Battery temp and "Regenerative braking reduced" warning

[ColonelBadger]

What temperature does the battery need to be to get "Regenerative braking reduced" when starting the car?

This morning I got in to go to work and put it in reverse only to be told Regen was reduced. The car was charged to 80% so it wasn't that. My only assumption was because the battery was cold, but it hadn't been that cold here; it had got to 27F outside the previous night but the car was in the garage. I wasn't expecting to see that until much colder.

 

[segbrk]

50-60F seems to be low enough for a slight reduction in regen.

 

[suchluke]

It's the combination of both State of Charge and outside temp. For example you may get a warning at 80% SOC and 50F outside. You may also get full regen when its 80% SOC and 75F+ outside. Also when it's below 50F and SOC is below 50% you may also get full regen. I don't know exact thresholds but hopefully you get the idea. This is all done to protect the battery health.

 

[ColonelBadger]

It's the combination of both State of Charge and outside temp. For example you may get a warning at 80% SOC and 50F outside. You may also get full regen when its 80% SOC and 75F+ outside. Also when it's below 50F and SOC is below 50% you may also get full regen. I don't know exact thresholds but hopefully you get the idea. This is all done to protect the battery health.

So bottom line its normal and everyone is seeing it as temperature drops. I guess I wasn't expecting it until way lower temps, but I'm new to EVs .

 

[suchluke]

Yes, completely normal. I am located in PA and observed similar warning when the temp dropped to 45F. Once I started driving and the state of charge reduced and battery temp increased the regen also increased. There is an indicator now around the speedometer when the regen is reduced it will be shown with the dashed line.

 

[mraschko]

So, I had the reduced braking warning come on as I was backing out of the garage this morning. Car was at 80% charge and said 56F. Now I haven't paid much attention to the garage temp leading up to this, but I'm pretty sure it's been similar lately and I haven't gotten the warning those other morning. I didn't notice any reduction in the regenerative braking either.

 

[jedwin]

I didn't notice any reduction in the regenerative braking either.

This is what I'm interested in hearing about from those who've lived with their cars for awhile: I'm *assuming* that the experiential difference when regenerative braking is "reduced" is fairly subtle in most cases, at least these temperature-dependent ones--as MrAschko found. Yes?

Conversely, when setting out at 100% charge, it would make total sense that most (all?) braking needs to be done with the physical brake, until there's enough battery capacity for regen to re-fill.

Are there times when the temperature-triggered regen reductions become noticeable enough to require frequent use of the physical brake? (other than when coming to a complete stop, where I can see it perhaps being needed)

 

[Pragmatic]

Read post #57 in the following thread for my experience lossing regen with a cold, not fully charged battery.

P

Post in thread 'Regenerative braking and range'

Jul 16, 2024

I have had a loss of regen at much less than 80%. Parking near the top of a hill plugged into a 120v outlet for two days and charged to close to 80%.
Leaving the Lodge I drive down a hill that varies between 5% and 14% grade down. It is a winding road where I accelerate to 40 (pressing accelerator but using little power) and slow quite quickly to 15 (using mostly regen). This is a steady down hill for approximately 10 miles with a total elevation loss of 1500 feet.
Not an alot of total elevation but fairly steep, steady and alot of drastic slowing events. Usually just before town I'll slow...

• Pragmatic

 

[ColonelBadger]

This is what I'm interested in hearing about from those who've lived with their cars for awhile: I'm *assuming* that the experiential difference when regenerative braking is "reduced" is fairly subtle in most cases, at least these temperature-dependent ones--as MrAschko found. Yes?

Conversely, when setting out at 100% charge, it would make total sense that most (all?) braking needs to be done with the physical brake, until there's enough battery capacity for regen to re-fill.

Are there times when the temperature-triggered regen reductions become noticeable enough to require frequent use of the physical brake? (other than when coming to a complete stop, where I can see it perhaps being needed)

At least my experience when it happened Tuesday, Regen breaking was quite a bit less than what I was used to. I generally use High Regen and it was at least behaving as Standard maybe less. It did get a lot better as I drove.

What I hadn't realize, even from the release notes of the software update that added the speedometer indication, is that Regen is VERY variable. By that I mean I hadn't realized because it the impact was so subtle that a lot of the mornings recently it was reduced. I saw a dashed line on the far bottom left of the speedometer that eventually went away, but the Regen felt normal. On Tuesday that dash was pretty much all the way up to approximately 9 O'clock on the dial and only then did I get the warning. So for others that are unaware, Regen appears to be VERY variable based on battery temp, but you only get a warning when it's reduced "enough".

 

[segbrk]

This is what I'm interested in hearing about from those who've lived with their cars for awhile: I'm *assuming* that the experiential difference when regenerative braking is "reduced" is fairly subtle in most cases, at least these temperature-dependent ones--as MrAschko found. Yes?

