# Increased Regen starting with Software Build v10.2 2021.4.11



## francoisp (Sep 28, 2018)

Has anyone seen an improvement with regen with 2021.4.11? I went out today with the temperature at around 29F and I had full regen (no"dots" on the line), even after spending an hour at store. Felt like summer was already here 😁. To be clear I did not charge the car prior to my trip nor did I precondition the battery.


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## garsh (Apr 4, 2016)

francoisp said:


> ... even after spending an hour at store.


That's the key. If you've been driving (in this case, you first drove to the store), and then leave the car parked for a short enough time, the heat generated during your drive seems to "bake" the battery while there's no "wind" flowing beneath the car to cool it down. It bakes the battery a little bit.


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## francoisp (Sep 28, 2018)

garsh said:


> That's the key. If you've been driving (in this case, you first drove to the store), and then leave the car parked for a short enough time, the heat generated during your drive seems to "bake" the battery while there's no "wind" flowing beneath the car to cool it down. It bakes the battery a little bit.


What I find curious is that normally when I leave home at a temperature in the low 30s, or even higher in upper 40s, I always get a message of "reduced regen". I did not get that today.


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## Theos1 (Oct 6, 2018)

Same NEW experience here; outside temp about minus 4 deg C, pre-heated for about 15 min and pretty well no regen loss. What puzzles me - driving M3 LR RWD delivered June 2018, software 2021.4.11 8a... - that even after a short drive in the below freezing temperature the car starts cooling the battery shortly after I stop driving. Maybe I should qualify; it sounds like cooling the battery - no internal fan going, no cabin heating or cooling - and I have heard from a number of people that it is indeed to cool the battery in the early M3 models. Does somehow not make sense to cool a battery that is still relatively cold.


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## francoisp (Sep 28, 2018)

garsh said:


> That's the key. If you've been driving (in this case, you first drove to the store), and then leave the car parked for a short enough time, the heat generated during your drive seems to "bake" the battery while there's no "wind" flowing beneath the car to cool it down. It bakes the battery a little bit.


It's 42F in my garage as I leave home and I'm getting full regen with no preheating.


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## francoisp (Sep 28, 2018)

Here is a following up comment regarding the change of the regen behavior (post #186). My thoughts are: either this latest version (2021.4.11) introduced a bug or Tesla has indeed made a change. I'm opting for the later. I noticed something peculiar on my ride yesterday. Ten minutes from my home (5 miles away) there is a substantial hill that takes me down into the valley with a lot of regen opportunities on that road. At the top of the hill, the car's top line showed no dot so I had full regen. As I drove down the aforementioned hill, I noticed that "dots" started to appear: 1 dot, then 2, then 4. It stayed at 4 dots until I reached the bottom of the hill. As I started driving along the river, the dots went away within a few minutes. So here's my thinking: the new regen algorithm now allows a certain amount of full regen at a lower temperature. However, depending on the battery temperature, if too much regen is taking place, the car will limit it. It would be nice if someone else had to chance to corroborate this (or invalidate it if it is the case).


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## garsh (Apr 4, 2016)

francoisp said:


> Has anyone seen an improvement with regen with 2021.4.11?


I decided to test out your assertion. My car was in my garage all night at about 48° F, which is usually enough for it to pop up the "regen limited" warning. Because of this, I usually try to charge my car for 30-45 minutes before leaving, just to warm up the battery and give me some regen. Today, I chose not to do that. Sure enough, I had MUCH more regen than I am accustomed to! The line still showed 3 or 4 dots at the bottom (battery was 50% charged), but that's still much better than it usually starts out under these circumstances.

It would be good if we could get a few more people to test this out and see if they notice a difference on 2021.4.11 as well.


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## Bigriver (Jan 26, 2018)

garsh said:


> It would be good if we could get a few more people to test this out and see if they notice a difference on 2021.4.11 as well.


