Ford Hybrids and cold weather
 

Hello all,
I have an interesting problem that just got better today. Background: I live in Laramie WY 7220ft and cold 9 months out of the year! My Ford Escape Hybrid '08 is a great snow car but due to the cold doesn't get nearly the fuel mileage our southern friends get (maybe 24mpg in the winter if lucky).

Problems this winter:

1. Transmission groans/grinds/ slips / wont really go forward or reverse without stepping on throttle in extreme cold maybe 0 degrees F and lower. Really noticable when under -15 F . Eventually after 10 to 20 mins of driving it returns to normal. Any idea if I am tearing something up?

2. Today while driving on a -25 F morning I get on a highway and attempt to go 65 mph. Well, when the rpms hit around 3800 the engine shuts down. This went on for 25 miles! Of course had I been on the Interstate that would have been dangerous only going 65 mph here!
When the car finally warmed up (40 miles later at the ski area) it was running fine and tranny was quiet. Oh, and no check engine light or anywarning chimes/signs.

Before anyone says I should 'use a block heater' I do, however I believe it isn't working now for whatever reason.

My guess is there is a rev limiter in the program for cold motor/tranny fluids? I had heat in the cabin btw.

Having been a mechanic a decade ago I feel like I am tearing stuff up!

Anyone else having issues like this?

Re: Ford Hybrids and cold weather
 

Hi prstone50,

I have the same issue with my 08 FEH here in Calgary, AB. We had a cold snap a few weeks ago where it was -35c (-31f) in the morning and I experienced the same issues as you. Yes, I plugged in the block heater overnight and although it warmed up the engine to the point where it would start easier, the transmission felt like it was slipping.

My fuel economy has taken a huge hit as well. In the summer I get about 7ltrs/100km (not sure what that works out to in MPG) however now, i'm averaging about 13ltrs/100km which in my mind, blows any fuel savings out of the water from the summer.

I've found that if I start my FEH up in the morning, let it idle for about 10 mins to warm up that its fine once I leave. The vehicle sure as hell doesnt go into EV at that temp though which completely defeats the purpose of a hybrid vehicle.

Overall i'm very happy with my 08 however looking back, I probably wouldn't buy another hybrid unless I lived somewhere warmer where the winters weren't 8-9 months of the year.

Re: Ford Hybrids and cold weather
 

Of course, the most beneficial way to secure your car during these several month is to opt for regular maintaining you car. A effectively working coolant program will keep your car from overheating. But, it also is accountable for defending it against engine corrosion.

Re: Ford Hybrids and cold weather
 

What was the purpose of this post?:confused: It has no connection to this thread and should be deleted.

Re: Ford Hybrids and cold weather
 

have an interesting problem that just got better today. Background: I live in Laramie WY 7220ft and cold 9 months out of the year! My Ford Escape Hybrid '08 is a great snow car but due to the cold doesn't get nearly the fuel mileage our southern friends get (maybe 24mpg in the winter if lucky).

Re: Ford Hybrids and cold weather
 

The main benefit of a hybrid system is regenerating energy during braking. You reuse that energy later when the car needs it. Driving in ev mode doesn't "save" any energy. Any energy in the battery pack that allows ev mode driving, has gotten there by burning gas and running the gas engine one way or another. In fact, if you force the ev mode more than the car tends to do on its own, you lose efficiency due to conversion losses: excessive conversion of energy into electricity stored in the battery pack and then taken back out for propulsion.

In addition to the energy regeneration, an Escape hybrid also benefits from the CVT, engine shut-down, a relatively small gas engine and the LRR tires. I suspect at such temperatures those with non-hybrids are suffering just as badly.

Re: Ford Hybrids and cold weather
 

The main benefit of a hybrid system is the hybrid SYSTEM. Regenerative braking is a small percentage of the "system" of saving gas. Think about it. How many miles a year is your foot on the brake pedal and how many miles a year is your foot NOT on the brake pedal?

Second, it's not the number of miles in EV mode, it's the number of MINUTES a year you are in EV modd that really saves a lot of gas. In warm weather there is almost zero idle time. In the cold there is a lot of idle time. Idle time = 0 MPG and very quickly lowers your average fuel economy per tank.

Third, there are NOT huge losses in converting energy from gas to electricty. Every large modern train locomotive burns diesel to turn a generator. The generated electricity turns an electric motor. The electric motor(s) turn the wheels on the locomotive. Every train locomotive is a hybrid. And has been since 1950's. There are greater losses when an internal combustion engine is connected to the wheels of a vehicle. Why? Because vehicles need to start and stop, and travel at speeds that constantly varry. Engines are most efficient only at certain speeds. Engines have very little torque at slow speeds when you need it most.
Electric motors have the most torque at slow speeds.

