How to best "glide" during pulse and glide

[James McGregory]

Hello,

 

Have a 2013 Fusion Titanium Hybrid, about 1500 miles. When I pulse and glide, I'm wondering whether I should apply maximum EV power during the glide phase, or just touch the pedal so that regen is inactive but the car is just coasting.

 

On my 37 mile commute from South Lyon, Michigan to Detroit, with the bulk occurring on I96-I696 at 70 mph, then pulse and glide down the M-10 ("the Lodge") from 62 to 50, I'm able to get about 47 mpg for the trip.

 

Great! But should I be using as much EV power as I can without triggering the gas engine during the glide as I can? Not clear on this. Thanks!

 

Sincerely - a fledgling hypermiler.

 

P.S. - OR, as I read around here more, is pulse and glide not as effective as just setting ECO cruise at 62 and letting it do it's thing? Is pulse and glide becoming disfavored with the newer hybrids? Thanks!

 

P.S.S. - Another question and didn't want to start new post if I don't have to - What is best? Fast acceleration to get up to speed, or "step on a tomato," slow acceleration? Any pros on here with objective experience on what is better? Thanks.

Edited June 19, 2013 by James McGregory

[neod192]

P.S.S. - Another question and didn't want to start new post if I don't have to - What is best? Fast acceleration to get up to speed, or "step on a tomato," slow acceleration? Any pros on here with objective experience on what is better? Thanks.

 

Hi, and welcome to the forum! I like to tap the gas pedal just enough to get out of EV mode, then accelerate slowly with constant pressure / power demand.

 

I tend not to pulse & glide, but get up to speed and keep the car in EV (if under 62) using EcoCruise. Over 62, I just set the EcoCruise at 65 and let the battery charge to 80-90%. Once it does that, I see 40-45 instant MPGs.

 

I drive mostly on I-94 around Ann Arbor and M-14 / US-275 and I-696 when I go visit my parents.

[acdii]

This is a hard one to answer mainly due to how people perceive pulse and glide.

 

Real P&G means you accelerate up to at the very least 5 over the speed limit. Once you reach that speed, you gently ease it into EV mode so you dont drop speed during the transition. It takes practice and a very light touch. Accelerating, some say steady aggressive works, some say gradual acceleration, so that all then depends, if you accelerate at 20 MPG for 90 seconds, or accelerate at 12 MPG for 30 seconds, which uses more fuel?

 

Once you get up to speed, the glide, depending on road conditions, you want to use as little battery during the glide as possible, and let the MPH drop as gradual as possible using the least amount of battery to do so. 60-45-60-45-60 is the idea. When done just right, you should be hitting 45 MPH when your battery is depleted enough for the ICE to kick on. This is called extreme Pulse and Glide and net results can be pretty high. Prius owners see 90 MPG doing it like this, but in reality, dangerous due to road rage when Bubba wants to run your butt off the road.

 

The other method is to try to maintain a steady speed using as little battery as possible, but this also causes more regen cycles, and doesnt return as good MPG as the above method does, but this is the one I prefer since Bubba isnt riding my buitt quite so close.

 

Another method is to just let the car decide. Ecocruise does this, but not as much as you the driver can do.

 

In the 2010-12 FFH, anything over 45 MPH was strictly on ICE, but applying similar techniques while on ICE returned very high numbers on the highway, I have seen as high as 65 on a trip, but the only one I can prove is 50 something on a 60+ mile trip. On the 10 when at speed you can feather the pedal in such a way as to get the instant over 40 and keep it there with a very gradual slowing, and a little pressure drops it to about 35 to accelerate back up to speed, and I consistently saw low to mid 40's driving like this, even in winter, depending on traffic and how far I drove. Long trips saw the best results, the short trips are what killed the overall winter miles.

[hybridbear]

Can someone explain the physics behind why P&G improves MPGs? I cannot comprehend the math behind it, and if I can't understand the math I don't believe it lol

 

Welcome to the Forum! I've found that a quicker acceleration up to speed is more efficient. Not extreme acceleration, but stepping on the gas hard enough that the power bar on the Empower screen is at about the 2nd line or maybe up halfway to the 3rd line

[lolder]

With pulse and glide, during acceleration, the ICE is loaded to a very efficient point. When you let up on the "go" pedal, the ICE stops and you use the speed ( kinetic ) energy as you coast down. Storage of kinetic and potential ( height ) energy is 100 % efficient so you regain all of it. If you carefully modulate the "go" pedal so that there is no energy into or out of the HVB while you do this, there will be little EV loss either. I can achieve 70+ mpg at 25-35 mph in a 2010 FFH this way. It's not worth the effort usually.

Edited June 20, 2013 by lolder

[hybridbear]

With pulse and glide, during acceleration, the ICE is loaded to a very efficient point. When you let up on the "go" pedal, the ICE stops and you use the speed ( kinetic ) energy as you coast down. Storage of kinetic and potential ( height ) energy is 100 % efficient so you regain all of it. If you carefully modulate the "go" pedal so that there is no energy into or out of the HVB while you do this, there will be little EV loss either. I can achieve 70+ mpg at 25-35 mph in a 2010 FFH this way. It's not worth the effort usually.

So during the glide portion you press the accelerator just enough to stop the car from charging but just slowing down due to friction. This can also be attained by shifting the car into Neutral, correct? I know that there are a host of other safety issues with shifting the car into Neutral at speed, I just want to understand the physics of the Pulse & Glide technique.

