EV Mode to 47MPH

[Oman]

By necessity there is loss at every point of conversion. If a gas engine can not directly drive a car 160 miles on a gallon of gas (heat to motion) - it won't be able to drive it 160 miles after converting heat to motion to magnetic force to chemical potential energy to electricity to magnetic force to motion. Plus you are starting with a full charge - energy that isn't included in the (G) of MPG.

 

Imagine your same test with a bigger battery in the volt. If the car can complete the entire EPA test without reverting to the generator at all then it gets 1,000,000,000,000 MPG (something would have to evaporate from the tank). Now that would be cool.

 

Jon

 

 

My point was that the EPA wasn't doing the test for the Volt - GM was. And I don't believe the EPA has said how they will measure the VOLT's EPA mileage when it hits production.

 

 

If you remember a few months ago, GM announced preliminary 'MPG' in the upper 200s. BS?...maybe not. Imagine the Volt has 1 gallon of gas on board and a full charge. You drive 40 miles (or more, assuming the gen set will maintain a charge level to operate in town..for instance) until the battery is depleted, stop, let the generator charge for 30 minutes (per the article above) and repeat the cycle until the gallon of fuel is depleted. Therefore, your MPG is easily computed. Nobody said they were contiguous miles.......

[Oman]

(I'm replying to myself :>)

 

As to the point of the EPA - GM and the government very much wants the EPA to rate the Volt in MPG. Something that can't be done without smoke and mirrors. This is so that us dumb Americans don't get too cornfused. The EPA knows better but it is a government entity. Any gas only system (like the FFH) can be rated in MPG (which is still a crummy system) but at least it is fairly honest. As soon as you add power from somewhere else you are lying if you use MPG in any way.

 

Jon

 

 

By necessity there is loss at every point of conversion. If a gas engine can not directly drive a car 160 miles on a gallon of gas (heat to motion) - it won't be able to drive it 160 miles after converting heat to motion to magnetic force to chemical potential energy to electricity to magnetic force to motion. Plus you are starting with a full charge - energy that isn't included in the (G) of MPG.

 

Imagine your same test with a bigger battery in the volt. If the car can complete the entire EPA test without reverting to the generator at all then it gets 1,000,000,000,000 MPG (something would have to evaporate from the tank). Now that would be cool.

 

Jon

 

 

 

 

 

If you remember a few months ago, GM announced preliminary 'MPG' in the upper 200s. BS?...maybe not. Imagine the Volt has 1 gallon of gas on board and a full charge. You drive 40 miles (or more, assuming the gen set will maintain a charge level to operate in town..for instance) until the battery is depleted, stop, let the generator charge for 30 minutes (per the article above) and repeat the cycle until the gallon of fuel is depleted. Therefore, your MPG is easily computed. Nobody said they were contiguous miles.......

Edited December 1, 2009 by Oman

[junehhan]

Since we are talking about the Volt, here is an interesting article I came across today as C&D test drive a prototype.

 

http://www.caranddriver.com/reviews/car/09q4/2011_chevrolet_volt_driven_in_range-extending_mode-car_news

[rpreuss]

Yesterday while driving home in my FFH, I was thinking about the discussion of giving the Volt a MPG rating, considering that it has two energy sources.

 

Compare it to my sailboat. (I really only wish I had one).

 

It is 40 feet long, and has a small auxiliary engine. With that engine, I get way over 1000 MPG based on the distance my vehicle travels and the amount of gas it uses. FANTASTIC!!

[str1der]

Back to the original topic of 47 MPH on EV mode. When you guys talk about this are you saying going from 0 to 47 without the ICE ever coming on? I've tried to start out as slow as possible and I can't get over 10 MPH without it coming on.

[ace43]

It is possible to accelerate from 0 to 47 in EV mode, but it requires perfect conditions. I have done it on downhill stretches through small towns where gravity and coasting were helping perhaps as much as the electric motor. The advertising is correct that you CAN use the EV up to 47 mph, but that is a bit misleading.

 

The point is that you CAN use the EV mode up to speeds of 47 mph, but not that you should consider it practicable to do so. It takes a loooooong time and can be done only under the kids of conditions I described above. Still, the fact that you can "pulse" to 40-45 mph and then use the EV mode to power the vehicle from there accounts for its great city mpg.

[Oman]

The marketing and technical material talks about EV mode supporting speeds up to 47MPH. The point is that any time the ICE can turn off because the power isn't needed will help mileage. At 45MPH previous hybrids had to keep the ICE running even when there was no power demand. All of this has little to do with "getting" to 47MPH. The idea is to allow the ICE to turn off whenever there is no high power demand and whatever incidental power is required can be supplied by recovered energy.

