Chevron's vanishing act...

coutinpe

coutinpe

Active Member
Folks: After reading on some electric car forum that you could maximize EV range and save brake pads by keeping max regen at all times thus doing "single pedal" drive, I tried to do that on my '18 Clarity PHEV. I was aware that except for SPORT mode the chevrons would disappear when stopping, and only used regen when driving long down slopes or when arriving to a red light with enough time, but when trying to keep regen always on 3 chevrons I noticed that they vanished in a few seconds after setup. I tried switching off ECON mode but no dice. They would only stay on in SPORT. I finally noticed that just accelerating a bit over the first mark on the tachometer was the trigger for the chevron vanishing. They only remain when coasting until stopping. Is that normal functioning? Thanks.
 
coutinpe said:
After reading on some electric car forum that you could maximize EV range and save brake pads by keeping max regen at all times thus doing "single pedal" drive
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I'm not sure that it's been proven that using the paddles is that much more efficient than using the brake pedal. From what we can observe by watching the power meter on the instrument panel, the brake pedal seems to use a comparable amount of regen as using the paddles. As far as we know when using the brake pedal only a small amount of friction brake is blended in for smoothness.

But for people who want to get maximum efficiency and are willing to adapt their driving style even for small gains, using the paddles is the way to go. I would put it in the same category as using energy efficient tires even when other types of tires might be more desirable in terms of handling, tire wear etc. And driving at a slower speed than you normally would to maximize efficiency. And also doing slow acceleration from stops. What I like about hybrids and the Clarity in particular is that you can do all of those things if you want to get maximum efficiency, but you can also drive the car the way you want to and still get really great efficiency.
 
The Clarity rarely uses the friction brakes to decelerate. Any difference in the total amount of recaptured energy between paddle and brake pedal usage is going to be negligible.

Yes, the regen chevrons will only maintain user settings while in Sport Mode. Default in other modes is the single, invisible chevron, upon acceleration.
 
Using the paddle plus the brakes results in significantly more regen than using either by itself. Just watch the power/charge indicator to see for yourself.
 
I found single pedal driving using Sport to be quite annoying and tiring for my right foot. I gave up on Sport and now use the paddles most of the time because they give a very smooth speed reduction. Pushing the brake pedal works too but I find its not as easy most of the time. Of course you always have to use the pedal at the end to come to a full stop.
 
coutinpe said:
Folks: After reading on some electric car forum that you could maximize EV range and save brake pads by keeping max regen at all times thus doing "single pedal" drive, I tried to do that on my '18 Clarity PHEV. I was aware that except for SPORT mode the chevrons would disappear when stopping, and only used regen when driving long down slopes or when arriving to a red light with enough time, but when trying to keep regen always on 3 chevrons I noticed that they vanished in a few seconds after setup. I tried switching off ECON mode but no dice. They would only stay on in SPORT. I finally noticed that just accelerating a bit over the first mark on the tachometer was the trigger for the chevron vanishing. They only remain when coasting until stopping. Is that normal functioning? Thanks.
Click to expand...
I think this is a common fallacy that raising the regen level on a car maximizes range and/or saves brake pads. Regen does put energy back into the battery, but it's not as efficient as coasting as much as possible. Any good EV will not use brake pads much at all when regen capability is available. My Hyundai Ioniq Electric allows the user to choose 4 different levels of regen from 0 (no regen) to 3 (maximum regen). It gives you complete control. That car is also extremely aerodynamic, so it's coasting ability is amazing. When I really want maximum range, I will set it to 0 and coast as much as possible. The 3 levels of regen in the Clarity are not very different from each other. I would say it's equivalent to levels 1 and 2 in the Ioniq.

The goal of efficient driving on a car with regen capability should not be to maximize regen, instead it should be to minimize accelerator use. If you have a situation where the car regens hard, but then you have to use the accelerator harder after that, you've wasted electricity.

