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Discussion Starter · #1 · (Edited)
In my experience with an Hybrid car the driving change, we become a little bit "virtuos" :) .
Talking with colleagues and friends that using Toyota hybrid engine for years, they told me the "sailing" driving techniques (I've translate from Italian to english the word "veleggio" commonly used in Italian to explain this techniques).
In simple word, always progressively speeds up and when you get the speed you need/want, release the throttle and just push a little bit; the car keep the speed in EV mode until there is a sufficient battery.
I've try with CR-V, the hybrid serie engine here it's different compared to Toyota, but I've try and it's working, after a straight of 3Km at 110Km/h I've release the throttle and then I pushed a little bit again and I keep about 3Km of straight at 92Km/h in EV mode only!
At the end of the straight, before the STOP, I used the left paddle first and then the brakes and I've recharge 2 battery notch.
I've reset the odometer before this test and computer sign 4.3L/100Km, I retraced the same straight keeping the throttle costantly at about 92km/h and at the end the computer sign 5L/100Km.
Anyway is useful in a short distances, in the Freeway isn't applicable, after 2-3Km the thermal engine coming to recharge the battery.
 

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Talking with colleagues and friends that using Toyota hybrid engine for years, they told me the "sailing" driving techniques (I've translate from Italian to english the word "veleggio" commonly used in Italian to explain this techniques).
In simple word, always progressively speeds up and when you get the speed you need/want, release the throttle and just push a little bit; the car keep the speed in EV mode until there is a sufficient battery.
In English, this is called "pulse and glide." Toyotas need to do it. Hondas shouldn't.

The engine in the Camry or RAV4 hybrid is at its most efficient, 40% to be precise, at about 2600 RPM and 59 horsepower. Unfortunately, when you are cruising on flat ground at your desired highway speed, depending on what speed that is, you only need about 15 to 20 horsepower.

If this engine were not in a hybrid, you would have only two choices about how to deal with that:
  1. Run the engine continuously at, say, 30% efficiency.
  2. Alternate between accelerating at 40% efficiency, and coasting while using no gas/petrol.
You would use more gas in the "pulse" part than you need to, but if you spend less than 75% of the time in that pulse phase, you use less gas overall.

A hybrid should be able to do this without accelerating. It can accomplish the same thing by charging the battery in the "pulse" phase instead of accelerating, and then using EV mode instead of the "glide" phase. Unfortunately, the Toyota hybrids face three difficulties. The engine is too big to do this perfectly, it has additional losses in the process where it charges the battery at these speeds, and it has difficulty doing EV mode while maintaining highway speeds. So you have to help it along by using both methods.

The engine in the Accord or CR-V hybrid is smaller. Its most efficient point, 40.8%, is at 2000 rpm and about 34 horsepower. It has no difficulty at constant highway speeds alternating between Engine Drive with Charge, and EV drive. Without changing the throttle.

You should try your test again, making sure that (A) the car is warmed up the same amount both times and (B) the State of Charge (SoC) is the same at the start and end both times. Part (B) can be hard to do, but it is necessary for a valid comparison.
 
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The honda is completly different to the toyota
I have stopped looking how much charge is in the battery
because the hybrid does the job so well I just enjoy driving it
 

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Discussion Starter · #4 ·
In English, this is called "pulse and glide." Toyotas need to do it. Hondas shouldn't.

The engine in the Camry or RAV4 hybrid is at its most efficient, 40% to be precise, at about 2600 RPM and 59 horsepower. Unfortunately, when you are cruising on flat ground at your desired highway speed, depending on what speed that is, you only need about 15 to 20 horsepower.

If this engine were not in a hybrid, you would have only two choices about how to deal with that:
  1. Run the engine continuously at, say, 30% efficiency.
  2. Alternate between accelerating at 40% efficiency, and coasting while using no gas/petrol.
You would use more gas in the "pulse" part than you need to, but if you spend less than 75% of the time in that pulse phase, you use less gas overall.

A hybrid should be able to do this without accelerating. It can accomplish the same thing by charging the battery in the "pulse" phase instead of accelerating, and then using EV mode instead of the "glide" phase. Unfortunately, the Toyota hybrids face three difficulties. The engine is too big to do this perfectly, it has additional losses in the process where it charges the battery at these speeds, and it has difficulty doing EV mode while maintaining highway speeds. So you have to help it along by using both methods.

The engine in the Accord or CR-V hybrid is smaller. Its most efficient point, 40.8%, is at 2000 rpm and about 34 horsepower. It has no difficulty at constant highway speeds alternating between Engine Drive with Charge, and EV drive. Without changing the throttle.