So I'm not a particularly astute observer of normal regen behavior; it's only something I occasionally notice the strength (or lack of). But I went on a 23 min test drive in my model 3 on 2021.4.11, starting from the garage with no preheating or recent charging, and had the following:

Time (min) Temp (F) Charge Dots
0 51 79% 10
3 39 79% 14
14 36 77% 9
23 35 75% 10
(Edit: I created a lovely table of my data, but when I submit, the spaces disappear.)

I think this may have been a little more regen than usual to start with, but I was a little surprised that regen really didn't increase, but of course the car was cooling down to the ambient temperature. I was on local roads going 40 to 50 mph, some hills and some flat.

Two asides:

Tesla really, really needs to use eyeballs older than 20 or 30-something in choosing their fonts. The regen line is so thin and light gray, it is almost invisible to me. I took pictures along the way and could then see the results when I got home.
In my white model 3, I passed a white model Y. It looked like "me" after Thanksgiving dinner. Just a bloated version of my car. I may or may not have puffed my cheeks out as I passed it.


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## garsh (Apr 4, 2016)

Quoting the relevant portion of JWardell's post to this new thread.



JWardell said:


> I started looking into reports of increased regen yesterday after I finally got my first update of 2020 to 4.11. Easy to wrap your head around when your dash gauges show battery power and temperature!
> 
> I still had absolute zero regen when my battery was 27-28F. I'm certainly glad is this isn't a bug that would charge the battery below freezing and potentially cause a fire.
> 
> ...


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## garsh (Apr 4, 2016)

garsh said:


> I decided to test out your assertion. My car was in my garage all night at about 48° F, which is usually enough for it to pop up the "regen limited" warning. Because of this, I usually try to charge my car for 30-45 minutes before leaving, just to warm up the battery and give me some regen. Today, I chose not to do that. Sure enough, I had MUCH more regen than I am accustomed to! The line still showed 3 or 4 dots at the bottom (battery was 50% charged), but that's still much better than it usually starts out under these circumstances.


I went for another drive today.
Car was charging after my morning trip until 8:46am (finished at 50%).
Garage was still at 48° F when I left again at 11:20am (2h34m after it stopped charging).
This time, it showed FULL regen - no dots at all!


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## francoisp (Sep 28, 2018)

Last night I charged the car to 90% and this morning my regen was much weaker. I'll try to limit charging it to 70% next time and see I get more regen.


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## JWardell (May 9, 2016)

I captured the transition during a drive today. Zero regen until min pack temp is -1C (max pack 4.75C) and then it climbs quickly:


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## garsh (Apr 4, 2016)

@JWardell , you don't happen to have an equivalent graph for an older version of software for comparison, do you?

I assume the Y-axis is degrees Celsius for the temperature measurements. But what's the y-value for the "regen power" measurement? The graph seems to suggest that you hit something close to full regen at 1° C - is that true?


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## JasonF (Oct 26, 2018)

It sounds like Tesla switched from a temperature-and-time model to a real time battery performance model. So it will let you regen somewhat until the battery performance starts suffering, and then it will curb regen. Or if battery performance gets better, it will give you more regen.


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## JWardell (May 9, 2016)

garsh said:


> @JWardell , you don't happen to have an equivalent graph for an older version of software for comparison, do you?
> 
> I assume the Y-axis is degrees Celsius for the temperature measurements. But what's the y-value for the "regen power" measurement? The graph seems to suggest that you hit something close to full regen at 1° C - is that true?


The Y axis is just units...so degrees C for temp, and kW for regen. 
So regen is now zero below -1C, and raises linearly to 20kW at 0C (I checked, there are fractional values in that short period). But 20kW is far far from full regen at ~150kW.
It's almost like they added a single line of code that if temp greater than zero, add 20 to previously calculated charge limit value.

I never specifically took a log to concentrate on the transition at the freezing point, but there is some chance, I will have to look through all my old logs.


