Bluecivichybrid, NASA,

I think that both of your finds are very important. I will update the guide. Here is what I propose on acceleration:

When starting from a stop or when accelerating in general, do so swiftly. To maximize the use of the assist and to have good fuel efficiency, accelerate at 2000RPM.

For gliding / coasting:

If you are gliding / coasting and using assist, you are depleting your batteries. At some point, the car will decide that it needs to replenish the batteries and will engage regeneration on it's own. When the battery gauge goes below 5 bars, the car will aggressively replenish the batteries. This will have a negative impact on your fuel efficiency. If you are approaching 5 bars on your fuel gauge, it is better to let the car slowly replenish the battery using 1 bar of regeneration in your glide rather than waiting for it to force you to use 3 bars of regeneration.

As a rule of thumb, if you have:

7-8 bars of battery charge: during glide mode, use anywhere between 0-5 bars of assist. Don't worry about the battery drain: you have plenty of battery charge to use.

5-6 bars of charge: during glide mode, use between 1-3 bars of assist. You don't want to keep draining the battery too much anymore. 5 bars of charge is the optimum level you settle at - reaching a balance between assist and regen during pulse and glide intervals so that your battery remains steady at 5 bars. This is a good equilibrium point, I found, where forced regen is at most 1 bar that hardly affects your FE.

0-4 bars of charge: don't enter glide mode until you get at least 5 bars of charge back again. During this state, there will be 3 or more bars of forced regen that impacts your FE significantly. You're better off holding your speed or doing some slight driving with the load. (let speed decrease 5-10 mph uphill, let speed increase 5-10 mph downhill by holding your throttle steady)

What do you guys think?

Stephane.

 

I've been driving in the #3 lane. Most people use the #4 to enter and exit the freeway, #1 & #2 are usually for the speed demons.

 

Hi All,

slight update. Please let me know your comments.

Thanks,
Stephane.

 

I think I've gotten into EV mode a few times now, although I really don't know how to tell. The HCH-06 gets good mileage when I have no bars in either direction on the charge/assist meter, after accelerating gently from a coast at 100 MPG. When I try to get a little assist, however, the MPG meter drops considerably. If I keep it in the middle, then the MPG stays around 60-70 and up to 100 on flat and slightly sloped surfaces, and 50-ish on steeper hills. This is all at 55-65 mph or so, and can last for more than 10 miles on the highway.

I really don't know if this is EV mode, but it is keeping my FE at around 50 mpg so far on this tank (250 miles), which is better than my average. It would certainly be higher if my neighborhood streets weren't so hilly.

 

I love this driving technique thread and it has helped me accomplish wonderful mileage.

I was wondering why the methology for increasing speed for highway driving (using no bars of assist) differs from increasing speed for city driving (using 4 to 5 bars of assist)

Cheers!

 

You can tell when you are in EV mode when your instantaneous mileage is 0 km/L or 100 miles and you have 1-4 (white bars) of assist.

Basically your 1-4 bars of assist are giving your car some horsepower to allow momentum to carry without utilizing additional fuel.

Cheers!

 

Hi Jeff,

glad it helps! For the increasing speed for highway, I still need more data for this. There are two lines of thought on this:

- Use as much assist as you can to get up to speed (while making sure that you are not racing the engine)
- Use as little assist as possible as the more assist that you use, the more you'll have the regen kicking in (and lowering your fuel efficiency).

This is the part that is evolving. Any input on that specific part would be very interesting. I haven't done a lot of highway driving yet (I will during the holidays).

Thanks,
Stephane.

 

Hi David,

When your fuel consumption display is pegged at 100MPG you're in the zone! If you remove your feet from the gas completely, you will see 1-3 bars of regen (depending on your state of charge - battery). If you very gently press the gas pedal, you will gradualy remove regen lines until your are in a real glide (i.e. no breaking by the regen). This is what you are doing from what I read in your post.

From there, to get the electric engine to help you increase the length of your glide, VERY gently press the gas pedal a bit more (and I mean VERY gently, this is the real tricky part). Doing so, you will see the following:

- Fuel Consumption Display stays at 100MPG
- 1-4 bars of assist

Thanks,
Stephane.

 

We really need better terminology for the HCH-II because people have been using the term 'EV mode' to mean several different things. I like Stephane's term, Zero Fuel Glide (ZF-Glide for short?). Even in ZF-Glide, there are three different modes.

1- ZF-Glide with regen. This mode is very simple to get into, just take your foot off the gas! It might take a second or two, but you'll be able to tell that you're in ZF-Glide mode because the instant mileage gauge will be pegged at 100 MPG (which is true for all three ZF-Glide modes described here). Unless you have a completely full battery or you are going up a hill, you will also see some bars of regen (green). Because the electric motor is being used as a generator in this mode, it acts as a brake on the drivetrain and slows you down. The deceleration rate is the greatest in this mode of ZF-Glide.

