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Discussion Starter #1 (Edited)
Now that the the weather has started to warm and I know that the van won’t be wasting away juice just to keep the batteries warm, I’ve been experimenting with just how high I can get the MPG(e). For driving around town at speeds no greater than 40 mph I seem to have found a method which allows me to squeeze even more miles out of a full charge. Here’s what I have tried: from a stop I get up to speed fairly quickly then immediately let up on the throttle. As soon as I let up on the throttle I switch the ‘transmission’ to ‘N’. This allows the van to actually coast further than if I had left it in ‘D’. I allow the van to coast until I’m around 5-7 mph under the speed limit. Then, I put the van back in ‘D’ again and give it some throttle to get up around the speed limit. Again, once I let off the throttle I also switch to ‘N’. The only time I put it back to ‘D’ is if I need to accelerate or if I need to slow down/stop and I can use the regenerative braking to help.

Today, on a 15 mile round-trip I was able to average abou 96 MPGe for the trip. My battery went from 100% down to 70%. Now it could be that my battery gauge is not that linear and the battery will drain faster as the percentage drops. Hard to say for sure. But it’s the first time I’ve been able to keep the MPGs above 90 for that many miles.

My theory is that the regenerative braking (which really occurs anytime you let off the gas) is really only beneficial when you are going to stop fairly imminently. At any other time it’s better to actually let the van coast. Anyone have any comments on this or have you had similar results?

Additional info added later this evening: After dinner I decided to just take the van out for a spin just to do some more experimenting. I put about 10-11 more miles on it for a total of about 26 miles for the day. The MPGe average for the entire day is pegged at 99.9 and my battery is down to 40%. Probably could get at least another 16-17 miles out of it before hitting 0%.
 

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You're right, it is better to coast. Regen and acceleration is a lossy process. Based on my experience, under the ideal conditions- steady moderate speed, flat terrain and mild temperature, it is entirely possible to exceed 40 miles by a good margin.
 

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Discussion Starter #4 (Edited)
¯\_(ツ)_/¯
I appreciate that reminder. I’m pretty sure the danger to the transmission of allowing the car to coast in neutral has to do with the way the bearings are lubricated. Most automatic transmissions pump the transmission fluid but only if the input shaft is rotating. So when you coast there is a danger that the bearings could become starved because the pump stops pumping. That is why most manufacturers do not recommend towing an automatic transmission car on the driven wheels for more than a few miles. I’ll have to do a little more research on this particularly as it relates to the PacHy transmission.

My initial thought is that it won’t be a problem due to the short distances and time periods I’m coasting (probably less than 1/10 of a mile for maybe 15 seconds at most). But I will definitely do some more research on it. So officially, I don’t recommend anyone do this. It’s just an experimental thing.

Just thinking about it a bit, I assume that if you are able to expertly ‘feather’ the throttle so could possibly get the same effect without actually switching to ‘N’. The goal would be to get the charge/drain gauge to read zero during the ‘coasting’ periods.
 

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Oh, I missed that part. Switching the Hybrid transmission to N doesn't change its drag or any other mechanical properties.You can reach the same effect by carefully modulating the gas pedal.
The same applies to the L mode. It is the same as a light braking.
 

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This sort of thing is more commonly known as "Pulse and Glide". It became popular with the Prius, particularly when the well-packaged second generation version came on the US scene in 2004 and Prius owners went apey trying to outdo each other in the quest for the highest fuel mileage.

While it is an effective technique, it takes effort. What's worse is how it affects surrounding traffic. For other drivers operating their vehicles in a normal manner (particularly in crowded urban environments), it's aggravating, if not downright dangerous and almost certainly contributed to the ire Prius drivers used to garner.

I'd just be happy with the perfectly adequate mileage achieved by normal, careful driving.
 

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Discussion Starter #9
Oh, I missed that part. Switching the Hybrid transmission to N doesn't change its drag or any other mechanical properties.You can reach the same effect by carefully modulating the gas pedal.
The same applies to the L mode. It is the same as a light braking.
Yeah, you would assume that modulating the gas pedal would have the same effect but it takes considerably more concentration. Also, just thinking about it some more would raise this question: if there is concern about damage to the transmission by coasting in neutral, might you also be concerned about modulating the gas pedel such that there is neither a charge or drain upon the battery? Does anyone know what the actual mechanism is in the PacHy that causes transmission fluid to be circulated?

I have a gut feeling that the warning in the owner’s manual is simply a holdover from the gas Pacifica for the most part. “This sounds good and partially applies so let’s just throw it in there for good measure.” I could be wrong on this but it would be nice to have an accurate understanding of how the transmission works. There was a link posted here somewhere to a very informative tear down video that enlightened me quite a bit on how the transmission works. It’s worth watching again.
 

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Discussion Starter #13 (Edited)
Simplicity. A hybrid drive/ transmission has maybe 10 major parts. Also electric motors don't drag the drivetrain nearly as much as the ICE, uncoupling them would save very little. You're not damaging anything by coasting in N, but the savings are minimal.
Ok, I believe you when you say that you’re not damaging anything by coasting in N. But I have to take issue with your belief that the savings are minimal. In a gas car, if you could do something that would improve your gas mileage by, say 5 mpg, would you try it? Sure. From what I can see, this technique improves my MPGe by at least 10. Now it’s true that I could probably achieve the same thing by feathering the throttle correctly but that’s difficult to do.