Conversely, when setting out at 100% charge, it would make total sense that most (all?) braking needs to be done with the physical brake, until there's enough battery capacity for regen to re-fill.

Are there times when the temperature-triggered regen reductions become noticeable enough to require frequent use of the physical brake? (other than when coming to a complete stop, where I can see it perhaps being needed)

The climate here doesn't get below 32F all that much, but I would say that cold-soaked in the 30s it feels maybe halfway to the "zero regen" feeling of a 100% charge. It is definitely noticeable, it definitely requires using the brakes. But it also only lasts the first 20-30 minutes of driving before the batteries get warmed up.

 

[mraschko]

This is what I'm interested in hearing about from those who've lived with their cars for awhile: I'm *assuming* that the experiential difference when regenerative braking is "reduced" is fairly subtle in most cases, at least these temperature-dependent ones--as MrAschko found. Yes?

Conversely, when setting out at 100% charge, it would make total sense that most (all?) braking needs to be done with the physical brake, until there's enough battery capacity for regen to re-fill.

Are there times when the temperature-triggered regen reductions become noticeable enough to require frequent use of the physical brake? (other than when coming to a complete stop, where I can see it perhaps being needed)

No. Not necessarily. I have had experiences prior to Lucid rolling out the regenerative braking warning where I have had NO regenerative brakes when the car is charged to 80%. Let me tell you, coming down a hill that gets spooky. I've complained to customer support but since it's not a consistent occurrence, no progress was made. I'm waiting to hit it again to see if I'll have received the warning or not.

 

[mraschko]

Today, I had the reduced regenerative braking warning 3 times in ~55F weather. Didn't notice any actual change in braking performance again, but I was driving on fairly flat roads 45mph or less.

 

[porkinz]

Is there any way to warm the battery prior to getting into the car so that regen is fully activated by the time I start driving?

 

[segbrk]

Is there any way to warm the battery prior to getting into the car so that regen is fully activated by the time I start driving?

If you're not plugged in and don't mind burning through some charge, you can start preconditioning as if you were going to fast charge. Or schedule your overnight charging such that it usually finishes just before you leave in the morning, the charging will warm the battery.
You should just make a habit of checking the regen via the power gauge on your dash before setting out though, so you know what to expect. At some point you're going to encounter limited regen for one reason or another, so best to be prepared for it.

 

[porkinz]

If you're not plugged in and don't mind burning through some charge, you can start preconditioning as if you were going to fast charge. Or schedule your overnight charging such that it usually finishes just before you leave in the morning, the charging will warm the battery.
You should just make a habit of checking the regen via the power gauge on your dash before setting out though, so you know what to expect. At some point you're going to encounter limited regen for one reason or another, so best to be prepared for it.

Thanks! Great idea! Any idea how long I should preconditioning needs in order to accomplish this? 5 minutes? 10? 30?

 

[segbrk]

Thanks! Great idea! Any idea how long I should preconditioning needs in order to accomplish this? 5 minutes? 10? 30?

I think the recommendation for preconditioning before fast charging is 45 minutes. Depends on how cold it is, I guess - I haven't really tried to time it. I'm guessing 5-10 minutes won't do much of anything though.

 

[porkinz]

Copy that thank you!

 

[jedwin]

If I keep the car plugged in when at home (somewhere I heard "a happy car is a plugged in car"??), then in winter I could presumably pre-condition prior to heading out, with the car topping itself off as needed, up to its pre-set max. Yes?

(I think that this, and/or pre-heating the cabin in winter, was the context where I heard that "happy car" phrase, elsewhere on the Forum, ie working from the assumption it'd be plugged in at home)

 

[borski]

If I keep the car plugged in when at home (somewhere I heard "a happy car is a plugged in car"??), then in winter I could presumably pre-condition prior to heading out, with the car topping itself off as needed, up to its pre-set max. Yes?

(I think that this, and/or pre-heating the cabin in winter, was the context where I heard that "happy car" phrase, elsewhere on the Forum, ie working from the assumption it'd be plugged in at home)

I’m not sure if you can precondition *while* on an L2 charger, but if you can, that sounds right to me.

And yes, in general, keeping it plugged in allows the car to manage its battery temp and charge as needed.

 

[jedwin]

And yes, in general, keeping it plugged in allows the car to manage its battery temp and charge as needed.

In winter and high summer, does this "manage the battery temp" include some heating and cooling, separate from triggering the "preconditioning" operation?

I guess I mean, then, does the battery conditioning (heating/cooling) system operate automatically when plugged in during extreme climate conditions? Or is there a setting to put it on, to ask it to do so?

Thanks!!