Questions on How the Hybrid Escape really works - GreenHybrid

David Lee · #1 (**permalink**) 09-09-2006, 06:34 PM

I've read some various things concerning how the Escpe Hybrid works and have asked Ford but have received no real answers from them. Any help would be appreciated.

I spend a considerable amount of time driving up and down in the mountains and I'm trying to determine how well, or how different the Escape Hybrid will operate in that environment

Concerning the charging of the batteries.

What tells the system to charge the batteries? Just stepping on the brakes?

The Escape brochure does not specify as I recall that the ICE will run to recharge the batteries if they are low though various other sources alude to this. What is the real story?

It the electric motor spinning all the time (like say a flywheel)? As dead weight unless told by its controller to act as a generator or as a motor? Or does it sit still until told to do one or the other?

Considering the CVT transmission (which is different from a manual or even a normal automatic transmission). If an Escape was on a long downhill pass, (such as Donner Pass, Highway 80 between Sacramento and Reno) is the transmission capable of downshifting to slow the downhill speed? If so is the electric motor providing some of the resistance and charging the batteries? If so, what if the batteries are charged or become charged while on the way downhill, is the resistance now less in the downshift mode? If the batteries are fully charged is there a load bank (like in a locomotive) that continues to provide some resistance such that your not slowing down by friction only? Is some braking required on a long downhill to convince the system to use regenitive braking?

I think that covers it and I'm being told to get to the dinner table.

Thank you for your help

David Lee

jginaz · #2 (**permalink**) 09-09-2006, 07:31 PM

There is much information on the technology available. I'll give you my experience. Last weekend I traveled from Phoenix to Prescott Valley Arizona through Yarnell. This involves a 6000 ft gain then down to 5000 where I stayed. I drove around town for a bit the next day and the day after that back to Phoenix. Total MPG for the trip was 34.4 MPG. Total miles, about 200. I have a 2007 FEH FWD.

Jay

Edit: I forgot to mention, it is still pretty hot here in Az so the air conditoner was on for the whole trip with minor exceptions when in Prescott.

occ · #3 (**permalink**) 09-09-2006, 07:58 PM

Quote:

Originally Posted by jginaz

There is much information on the technology available. I'll give you my experience. Last weekend I traveled from Phoenix to Prescott Valley Arizona through Yarnell. This involves a 6000 ft gain then down to 5000 where I stayed. I drove around town for a bit the next day and the day after that back to Phoenix. Total MPG for the trip was 34.4 MPG. Total miles, about 200. I have a 2007 FEH FWD.

Jay

Edit: I forgot to mention, it is still pretty hot here in Az so the air conditoner was on for the whole trip with minor exceptions when in Prescott.

Jay, can I ask if you remember what average speed you were doing during the climb and the descent, to get your total of 34.4MPG?

jginaz · #4 (**permalink**) 09-09-2006, 08:43 PM

OCC,
On the first leg of the trip it was 55-65mph until the climb to Yarnell probably 40 miles. Then it was pretty slow going due to switchbacks etc so probably 30 miles of <35 miles per hour. In town it is 30 MPH on back roads, 45 on the highway so maybe 30 miles of a mixture of the two. Then back was 65-75 with a lot of drafting of a semi total of 90 miles. At the end about 5 miles of 35-40 to get home. If we take the freeway on the uphill and go 75 when possible 65 through the steep part, we only get about 27-28 MPG for that leg. Still not bad for continuous uphill at a pretty good speed with the air conditioner on.

Jay

gpsman1 · #5 (**permalink**) 09-09-2006, 11:12 PM

I run my 2005 in the Colorado Rockies ( 4700 ft to 10,000 ft ) all the time with FANTASTIC results.
( see bottom signature line )

My comments in red below:

Quote:

Originally Posted by David Lee

I spend a considerable amount of time driving up and down in the mountains and I'm trying to determine how well, or how different the Escape Hybrid will operate in that environment.

VERY WELL if you are gentle on the uphill, and do a lot of "coasting" on the downhill... ie. let gravity do most of the work and don't use a lot of gas pedal to speed up on the downgrade... let speeds flutter 5 or 10 miles per hour above and below the posted speed limit. Keep load ( or RPM ) constant, and let speed fluctuate.