BACK TO THE ORIGINAL POST

The transmission IS NOT SLIPPING IN COLD WEATHER. It can't do that. Not possible.
Your senses are being fooled by your past driving experience. This is like no other car!
What is happening is at very cold temperatuers is you are not getting any battery assist.
You are driving with a part of your hybrid "system" not working.
It is working properly, just not what you are used to. No damage is occuring.
Any battery is a chemical process. Chemical reactions are inhibited at cold temperatures.

In warm weather that battery adds about 40 horsepower to your system.
More importantly, it adds about 400 pound-feet of torque to the system to launch you from a dead stop. Now freeze the battery, and you loose that "help" to the small, low torque, high effieciency Atkinson engine, that now has to do all the work.

It "feels like" the transmission is slipping based on your past experience. The engine revs and the car doesn't move much because A) it is trying to generate the power the battery can't provide at cold temperatures [the why] and B) the engine revs and the car doesn't speed away because of the planetary gear transmission [the how] is sending engine power to the generator to make electricity, not turn the wheels. The generated electricity (not stored battery electricty) then gently drives the wheels.

What you feel is odd, but totally normal, and by design.

Re: Ford Hybrids and cold weather
 

Perhaps you could tell me how the hybrid battery gets charged, other than by regeneration? It's by using some of the output of the gas engine to generate electricity. This is not a Rube Goldberg device; it puts load on the gas engine and so it burns additional gas.

The difference in mileage for a hybrid vs a non-hybrid in stop-and-go traffic is exactly because of the recovery of the energy normally wasted during the stops. Same for going up and down steep hills.

Today I drove up a road that rose 2000' total vertical. At the top it flattened out, and the FEH immediately went into ev mode. That's kind of dumb because it means it was putting extra load on the gas engine to generate electricity to charge up the traction battery even though there was already plenty of load required to climb the hill. Probably the SOC was at 53% at the top. And when I started back down, I needed all the battery capacity available for engine braking. But at 53%, it was 13% above the minimum 40% and so it went to the maximum, 60% sooner than it would have from 40%. So I got half the engine braking I could have used and had to resort to using the friction brakes to keep the speed under control.

After sitting at the top for a couple of hours at 32F, I started down. The FEH would not go into ev mode during any of the three brief flat sections (tight 25mph corners) on the way down. The traction battery was charged to the maximum limit because the grade for the 2000' vertical descent requires prolonged engine braking. Despite the battery being at full charge, it would not go into ev mode because the gas engine was not working hard enough to keep itself and the catalytic converter warm. On a summer day on this same descent, it will go into ev mode on those corners. In turn, this depletes the traction battery and so makes more capacity available for more engine braking when the grade resumes. So warm weather also reduces wear on the brakes.

Again, ev mode does not happen by magic and the traction battery does not get charged by magic. Any charge in the traction battery is there because of burning gas. That can be done by using part or all of the output of the gas engine to act as a generator, by regenerative braking, or regenerative engine braking. Any charge gained by the traction battery by braking from faster speed or engine braking down a hill, got there because the gas engine was run to reach the speed or climb the hill.

The more minutes you are in ev mode OR the more distance you do in ev mode, the more the gas engine has to be run to create the electrical charge to power that ev mode.

It doesn't make sense to equip cars with both gas and electric motors UNLESS there is a regeneration system. And that requires a battery or capacitor or some means to store energy. Otherwise cars would have had both long ago, and, unlike a locomotive, you never see a car with both that does not have a regeneration system. Even the KERS system on most Formula 1 cars, that makes them hybrids, uses a battery.

Even in warm weather, there is several minutes of idle time following a "cold" start. Even if it's warm enough that there's no need to heat the traction battery, the gas engine and catalytic converter need to be heated to operating temperature. In cold weather the engine needs to run a lot, when in cold weather it would not, to keep these things warm. That's in addition to keeping the traction battery warm.

I didn't say or imply that the losses were "huge". It's basic physics that converting energy from one form to another involves losses. So unnecessarily "forcing" the hybrid system into ev mode more that it would do so just on it's own, will be less efficient than just using the gas engine directly for propulsion. Even the FEH's owner manual says that you probably will get worse mileage if you cause the ev mode to operate more than it would by itself.

But, and this is a big but, diesel locomotives have no provision for regeneration. They have no storage battery. If they did, it would have to be massive to be of any value. Instead, they have large banks of resistors to dissipate braking forces, from the wheels to the generator, as heat.

The performance characteristics of trains are well suited to electric motors and are extremely different from the operating characteristics of cars. That's why trains in Europe are run straight with electricity and don't bother with the inefficiency of diesel motors on the locomotives.