 

Some years ago the car companies experimented with what amounted to a 1-way clutch on the drive train. Whenever you let off the gas the engine would idle and the wheels would free-spin. Pretty much like dropping into neutral or pushing the clutch whenever you were not on the gas. There were several problems: First off some people just were so used to engine braking that they got into accidents because the car didn't slow down when you let off the gas (which was the whole point). Second you overheated the already crummy brakes faster. Third it took time for the engine to come back up to speed when you next hit the gas.

 

The EV mode in the hybrid is a compromise. There is a motor/generator that makes up the difference in speed between the wheels and the ICE. There is never ever a disconnect between the ICE and the wheels. This motor can spin up to a speed difference equivalent of 47MPH between the ICE and the wheels. So the ICE can be off and the wheels can be spinning at a rate equivalent of 47MPH. Once you go over that the ICE needs to run at a certain minimum RPM (likely 900), so the ICE can essentially idle up to maybe 55MPH.

 

Driving around in EV mode without any ICE at all feels good but doesn't really do much except jump the real-time MPG up. The energy used isn't available for ICE assist later so the instant MPG will be worse at a later time. Overall the idea is to recover as much as possible, keep the ICE off when there is no demand for power, and boost the ICE with electric to keep it from running in inefficient RPM/Power ranges.

 

 

 

Jon

 

 

 

 

It is possible to accelerate from 0 to 47 in EV mode, but it requires perfect conditions. I have done it on downhill stretches through small towns where gravity and coasting were helping perhaps as much as the electric motor. The advertising is correct that you CAN use the EV up to 47 mph, but that is a bit misleading.

 

The point is that you CAN use the EV mode up to speeds of 47 mph, but not that you should consider it practicable to do so. It takes a loooooong time and can be done only under the kids of conditions I described above. Still, the fact that you can "pulse" to 40-45 mph and then use the EV mode to power the vehicle from there accounts for its great city mpg.

[str1der]

Ok that makes sense. Just wanted to make sure I wasn't missing something. Yes mine cuts off at times when I'm coasting. I've just never seen on a flat surface where I can get up to any kind of speed without the ICE.

[ace43]

I think it is possible to get to 47 mph in EV mode only in the FFH. It probably doesn't make any sense to try to do that, plus it will take a long time and drive you and the people behind you nuts. But, for example, driving through small towns you can keep the car below 47 mph and use the EV mode to gain speed on flat runs or downhill runs and use that accumulated speed and momentum to get you up a hill you might be approaching.

 

The advertising about the EV "up to 47 mph" is a little misleading. The tendency is to think that you can use the EV mode alone to get to 47 mph and that is really not practical in real-world conditions. But being able to go into EV mode alone under 47 mph is very valuable because the ICE is off during those conditions and your mileage rate does increase markedly. It does increase battery drain, but the regenerative feature of the braking system compensates for a lot of that loss and the ICE does also. The battery serves to dynamically interrelate the EV and ICE power components. The system works quite nicely.

 

Where the FFH really seems to shine, in my limited experience with it, is on roads with a 45 mph limit where you can keep the car in the EV green zone and maximize mileage. The SmartGauge cluster allows the driver to make a game of it and make getting better mileage enjoyable and challenging. It really can seem like driving a video game except the results in terms of better mpg are quite real.

[bdrool]

When I was researching my car back in June, I talked to a Ford rep at a special event. What he told me was the EV mode can handle up to 47MPH by itself. The reason for the limit is to prevent damage to the electric motor from over revving. One thing you can try to verify this, and I already did, is to coast down a long hill. When the MPH is at 47+ the ICE will start even though you don't need it. This is the biggest advantage over the competition because they can only do around 25MPH in EV mode.

[Bigkart]

You folks act like the electric motor is of no value above 47mph. Based on the gauges I'm watching on my dash, that's not true. It may not run exclusively as an EV above 47 mph, but the electric motor does continue to provide an assist. Watch the blue arrows, especially if you're running 50mph and have a very well charged battery. The electric motor will assist and your MPG indicator will peg, or go close to it. When the battery is run down to 1/2 charge or less, you'll see less of the assist.

 

As for over-revving an electric motor, I don't know how fast you'd have to spin it for that to happen. It's not like pistons, or even the Mazda rotary. Nothing is going "boing". My guess is its simply a matter of the amount of power required to move the vehicle through the air and the efficiency of the ICE vs. use of battery (rate of discharge).

 

Finally, while I don't run out of patience, I do usually run out of battery before getting from 0 to 47. You'd have to be able to do that in about 3/4 - 1 mile to do it within the stored capacity, and that's unlikely on a flat road.

 

Bob

[Oman]

There are two electric motors (which both also act as generators too). The one that limits the ICE to wheel speed differential is essentially the transmission (3rd input into a single planetary gear set) and is referred to as MG2. I think the software limits the RPM of MG2 to 6,400 RPM. Over that there is risk of it ripping apart. Reciprocating parts are not the only limiting factor for rotational maximum speed, sheer rotating mass forces stress limits speeds as well.