Concerning the charging of the batteries.
What tells the system to charge the batteries? Just stepping on the brakes?

Several different inputs, probably 2 dozen, are used to determine when to charge/discharge the batteries.

The Escape brochure does not specify as I recall that the ICE will run to recharge the batteries if they are low though various other sources alude to this. What is the real story?

The gas engine will run to specifically charge the battery, if the chrage is very low. This almost never happens. Usually, the engine will come on to keep the catalyist at optimum temperature to reduce emissions before the battery gets that low. So while it's keeping things "hot" it is also re-charging, if needed. 5 minutes of engine off at 65'F will cool things enough to evoke engine re-start, ( for 30 seconds ) but few of us have red lights longer than 5 minutes.

Is the electric motor spinning all the time (like say a flywheel)? As dead weight unless told by its controller to act as a generator or as a motor.

In short, YES!

If an Escape was on a long downhill pass, (such as Donner Pass, Highway 80 between Sacramento and Reno) is the transmission capable of downshifting to slow the downhill speed?

Yes and No. It will spin the motors and/or engine at higher RPM to create resistance, yes, but there is no "downshifting" as this car ( ie. transmission) does not shift... EVER!

If so is the electric motor providing some of the resistance and charging the batteries?

Yes, to a point. 2-3 minutes/miles of contstant downgrade will have the batteries at maximum charge.

If so, what if the batteries are charged or become charged while on the way downhill, is the resistance now less in the downshift mode?

Again, not a simple answer. If the battery pack is fully charged, the wheels will spin the large motor to act as a generator and create drag.
The wattage from the motor/generator will be sent to the smaller starter motor/generator. The smaller starter motor will consume the wattage by spinning the gas engine at about 4,000 RPM. This combined action very cleverly re-creates the same amount of slowing that a conventional low gear would. Again, this car cannot really "change gears". Oh... even though your gas engine is spinning at 4,000 RPM, you will get upwards if 200 MPG during these downhill sections. No gas needs to be consumed ( or very little ) since the electrics are doing all the "work". Again, very clever design!

If the batteries are fully charged is there a load bank (like in a locomotive) that continues to provide some resistance such that your not slowing down by friction only?

No, but this was explained above.

Is some braking required on a long downhill to convince the system to use regenitive braking?

No, if your speed increases by gravity with your foot off the gas, mild regeneration will occur automatically.

For what it's worth, the electictric motor acting as a generator provides up to 50% of your braking effort. Thus your brake pads are used 50% less often, and/or 50% less strongly than a traditional car, and should last at least twice as long. You do however have 4 wheel disc brakes, that can provide 100% of your braking in emergency conditions.

I think that covers it and I'm being told to get to the dinner table.

Thank you for your help

David Lee

empowah · #6 (**permalink**) 09-30-2006, 09:05 PM

This thread has been extremely helpful... I also have a question that is related to regenerative braking.

Will the electric motor provide any resistance and recharge the batteries on a flat road, foot off the gas (until it rolls to a stop)?

If not, is it possible to keep the batteries charged with only regenerative braking? My commute to school is ~3 miles, and it would be awesome if the ICE won't turn on.

gpsman1 · #7 (**permalink**) 10-01-2006, 12:38 AM

Quote:

Originally Posted by empowah

1. Will the electric motor provide any resistance and recharge the batteries on a flat road, foot off the gas (until it rolls to a stop)?

2. If not, is it possible to keep the batteries charged with only regenerative braking? My commute to school is ~3 miles, and it would be awesome if the ICE won't turn on.

#1 Yes. There is a slight bit of regeneration anytime you take your foot off the gas, if the battery is low, and you are traveling at a decent speed. Experienced drivers have found ways to eliminate this resistance when NOT desired, such as coasting down a long hill. Neutral will eliminate resistance is most cases ( but surprisingly, not all! ) and so will depressing the accelerator pedal a slight bit, but not enough to accelerate... like a 2mm depress.

#2 In stop & go or slow & go conditions, most, but not all of the recharging will come from regenerative braking. In real life, you tend to need more power than regenerative brakes can put back in.

Sadly, short commutes, those less than 5 miles are poor on gas mileage from a cold start. The engine / catalyst needs to be at full temperatures, and the battery at a high state of charge for the real hybrid advantage to kick in. This normally occurs AFTER 3 miles or more.