Which is why non-hybrid road vehicles have transmissions. And clutches. Yes, gas engines have sweet spots. That's why more and more cars have more gears or cvt's. But the efficiency of the engines with multiple fixed gear transmissions outside the sweet spots are not compromised a huge amount. That's why non-hybrids get highway mileage competitive with hybrids. Where the mileage difference is large, which is in urban driving, is because of the hybrid's regeneration system.

Re: Ford Hybrids and cold weather
 

xspirt,

Several items I take issue with...

1) Coasting will also charge your traction battery just like regenerative braking will. This is an often missed point.

2) The engine needs to get up to temperature after a cold start (and even a few minutes for warm start) to get the engine and converters up to the correct temperature. The engine might as well be charging the battery during that time as it will have MORE than enough capacity to move the car.

3) The electric motors will supplement the gas engine as required to increase the operating efficiency while moving.

4) Non hybrids of the same size and power range will still be an order of magnitude less efficient on the highway due to most hybrids using an Atkinson cycle engine and supplemental power from the electric engines.

5) While using the gas engine only, the increased fuel burn to additionally charge the battery is minimal as the ECU will look at the engine load and adjust it accordingly.

Modern hybrids are not simple, not easy to decipher and will be a constant source of arguments until long after we are gone.....

Re: Ford Hybrids and cold weather
 

Yes, but any speed that can be retarded by generating electricity while coasting, was attained in the first place, directly or indirectly, by running the gas engine. This is not true of a plug-in hybrid, of course. Generating current while coasting simply has to reduce speed, and regaining that speed either depletes the battery and/or uses gas to run the engine.

The FEH has two modes of coasting. On is in D, and you don't see the charge instrument needle move into the charge range. I think it moves a bit, but it's so little it's hard to tell. It would be a violation of the laws of physics for this to happen without reducing the vehicle's speed.

The other coasting mode is in L. You can feel the vehicle slowing down and the charge indicator will obviously be in the charge range. The loss of speed in either mode can only be recovered by burning more gas, or by depleting the battery (which can only be replaced by burning more gas).

I'm lucky to live at the top of a slight hill, so I try to arrive at home in ev mode. This depletes the traction battery, so that when the gas engine is idling after the next cold startup, it is also recharging the battery to the neutral or midpoint of capacity. What you describe is also why FEH drivers are advised to not let the car sit and warm up, to drive off as soon as the engine starts. I release the parking brake and put on my seatbelt before starting it.

I've noticed that while the car warms up, it idles at a constant speed and the charge needle stays in the neutral spot. So the propulsion must be coming from the engine generating electrical power. When I brake during this phase, the charge needle shows no regeneration. This must be because the gas engine must be run to warm things up. Soon, the engine speed will vary, and soon after that braking will result in charge being generated. And after that, engine shutdown can happen and ev mode is available.

Here I have to disagree. The electric propulsion motor can increase the power available to propel the vehicle, but does not make it more efficient. Any power provided by the electric motor came from the battery, and ultimately that energy got to the battery by burning gas in the gas engine. The hybrid system does not create energy anywhere by itself. Any energy used by the FEH comes from the gas burned by it.

The charge gauge will indeed show boost coming from the electric system while speeding up or climbing a hill. And that helps efficiency. But that boost is available only because something charged the hybrid battery at some point. And that charging required burning gas, either to gain speed or to climb a hill, or to overcome engine load added for "background" charging of the battery.

But an equivalent non-hybrid could have exactly the same engine running the Atkinson cycle, and could even have the same or equivalent eCVT. Highway driving is where the hybrid system has the least effect, and it certainly does not create or contribute energy from thin air. As I said above, any contribution by the traction battery via the electric propulsion motor originally, one way or another, came from burning gas. And it's more efficient to burn gas to power the gas engine to power the wheels, than it is to burn gas to power the engine to turn a generator to charge a battery and then use the battery to turn an electric motor to turn the wheels. And note that diesel locomotives don't work either of these ways.

WHATEVER amount of energy is used to charge the battery or is provided by the battery, originally comes from burning gas in the gas engine. The hybrid system and/or the ECU have no ability to create energy, large or small amounts, by itself.

While the minute detail of how systems such as the FEH's hybrid system works certainly is complex, the basic principles are quite simple and have been understood for a long time. The disagreements seem to come from the idea that many have that the propulsion provided by the hybrid system in ev or combined mode comes out of nowhere. They somehow have this impression that ev mode comes for free. I don't know why people see it that way and why they can't see that any propulsion expressed by a hybrid vehicle entirely originally came from burning gas.

I want to add that ev mode in the FEH is more like a "party trick" than something earthshaking. It's not that useful since it's not very powerful, and any propulsion provided came, one way or another, from burning gas. What makes hybrids more efficient than non-hybrids is their ability to capture and re-use the energy normally lost while braking.