Battery Health and Regen Behavior

[CKwik240]

So sometime around the end of the year, my battery range dropped from about 267-270 at 90% down to about 240 miles. It was a rather abrupt drop rather than gradual. Used to get about 287-289 miles at 100%. Yessir estimated the max range at 268. I don't drive the car down to low range to often but I was down to about 25% on Sunday. Let it sit for about an hour unplugged with sentry off before letting it charge.

Monday morning I noticed the range was a bit higher (can't remember the exact number) at 90% so I increased the charge to 100% but didn't have time for it to top out before leaving for work. It hit about 265 miles of range at maybe 95%.

So Monday night, I let it charge to 100% and woke up to 270 miles of range. So perhaps I need to try and bring the range down and to of a few times while allowing it to sit a bit without charging. But what was weird was that usually when I charge to 100%, I get a warning telling me my Regen will be limited for some time. Didn't get such a warning this time.

Ultimately, my 2 questions are:
1. Is such an abrupt drop in range normal?
2. Is the lack of limited Regen normal at fill charge in this scenario?

TIA.

 

[UncleCreepy]

The estimated range usually decreases when it gets cold. I was down to like 465 km last winter but when it got warmer it got up to 478. This winter (so far) it's down to 456 km. It appears to be a normal mixture between degradation and temperature.

The available regen depends on state of charge and temperature. With a full battery there is very little regen possible. With a cold soaked battery you're not getting any regen at all regardless of the state of charge. On a side note, there may still be a little deceleration when you take the foot off the go pedal because even though you're not technically regenerating (i.e., putting energy back into the battery), the car will get the energy it requires from the motors instead of from the battery when you slow down. Give it a try with the heater off vs at full power. There is a noticeable difference.
But to answer your question yes, it is perfectly normal to have little to no regen when the battery is fully charged.

 

[jjrandorin]

So sometime around the end of the year, my battery range dropped from about 267-270 at 90% down to about 240 miles. It was a rather abrupt drop rather than gradual. Used to get about 287-289 miles at 100%. Yessir estimated the max range at 268. I don't drive the car down to low range to often but I was down to about 25% on Sunday. Let it sit for about an hour unplugged with sentry off before letting it charge.

Monday morning I noticed the range was a bit higher (can't remember the exact number) at 90% so I increased the charge to 100% but didn't have time for it to top out before leaving for work. It hit about 265 miles of range at maybe 95%.

So Monday night, I let it charge to 100% and woke up to 270 miles of range. So perhaps I need to try and bring the range down and to of a few times while allowing it to sit a bit without charging. But what was weird was that usually when I charge to 100%, I get a warning telling me my Regen will be limited for some time. Didn't get such a warning this time.

Ultimately, my 2 questions are:
1. Is such an abrupt drop in range normal?
2. Is the lack of limited Regen normal at fill charge in this scenario?

TIA.

Consider reading the first post in the following thread (the rest of the 72 pages of posts is mostly discussion around the topic).

How I Recovered Half of my Battery's Lost Capacity

This part needs to be highlighted because it is precisely the opposite of what the car asks us to do. Last month came back from a road trip with about 5% left, as soon as I press PARK the car gives me a warning to charge it ASAP to minimize the risk of going below zero. I obeyed and...

teslamotorsclub.com

1. Depends. its an estimate, and sometimes the computer estimates better than other times, or it drops during the winter.
2. Depends on if you have the blended brake setting on or not:

Model 3 Owner's Manual | Tesla

Understand your vehicle's braking system and stopping features.

www.tesla.com

Regenerative Braking​

Whenever Model 3 is moving and your foot is off the accelerator, regenerative braking slows down the vehicle and feeds any surplus power back to the Battery. By anticipating your stops and reducing or removing pressure from the accelerator pedal to slow down, you can take advantage of regenerative braking to increase driving range.
Vehicle deceleration due to regenerative braking may vary depending on the current state of the Battery. For example, regenerative braking may be limited if the Battery is cold or is already fully charged.
To experience the same amount of deceleration whenever you release the accelerator pedal, regardless of the state of the Battery, you can choose to have the regular braking system automatically engage whenever regenerative braking is limited. Touch Controls > Pedals & Steering > Apply Brakes When Regenerative Braking is Limited.
Note
If Apply Brakes When Regenerative Braking is Limited is enabled and applying the brakes, the brake pedal may move and it may feel stiffer when pressed. This is expected and does not change your ability to slow down Model 3.