On a hot day, on the way home, you could get 2 out of 3 miles on battery alone.
I suspect all 3 miles will use gas on the way there on a cold engine.

Tim K · #8 (**permalink**) 10-01-2006, 08:50 PM

Quote:

Originally Posted by empowah

If not, is it possible to keep the batteries charged with only regenerative braking? My commute to school is ~3 miles, and it would be awesome if the ICE won't turn on.

The real answer is no. Unfortunately, when it comes to energy you can never recover the same amount as you put in. In other words....if you accelerate to 30mph and then slow down to zero you will not end up with the same amount of charge on your battery as you started with. There are losses in the system and you will likely end up with 1/2 or less charge than you started with. A mix of open roads and stop and go driving is great. The open roads let you charge up while the ICE is running then you can EV on battery for a while during the stop and go parts. I think the suburbs are the ideal setting for this type of hybrid. While hybrids are great in the city with ICE shutdown at idle, too much stop and go prevents sufficient recharge of the batteries and does not let the vehicle shine.

Also, I know that with my morning "commute"....

(which involves a 7 mile roundtrip drive straight through the nation's 5th (or 6th?) largest city to drop off my wife at work and my son at daycare and then back home for my walk to work)

....that from any start the ICE must run to bring the CAT up to operating temp. A cold start means about 1-1.5miles of driving on average. Since your engine HAS to run, your vehicle will use this opportunity to charge up. The worst scenario is a cold start right into stop and go traffic. Running the ICE at idle will kill your gas mileage. If you can, choose a route that lets you drive as much as possible without stopping for the first mile or so. I jump on the highway for the first 1/2 of my drive. The alternative is traffic lights every block. It is a little out of the way, but takes about the same amount of time and results in about 5mpg difference.

Once it reaches temp, you can then run in EV mode. Depending on your commute, you may be able to do the final 1/2 or 2/3's in EV mode. When you leave work you will again have the ICE run until the CAT reaches temp.

The other lesson here is DON'T drive to lunch.....make a coworker do it....the two short trips will kill your average!!!

TeeSter · #9 (**permalink**) 10-01-2006, 10:05 PM

Quote:

Originally Posted by Tim K

The other lesson here is DON'T drive to lunch.....make a coworker do it....the two short trips will kill your average!!!

On the other hand don't be too discouraged. The vehicle still gets very good mileage even in these poor conditions. I commute only 9 miles to and from work each day. I actually do drive to lunch (about a mile) and back [no offense but if the goal is better environmentalism shouldn't we ride in my car rather than someone elses]. My average in the summer? I'm doing about 30-31 MPG, thats in one of the 4WD models, driving normally. I don't "Pulse & Glide" (I have no patience for all the shift and acelerator work) and my tires are still at the stock recommened 35PSI.

Under those conditions with a 4WD I believe 30-31 is very decent, escpecially considering I've been told the regular 4WD Escape gets 17MPG---ON THE FREEWAY!

GaryG · #10 (**permalink**) 10-01-2006, 10:15 PM

I agree Tim, you must have the ICE/generator charging system for maintaining the battery SoC for the most part. The key IMO is to use regen to reduce the amount of ICE/generating to a minimum.

There is a minimum speed of ~20mph and a maximum speed of ~35mph to get the best FE possible. The less stops and speeds under 20mph and over ~35mph is where I find the best FE. After the battery is drained, I use regen with the fake shift in "L" twice after I coast from EV at ~31mph to 25mph. If you use the fake shift in "L" at ~35mph, you end up with an EV glide at ~31mph shifting to "N" for the coast to 25mph. Back to "L" and accerate to 30mph in EV for another glide in "N" down to 25mph. Most likely you will only make it to ~27mph before a restart of the ICE. Accelerate to 30mph for a full fake shift with a dead battery to 27mph. At this point, increase speed under ICE to ~35mph for the second fake shift to go to EV at 31mph. Repeat as long as you can. Higher speeds to 43mph will increase your mpg, but not as good as the lower speeds.

It is the combination of regen and ICE/generator charging that can bring my MPG over 70mpg in the FWD FEH. I estimate 70% of the time is in EV with the minimum 25mph maximun 35mph technique above. This is all possible with max regen charging.

GaryG