I drove 4 hours South to Minneapolis, MN last weekend and with an attached, relatively warm garage and outside temps in the 20's F, saw a lot of EV mode over the weekend, which I rarely have in Fargo this winter. The warmer garage seemed to help a lot more than just a block heater.

 

Unusually cold here this morning (18 degrees in Charlotte, NC). I noticed two things this morning:

- Longer than normal battery charge time. It took about 15-20 minutes befroe the EV even kicked in and then there were several times while we were stopped that the combustion engine kicked in

- Higher than normal RPM

 

Try weeks of -25 that we recently had here in mid E Canada. During those times I just kept the FEH plugged in all the time. Doing this, I noticed the battery temps kept fairly warm, however it would still take a drive of 45 minutes or more to get EV. Pretty much your economy is whatever you get from that little engine as I'd say EV time is probably 1% or less!

 

Don't underestimate this hybrid car in the cold.
Just because you don't get much EV time, doesn't mean you are not getting plenty of electric assist when driving. The battery is working all the time ( at reduced rates ) on the coldest of days.

Also, if you did have EV at -25 degrees, you wouldn't be happy either.
Before long, the inside of the car would be sub-zero!
No gas = no heat for you too!

 

I have problems with my 2008 FEH In cold weather. I don't have any gauges to help pinpoint the problem. All I know is in cold weather(the colder the worse it gets) is the Engine RPM gets very high and the gas mileage drops drastically. At 6 degrees it went from 35 to 20MPG.

 

When it is single digit temperatures or colder, it is very difficult to obtain stellar fuel efficiency in any vehicle, hybrid or not. It is a lot easier to obtain improved fuel efficiency in cold weather if one uses an engine block heater--option 41H in the Escape--for several hours prior to startup and even better if one has the 2005-07 models with the wired connection to the hybrid battery heater. Do you have a front grille wind block for these temperatures?

 

I had my first 35 degree weather in my '09 and seen a marked decrease of 12mpg in my normal commute. Never had that kind of decrease in my '05 FEH and I think I now know why. Your '08 and my '09 FEH does not have the heavy regen as the older models using "L". The only way to get heavy regen in the '08 and '09 is the brake pedal. My engine temperature was fine, but the HV battery took much more time to warm-up and perform properly. I noticed a much slower rise in battery SoC with the generator and this was my problem.

I knew the only way to break this cycle was to accelerate slowly to faster speeds and get some heavy regen from the brake pedal to heat-up the HV battery. It worked with a few times and everything went back to normal with generator charging.

I'm sure your much colder weather will not work as well as this trick for me but you need to understand this is the big problem. The generator/motor controls engine idle with HV battery power. If the battery is having problems charging and discharging because of being cold, the generator does not get the power to control idle corectly. This is called a secondary idle and it is controlled my the engine. You can see a secondary idle when you shift to neutral where no power will go into or out of the eCVT. The engine can only charge the battery above 6mph with the shifter in neutral, but the generator/motor can't control idle. Once the HV battery is at a good operating temperature, try to keep it there with constant EV use.

GaryG

 

I totally agree with Gary's prior post.
And if Gary and I agree, you know you can take it to the bank as true!


My car, cold weather, cold battery, low MPG.
Gary's car, cold weather, cold battery, low MPG.

My car, cold weather, warm battery, higher MPG.
Gary's car, cold weather, warm battery, higher MPG.

My car, charging and dis-charging warms the battery fairly quickly.
( I'd say on average 1 degree per minute )*
Gary's car, charging and dis-charging warms the battery.
( you'll have to ask Gary if it was about 1 degree per minute )

Keep in mind though, if your battery starts at zero, it will take an hour to get to the "normal" range of 60-85 degrees.

-John

*If I brake unusually hard, to get EXTRA STRONG REGEN in sub-freezing weather, I can warm the battery about twice as fast, or 2 degrees per minute, provided I'm in stop-n-go with opportunity to brake once a minute... which is not that often for me. 2 days ago, outside air was +16 degrees, and in 40 minutes of city driving, my battery was so hot the fans were running at high speed... Oh yeah.... I was getting 36 MPG at +16 degrees after every thing was warm. The key is... if you have enough drive time to get everything warm. Short trips... expect 24-26 MPG.

 

I have a similar problem with my 08. I have made 60 mile trips in 20 degree weather, and never got any braking regen, or boost giving me 22 mpg for the trip. Then, on other 20 degree days, I got both in a few miles and got 29 mpg for the same trip. I have complained to FORD about this, and the engineers have been examining the data they took from my car for over a month now. I think they are stumped.

Aside from the intermittent no hybrid functions; I have found that the traction battery warms up faster if I drive in 'L' instead of 'D', and do a lot of accel/decel for the first few miles. That cycles more current through the battery which generates heat and warms it up.

 

Kephra-

I do not think your car has any "problem".
Your car sounds like it bahaves normally for the conditions.
If you attach a ScanGauge or other scan tool and monitor all the parameters, temperature of the battery pack in particular, I think you will understand things better.

HTH,
-John