Regen issue?

[cylarian]

I am having a problem with regen braking being limited on my 2018 M3. I charge the car to 80% nightly. Temperatures here are in the 40s in the morning, but warm to mid 60's during the day. This has been going on for over 6 weeks. If regen braking returns to normal, it is limited again after another nightly charge to 80%. Local Service Center is telling me this is due to temperature and is 'normal' - but my vehicle has never experienced limited braking like this in these kinds of temperatures in the last 5 years. Anyone else experiencing this and/or have advice how to escalate this since my Service Center doesn't have a solution?

I ran into the same issue as you. Same temperature range, and this was the first winter season in years that I've seen limited regen all the time. The only way for me to get full regen back is to drive the car down to ~40-50%.

 

[AlanSubie4Life]

Why would this affect my vehicle and not others in my area under the same kind of temperature conditions?

Aside from the valid reasons that @jjrandorin gave:

This is all to prevent lithium plating of your battery, and it is possible that not all batteries have the same susceptibility (certainly LFPs will not, but I mean different NCAs - for example from the end of 2020 to the middle of 2021 a new NCA battery was introduced, which will be different).

And it may also depend on how you have used your battery (which may affect the BMS perception of the health of your battery - internal resistance, etc.). So even vehicles of identical vintage under identical conditions may not be the same (though I would expect that most of the time they would be very similar).

Just turn on emulated regen braking and forget about it. You can tell when it is happening because you’ll hear the telltale whining of the car creating heat from regen to dump into the battery going downhill (a whine very similar to Supercharger preheating). So you don’t need to worry about “forgetting” that you’re wasting energy.

 

[tsmith227]

Aside from the valid reasons that @jjrandorin gave:

This is all to prevent lithium plating of your battery, and it is possible that not all batteries have the same susceptibility (certainly LFPs will not, but I mean different NCAs - for example from the end of 2020 to the middle of 2021 a new NCA battery was introduced, which will be different).

And it may also depend on how you have used your battery (which may affect the BMS perception of the health of your battery - internal resistance, etc.). So even vehicles of identical vintage under identical conditions may not be the same (though I would expect that most of the time they would be very similar).

Just turn on emulated regen braking and forget about it. You can tell when it is happening because you’ll hear the telltale whining of the car creating heat from regen to dump into the battery going downhill (a whine very similar to Supercharger preheating). So you don’t need to worry about “forgetting” that you’re wasting energy.

So are you suggesting that my battery may not be in optimal health and that's why it cannot accept full regen breaking as it once did? My larger concern is this is an early indication of a battery issue, though Tesla doesn't want to admit it. The SC has not offered any explanation that makes sense -- they're trying to tell me it's normal due to cold weather but I know that's not true given the history of driving the car in these same weather conditions for several years.

 

[AlanSubie4Life]

So are you suggesting that my battery may not be in optimal health and that's why it cannot accept full regen breaking as it once did

No. Just that batteries may vary in that ability. To be clear, there may be no such differences for a battery of a given type. But in the end the BMS in each car follows a different path, and could that mean (slight) regen differences? Maybe.

Who are you comparing to (in 100% identical conditions)? Which vehicle?

If you live on a hill or have long downhills you’ll see this much more than others, because lack of regen “builds up.”

 

[tsmith227]

No. Just that batteries may vary in that ability. To be clear, there may be no such differences for a battery of a given type. But in the end the BMS in each car follows a different path, and could that mean (slight) regen differences? Maybe.

Who are you comparing to (in 100% identical conditions)? Which vehicle?

If you live on a hill or have long downhills you’ll see this much more than others, because lack of regen “builds up.”

I don't live on a hill or drive in any hilly areas. My charging habits, driving, conditions, and the winter temperatures haven't changed during the time I have owned the vehicle. Obviously, I can't compare say the comparison to other vehicles match conditions 100%. But in conversations with other Tesla owners in my area who have M3 of the same year, no one has ever experienced this. I have a hard time accepting this recent change is due to "cold weather" since this has never been an issue for winters past.

 

[AlanSubie4Life]

I don't live on a hill or drive in any hilly areas. My charging habits, driving, conditions, and the winter temperatures haven't changed during the time I have owned the vehicle. Obviously, I can't compare say the comparison to other vehicles match conditions 100%. But in conversations with other Tesla owners in my area who have M3 of the same year, no one has ever experienced this. I have a hard time accepting this recent change is due to "cold weather" since this has never been an issue for winters past.

As has been mentioned the software has changed.

Regarding comparisons - do you keep your car in an attached garage? How about the people comparing to? What SOC level do they use? Do they use the regen emulator?

It’s normal to have regen dots if it is slightly cold (50 degrees) and your SOC is above 60%. You don’t have hills but if you did it would get worse as you went downhill, before it got better. Can only accept so much regen and then it restricts it more.

Just keep SOC at 55% if it works for you, and ignore it.

 

[WhiteandBlack]

There is no way to escalate it. Tesla changed the algorithms for regen braking (probably because regen braking is similar to supercharging with the amount of energy put in the battery), so regen is less strong than it was before, and it appears its more sensitive to temperature.

There is no one who is going to change this for you, and no way to escalate it. Change your brake options to use the regular brakes when regen is limited, that is the only option you have.

Very valid comment and my experience as well. Tesla SC are like a brick wall.

But I would question why Tesla can’t use diagnostic outputs to evaluate and report on vehicle performance to customers. To provide comfort and confidence in their products.

How do we know if one of our problems are not a component part failure, malfunction, or simply a part not performing to specification, or not.

(And well, then there are over the air changes to core features on vehicles after you buy it, without your prior agreement Imagine buying a Ferrari, and an over the air update disables one of its gears or switches out 4 cylinders to save fuel, Mmm. Maybe not a good example but you get the drift.)

