notfred
Posts: 530
Joined: Thu May 07, 2015 2:28 pm

Re: Regenerative Braking

Fri Jan 15, 2016 4:33 pm

Exactly. The problem with using the brake pedal for controlling the regen is that Kia did too good a job and I'm not convinced that I can feel when the hydraulic brake system starts to come in. Using B mode I know that even if I let off the accelerator pedal totally then there is no energy being lost to the hydraulic brakes.

ZuinigeRijder
Posts: 137
Joined: Thu Dec 31, 2015 3:59 am

Re: Regenerative Braking

Sat Jan 16, 2016 6:43 am

What I understand is that regeneration is only 30% efficient for the Kia Soul EV, so it is always better to do no regeneration at all. So in principle it would be better to set it to 'N' and only use regeneration when you have to do more slow down. According to the User Manual it is not good for the transmission to put it in 'N' while driving. The most optimal would have been if the 'D' would NOT regenerate (so like a 'N') and you could regenerate e.g. with a handle on the steering wheel. Actually, the upcoming Chevrolet Bolt has something like this.

Image

Youtube 2017 Chevrolet Bolt EV interior walkthrough: https://youtu.be/kqA_tG8yjvs

AyeJay
Posts: 41
Joined: Fri Oct 17, 2014 1:59 pm
Location: sf bay area

Re: Regenerative Braking

Fri Jan 22, 2016 3:27 pm

notfred wrote:Sure it is better to coast than to slow down with regen and then accelerate again, but the reality of driving on city streets is that you spend very little time at constant speed. It's way better to use regen than it is to use the brakes!


Using regen 'in place of' brakes as much as possible in city driving works for me.

On the highway I've found 62 mph maximum is optimal for range in general.

-- On the highway going down a hill I will allow the car to 'coast' increasing speed (well above 62 mph) by depressing the accelerator pedal or toggling up the cruise control until I'm back on a level grade (where I return to 62 mph).
- 2015 KIA Soul EV base
- 1982 VW 'Caddy' Rabbit TD Pickup

kmaluo
Posts: 37
Joined: Thu Jan 14, 2016 5:05 pm

Re: Regenerative Braking

Fri Jan 22, 2016 8:29 pm

mtndrew1 wrote:
kmaluo wrote:
notfred wrote:Sure it is better to coast than to slow down with regen and then accelerate again, but the reality of driving on city streets is that you spend very little time at constant speed. It's way better to use regen than it is to use the brakes!


I respectfully disagree with you. Using the brake pedal allows you to adjust the amount of regen you need instead of maxing out momentum loss everytime you ease off the gas pedal.


I do exactly this in B by varying the throttle; I don't just jump off the accelerator into full regen.


You're right this method does work well!

GizmoEV
Posts: 198
Joined: Fri Mar 06, 2015 7:39 pm
Location: Kelso, WA

Re: Regenerative Braking

Thu Jan 28, 2016 11:33 am

It appears there are some misconceptions surrounding the use of regen and how it works with the Kia Soul EV. It would be worth your time to select the EV display and change to the screen where you can see the power that the drive system is using.

While driving and when safe to do so, watch the power value. Note that as you go from steady state driving and slowly let up on the throttle you will see the value decrease, eventually hit zero, and then become negative. Do this in both the D and B mode. Pick a speed and notice how much max regen there is when in D mode and you fully let off the throttle and then compare the same scenario while in B mode.

Also, notice what happens to the regen value when fully off the throttle and you slightly press on the brake pedal. Only press it enough that the brake lights would come on but the friction brakes don't. There is a very slight increase in the regen power. Note that even if you press the brakes harder that the max regen doesn't increase. This can take a bit of testing because the value is constantly changing. The amount of regen doesn't appear to be tied with how hard the brake pedal is pushed aside from the small initial increase when the brake lights would have come on. This is true in both modes. Because of this and the fact that regen isn't a fully off or on event it is more efficient to drive properly in the B mode than in D mode.