 

[AlanSubie4Life]

2. Is the lack of limited Regen normal at fill charge in this scenario?

Touch Controls > Pedals & Steering > Apply Brakes When Regenerative Braking is Limited.

Yes, if the OP has this option turned on, presumably the message will not show up.

Note that turning this option on/off affects whether or not the regen bar shows friction brake use when in FSD or AP. IIRC you have to turn it on to display friction brake use (by the car - driver brake input is NEVER displayed, presumably to avoid mode confusion).

 

[CKwik240]

The estimated range usually decreases when it gets cold. I was down to like 465 km last winter but when it got warmer it got up to 478. This winter (so far) it's down to 456 km. It appears to be a normal mixture between degradation and temperature.

The available regen depends on state of charge and temperature. With a full battery there is very little regen possible. With a cold soaked battery you're not getting any regen at all regardless of the state of charge. On a side note, there may still be a little deceleration when you take the foot off the go pedal because even though you're not technically regenerating (i.e., putting energy back into the battery), the car will get the energy it requires from the motors instead of from the battery when you slow down. Give it a try with the heater off vs at full power. There is a noticeable difference.
But to answer your question yes, it is perfectly normal to have little to no regen when the battery is fully charged.

I didn't think much of it when it started for to colder than usual whether (I'm in socal). But temps are warmer and inline with temps before I started seeing this. Heater is hardly on at this point.

Ultimately I was just trying to see if 100% charge would still cause a decreased Regen warning if battery capacity degrades or is not calibrated accurately.

 

[CKwik240]

Consider reading the first post in the following thread (the rest of the 72 pages of posts is mostly discussion around the topic).

How I Recovered Half of my Battery's Lost Capacity

This part needs to be highlighted because it is precisely the opposite of what the car asks us to do. Last month came back from a road trip with about 5% left, as soon as I press PARK the car gives me a warning to charge it ASAP to minimize the risk of going below zero. I obeyed and...

teslamotorsclub.com

1. Depends. its an estimate, and sometimes the computer estimates better than other times, or it drops during the winter.
2. Depends on if you have the blended brake setting on or not:

Model 3 Owner's Manual | Tesla

Understand your vehicle's braking system and stopping features.

www.tesla.com

Regenerative Braking​

Whenever Model 3 is moving and your foot is off the accelerator, regenerative braking slows down the vehicle and feeds any surplus power back to the Battery. By anticipating your stops and reducing or removing pressure from the accelerator pedal to slow down, you can take advantage of regenerative braking to increase driving range.
Vehicle deceleration due to regenerative braking may vary depending on the current state of the Battery. For example, regenerative braking may be limited if the Battery is cold or is already fully charged.
To experience the same amount of deceleration whenever you release the accelerator pedal, regardless of the state of the Battery, you can choose to have the regular braking system automatically engage whenever regenerative braking is limited. Touch Controls > Pedals & Steering > Apply Brakes When Regenerative Braking is Limited.
Note
If Apply Brakes When Regenerative Braking is Limited is enabled and applying the brakes, the brake pedal may move and it may feel stiffer when pressed. This is expected and does not change your ability to slow down Model 3.

I read through several pages of that post on the past and again when this issue came up. It's good info bit doesn't necessarily answer my questions in the first several pages though I may not recall any discussion about Regen capability as I read it before I noticed this issue.

Good idea checking on the blended brake. When it came out, I had only charged to 100% a couple of times before, so I didn't really do anything with it so I'm not sure what it's set to now. May need to test at 100% again if it's blending the brakes.

 

[CKwik240]

Yes, if the OP has this option turned on, presumably the message will not show up.

Note that turning this option on/off affects whether or not the regen bar shows friction brake use when in FSD or AP. IIRC you have to turn it on to display friction brake use (by the car - driver brake input is NEVER displayed, presumably to avoid mode confusion).

Interesting, but I only have cruise control so it doesn't sound like it applies.

Thanks everyone for the input. Just need to find time to draw down SOC to near zero in hopes I can bring the max range back up. My driving fluctuates wildly at times so I'm not too keen on doing so until a long trip or when I know for sure I don't need a moderate available range. I'm not so concerned my current estimated max range won't get me where I need to go, but my curiosity about it has me a bit anxious as to whether or not I've actually lost so much range so quickly and why. The engineer in me needs answers... Lol

 

[AlanSubie4Life]

Interesting, but I only have cruise control so it doesn't sound like it applies.