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## francoisp (Sep 28, 2018)

JWardell said:


> The Y axis is just units...so degrees C for temp, and kW for regen.
> So regen is now zero below -1C, and raises linearly to 20kW at 0C (I checked, there are fractional values in that short period). But 20kW is far far from full regen at ~150kW.
> It's almost like they added a single line of code that if temp greater than zero, add 20 to previously calculated charge limit value.
> 
> I never specifically took a log to concentrate on the transition at the freezing point, but there is some chance, I will have to look through all my old logs.


If you do further studies it would be nice to compare similar scenarios for 25%, 50% and 75% charge level. With everything being equal my hypothesis is that with a lower charge level, the car will allow stronger regen.


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## Gtimart (Dec 22, 2019)

@JWardell , full regen of 150kW? I've never seen anything higher than 85.0kW of max regen on ScanMyTesla on my dual motor. Is SMT wrong? I was under the impression 85kW was the max, and I've never seen anything higher than that while using regen. 
As for the latest update changing the regen on cold batteries, plenty of people on the Quebec Tesla facebook groups have noted it too. It's a major enhancement. I've never seen 85kW regen with a 14oC battery before. There is some additional logic on the max regen, it's not just the battery temperature. When accelerating hard-ish, the max regen seems to raise faster, with the battery temp seemingly staying equal. When using regen to slow down, the max regen drops every second. The BMS would not let you regen for minutes when going down a big hill, on a cold battery. It's reassuring to see. I'm sorry I don't have precise, scientific measurements. I just look at SMT while driving...


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## tivoboy (Mar 24, 2017)

Yeah, that sounds pretty darn high. I could imagine though If this was temp and location aware, coming down from a high elevation for a long stretch, like over the grapevine on the I5 in CA either direction, or down from Tahoe elevation for 15-20 miles, one could really recapture a LOT of KW easily. I usually find on a stretch like that I can go 15 to sometimes 20 miles and have the % or Miles remaining REMAIN at the same number until bottoming out. But think about it though, 150KW regen, would be like having an onboard supercharger!.. would that be only with the dual motors?


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## Mesprit87 (Oct 29, 2017)

Well, long downhill 2 km slope getting out of my village, can actually see negative consumption at the bottom during summer.
Of course winter is another story, in the garage at 14C and charged to 80% I use to not get much back. I would get some small amount and then it would taper off with the limited regen message. 
Now with this new version, same thing but higher regen initially. I do like that it doesn't take long to be able to use that same higher regen for short while during normal driving on flat roads. In the same conditions with the old versions I use to have to try real hard to stop without using the brakes. 
For me it is a good improvement that will show in my consumption, the fact that they still limit the max regen of the day in time and level tells me they did their homework and my battery life should be safe.


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## tivoboy (Mar 24, 2017)

Mesprit87 said:


> Well, long downhill 2 km slope getting out of my village, can actually see negative consumption at the bottom during summer.
> Of course winter is another story, in the garage at 14C and charged to 80% I use to not get much back. I would get some small amount and then it would taper off with the limited regen message.
> Now with this new version, same thing but higher regen initially. I do like that it doesn't take long to be able to use that same higher regen for short while during normal driving on flat roads. In the same conditions with the old versions I use to have to try real hard to stop without using the brakes.
> For me it is a good improvement that will show in my consumption, the fact that they still limit the max regen of the day in time and level tells me they did their homework and my battery life should be safe.


I pulled my C63 out of the garage over the weekend (I had started it, but not driven in since about November 2020) and basically forgot to put my foot down on the brake at the stop sign at the end of the street.. I've always been a lift of the go peddle FIRST driver, but my foot essentially has lost it's muscle memory to pivot over and HIT THE BRAKE!


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## Mesprit87 (Oct 29, 2017)

tivoboy said:


> I pulled my C63 out of the garage over the weekend (I had started it, but not driven in since about November 2020) and basically forgot to put my foot down on the brake at the stop sign at the end of the street.. I've always been a lift of the go peddle FIRST driver, but my foot essentially has lost it's muscle memory to pivot over and HIT THE BRAKE!


