I'm a new owner of a MMH. I now have about 3,000 miles on the vehicle and absolutely love it. Like most hybrid owners I've been trying to maximize my fuel economy and try to drive in a very conservative manner.

I must say that I'm surprised that it's so difficult to keep the MMH in EV mode when accelerating from a stop. Even very modest pressure on the accelerator causes the ICE to start at only 10 to 15 MPH. In order to keep the MMH in EV mode I must barely touch the accelerator and then I can mange to get up to about 30 MPH before the ICE starts. But that results in excrusiatingly slow acceleration - 0-30 MPH takes about 20 to 25 seconds and can only be done when there is no other vehicle behind me.

Is this the way my MMH is supposed to function? It seems as though the vehicle should be designed to provide greater acceleration in EV mode before calling for the ICE to start. Comments please.

 

Doug,

Your experience sounds normal. The electric motor really isn't powerful enough for anything but the lightest acceleration (AWD being even worse than FWD due to weight).

However, over time you will get more EV. My 2005 seemed to "break in" over time and EV stays on more and more as you put more miles on it.

Also, you get used to the slower acceleration. Although you have to choose when to "EV it" (i.e. slow accel)---downtown DC is not the place to test that.

I'm sure you'll get many more comments on this subject.

Nate

 

Hi Doug,

I also own a 2008 MMH with about 3k miles -- and I have been noticing that I can keep EV mode much more now than previously. The best way to keep EV is to accelerate slowly on level road. Even the slightest of an incline and the ICE will kick in around 10 MPH.

At the same time, I think keeping EV for long periods doesn't really help. The battery runs out between 1 and 2 miles anyway, so ICE will start up then just to recharge.

My experience for best fuel economy has been to keep my RPMs around 2k, and not worry about EV.

Love the MMH, for sure. It's a great SUV.

 

Another new owner here with about 1K miles on my MMH. I find that I'm spending more time figuring out how to get into EV on the deacceleration side rather than the acceleration side. I have at least another month of using the evil red button (A/C) as temperatures here are well into the 90's. The engine kicks in pretty regularly for me accelerating between 10-15 MPH.

Never coming to a complete stop seems to yield the best results but lights and traffic don't always cooperate.

My wife and I enjoy our MMH so much that I'm ordering one for her!

 

allot of energy is used to move ANY car from a dead stop. Having the engine start at 15 to 20 mph is not that bad. Use L gear and use the ICE to accell just past speed limit, then use light throttle and if under 40 mph tap the brakes twice and this should cause the ice to shut down. Energy is energy and having to recharge the battery when you don't have to will use more energy than you saved. I think the strategy is to leave the battery in a low state of charge when you stop, because the ICE will run when you start up.

 

Not true, if you blast away from a light, most of the power comes from the electric motor. The assist gauge will peg right. I have not had the assist gauge even halfway pegged in EV before the ICE kicks on. This is what Ford chose to do, but not for want of electric power.

 

True, but realize that Ford chose to do it for a reason. In normal driving (after shes broken in) the amount of electricity used to get the car moving in EV would be balanced out by the amount of electricity put into the battery while driving and braking. Its all a matter of balancing it out. If I drain the battery dry with every acceleration and I have to use extra RPM's to charge it again... that could in fact be less efficient. The electric motors are the most efficient at low RPM and high torque. Once the vehicle is going a certain speed that isn't true anymore and its time to bring in the ICE with its high RPM and lower torque to keep the vehicle going. You use both all the time to find the most efficient point to operate at (ie the electric motor at an effient part of its RPM to produce a portion of the torque and the ICE at its RPM to produce the rest balanced by the RPM needed to move the car at a fixed speed.

That engine comes on for a reason... (after its broken in) for a "normal" driver its probably a pretty good approximation of the best place for the switchover to occur. A NON-normal driver, ie a hypermiler will be able to drive the car differently and probably would like it to be in a different place... but the car was built for the average person to get the best mileage possible when they drive it like they would any other car.

Thats why people can hypermile it and do better and thats why one could make tweaks and drive differently and do better.

Cost is in there too of course.

 

When I drive in EV now that my FEH is broke-in, I can accelerate very fast in EV if I need to. I never thought I would be watching the assist gauge so much a year ago, but I do now. The Assist Gauge is how I stay in EV the longest. It doesn't take maintaining the highest torque possible for the motors in EV to drain the battery from a take-off. When traffic permits, my take-off in EV is very slow so the battery will last much longer to get up to 30mph. The reason I don't accelerate much pass 30mph, is because it takes to much stored energy fighting the wind resistance. I find it's much better to accelerate with the ICE above 30mph, but go EV and hold a steady state speed with the electric motors.

When your vehicles gets broke-in, your really going to love the FEH/MMH in EV mode.

GaryG

 

An often over-looked fact is, you can get MORE battery assist after the engine is started. Why? Because when you are in EV mode, the car has to keep enough power ( both watts and torque ) in reserve to crank the engine up to 1000 RPM before it sends it any fuel.

Once the engine is already started, the car needs no reserve.

A rough estimate is, in EV, you are only allowed two-thirds of available battery power. One-third is kept in reserve to start the car.

Once the engine is started, 100% of battery power can go to the wheels.
-John

 

I believe the reason Ford chose to do this was primarily to minimize the impact of turning the ICE on when in motion. Ford seemed absolutely intent on making the FEH's hybridness transparent to the average driver, even at the expense of fuel economy.