You should try your test again, making sure that (A) the car is warmed up the same amount both times and (B) the State of Charge (SoC) is the same at the start and end both times. Part (B) can be hard to do, but it is necessary for a valid comparison.
Hi Jeff, thank you for the detailed explanation, are you an Honda or Toyota engineer!?
Anyway the new Toyota RAV4 it's more efficient overall, the gas consumption it's less then CR-V, also probably thanks to large battery.
In my opinion CR-V it's more fun and smooth (thanks to e-cvt) to drive compared to RAV4

I agree with your test examination, probably the step B wasn't equal, it's difficult to be precise without a SoC percentage.
MAke another test will be impossible for me with this hard Italian lockdown!!
 

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Hi Jeff, thank you for the detailed explanation, are you an Honda or Toyota engineer!?
Engineer, yes. Automotive engineer, no. But I was appalled at how much misinformation exists about them when I bought my Accord Hybrid 18 months ago, so I looked for (and found) a lot of technical papers on the system.

Anyway the new Toyota RAV4 it's more efficient overall, the gas consumption it's less then CR-V, also probably thanks to large battery.
The size of the battery has little to do with it. It acts as a buffer only - much like a water tank on a hi-rise building. You fill the tank overnight, so that during the day you have access to more flow than the water system can provide alone. But it isn't "free" water during the day.

But I'm not convinced that the difference is that much. At 12,000 miles a year, a typical number in this country, the rating accounts for less than 16 gallons.
 

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Discussion Starter · #7 ·
Engineer, yes. Automotive engineer, no. But I was appalled at how much misinformation exists about them when I bought my Accord Hybrid 18 months ago, so I looked for (and found) a lot of technical papers on the system.
The last Accord it's a very beatiful car, I don't understand why in Italy wasn't sell since '90, may be because the people preferer a station wagon and SUV.

The size of the battery has little to do with it. It acts as a buffer only - much like a water tank on a hi-rise building. You fill the tank overnight, so that during the day you have access to more flow than the water system can provide alone. But it isn't "free" water during the day.
The battery/buffer it's charge by brake and deceleration, during city trips, the ideal field of the hybrid (many stops, lamps, restarts) you can charge and use this extra battery ; in my opinion has a significant amount of influence. Otherwyse why Toyota increase the battery ? It's a very expensive and heavy part.

But I'm not convinced that the difference is that much. At 12,000 miles a year, a typical number in this country, the rating accounts for less than 16 gallons.
I agree, but is subjective, myne is 8000 miles a year, here 16 gallons it's 88€ (96$) isn't a great difference (here the average salary it's half compared to US), but double or triple year miles some peoples can think different.
 

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The battery/buffer it's charge by brake and deceleration, during city trips, the ideal field of the hybrid (many stops, lamps, restarts) you can charge and use this extra battery
Even in city driving, most of the charge that goes into the battery comes from the engine+generator, not regenerative braking. And any that does come from regen, except long downhill runs, gets used accelerating back up to speed.

Watch the charge level gauge and the Power Flow Meter. Depending one which mode (ECON/NORMAL/SPORT) you are in, the car will try to keep the charge level within about 1/4 of the total range. In ECON, it's 30% to 50%. When it goes above that range, it will use EV mode to drain it. When it gets below, it will run the engine to charge the battery.

Otherwise why Toyota increase the battery ? It's a very expensive and heavy part.
In what? I'm not aware of an increase, but the RV4 could need it to make sure it can use AWD when needed; the CR-V uses a mechanical connection, so that is not a problem.
 

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Discussion Starter · #9 ·
  • Even in city driving, most of the charge that goes into the battery comes from the engine+generator, not regenerative braking. And any that does come from regen, except long downhill runs, gets used accelerating back up to speed.

    Watch the charge level gauge and the Power Flow Meter. Depending one which mode (ECON/NORMAL/SPORT) you are in, the car will try to keep the charge level within about 1/4 of the total range. In ECON, it's 30% to 50%. When it goes above that range, it will use EV mode to drain it. When it gets below, it will run the engine to charge the battery.
I agree in part, the most charge come from engine+generator (about 60-70%?), but In city driving brake recharge it’s important and EV it’s always use for restarts.