As for using neutral to coast down a hill at a higher speed than using regen to maintain speed being more efficient, that depends. The faster you travel the more of your potential energy is lost to air friction. That difference in air friction between say 60mph and 70mph could have been turned into recovered energy if the speed were kept at 60mph which then would have been used to propel the vehicle the extra distance that would have been coasted by the higher speed. This is especially true if the terminal speed was 70mph. Most of the way down the hill air friction was keeping you at 70mph but you only benefit from the extra 10mph of roll-out at the bottom of the hill. It would have been better to regen down the hill at 60mph then use the regenerated energy on the roll-out that the 70mph speed would have given. This is exactly the method I used driving from the charge station in Castle Rock, WA to Coldwater Lake, up Mt. St. Helens. The trip normally can't be done on a full charge so driving slower on the way up helped but still didn't have enough range to make it back to the charging station. By driving only 45mph and using regen on the way down there was ample range. In any case, without hard data for a given situation it is difficult to make a claim either way.
David D. Nelson

Blue 2016 Soul EV+ & Cloud 2018 Soul EV+ :D :o

kmaluo
Posts: 37
Joined: Thu Jan 14, 2016 5:05 pm

Re: Regenerative Braking

Sat Jan 30, 2016 12:36 am

GizmoEV wrote:Note that even if you press the brakes harder that the max regen doesn't increase. This can take a bit of testing because the value is constantly changing. The amount of regen doesn't appear to be tied with how hard the brake pedal is pushed aside from the small initial increase when the brake lights would have come on.


On my 2016 plus, the regen definitely increases with the amount of brake pressed. In fact, I can get -47 kw of regen in D with the brake pedal from 50mph. This is the same as no brake while in B.

GizmoEV
Posts: 198
Joined: Fri Mar 06, 2015 7:39 pm
Location: Kelso, WA

Re: Regenerative Braking

Sun Jan 31, 2016 5:01 pm

kmaluo wrote:
GizmoEV wrote:Note that even if you press the brakes harder that the max regen doesn't increase. This can take a bit of testing because the value is constantly changing. The amount of regen doesn't appear to be tied with how hard the brake pedal is pushed aside from the small initial increase when the brake lights would have come on.


On my 2016 plus, the regen definitely increases with the amount of brake pressed. In fact, I can get -47 kw of regen in D with the brake pedal from 50mph. This is the same as no brake while in B.

I'll have to go test mine again because I wasn't seeing that before.
David D. Nelson

Blue 2016 Soul EV+ & Cloud 2018 Soul EV+ :D :o

GizmoEV
Posts: 198
Joined: Fri Mar 06, 2015 7:39 pm
Location: Kelso, WA

Re: Regenerative Braking

Sun Feb 07, 2016 12:10 am

GizmoEV wrote:
kmaluo wrote:
GizmoEV wrote:Note that even if you press the brakes harder that the max regen doesn't increase. This can take a bit of testing because the value is constantly changing. The amount of regen doesn't appear to be tied with how hard the brake pedal is pushed aside from the small initial increase when the brake lights would have come on.


On my 2016 plus, the regen definitely increases with the amount of brake pressed. In fact, I can get -47 kw of regen in D with the brake pedal from 50mph. This is the same as no brake while in B.

I'll have to go test mine again because I wasn't seeing that before.


I had a chance today to take my Kia out and test the regenerative braking in D and B mode. What I found is that I can in fact get high regen power in D mode if the brake pedal is pressed hard enough. If however, you shift into B mode the regen current increases and you have to back off the brake to keep the same rate of deceleration. This means that the friction brakes are definitely working more in D mode than in B mode. Any braking done by the friction brakes is lost energy that can't be recuperated by regen. B mode is still more efficient than D mode when driven properly.
David D. Nelson

Blue 2016 Soul EV+ & Cloud 2018 Soul EV+ :D :o

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