If you lived here in Québec you wouldn't lose that reflex. I'd like to lose it but -25C just annihilate any regen, your brain has to do a special contorsion since the same car used to give you regen just a few hours before the cold soak! My first experience was at gate at work with my then month old car. My heart still pumps just thinking about it


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## francoisp (Sep 28, 2018)

tivoboy said:


> I usually find on a stretch like that I can go 15 to sometimes 20 miles and have the % or Miles remaining REMAIN at the same number until bottoming out.


Once I had a negative kwh usage on my trip after going down a hill.


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## JWardell (May 9, 2016)

Gtimart said:


> @JWardell , full regen of 150kW? I've never seen anything higher than 85.0kW of max regen on ScanMyTesla on my dual motor. Is SMT wrong? I was under the impression 85kW was the max, and I've never seen anything higher than that while using regen.
> As for the latest update changing the regen on cold batteries, plenty of people on the Quebec Tesla facebook groups have noted it too. It's a major enhancement. I've never seen 85kW regen with a 14oC battery before. There is some additional logic on the max regen, it's not just the battery temperature. When accelerating hard-ish, the max regen seems to raise faster, with the battery temp seemingly staying equal. When using regen to slow down, the max regen drops every second. The BMS would not let you regen for minutes when going down a big hill, on a cold battery. It's reassuring to see. I'm sorry I don't have precise, scientific measurements. I just look at SMT while driving...


Yes, sorry, what we are actually looking at is the BMS's maximum allowed charge rate, which regen follows until it hits its upper limit, which is defined by the system configuration (rear/AWD/performance), but the charge limit continues to climb with temp to allow for 250kW charging.
It also varies with voltage, and maybe coolant temp and flow as well, so yes stomping on the pedals temporarily affects it as well.


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## Gtimart (Dec 22, 2019)

So, it would be safe to assume that our cars can now also charge a bit faster when the batteries are cold, at a supercharger? That would also be great news for us Canadians 😀


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## JWardell (May 9, 2016)

Gtimart said:


> So, it would be safe to assume that our cars can now also charge a bit faster when the batteries are cold, at a supercharger? That would also be great news for us Canadians 😀


I think so. Sure could have used it last week when I sat at a charger for an hour getting no more than 23kW. It doesn't help that I only have one motor to slowly heat the pack.


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## GDN (Oct 30, 2017)

JWardell said:


> I think so. Sure could have used it last week when I sat at a charger for an hour getting no more than 23kW. It doesn't help that I only have one motor to slowly heat the pack.


So a couple of points - was this done perhaps to reduce charge times and we just haven't really realized that yet and on the second point, are both motors truly used to heat the battery? I guess the flow should be there, I just hadn't thought about it, I assumed only the larger rear motor.


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## Gtimart (Dec 22, 2019)

GDN said:


> So a couple of points - was this done perhaps to reduce charge times and we just haven't really realized that yet and on the second point, are both motors truly used to heat the battery? I guess the flow should be there, I just hadn't thought about it, I assumed only the larger rear motor.


Both motors are indeed used to generate heat for the battery, 3-3.5kW each. When driving, the rear has a hard time generating heat because it needs to move the car. I believe that's where the dual motor shines (apart from acceleration and awd obviously 😉)


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## JasonF (Oct 26, 2018)

tivoboy said:


> I pulled my C63 out of the garage over the weekend (I had started it, but not driven in since about November 2020) and basically forgot to put my foot down on the brake at the stop sign at the end of the street.. I've always been a lift of the go peddle FIRST driver, but my foot essentially has lost it's muscle memory to pivot over and HIT THE BRAKE!


I drove someone else's ICE car in late 2019, and the passengers thought I was crazy when I complained that the car has awful regen braking.

But the funniest moment was when I had to move that same car later in the day. I put it in park and enabled the parking brake, and then got out. Almost shut the door before I realised the engine was still running.


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## Rich M (Jul 28, 2017)

Came here just for this thread. After the update regen has been wonderful! With garage at 44F and only 5-10 min of preheating, that usually means I'm in regen jail for the entire (short) trip, but no dots at all now. I really hope it wasn't an error and doesn't get taken away in a future update.