So, in my Clarity, I never try to change the regen levels, and never use the paddles. Using the brakes will give me the same amount of regen. In the Ioniq, I mostly just use the defualt regen level of 1. If I think about it, and want to be slightly more efficient, I will occasionally set it to no regen. The only time I ever use 2 or 3 is if I'm in stop and go traffic and I want to not move my foot to and from the accelerator and brake as much.

Everyone is different in their thinking with these cars. The people that frequent forums like this are generally more geeky and like thinking this all out and actively think about these things while driving. The vast majority of drivers though (me included), don't want to think so much about it when driving. Don't get me wrong, I occasionally geek out and try to get an extremely efficient trip in the Ioniq. That car provides you with a lot of consumption information like miles/kwh. Once in a while, I'll try to do a certain trip and get it above 5 miles/kwh:)
 
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Mark W said:
Regen does put energy back into the battery, but it's not as efficient as coasting as much as possible. Any good EV will not use brake pads much at all when regen capability is available. My Hyundai Ioniq Electric allows the user to choose 4 different levels of regen from 0 (no regen) to 3 (maximum regen). It gives you complete control. That car is also extremely aerodynamic, so it's coasting ability is amazing. When I really want maximum range, I will set it to 0 and coast as much as possible. The 3 levels of regen in the Clarity are not very different from each other.
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Excellent post. I would add that the Clarity has 4 regen levels. There is a default level and 3 additional levels. Zero regen is possible, if one chooses to shift to neutral on the fly or by delicately operating the accelerator to keep the power needle in the neutral position.

I would find either of those methods supremely annoying. So, I just live with what Honda provided. Having a driver selectable zero regen option would have been a nice feature.
 
Mark W said:
I think this is a common fallacy that raising the regen level on a car maximizes range and/or saves brake pads
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Yes, I agree with you... I think there are some misconceptions with the Clarity and the paddles too.

Some believe that the paddles magically prevent the use of the friction brakes. In my experience, the brake pedal prevents the use of the friction brakes just as well as the paddles do (maybe better)... The brake pedal exerts just as much (or more) regeneration as the paddles do. The friction brakes generally only are applied for an emergency panic stop (which is rare), or at the very end of the stopping process to come to a full stop. Whether you are using the paddles or not, the friction brakes are always used to complete the stopping process. The regeneration by either means does reduce wear an tear on the brake pads / rotors as it does with any EV.
 
Mark W said:
I think this is a common fallacy that raising the regen level on a car maximizes range and/or saves brake pads. Regen does put energy back into the battery, but it's not as efficient as coasting as much as possible. Any good EV will not use brake pads much at all when regen capability is available. My Hyundai Ioniq Electric allows the user to choose 4 different levels of regen from 0 (no regen) to 3 (maximum regen). It gives you complete control. That car is also extremely aerodynamic, so it's coasting ability is amazing. When I really want maximum range, I will set it to 0 and coast as much as possible. The 3 levels of regen in the Clarity are not very different from each other. I would say it's equivalent to levels 1 and 2 in the Ioniq.

The goal of efficient driving on a car with regen capability should not be to maximize regen, instead it should be to minimize accelerator use. If you have a situation where the car regens hard, but then you have to use the accelerator harder after that, you've wasted electricity.

So, in my Clarity, I never try to change the regen levels, and never use the paddles. Using the brakes will give me the same amount of regen. In the Ioniq, I mostly just use the defualt regen level of 1. If I think about it, and want to be slightly more efficient, I will occasionally set it to no regen. The only time I ever use 2 or 3 is if I'm in stop and go traffic and I want to not move my foot to and from the accelerator and brake as much.

Everyone is different in their thinking with these cars. The people that frequent forums like this are generally more geeky and like thinking this all out and actively think about these things while driving. The vast majority of drivers though (me included), don't want to think so much about it when driving. Don't get me wrong, I occasionally geek out and try to get an extremely efficient trip in the Ioniq. That car provides you with a lot of consumption information like miles/kwh. Once in a while, I'll try to do a certain trip and get it above 5 miles/kwh:)
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A related misconception that I have heard more than once is that driving in stop and go traffic is more efficient than driving at steady speed in light traffic because of regen. When in reality it's simply the lower average speed when you are in traffic. Doesn't help a gas car as the friction brakes waste the energy that is otherwise saved. But since regen doesn't waste very much energy then you get nearly the full benefit of the slower speed.
 
