Regen Braking Temporarily Reduced - Every time

[Mvdaog]

This is all so silly. Preconditioning and warming the battery up prior to leaving for your half hour drive using electricity through the charger doesn’t make sense. You either put energy in before leaving or put it in when you get back. You can’t come out net positive by warming the battery up prior to leaving. The amount of electricity used to warm up the car and battery for an hour before leaving is a waste compared to decreased regeneration loss that you’ll replace when you plug back in!
The only reason it would make sense to warm everything up and get your regen before departing is if you were planning on doing a 400km drive without any chargers in between and needed to maximize your efficiency for this trip to make it on a single charge. Everyone’s geeking out and paying too much attention!

 

[pt19713]

This is all so silly. Preconditioning and warming the battery up prior to leaving for your half hour drive using electricity through the charger doesn’t make sense. You either put energy in before leaving or put it in when you get back. You can’t come out net positive by warming the battery up prior to leaving. The amount of electricity used to warm up the car and battery for an hour before leaving is a waste compared to decreased regeneration loss that you’ll replace when you plug back in!
The only reason it would make sense to warm everything up and get your regen before departing is if you were planning on doing a 400km drive without any chargers in between and needed to maximize your efficiency for this trip to make it on a single charge. Everyone’s geeking out and paying too much attention!

Can you show us your data to prove otherwise?

 

[Mvdaog]

Can you show us your data to prove otherwise?

To prove what, sorry? That using energy prior to departing by turning on the hvac can’t possibly be less than the energy gained by more regeneration? Or are you asking about something else?
That’s just common sense. The car can recover some energy during regeneration but it doesn’t produce more than it consumes (on flat). The only reason to precondition to get more regeneration like I said is if you need to make it further on a charge.

 

[pt19713]

To prove what, sorry? That using energy prior to departing by turning on the hvac can’t possibly be less than the energy gained by more regeneration? Or are you asking about something else?
That’s just common sense. The car can recover some energy during regeneration but it doesn’t produce more than it consumes (on flat). The only reason to precondition to get more regeneration like I said is if you need to make it further on a charge.

This isn't just about trying to net more than what's consumed during pre-conditioning. No one here is trying to generate more brake regen to net a higher battery percentage. The recent discussion is more more about making sure the battery is warmer than if you were to not pre-condition it. The battery is more efficient at warmer temps, you have more power at warmer temps, and you have more brake regen at warmer temps. I'll spend the 15 minutes to pre-condition and the $0.16 that it's going to cost me. Obviously I'm not trying to convince you nor will I try. You're adult and can make your own decisions.

Pretty much everything on page 2 is explaining to people why the brake regen is reduced when the battery is cold.

 

[Puma2020]

Yep, I get that message daily now. Tesla in winters. Of course it is much colder here now.
My baby likes to be in the garage (not heated though) and she likes it when I turn on climate controls before I get ready to leave.
I think of it as foreplay. When she's happy, I'm happy.
I also like getting in a nice 70 degree car when it is 30 outside.

Without preheating, I see lots of dots.


After a reasonable amount of time, less dots but also less range.


Nothing drastic, it's just the future that is here now.
Hakuana Matata.

 

[Mvdaog]

Yea. I get that, I used to do a lot of preconditioning and all that too. But I realized that it costs more energy to our planet to do that than to not so I just don’t bother anymore. My efficiency numbers might not look quite as good now in my trip calculators but I’m saving a little bit of energy from the grid. To each their own though it’s really almost a wash whether you do or not so if you like more regeneration go for it!

 

[GtiMart]

...and for that purpose, I would love it if we could choose whether we precondition the battery or not, when we turn the cabin conditioning on for human comfort. I would NOT precondition the battery for a 2-5km drive... I would definitely precondition the battery for a 30min+ drive...

 

[5UBV3T]

I just want to remind everyone on this thread that their Tesla has brakes. That's that pedal on the left you used to use in your old car to slow down. It will help you slow down when the temperature and/or your battery's SOC affects your regen braking.

I've only had my MY for 8 days so I still remember what that thing is. I'm taking a screen shot of this reply and making it my desktop background so in a few week when I forget what the brake pedal is for, it will remind me.

 

[JonMu]

Tesla has brakes

That's just crazy talk!

 

[HeyEph]

That's just crazy talk!

#HateBrakes

 

[2101Guy]

Yea. I get that, I used to do a lot of preconditioning and all that too. But I realized that it costs more energy to our planet to do that than to not so I just don’t bother anymore. My efficiency numbers might not look quite as good now in my trip calculators but I’m saving a little bit of energy from the grid. To each their own though it’s really almost a wash whether you do or not so if you like more regeneration go for it!

are you sure about that? You are Sure that more KWH are lost during preconditioning vs not preconditioning and thus losing more KWH (and having to use electricity to replenish those lost KWH) during driving on a cold battery?

 

[pt19713]

are you sure about that? You are Sure that more KWH are lost during preconditioning vs not preconditioning and thus losing more KWH (and having to use electricity to replenish those lost KWH) during driving on a cold battery?

Generally speaking, it'll net more power needed to charge than what you'll regen back and higher efficiency due to a warmer battery. There will be exceptions, like a one way trip down a hill, where max regen will be beneficial since you can regen up to 78 kW.