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## francoisp (Sep 28, 2018)

Rich M said:


> Came here just for this thread. After the update regen has been wonderful! With garage at 44F and only 5-10 min of preheating, that usually means I'm in regen jail for the entire (short) trip, but no dots at all now. I really hope it wasn't an error and doesn't get taken away in a future update.


Do you remember what was your battery level when you noticed the increased regen?


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## Rich M (Jul 28, 2017)

francoisp said:


> Do you remember what was your battery level when you noticed the increased regen?


About 50% the first day after the update and 40% the second. Snowflake icon was on the entire time.


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## MrWugz (Jun 27, 2017)

I've had a chance to compare a few of the regen curves under 2021.4.11 to my previous data on Reddit here. The data is still messy as due to time constraints these had to be captured during drives with ORBW outputting variable heat as opposed to sitting in the garage and getting the full 7 kW steady battery heating curve from cabin preconditioning while maintaining a single SoC, but based on what I've seen so far and as everyone already suspects, there has been a measurable increase in regen under the new firmware at nearly every state of charge, with lower SoCs seeing bigger gains.

90-80% is the least affected, adding about 5 kW at each temperature across the board, or conversely hitting the same regen curve as previously but at 1-2°C cooler temps.
80-70% shows a marked increase of 10-20 kW over previous values, now peaking with full regen at 16°C as opposed to 20-24°C previously.
70-65% previously followed closely with 80-70% but now shoots up to a nearly full regen bar at as little as 8-9°C. It even beats the old 30% curve after about 5°C
55-50% starts higher even sooner but quickly matches curves with the new 70-65%, peaking the UI regen bar at 8-9°C and hitting 85 kW at 13°C

The cutoffs for heating from charging & preconditioning seem to be the same, at about 10°C and 20°C (± a few) respectively, so any previous battery heating routines/habits you'd developed will now net you more available regen in the cold.


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## kornerz (Sep 27, 2017)

For my 2019 SR+, it looks like available regen increased significantly.
Before this update BMS maximum regen displayed was around 55-60kW, and observed maximum regen (negative power reading at the battery during regen) was around 50-55 kW.

Now it displays 75kW of available regen, and I've been able to see 65kW of actual regen, which is a significant improvement over 50kW available previously.

Also, I don't think I've seen maximum drive unit power more than ~210 kW before the update - and today it reached 225kW, making my 2019 SR+ a 300HP car


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## tivoboy (Mar 24, 2017)

JasonF said:


> I drove someone else's ICE car in late 2019, and the passengers thought I was crazy when I complained that the car has awful regen braking.
> 
> But the funniest moment was when I had to move that same car later in the day. I put it in park and enabled the parking brake, and then got out. Almost shut the door before I realised the engine was still running.


Where I hope ICe goes QUICLY is to make everything a sort of hybrid, with limited onboard KWh storage.. but at least at THAT point the regenerative braking experience would be very similar to a BEV,/EV and we could develop similar driving habits for all cars.


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## PiperPaul (Oct 31, 2018)

garsh said:


> I went for another drive today.
> Car was charging after my morning trip until 8:46am (finished at 50%).
> Garage was still at 48° F when I left again at 11:20am (2h34m after it stopped charging).
> This time, it showed FULL regen - no dots at all!


Confirming here in the Great White North (even tho it's been a very mild winter) that 2021.4.11 gives my M3 much better regen in temps hovering around freezing.

I was more intrigued by the mention of "dots" in several posts. Didn't have a clue what was meant. 
So I enlisted my wife's help while we drove for our grocery pickup. And lo and behold at the top of the screen, in the new format, the energy flow line is actually still there. And under 100 power magnification there are actually dots at the very left of where the green regen shows up. Who knew???
And the $64K question (I know, I'm ignoring inflation) is what the heck do they mean? 
I hope they are not critically important because to actually see them while driving means I would have to pull over and move really close to the screen and I suspect that would defeat the point.
Overall, as many have pointed out, I don't understand why with all the blank real estate on the screen, the designers chose 4 point font for information. 
I'm glad I prefer to watch the road, other traffic, pedestrians, traffic signals, etc. Call me crazy. Call me for dinner.