In what? I'm not aware of an increase, but the RV4 could need it to make sure it can use AWD when needed; the CR-V uses a mechanical connection, so that is not a problem.
Many RAV4 Italian reviews claim an increase battery compare to the previous gen, but as you teach, I’ve search official docs and I’ve found Old RAV4 and the New RAV4 specs in Toyota Italy website.Again, you right, the battery is the same 4.22kwh vs CR-V 1.6kwh. I haven’t found official docs of Honda, can you share your source/link?
Probably with AWD and two Electric engine need more battery, but it’s the same capacity as the FWD.
Anyway, the result is less consumption.
Toyota sells millions of HEV during over 20 years , they believe and improve the system more than any other.
My choice was an Honda (almost a bet in hybrid) for the driving pleasure, superior internal, external design and price.IMO
 

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I agree in part, the most charge come from engine+generator (about 60-70%?), but In city driving brake recharge it’s important and EV it’s always use for restarts.
The point is that a hybrid needs to have usable charge in the battery in order to operate. But it can't anticipate a braking event will occur to charge them, and can't use the energy it gets from one to return to the same state it was in before a braking event started. So it has to be designed to rely on engine+generator.

Many RAV4 Italian reviews claim an increase battery compare to the previous gen, but as you teach, I’ve search official docs and I’ve found Old RAV4 and the New RAV4 specs in Toyota Italy website.Again, you right, the battery is the same 4.22kwh vs CR-V 1.6kwh.
All the reviews I've seen, that mention it, say the latest generation RAV4 has the same 1.6 kWh nickel battery that the Camry uses in its higher trims. It is in the 2019 RAV4 (The 2019 Toyota RAV4 Hybrid Is the RAV4 to Have). I have seen at least one review that says it is still 1.6 kWh in 2020; but since there is very little change, there are few mentions of the actual specs.

And the CR-V has 1.3 or 1.4 kWh in what I have seen.

Again, since all of the energy put into the battery has to come from gas/petrol (regen brakes recovers energy from gas), the size of the battery can't directly affect mileage. The increased weight (the battery you suggest weighs about 50 kg/110 lbs more) can decrease it a little, and increased power from the battery makes it more flexible an might increase it a little, but neither is worth the extra cost and weight.

I haven’t found official docs of Honda, can you share your source/link?
Development of 2.0 L Engine for New Accord Hybrid is a starting point.
 

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In English, this is called "pulse and glide." Toyotas need to do it. Hondas shouldn't.

The engine in the Camry or RAV4 hybrid is at its most efficient, 40% to be precise, at about 2600 RPM and 59 horsepower. Unfortunately, when you are cruising on flat ground at your desired highway speed, depending on what speed that is, you only need about 15 to 20 horsepower.

If this engine were not in a hybrid, you would have only two choices about how to deal with that:
  1. Run the engine continuously at, say, 30% efficiency.
  2. Alternate between accelerating at 40% efficiency, and coasting while using no gas/petrol.
You would use more gas in the "pulse" part than you need to, but if you spend less than 75% of the time in that pulse phase, you use less gas overall.

A hybrid should be able to do this without accelerating. It can accomplish the same thing by charging the battery in the "pulse" phase instead of accelerating, and then using EV mode instead of the "glide" phase. Unfortunately, the Toyota hybrids face three difficulties. The engine is too big to do this perfectly, it has additional losses in the process where it charges the battery at these speeds, and it has difficulty doing EV mode while maintaining highway speeds. So you have to help it along by using both methods.

The engine in the Accord or CR-V hybrid is smaller. Its most efficient point, 40.8%, is at 2000 rpm and about 34 horsepower. It has no difficulty at constant highway speeds alternating between Engine Drive with Charge, and EV drive. Without changing the throttle.

You should try your test again, making sure that (A) the car is warmed up the same amount both times and (B) the State of Charge (SoC) is the same at the start and end both times. Part (B) can be hard to do, but it is necessary for a valid comparison.
I can’t find any bte or bsfc charts. Where did you find the stated maximum efficiency of 40.8% at 2,000 rpm’s stat for this honda engine?
 

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I can’t find any bte or bsfc charts. Where did you find the stated maximum efficiency of 40.8% at 2,000 rpm’s stat for this honda engine?
That link I just gave to Cipo80. I added the MPH axis, for the Accord; the CR-V has about 10% larger tires. The test of the article says 208.1 g/kWh is 40.8% efficient.
138260
 

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Jeff, why didn’t you buy the CRV hybrid like the Accord?
Because I bought my CR-V 3 years before the hybrid came out?
 

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Discussion Starter · #19 ·
It’s a good average, mine after 3000 miles is 42.7mpg, only highway really increase the consumption. In my home-work trip I’m at 50mpg.
 
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