 

[jcanoe]

This evening I learned something new about the Tesla vehicle status screen. The 1st photo shows the familiar alert icon and the full message "Regenerative Braking Temporarily Reduced Yada Yada"



The 2nds photo shows just the alert icon (green circle with lower case letter "i").



I learned that if you swipe left on the alert message text the alert will collapse into just the alert icon. I did not know that until tonight.

 

[Gizmotoy]

I see this all the time too. I thought it was broken so I actually have a service center visit scheduled. The Model Y sits in the warm garage and when I leave I have 100% regen. After about 15-20 minutes of driving, it pops the regenerative braking is reduced warning. I'd be surprised if driving it actually reduces the battery temps, so there has to be some other factor at work.

My Model S is much more predictable. If it's cold, regen is gradually increased as you drive.

 

[pt19713]

I see this all the time too. I thought it was broken so I actually have a service center visit scheduled. The Model Y sits in the warm garage and when I leave I have 100% regen. After about 15-20 minutes of driving, it pops the regenerative braking is reduced warning. I'd be surprised if driving it actually reduces the battery temps, so there has to be some other factor at work.

My Model S is much more predictable. If it's cold, regen is gradually increased as you drive.

Your S uses the heated filaments to heat the cabin. The Y uses the heat from battery to heat the cabin, which is why the battery temps drop under most winter driving conditions.

Here's a 33 minute drive I logged. Ambient temp 26F. Battery was at 71F at the start of the drive, ended at 67F.
For some reason the front stator motor temps got removed from the plot. Once the motors cooled down from the preconditioning temps to the normal operating temps after 10-12 minutes, the battery packs started to cool down despite limited use of the in-cabin heat. I turned on the defrost a few times, so about 6 times during the drive with duration of 30-45 seconds, just enough to clear the windows. I wanted to test the battery temps during a drive with limited use of the heat. The next time I log the data, I'll see how much more heat the battery loses if I leave the HVAC on the whole time.

Note, I had full brake regen at the start and after 10 minutes, brake regen was slightly limited.

 

[TomServo]

After watching several of Bjorn's YouTube video's I now have a much better understanding of what's going one. Unfortunately you need a gizmo like ScanMyTesla to see how the car is behaving/reacting to various stimuli i.e. OAT, Battery Temp, Pre-Conditioning etc.

Even plugged in and sitting in a cold garage (say 45 degrees) over night will cause the battery pack to get COLD. I find pre-conditioning for at least 15 minutes before driving reduces the loss of re-gen. I can usually get the # of dots down to 4 or 5 and that's good enough for the car to feel almost normal and no warning message pop up.

But the trick is to remember to pre-condition prior to driving? If I'm running errands we just hop in the car like we have done for 50+ years and go. And the pack will NEVER get warm enough to give you "full regen".

 

[jcanoe]

If you have a daily routine or a weekday commute (before many started working from home) you can set a scheduled departure time for Monday thru Friday or All Week. The Tesla will wake up and start preconditioning the vehicle about 30 minutes before the scheduled departure time. If you leave a little earlier or later than the scheduled departure time it won't matter. The preconditioning cycle will end 30 minutes after the scheduled departure time.

 

[pt19713]

Even plugged in and sitting in a cold garage (say 45 degrees) over night will cause the battery pack to get COLD. I find pre-conditioning for at least 15 minutes before driving reduces the loss of re-gen. I can usually get the # of dots down to 4 or 5 and that's good enough for the car to feel almost normal and no warning message pop up.

But the trick is to remember to pre-condition prior to driving? If I'm running errands we just hop in the car like we have done for 50+ years and go. And the pack will NEVER get warm enough to give you "full regen".

I think as long as people colder climates accept that not having full brake regen (in a Model Y) is going to be the norm and that having a few dots isn't the end of the world, we should be fine. Having 5-7 dots is a reduction from 78 kW max regen down to about 60-65 kW. The only time you'll hit 78 kW is from an abrupt high speed. Lifting off the accelerator pedal even from 55-60 mph still only regens around 50-60 kW. If people feather the pedal, they'll get back around 20-25 kW at higher speeds, 10-15 kW at lower speeds.

Just some input from various testing with the SMT app. I can log and graph the data if people are still suspect.

 

[mswlogo]

I charge to about 90%, but even after driving for 20miles, every time I get in my car, I get the "Regen Braking is Temporarily Reduced".

This shouldn't be the case when it's 60deg out and I'm at 90% or lower, right?
Anything I can do to fix this myself?

How cold it was over night is what matters more than how warm it is while your driving.

I stopped charging to 90% because all it did was cut into regen. To me it was a little birdie telling me that 90% is to high.

The combination of high SOC and cool temps (over night) will trigger limited regen. It takes quite a bit of driving to warm the battery. Especially if driving with a light foot.

Note that as long as you have some regen you can be pretty efficient. And it’s not that often you actually hit 100% regen when it is available. Watch the gauge, it rarely ever pegs on regen in normal efficient driving.

 

[Pianewman]

STOP LOOKING AT THE DOTS! YOUR REGEN WON'T MATTER WHEN YOU REAR END THE IDIOT THAT STOPPED IN FRONT OF YOU W/O WARNING!!!