 

And yes, both the motors actually do real work over and under 47MPH. In fact MG2 is always either generating or consuming power. Under heavy load (when the ICE is at high RPMs) MG2 is generating a large amount of current which is fed right back into MG1 and at the same time if there is power in the HV battery that is also fed into MG1. That is "the other way" that the stored energy in the battery is used - helping out the ICE under load. That is also why MG1 is rated for more power than the HVB can output.

 

Jon

 

 

 

You folks act like the electric motor is of no value above 47mph. Based on the gauges I'm watching on my dash, that's not true. It may not run exclusively as an EV above 47 mph, but the electric motor does continue to provide an assist. Watch the blue arrows, especially if you're running 50mph and have a very well charged battery. The electric motor will assist and your MPG indicator will peg, or go close to it. When the battery is run down to 1/2 charge or less, you'll see less of the assist.

 

As for over-revving an electric motor, I don't know how fast you'd have to spin it for that to happen. It's not like pistons, or even the Mazda rotary. Nothing is going "boing". My guess is its simply a matter of the amount of power required to move the vehicle through the air and the efficiency of the ICE vs. use of battery (rate of discharge).

 

Finally, while I don't run out of patience, I do usually run out of battery before getting from 0 to 47. You'd have to be able to do that in about 3/4 - 1 mile to do it within the stored capacity, and that's unlikely on a flat road.

 

Bob

[lolder]

Jon, I think MG1 and MG2 may be reversed. I think MG2 is the big traction motor/generator.

Lee

[acdii]

I like to arrive home with a low battery.

 

 

 

Just a note on his, beware that in cold weather, it can sap battery strength, and one morning you may go out and find the motor wont run up. Unlike a conventional car, the 12V battery is not the one that starts the engine, it's the traction battery. Been there, done that, wasn't pretty. I drove home and wore down the pack to 2 bars, and it got below 0 that night, the next morning, the pack was dead, had to have it towed 60 some miles to the nearest dealership that had a hybrid battery charger, and cost me several hundred dollars to get it running again. Don't go below a 50% charge when its going to be sitting out in the cold, or it may not start.

[rlawson4]

Just a note on his, beware that in cold weather, it can sap battery strength, and one morning you may go out and find the motor wont run up. Unlike a conventional car, the 12V battery is not the one that starts the engine, it's the traction battery. Been there, done that, wasn't pretty. I drove home and wore down the pack to 2 bars, and it got below 0 that night, the next morning, the pack was dead, had to have it towed 60 some miles to the nearest dealership that had a hybrid battery charger, and cost me several hundred dollars to get it running again. Don't go below a 50% charge when its going to be sitting out in the cold, or it may not start.

 

I appreciate the tip. I don't need the hassle of having the car towed.

[cbislander]

My drive to work is usually 8 km (5 miles). The EV mode usually kicks in on level driving and will last depending how much inertia the car has and how often I have to stop. It will not stay on for an extensive amount of time unless you are going slowly downhill. If the EV mode has to do the work, your battery level will fall fairly quick. The gas engine or ICE will kick in to drive the car and recharge the battery.

 

My best average fuel economy has been around 5.7l per 100km (48MPG Imperial or 40 MPG US). Under current winter conditions and with snow tires it is around 6.8l per 100km (40MPG Imperial or 33MPG US).

 

I am still learning how to drive it more efficiently.

 

I am quite happy with the results so far.

 

 

Newby here. After doing my due diligence and looking in past posts on this topic (and finding nothing specific to this question), I have a question for you folks. I am in the market for a new fusion (on the Ford A Plan), and I'm wondering about the "up to 47 MPH in the EV mode" claim seen online.

 

If my battery is fully charged, and the FFH is warmed up to proper operating temp, can I make it to work (about 12 miles, max speed limit 45 MPH) solely on the EV mode? I understand the variables of uphill vs. downhill and level driving, etc., but the prospect of using little or no gas on my daily commute in a really cool looking car is quite appealing!

 

Thanks - Pete

[Rex362]

i'm in ev mode up to only 30 mph ....I have no downhills here

[cbislander]

Last year Ford sponsored a Fusion Hybrid endurance event of sorts. Using professional drivers and engineers, they used hypermiling methods to get the most out of 1 tank of gas. Ofcourse, it was much more than what anyone else would get. Here is the hyperlink below, in case you did not read it.

 

http://www.thefordstory.com/green/ford-hybrids-racking-up-sales-and-mileage/

 

One trick that they used was "pulse and glide". You accelerate your car to get a good momentum and ease off the pedal so the EV mode would kick in. At that point you apply enough pedal to keep within the EV mode range to keep the speed up. Once the battery is fallen below half, try to use the gas engine to both charge your battery and drive the car.

 

It is one method that I am still trying to master. As I have said before, the weather and my short commute has had some impact on my results.

 

 

i'm in ev mode up to only 30 mph ....I have no downhills here