Thanks everyone for the input. Just need to find time to draw down SOC to near zero in hopes I can bring the max range back up. My driving fluctuates wildly at times so I'm not too keen on doing so until a long trip or when I know for sure I don't need a moderate available range. I'm not so concerned my current estimated max range won't get me where I need to go, but my curiosity about it has me a bit anxious as to whether or not I've actually lost so much range so quickly and why. The engineer in me needs answers... Lol

This range loss is normal. Separate issue from your regen.

That option is applicable even if you just have AP because the car can brake on its own. And also if it is enabled it won’t bug you about limited regen.

 

[jjrandorin]

I read through several pages of that post on the past and again when this issue came up. It's good info bit doesn't necessarily answer my questions in the first several pages though I may not recall any discussion about Regen capability as I read it before I noticed this issue.

Good idea checking on the blended brake. When it came out, I had only charged to 100% a couple of times before, so I didn't really do anything with it so I'm not sure what it's set to now. May need to test at 100% again if it's blending the brakes.

I wasnt referencing that thread for regen braking. I was referencing it for:

So perhaps I need to try and bring the range down and to of a few times while allowing it to sit a bit without charging.

 

[CKwik240]

I wasnt referencing that thread for regen braking. I was referencing it for:

That thread didn't really answer the questions I had in the first few pages that I recall. I had 2 specific questions. Just looking for answers to them. That's all.

 

[AlanSubie4Life]

That thread didn't really answer the questions I had in the first few pages that I recall. I had 2 specific questions. Just looking for answers to them. That's all.

1. Is such an abrupt drop in range normal?
2. Is the lack of limited Regen normal at fill charge in this scenario?

1) Yes. Often steps up or down. Perfectly normal and expected to see large shifts in the rated range, which of course are usually not physical.
2) Yes. Check your config to confirm.

 

[derotam]

Interesting, but I only have cruise control so it doesn't sound like it applies.

Thanks everyone for the input. Just need to find time to draw down SOC to near zero in hopes I can bring the max range back up. My driving fluctuates wildly at times so I'm not too keen on doing so until a long trip or when I know for sure I don't need a moderate available range. I'm not so concerned my current estimated max range won't get me where I need to go, but my curiosity about it has me a bit anxious as to whether or not I've actually lost so much range so quickly and why. The engineer in me needs answers... Lol

At 100% SOC whether with a degraded battery or not, presumably your regen would be limited mainly because it can't put more charge into an already full battery. And when I say full I mean at capacity, whatever that 100% capacity is. Battery degradation changes the 100% capacity. A bad BMS calibration changes the capacity(in regards to what the car thinks).

You don't need to charge to "near zero". 20% is plenty sufficient. The car also needs sit there for a while so that the battery level can stabilize before the BMS will take a measurement to use for calibration. I believe the time period is an unknown value but I would guess more than 1 hour. And whether required or not I would probably make sure sentry is off so that the car can properly sleep as well.

 

[CKwik240]

1) Yes. Often steps up or down. Perfectly normal and expected to see large shifts in the rated range, which of course are usually not physical.
2) Yes. Check your config to confirm.

That's helpful. A large drop seemingly overnight seemed excessive.

I did have blended braking on Afterall. Charged to 100% overnight and about to drive to work so I'll confirm if Regen becomes limited.

Thanks.

 

[CKwik240]

At 100% SOC whether with a degraded battery or not, presumably your regen would be limited mainly because it can't put more charge into an already full battery. And when I say full I mean at capacity, whatever that 100% capacity is. Battery degradation changes the 100% capacity. A bad BMS calibration changes the capacity(in regards to what the car thinks).

That was my thinking, which is why I was concerned.

You don't need to charge to "near zero". 20% is plenty sufficient. The car also needs sit there for a while so that the battery level can stabilize before the BMS will take a measurement to use for calibration. I believe the time period is an unknown value but I would guess more than 1 hour. And whether required or not I would probably make sure sentry is off so that the car can properly sleep as well.

Understood. Still not a convenient thing to do considering my driving habits. But I'll figure it out, probably after my business travels next week. Wife will be driving the car while I'm gone and I'm not going to task her with this.

 

[AlanSubie4Life]

A large drop seemingly overnight seemed excessive

Yep, happens all the time! Very normal.