What is the best way/speed/etc to handle hills short ones and tall ones

 

I would say, monitor the RPMs and use fake shifting to temporary reduce the high RPMs often seen on uphills. Sometimes you can hold the RPMs constant on shorter hills without losing too much speed. Somewhere on this site is a graph of torque in relation to speed if one wants to determine optimum RPM ranges.

It is also true you need to also monitor the speed of your vehicle in regards to the speed limit and to avoid hindering other vehicles.

 

The best way I find to handle hills is in EV going up and replacing the HV battery SoC on the way down with regen. If I make it say half way up from hitting the bottom of the hill in EV with a FS in "L" at ~38mph, I hold my speed by kicking on the ICE and holding RPM's below 2500rpm with traffic. If traffic permits, I hold at 1800rpm's going up and slowly lose speed as I get to the top.

If I'm at to slow of a speed at the top, I accelerate on the down slope with the help of the elevation going down. Once I get to a good regen speed (30-40), I go EV and use "L" and "N" to control speed to prevent a restart over 40mph. This is how I handled the rolling hills at the Hybridfest MPG Challenge for a 26 mile RT for a 61.8MPG average.

GaryG

 

Gary, I heard the highest hil in Florida is a freeway overpass!

 

Sorry, I just HAD to say that.

I have driven the FEH up Palomar Mountain a number of times. Up an back down always improves my MPG reading taken at the same point where I start up the mountain. I leave it in drive and try to stay off of the brakes as musch as possible. There are enough curves, etc that I need to brake for to charge the HV battery. And, simple coasting is way more efficient than charging, then discharging the traction battery.

 

Alright David, but how do you explain how well I did in the rolling hills where I've never driven the FEH? I didn't know what to expect from one hill after another in Madison where I've never been or driven before that day. I feel good about knowing how to climb hills and going downhill as far as FE in a FEH. Regen is king if you know how to control it IMO.

GaryG

 

Gary, can you explain this technique in more detail? What exactly do you do to "prevent a restart over 40mph" ? Won't the ICE always restart above 40mph even in neutral?

 

My experience with rolling hills = reduced MPG. So, I am interested in Gary's technique!

 

I'm also curious on how one can prevent the ICE from restarting once you approach and exceed 40mph?

 

Billy, David and Don, you cannot exceed ~40mph in EV, I just use the shifter to control the speed at or near ~40mph. When I reach that point that the ICE is going to start, I go to "L" briefly to pick up a little regen and then back to "N" to pick up speed again. If I need more of a charge, I let it start up and combine the small generator and regen in "L" to pack a faster charge in the battery. Watch your instant MPG while your letting off the go pedal in "L" and you will see the ICE cuts way back on gas. It's not a fuel cut like when you get a run-up, but it's a very good way for both generators to bring up SoC using very little fuel.

What I've found is I am limited here in flat Florida in taking advantage of the torque curve of the ICE and the advantages of "L" regen to continue EV as long as possible. These rolling hills, bridges and overpasses allow me to take advantage of what I know about a low HV battery taking a quicker charge, how to take advantage of the ICE torque curve and how to use both generators while saving fuel.

On long hills where you climb for long distances, all you can do is take advantage of the torque curve by finding the lowest RPM with an acceptable speed on that curve and holding it as steady as possible. Anytime I see the RPM bouncing around, I'm wasting fuel. If anything, I try to reduce RPM every chance I get. Remember, every revolution of the ICE is filling 4 cylinders with fuel mixture, so you can see how important it is to maintain the lowest RPM possible. Also, the PCM can adjust much better when it's not told to constantly change load and RPM at the accelerator pedal. For this reason, I drive with my right shoe off for better control, and use CC on flat roads.

Think of the FEH/MMH as fine piece of equipment and operate it as a master artist would use a brush or his hands. If you just want to get in it and drive, don't expect it to give you the best mileage.

GaryG