High regeneration vs Low - Jaguar I-Pace EV400 Forum
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post #1 of 16 (permalink) Old 04-28-2019, 02:12 PM Thread Starter
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High regeneration vs Low

Seems to me that when highway driving (NOT city driving) it shouldn't make much difference which mode you're in. My (admittedly weak) grasp of physics tells me that if a certain mass has to be brought to a stop in a certain place, high regeneration will require power until close to the stopping point, then lots of regeneration will occur over a short time when the right foot lifts.

With low regeneration you take your foot of the "gas" earlier, so you have low regeneration but for a longer time. My guess is the result should be the same amount of juice fed back to the battery.

This argument assumes no use of the brakes, of course, until the stop is made. And it would not apply in stop and go traffic where you can't take time to anticipate a stop.

Anyone with a better scientific background care to comment?
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post #2 of 16 (permalink) Old 04-28-2019, 04:22 PM
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Not necessarily more scientific, but I've logged a lot of miles hypermiling.

First, we normally buy a nice car to enjoy it. So that comes first. Drive it the way that makes driving pleasant for you.

Now about hypermiling. The higher kW load you put on the electrics in either direction the more kWh is consumed as heat and the more cooling is used. A fast charge or discharge loses more power per mile. On paper it would seem blasting off from 0 to 50 mph then max regen back to 0 would cover distance at a faster average speed, hence save power, but I've seen the opposite. It's not huge like a gas car, but it's there.

So keeping the rate of acceleration and deceleration low improves range. For many drivers, it's easier to keep the regen peak down by using low regen augmented by the brake only if necessary. This also keeps you looking further ahead, so you decel earlier and accel more gradual.

The brake pedal regens at first, until you run out of regen capacity, then it uses the friction brakes. The friction brakes appear to always be in use at very low speed, say under 4 mph, so try to avoid complete stops.

Note: You will hear the exact opposite, and you will hear it doesn't make a difference. I base this on trying to achieve maximum miles per kWh in a car with a smaller battery that I can run empty since it has a gasoline generator should I run short. And when I tried to hypermile the I-Pace, I saw a similar effect, but I can't run it 'dry' too often.
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post #3 of 16 (permalink) Old 04-28-2019, 05:20 PM
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Yeah it's mostly about the electrochemistry of the battery. High regen puts juice back into the battery at a higher rate than is optimal; it's analogous to high acceleration, when lots of power is drawn and efficiency is not as good as when you press that pedal more gently. That said, I prefer high regen for its superior control via the pedal. Either way (low or high regen) you have to pay some attention and adjust your driving style to get the most out of your electrons -- if that's your objective. Mine is usually to get from A to B not with the greatest efficiency but with the most fun.
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post #4 of 16 (permalink) Old 04-28-2019, 05:43 PM
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The nice thing about high regen is that, when you need to panic stop, you have a lot of braking happening before you even reach the brake pedal. I consider this safer. The bad parts are that, when switching back and forth between ICE and EV, you'll expect or not expect the regen braking. It gets confusing and cuts smoothness. Also you have to have more constant pressure on the pedal. Replacing the return spring with a lighter one might make the driving physically easier.
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post #5 of 16 (permalink) Old 04-28-2019, 06:40 PM
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Quote:
Originally Posted by jsimon7777 View Post
The nice thing about high regen is that, when you need to panic stop, you have a lot of braking happening before you even reach the brake pedal. I consider this safer. The bad parts are that, when switching back and forth between ICE and EV, you'll expect or not expect the regen braking. It gets confusing and cuts smoothness. Also you have to have more constant pressure on the pedal. Replacing the return spring with a lighter one might make the driving physically easier.
This is me right now. I have a Land Rover Discovery Sport loaner while they work on software updates and suspension work on my I-Pace. Sometimes, I let go of the accelerator and expect the Discovery to slow down, but I quickly have to press the brake pedal
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post #6 of 16 (permalink) Old 04-28-2019, 06:47 PM
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I agree high vs low is about the same if you do not hit the brakes. And even then as you use the brakes moderately there is more regeneration so still not a big deal. Choose the setting of your preference and enjoy the vehicle.
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post #7 of 16 (permalink) Old 04-29-2019, 08:52 AM
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I prefer the Low regen because the car coasts a bit more and the break lights don't come on since there isn't sudden deceleration. High or Low really depends on how you like the car to feel. As JSimon7777 says, there is a safety factor with high regen. If you are trying to achieve best mileage, I've found I get better mileage with low regen.

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post #8 of 16 (permalink) Old 04-29-2019, 01:02 PM Thread Starter
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Thanks for all your responses. So far I've found that (a) high regeneration in the city is wonderful - one pedal driving is great and (b) on the highway low rejoin feels much better.
What I'd like is if the short-cut button on the left side of the steering wheel could be set to change the regeneration mode without having to go into My EV/ Set Up in the menu. Alas, it appears this is not one of the choices you can make.
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post #9 of 16 (permalink) Old 04-29-2019, 05:30 PM
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Quote:
Originally Posted by gbillcb View Post
Thanks for all your responses. So far I've found that (a) high regeneration in the city is wonderful - one pedal driving is great and (b) on the highway low rejoin feels much better.
What I'd like is if the short-cut button on the left side of the steering wheel could be set to change the regeneration mode without having to go into My EV/ Set Up in the menu. Alas, it appears this is not one of the choices you can make.
Yes it would be nice to have a short cut so you don't have to take your eyes off the road. Even with being able to customize your main display and put myEv on the front, you still go a couple clicks deep. This is one time that a button or paddle or a different programmable widget on the InControl would be nice to have.

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post #10 of 16 (permalink) Old 04-29-2019, 07:36 PM
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I can't wait for fully autonomous systems to roll out because it can help to optimize range by factoring in more than what we can and doing it faster than we can.
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