2- ZF-Glide with NO regen or assist. This mode takes a bit more work than the first one. Once you get into mode 1, a small amount of pressure on the accelerator will eliminate the bars of regen. The farther you press the pedal, the fewer regen bars you will see. If you go too far, you will start to see some assist bars (white), which is mode 3 (below). You want to position the pedal so that you see no bars of green regen and no bars of white assist. In this mode, you will get the farthest glide distance possible without using the battery (we'll see why that's advantageous later). Use this mode if your battery is at 5 bars or less.

3- ZF-Glide with assist. Once you are in mode 2, pressing the pedal a bit further will give you a few bars of assist, but you have to be careful because if you go too far, you will drop out of ZF-Glide mode completely (you'll be able to tell because the instant mileage gauge will no longer be pegged at 100 MPG). There's a fine line between no assist and dropping out of ZF-Glide, so you have to be very gentle on the pedal. It takes some practice, but once you get the hang of it, it's pretty easy. The number of bars of assist you can get without dropping out of ZF-Glide depends on several factors, but 4 is about the practical limit. 5 is possible, but it takes a very steady foot and it usually doesn't last long. This is the only real 'EV mode' because it's the only mode where the electric motor is actually pushing the vehicle. The electric motor is only 20 HP, so it's not strong enough to accelerate the car alone, or even maintain a constant speed unless you are going very slow or down an incline, but it can considerably lengthen your gliding distance which can have a big impact on mileage.

So why not just use mode 3 all the time? Well, the electricity doesn't come for free, any power you take out of the battery has to be paid back with regen, and since the process is not 100% efficient, you have to pay back more in regen than you took out in assist (just like paying interest on a loan). The car is programmed to protect the charge level in the battery in order to lengthen its life, so if you let the battery level drop too low (about halfway), the car will force regen to bring the battery level back up. When this happens, it may be impossible to get into modes 2 or 3 as described above.

Bluecivichybrid posted some general rules of thumb that I'll paraphrase here.

1- If your battery level is 6 bars or more, use mode 3 as much as you want to extend your glides.

2- If your battery level is 4 or 5 bars, don't use mode 3. The forced regen that will result will wipe out any gains that you might get from using the electrical assist to extend your glide (and in fact you might end up with lower overall mileage than if you just stick to modes 1 & 2). At this point you want to look for regen opportunities as much as possible to get that battery level back up. You can mazimize regen in many cases by extending you braking distance. Instead of waiting until the last minute to brake when approaching a red light, start braking earlier. Use the regen gauge. If you see all 20 bars of regen, you may be wasting some of your kinetic energy (not using it for regen). Ideally, you would want to see just under 20 bars so you know you're not wasting any, but that's hard to do. Just take note of how much brake pressure you need to keep it just below 20 and stay in that neighborhood.

3- If your battery level is below 4 bars, you probably won't be able to even get into mode 2. Take advantage of every regen opportunity you can.

 

Nice thread.

A few comments:
1) Please fix the spelling of "brake." "Breaking" is either the practice of destroying things or a dance style popular in the 1980's. Cars and trucks have "brakes" which slow the vehicle down. Peace.

2) I'm not entirely convinced on this topic, but I'm open to discussing it (maybe covered elsewhere):

"If you are city driving, go ahead and use as much assist as you can (up to 4 or 5 bars). Whatever battery you are using in city driving, you will be able to refill it using breaking."

My intuition tells me that the most efficient way to drive the car is only using the internal comustion engine (ICE) with no electric boost. This is because power directly from the ICE to the wheels will be more efficient than power created by the ICE, converted to electricity (some loss), stored in the battery (some loss), retreived from the battery (some loss) and driving the electric motor (some loss). So, this would seem to argue that the best mileage would be obtained by avoiding "hitting the pack" (either charging or discharging the batteries) as much as possible. I think xcel recommended that in another thread; seems to make sense. Makes you drive like a slug ("slugging," as in ICE only, accelerating or driving slowly) and potentially subject to other drivers' road rage, but there you are.

However, the whole powertrain (ICE, electric motor, transmission) is a complex beast, so there may be offsetting reasons why maximizing assist in city acceleration makes more sense. For example, assist may kick in when the transmission is in a ratio range more suitable to the electric motor offsetting the losses by generating and using the electricity, etc. I don't know what the "round trip" losses are (round trip being ICE->electricity->battery->electric motor).

Then there is the discussion about using boost to make the green lights so you don't have to stop, etc. That seems like a really good use of the electricity that would make it advantageous over "slugging."

3) Would it be prudent to recommend using second gear / sports gear in stop and go traffic? It keeps the autostop from cycling the ICE on/off and drops the transmission ratios into a lower speed range that might be more efficient in stop and go traffic. The owner's manual recommends to use second in stop and go.