Hi.

I have my 2008 HCH II for over a month now. Have been getting good fuel economy. 1st tank at 47 MPG, now at above 50 MPG.

I have read a lot on hypermiling and has been applying these methods. However, I have noticed that my HCH will not get into full Electric mode above 30MPH (50 km/h ). I have seen videos on youtube

http://www.youtube.com/watch?v=kerNi...eature=related

showing the vehicle running in all Electric Mode at 68 MPH.

Wonder if there is any software changed "forcing" the car to disengage all electric mode above 30MPH. Else I think I will be getting even better MPG.

I live in Singapore, that is why I indicated 50km/h (we use metric) which is equal to 30 MPH approx.

Just wonder if anybody out there facing same issue?

 

His car is not in "full electric mode" because the engine is still running.

He is mostly coasting - you can tell because it starts out with no electric assist and then only a small bit of electric assist.

If you are on level ground or going downhill this is possible at the speed he is going, but only if you are very light on the accelerator.

If your car is at normal operating temperature and you lift your foot off of the accelerator, the MPG gauge should go up to >100. There is nothing special about this, and it is not "all electric mode"

 

From the Honda "sales" literature, at 35 or below, the hybrid may shut off all fuel injectors depending on a variety of conditions. Seems to me that would indicate electric only mode.

I've been able to get my vehicle into the > 100 mph mode with minor electric assist at many speeds but rarely above 60 mph. While it may not be in pure electric mode, fuel economy shoots up rapidly - in fact, if you reset your B trip meter while in this mode the mpg goes off the charts. The engine may still be spinning, but fuel is not being used. Unless fuel is used with the injectors off?

 

It is not pure electric mode if the pistons are still going up and down and you can only get a minuscule amount of electric assist - it's coasting - basically putting your car into neutral without actually putting it into neutral.

That's MY opinion - likely I'll get 100 people telling me I'm wrong, but it's just my opinion as an electrical engineer.

 

#1:
Although the pistons are still moving, no fuel is flowing to the engine. Putting it into neutral from EV mode, you can see the iFE gauge drop significantly. At least that is what I have been told. I have no concrete evidence, and for all I know it could be BS.



Getting you car into EV mode above 50Km/h is possible, but with only 1-3 bars of assist. At that speed, those assist bars aren't doing anything but slowing your deceleration. You are technically in "EV mode", but your electric motor isn't propelling you forward. Most of the time the main forces in EV mode are inertia and gravity. I have rarely seen the electric motor actually increase my speed, without the engine, on a flat surface. And when it happens it is usually speeds in the teens.

IMO, if you could get into EV mode at high speeds, you would actually see a decrease in FE, because your battery would quickly be depleted and you would go into forced regen (unless you had a plug in or solar system).

Just my 2 cents.

 

I've been able to maintain a speed of about 15 mph on the flat for about 1/4 mile in "ev" mode. But never able to accelerate. It is so touchy to get in this mode that it makes me think, why bother? And this little electric motor and battery pack is not designed to be stressed like this.

 

Martin, you are not wrong. You are entirely correct. This operational anomaly is called “Fuel Cutoff Mode” (FCO). It’s a feature built into automobiles of all kinds, not just hybrids. I see it frequently on my daily driver, a 2002 Ford Ranger Pickup with manual transmission. My Ranger goes into this mode when I’m in 5th gear, speed above 40mph, and I quickly release my foot from the accelerator pedal. It takes about 2-3 seconds before the ECU places the vehicle into FCO mode.

Using my ScangaugeII, I can see MPG go to Maximum, Horsepower drop to Zero, Gallons per Hour drop to zero, Fuel Pump pulse count drop to zero, and Open Loop operating mode. The engine is spinning, but consuming ZERO fuel, so during these short intervals I’m getting unlimited mileage. The other noticeable behavior is compression breaking, so it won’t coast as fast as it would in neutral. Shifting into neutral inhibits FCO mode, so coasting in neutral consumes a small amount of fuel vs. FCO mode.

Until I became familiar with FCO mode, I used to assume that coasting in Neutral was the most fuel efficient way to save gas. But I have been wrong my whole life. My wife drives our Escape Hybrid, so I haven’t experienced FCO mode in this vehicle, but many other posters on GH have commented on it on the FEH/MMH forum.

 

I think that coasting in neutral takes your car out of FCO mode, thus consuming fuel.

Thanks for explaining it so well Ken. I think you have an excellent understanding of the FCO concept.

 

The Civic Hybrid is a little different than that. When in FCO, there is no compression braking. If I get in glide with the valves closed (iFCD pegged, no assist and no regen), I can coast for miles on the slightest of downhills. Or, I can even accelerate slightly by using assist if I'm going less than 30mph. I've only managed FCO in the MMH a few times, but there is noticably more drag (compression braking) in that car. I have not plugged the scan gauge into the HCH to see what I am assuming is 9999mpg, but I have reset my trip computer on a long hill and it was still at "--" or zero gallons/mile at the bottom of the hill so no fuel was consumed.

Back to the original poster, I have seen EV assist as high as 60mph, but it was on a downhill so the motor didn't have to work too hard. On flat ground, I have trouble getting EV assist (while in fuel cut mode) above 40mph. EDIT: Using the EV assist mode is noticably worse for fuel economy based on my experience--it gives you a quick boost, but then takes it all back away when the car goes into forced regen and will not glide as efficiently.