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## francoisp (Sep 28, 2018)

PiperPaul said:


> Confirming here in the Great White North (even tho it's been a very mild winter) that 2021.4.11 gives my M3 much better regen in temps hovering around freezing.
> 
> I was more intrigued by the mention of "dots" in several posts. Didn't have a clue what was meant.
> So I enlisted my wife's help while we drove for our grocery pickup. And lo and behold at the top of the screen, in the new format, the energy flow line is actually still there. And under 100 power magnification there are actually dots at the very left of where the green regen shows up. Who knew???
> And the $64K question (I know, I'm ignoring inflation) is what the heck do they mean?


On the left side, the dots signify that a limit is imposed on regen. On the right side, the dots signify that acceleration is limited.

Tesla limits power for many reasons.
Here are just a few examples:
• Acceleration may be limited when the
Battery is reaching a low state of
charge or if the powertrain is hot.
• Both acceleration and regenerative
braking may be limited when the
ambient temperature is either very
warm or cool.
• Regenerative braking may be limited
when the Battery is fully charged.


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## PiperPaul (Oct 31, 2018)

francoisp said:


> On the left side, the dots signify that a limit is imposed on regen. On the right side, the dots signify that acceleration is limited.
> 
> Tesla limits power for many reasons.
> Here are just a few examples:
> ...


Thanks for the explanation.
I have never pushed the car nearly enough to have either the green regen line or the grey power line get close to the dots.
I guess my sphincters are limiting my right foot before the power management software kicks in. I do prefer to keep the car out of the ocean.


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## Rick Steinwand (May 19, 2018)

PiperPaul said:


> Thanks for the explanation.
> I have never pushed the car nearly enough to have either the green regen line or the grey power line get close to the dots.
> I guess my sphincters are limiting my right foot before the power management software kicks in. I do prefer to keep the car out of the ocean.


You talk like I think. Keep it coming....


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## iChris93 (Feb 3, 2017)

Rick Steinwand said:


> You talk like I think. Keep it coming....


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## Lon12 (Oct 18, 2018)

Had a chance to try this update today and watch it with SMT. Was +3C OAT and battery at 14C. Although it gets rid of the regen dots initially, the max regen value goes up and down like crazy. Even triggers that annoying message about regen has been reduced. I was seeing max regen values going from 79 down to 35 every time I decelerated. I would see no regen dots then shortly half the bar populated with dots.
I think I preferred it when the dots were more steady.


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## tivoboy (Mar 24, 2017)

I was able to try the REDUCED regen today since I charged up to full yesterday for the first time in a long time (314 still on the final fill up).. but, at that SOC 100%, and COLD outside, there is very very limited regen if any. What I do NOT like is that when approaching a stop sign, and lift off the go pedal, there is a BRIEF instant where I can feel the motor or regen and then it clicks off or releases.. So, at first lift it DOES a tiny bit of decell, but then it releases. so, my feeling is that this experience is not a good one since the driver for a split second has the conditioned experience that regen is available, and then its switches off and deceleration goes to 0


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## Lon12 (Oct 18, 2018)

Even with the battery temperature at 20ºC today I was getting the max regen value going from 70 down to below 30 and getting the reduced regen braking message after a long downhill run. Hope they fix this before next winter.


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## francoisp (Sep 28, 2018)

Lon12 said:


> Even with the battery temperature at 20ºC today I was getting the max regen value going from 70 down to below 30 and getting the reduced regen braking message after a long downhill run. Hope they fix this before next winter.


I don't know what your charge level was but I find that when the remaining charge is above 80% I get a lot less regen than when the charge is around 70% at lower temperature. It's also possible that the car was trying to limit overheating of the battery.


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