What you want to do is every time you’re driving the car and you ease off the gas you want your charge meter to remain neutral. You don’t want to show regenerative charging every time you ease off the throttle. Even though it sounds good, regenerative braking is less efficient at recouping energy than simply allowing the van to coast and use up that energy in moving the car forward. I believe that the regenerative effect while in ‘D’ is solely to make the vehicle ‘feel’ like an ordinary gas engine vehicle. In a gas engine when you ease off of the throttle there is a little bit of drag caused by the engine that you would not have if you had shifted the car into neutral. The regenerative braking is really only helpful when you *must* brake. It is not helpful when you’re easing off the pedal merely because you’ve reached your desired cruising speed.

Think of it in more practical terms. You’re starting off from a stop. You accelerate the vehicle to get it up to the speed limit. You notice that you have now reached the speed limit so you ease off the throttle because you know that’s how to maintain the speed limit without going over. However, because you can only imperfectly control your car, you ease up just a little too much. Now, not only are you not supplying enough energy to the wheels to maintain your speed, but you’re also experiencing some mild regenerative braking. Look at your charge meter. It’s showing a small charge on the battery. You are somewhat inefficiently putting some of the energy you used to accelerate back into the battery. This is all fine and dandy when you are coming up to a stop light and you *must stop*. But, in normal cruising it doesn’t help. The extra energy is more well spent in allowing the car to ‘coast’ forward than it is to recharge the battery.

My opinion is that the *only* reason a hybrid applies regeneration while the car is in ‘D’ is that it just feels right and most people would freak out a little bit if they lifted their foot off the accelerator and the car just seemed to coast instead of having some drag to slow it down. Chrysler could have designed the car to effectively ‘coast’ when you lift your foot off the gas but they instead chose to engage a small amount of regenerative braking so that the car ‘feels’ normal. But I say you can increase your energy economy by probably 10% if you use this method. It doesn’t even need to be ‘pulse and glide’ per se. It just needs to be no regenerative action while cruising. Only apply the regeneration when the brakes are applied or the selector is in ‘L’.

Added thought: as an imperfect human contolling the speed of the car (as opposed to a machine or electronic system that can do it more precisely), when we drive our cars we are constantly tweaking the throttle. If the speed limit is 30 we accelerate to 30.5 then lift our foot off the gas and decelerate to 29.5. It’s a constant effort. No one can perfectly control the speed especially with driving up and down inclines etc. All I am saying is that when we imperfectly decelerate a tiny little bit too much, instead of the car giving that energy back to the battery it should give the energy to the wheels.
 

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Discussion Starter #14 (Edited)
Simplicity. A hybrid drive/ transmission has maybe 10 major parts. Also electric motors don't drag the drivetrain nearly as much as the ICE, uncoupling them would save very little. You're not damaging anything by coasting in N, but the savings are minimal.
And in actuality, putting the selector in ‘N’ doesn’t really decouple the engine or motors from the wheels it merely shuts off drive to the motors and shuts off the regenerative effect. If only we could have a position on the selector named ‘DE’ for ‘Drive more Efficiently’ that would shut off the regenerative effect but not shut off the drive to the motors.
 

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The first few months we had ours I did the same N trick to maximize electric distance. Once I learned it goes against whats in the manual I stopped. Another argument against coasting in N is the fact that the regenerative breaking does not activate at all when in N. So if you forget or dont have time to shift back to D or L when you need to stop, you are relying only on the break pads, you do not have the additional stopping power of either the engine or the regenerative breaking system. If you forget this for even one stop, the regen you lost would cost far more than the savings of coasting in N.
 

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And in actuality, putting the selector in ‘N’ doesn’t really decouple the engine or motors from the wheels it merely shuts off drive to the motors and shuts off the regenerative effect. If only we could have a position on the selector named ‘DE’ for ‘Drive more Efficiently’ that would shut off the regenerative effect but not shut off the drive to the motors.
PacDave, I agree with everything you wrote in this and previous post, except that I don't think that the coasting will result in a measurable energy economy. Most of the time a vehicle needs an energy to maintain its speed. And coasting in a normal traffic isn't really possible.
 

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Discussion Starter #17 (Edited)
PacDave, I agree with everything you wrote in this and previous post, except that I don't think that the coasting will result in a measurable energy economy. Most of the time a vehicle needs an energy to maintain its speed. And coasting in a normal traffic isn't really possible.
I will keep experimenting with this and make an update on it. And I’ll try to be objective if I’ve had an error in judgement. Maybe some others will do similar experiments and report their findings.

Also, for anyone who’s interested, I found this article on Wikipedia (scroll down to “pulse and glide”):
https://en.m.wikipedia.org/wiki/Energy-efficient_driving#Pulse_and_glide

Not that I’m saying that everything you read on Wikipedia should be believed but I do see some valid points made there.
 

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The Wiki article is correct when applied to the traditional ICE vehicles. Pachy actually works even better- when driving in the Hybrid mode it stops the ICE every time you let go of the gas pedal and tries to drive on electric a little bit under light loads.
 

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Discussion Starter #19
The Wiki article is correct when applied to the traditional ICE vehicles. Pachy actually works even better- when driving in the Hybrid mode it stops the ICE every time you let go of the gas pedal and tries to drive on electric a little bit under light loads.
Here’s an article on electric motor efficiency:

https://physics.stackexchange.com/questions/46113/why-is-an-electric-motor-more-efficient-at-higher-loads

This is just one article and it’s a generalization but most other references I found also show that electric motors are less efficient at lower loads (pretty much like gasoline engines).
 
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