temperature, the HVB temperature is down to -2.2 F.  The estimated range is down to 15, from 25 in the summer.  As always, when it is -15 F, the Intelligent Access Key (IAK) loses its intelligence.  In order to start the car, I have to put the IAK in the backup slot.  It cannot be used to unlock the doors either.  It simply does not work when it is this cold.  Has anyone else that has left their car out in -15 F temperature overnight had this problem?

Presumably the key is in your pocket and you just came out of a warm house.  It's not the key, it's the transceiver in the car that isn't working.  Next time see if you can open the trunk with the pushbutton beside the license plate lamp.  There is another transceiver back there.