Frankwell said:
A related misconception that I have heard more than once is that driving in stop and go traffic is more efficient than driving at steady speed in light traffic because of regen. When in reality it's simply the lower average speed when you are in traffic. Doesn't help a gas car as the friction brakes waste the energy that is otherwise saved. But since regen doesn't waste very much energy then you get nearly the full benefit of the slower speed.
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I don't think its just the lower average speed. Its also that the car is coasting or near-coasting some of the time and that averages out to higher efficiency than steady speed.
 
David Towle said:
I don't think its just the lower average speed. Its also that the car is coasting or near-coasting some of the time and that averages out to higher efficiency than steady speed.
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That would be the pulse and glide effect, which used to be especially popular among hypermilers in the early Prius days. It requires coasting in neutral for maximum effect, although coasting with regen would probably still have some benefit just not as much. The efficiency comes not so much from the coasting, but because most gas engines are more efficient during acceleration, so in the pulse glide method you accelerate fairly quickly at the most efficient power level for your gas engine (if you are able to determine what that is). This efficiently builds up kinetic energy, which you can then use in the coasting phase. Ideally with the engine shut off during coasting, which is why it works well with hybrids that shut off the engine during coasting. I don't think it would help in EV mode though since you wouldn't get an efficiency gain during acceleration.

Also it seems like there is usually not a lot of coasting possible in many stop and go situations, depending on what traffic is doing. Unless you can see far enough past the car in front of you and with some diligence be able to anticipate ahead of time when they will be slowing so that you can begin coasting before they step on their brakes. And then ideally when they start speeding up you would remain at slow speed to let them get ahead, so that you could then quickly accelerate. Although whoever is behind you might get somewhat annoyed when you don't start moving right away.
 
Frankwell said:
That would be the pulse and glide effect, which used to be especially popular among hypermilers in the early Prius days. It requires coasting in neutral for maximum effect, although coasting with regen would probably still have some benefit just not as much. The efficiency comes not so much from the coasting, but because most gas engines are more efficient during acceleration, so in the pulse glide method you accelerate fairly quickly at the most efficient power level for your gas engine (if you are able to determine what that is). This efficiently builds up kinetic energy, which you can then use in the coasting phase. Ideally with the engine shut off during coasting, which is why it works well with hybrids that shut off the engine during coasting. I don't think it would help in EV mode though since you wouldn't get an efficiency gain during acceleration.
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It does work with electric motors on our cars also. I estimate it bumps my range per charge by about 5 miles, typically from 65 to 70. In both drive and regen there is maybe 90% efficiency for the motor, you avoid that loss holding the needle at zero or switching to neutral.
 
David Towle said:
It does work with electric motors on our cars also. I estimate it bumps my range per charge by about 5 miles, typically from 65 to 70. In both drive and regen there is maybe 90% efficiency for the motor, you avoid that loss holding the needle at zero or switching to neutral.
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Pulse glide is well documented as working on hybrids but I can't find anything on it working on EV's. I wonder if in your case when you have tried it you had a lower average speed for the trip and that's what caused the increased range.
 
I may be off base, but I think the point is that it is more economic to use the potential "regen" energy to accelerate if you are going down a hill rather than to use the electric motors to push it into the battery with at most a 90% efficiency. This is why a cruise control with too tight a speed constraint for the speed will hurt mpg, but one with too loose a constraint will annoy drivers (too slow up hill, too fast down). Similarly, it is better to coast to a stop than to use regen to do it, just as described earlier, hard to perfectly do and may annoy those behind you that you have too big a following distance to the car in front of you.
 
The range game is largely a mental construct. It’s hardly worth the effort to write these few sentences, but I still have a bit of coffee to finish. There’s a certain amount of energy in the battery. How we use that energy determines the distance the vehicle will travel. Speed, or average speed, is only one factor. It is not the determining factor.

Carry on.
 
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