Regen Braking Decline Toward 100% Charge: Binary or Graduated?

[Penman61]

I know that charging to 100% inactivates regenerative braking.

My question: Is that a graduated inactivation, with regenerative braking getting gradually less effective as you charge to 95, 96, 97%...?

Or does that regen inactivation happen ONLY once you reach full 100%, and you have regen braking even at, say, 99%?

I'm about to take a long trip and want to charge as high as possible without losing regen.

 

[jjrandorin]

I know that charging to 100% inactivates regenerative braking.

My question: Is that a graduated inactivation, with regenerative braking getting gradually less effective as you charge to 95, 96, 97%...?

Or does that regen inactivation happen ONLY once you reach full 100%, and you have regen braking even at, say, 99%?

I'm about to take a long trip and want to charge as high as possible without losing regen.

If thats important to you, is there some reason you dont just turn on the blended brake option that simulates regen when its limited due to battery ability to accept regen for any reason?

I dont use that setting myself, but its specifically for this type of thing.

Anyway, I dont believe the loss of regen is binary, its gradiated, and it also is not just because of battery being full, it can also be because of battery temperature.

 

[Penman61]

Forgot about the blended brake option; I will look into it. Thanks.

Mostly I want to know whether regen braking deactivation is graduated as you get close to 100% charge. Trying to understand how my new car works.

 

[ucmndd]

Yes, it is gradually reduced as the battery gets closer to 100% as the pack’s max charging rate is reduced.

 

[Cosmacelf]

Use the blended brake option to maximize range. Charge to 100%. Done.

 

[Penman61]

Yes, it is gradually reduced as the battery gets closer to 100% as the pack’s max charging rate is reduced.

Thank you! That answers my question.

 

[QtownTaxiGreg]

How does blended brake optimised range?

To my mind charge to 100% and remember to brake as required would make for longest range.

 

[Rocky_H]

My question: Is that a graduated inactivation, with regenerative braking getting gradually less effective as you charge to 95, 96, 97%...?

Let me describe a different scenario that you probably already know the answer to, which answers this question too.

What happens when you're at a Supercharger charging up to full?

Does it stay at a high power rate all the way up to 95, 96, 97, 98% and then suddenly cut off to nothing when it reaches 100%? No, obviously not. That's not how battery charging works. It gradually tapers down the amount of charging power the battery can accept.

That is EXACTLY the same phenomenon that is happening with the regenerative braking. Full regen under ideal conditions is around 60 kW-ish? There's no way the battery will accept 60 kW when it's over 90% full, so it is already in that tapered slower charging realm, and is in the gradually reduced charging area. It's the same thing.

 

[AlanSubie4Life]

Thank you! That answers my question.

You’ll also notice that over short time periods, the more regen you do, the more limited it becomes. This is not because of increasing SOC during a long continuous regen event. It is much more severe than that.

This is probably because it takes time for the lithium ions to intercalate, and if you regen too much all at once, regen can become very limited. It’s a rate-limited process which results in a memory effect.

Usually you’ll notice this on >0.5-1 mile downhill grades.

If you turn on the braking when regen is limited option, of course you won’t really notice it. (It is actually still noticeable - the car will make battery warming whining noises whenever regen is limited whether or not emulation is enabled. So you’ll start to hear that at the bottom of a long downhill at high enough SOC even if you started with no regen limitations.)

As usual, regen limitation behavior can be seen by looking at the regen bar - assuming braking when regen limited is turned OFF - you’ll see increasing dots in the left hand side as it becomes more limited.