[lolder]

That's correct. Just modulate the pedal so there are no HVB charge or discharge indications. P & G originated before full hybrids. They turned the key off in neutral ( and lost AC, power steering, etc.) The eCVT hybrids kind of do it automatically except they charge the HVB slightly with the built in drag coasting with the ICE off. If you add a little pedal pressure, that will be minimized. You can also minimize the charge during ICE acceleration with modulation of the pedal. You then have true P & G. The ICE runs very efficiently in the acceleration and the kinetic energy storage has no loss. There is a lot of loss in the HVB energy storage. I wouldn't bother shifting to "N". That's really only there for design rules and car washes ( and it confuses the people there too ). Most of the P & G methods demand too much attention on the road and saves pennies in a full hybrid.

Edited June 21, 2013 by lolder

[acdii]

 

You can also minimize the charge during ICE acceleration with modulation of the pedal.

 

 

 

The one thing P&G in the Fusion and Cmax doesnt help with is the recharging, since this system relies heavily on the ICE propelling and charging at the same time. In the other Hybrids, Prius, TCH and 10-12FFH once above 45, there is no EV, and the charging system never puts a full charge in unless its doing a conditioning cycle, so above 45, the P&G is exactly like lolder said. This is why Interstate speeds need a full charge before you can start feathering to get the most MPG, and gliding above 65 doesn't work well, but if you can get the arrows to disappear when cruising, then it is in its "zone". There is no off switch for the recharge, the computer will send a charge to the pack no matter how much you try to regulate it. Nature of this new beast.

[lolder]

The full charge in the 2013 is probably not full because it will leave some headroom for a long, high speed regen stop but it's the point the system likes. Even there, the EV system is often tweaking the operation but so slightly it's difficult to observe. In my flat area of Florida, a lot of roads aren't crowned for drainage but graded in an undulating manner longitudinally. About every 200 yds. the road reaches a low point by a culvert that's about 1 1/2' lower than the high points. This is almost unnoticeable and most probably attribute it to poor construction but it is that way by design. In the 2010 FFH over 47 mph, the HVB charges and discharges on these tiny hills to keep the ICE power more constant. It's clear that at highway speeds ( 40- 60 and above ? ), the least EV action yields the best mileage.

[vangonebuy]

Getting a true P&G to set between charge and discharge for more than 2 seconds, Is not easy.

Computer wants to do something. Constant monitoring and Very slight adjusting of foot pressure is needed.

 

I haven't yet got a full charge in my battery. Ever.

So, I don't know how that will affect the results.

 

Great discussion..Thanks, for your knowledge.

[milleron]

Let's bump this topic back up.

 

What do you cognoscenti on this thread believe will be the ramifications of the new firmware upgrade on highway driving technique?? Lolder said "the least EV action yields the best mileage." If they allow EV mode to activate at speeds up to 85 mph (!?!?), it will make "EV action" unavoidable. What will that do to freeway efficiency???

[corncobs]

We all don't know what raising the threshold will do to the efficiency but I can't imagine that Ford would provide a software update which is targeted to improve interstate FE and doesn't deliver better results.

 

Even today you can avoid EV mode when traveling at 55 or 60 MPH you just can't use ECC. With a high SOC the EV threshold in the Empower screen sits just around the first white bar. As long you keep the ICE demand above the level it doesn't go into EV mode and the instant MPG are quite high.

 

We don't know what we don't know until the first FFHs are running the new software and we hopefully get some awesome feedback from forum members.

 

Maybe some of our honored members driving an Energi could provide us with some inside how the Energi behaves driving at higher speeds and how the EV modes kicks in and out.

Edited July 20, 2013 by corncobs

[lolder]

I don't think any software change will alter the fact that EV mode at cruising speeds is less efficient. If the higher speed lets the ICE shut off when you coast, that's OK. If it lets EV cycle on and off at higher steady speeds, that's not OK. If it reduces the coasting drag ( which is part of EV ), that's fine. Anything that reduces HVB charge or discharge at higher speeds is good. I don't expect much from this software update.

[jeff_h]

Maybe some of our honored members driving an Energi could provide us with some inside how the Energi behaves driving at higher speeds and how the EV modes kicks in and out.

 

It acts the same as the FFH does at 60 now... yesterday we took a trip down I-95 for 35 miles (where I had the CC set on 70), then 12 miles on rural road with speed limits of 45-55 and I set the CC right at those.... and it was over 90 degrees, so AC was on the entire time. Trip was 47 miles and 43.2 MPG, which was all on EV-later mode.

[hybridbear]

It acts the same as the FFH does at 60 now... yesterday we took a trip down I-95 for 35 miles (where I had the CC set on 70), then 12 miles on rural road with speed limits of 45-55 and I set the CC right at those.... and it was over 90 degrees, so AC was on the entire time. Trip was 47 miles and 43.2 MPG, which was all on EV-later mode.

How long does the Energi stay in EV at those higher speeds (i.e. 65+ MPH) once you're not going downhill? Does it deplete the battery so that you don't get ICE High mode?

[acdii]

It may provide more assist than actual drive at the higher speeds. Wont know until it is actually in a car though.

[majorleeslow]

Pulse and glide only works if your pulse part gets you to a decent SOC. otherwise you'll be pulsing through the glide portion. lol.

 

If someone shares the Kw and type of motors MG1 and 2 are, we can figure out some math.