Problems may not be a safety risk, but do limit the enjoyment of the vehicle. Why cannot one vehicle have a fault, and others not.

If you cannot escalate and get quantifiable data to explain what is happening, even if it gives confirmation that the vehicle is operating within specification, how can you have confidence in the vehicle.

Defects in manufacturing, in software development, and from wear and tear are a fact of life. Not all component parts, in all vehicles, manufactured by a single manufacturer, will always be perrrfect. Defects occur.

How are these assessed and managed. After all, Tesla is a technology company isn’t it!

I would question why Tesla can’t use diagnostic outputs to evaluate and report on vehicle performance to be shared with customers.

Tesla must have diagnostics tools and standards against which their diagnostic tools can evaluate output.

They simply need to develop a means of explaining, sharing and educating customers with quantified benchmarking data.

Maybe the EV market is just too immature, but I expect some other manufacturers will soon provide this info, as a product and service differentiator.

With all the new competitors coming to market, new options are bound to appear. Manufacturers will have to provide more definitive responses to customer concerns.

The bonus of competition and choice.

Anyway, just my thoughts.

 

[jjrandorin]

Manufacturers will have to provide more definitive responses to customer concerns.

Sure, just like all the current legacy car manufactures currently do. They all report every detail of the operation of the car to the customer, without any need for the customer to use third party apps or forums to find that information. /s

 

[WhiteandBlack]

Sure, just like all the current legacy car manufactures currently do. They all report every detail of the operation of the car to the customer, without any need for the customer to use third party apps or forums to find that information. /s

Sorry but I may have read things wrong, but it seems to me that people are suggesting that a 50% reduction in range should be accepted as a solution, because the SC cannot help. That’s a bummer.

My take would be the SC owes more support in the circumstances.

I am unsure why such a compromise is needed. Why are we expected to accept less than we had, and less than the product we paid for. Sorry this is just me thinking aloud.

Yes I noticed the comment regarding the software change..has this software change been confirmed by Tesla or a best guess cause. It’s the first I have heard of such a change. Either way such a change would appear to have been made without notification or explanation on cause and effect.

To me brake regen/ one peddle driving is a core EV feature. Not an option.

But I deviate from the discussion on legacy manufacturers.

My take is, we are in a new world of motoring.

We are driving a computer on wheels and, legacy manufacturers are just that a legacy (the past), built on primarily mechanical components, not controlled or managed by computers. With new technology comes new ways of doing things. New expectations.

Sorry to sound pious, but I believe we have to forget what was, and embrace what is. , and we should not have to compromise on core features, simply because the manufacturer changed their minds midway through the ownership model, on their software design.

But, one legacy concept I am still clingy too is, I still believe we should get the product we paid for

Legacy manufacturers and service departs could and did test component parts, and when asked, provide technical details in support of issues at hand. That has been my experience anyway. Maybe coz I always ask. And where legacy manufacturers evolve into computer based products then my above comments on Ev’s apply equally to them.

I do not expect manufacturers to provide data without cause, but if they are presenting a point of view based on empirical evidence in their possession, and further if their explanations do not explain my concerns, then yes I expect them to present that evidence to me.

 

[jjrandorin]

Sorry but I may have read things wrong, but it seems to me that people are suggesting that a 50% reduction in range should be accepted as a solution, because the SC cannot help. That’s a bummer.

This is not one of the many "range" threads. This thread is about someone complaining about amount of regen (its "regen issue" not "range issue"). Perhaps you ment to reply to a different thread? There are plenty (and I mean plenty) of threads here about range, but thats not this one and I am not commenting on range.

 

[WhiteandBlack]

Sure, just like all the current legacy car manufactures currently do. They all report every detail of the operation of the car to the customer, without any need for the customer to use third party apps or forums to find that information. /s

This is not one of the many "range" threads. This thread is about someone complaining about amount of regen (its "regen issue" not "range issue"). Perhaps you ment to reply to a different thread? There are plenty (and I mean plenty) of threads here about range, but thats not this one and I am not commenting on range.

Yup understand. Appreciate the reality check. I did deviate a bit there. Again thanks.

I sort of lost focus in regards the comment above “Just keep SOC at 55% if it works for you, and ignore it.”

 

[izzzyyd]

braking regen 100% is no longer consistent, sometimes it flings your head to the windshield how it used to be, other times in just coasts…

Anybody experience this? I’m not talking about regen is low mode.

Talking about when you have full regen available it’s stopping power is inconsistent.

Before it used to be full head into the windshield 100% of the time.

It’s like having a regular car and pressing the brakes 50% gives you a range of 30-70% stopping power randomly…

The car is unsafe to drive as I have no idea what sort of stopping power will be applied I’ve almost gotten into 2 close calls because of it.

This seemed to have occurred after the last update, also first time I’ve ever seen the low regen message come up since owning the car.

Any issue to remedy this, thinking of just possibly selling it at this point it’s too unsafe to assume how it’s going to brake. Or I have to stay 10 car lengths behind

It’s ridiculous that this is even an issue, no car I’ve ever owned had stopping power randomly deviate, even when your brake pads start giving out the consistently wear and you know what to expect.

 

[izzzyyd]

Problem is even with use brakes when no regen, once full regen is on it starts acting inconsistently and no braking is applied to match

 

[izzzyyd]

Aside from the valid reasons that @jjrandorin gave:

This is all to prevent lithium plating of your battery, and it is possible that not all batteries have the same susceptibility (certainly LFPs will not, but I mean different NCAs - for example from the end of 2020 to the middle of 2021 a new NCA battery was introduced, which will be different).

And it may also depend on how you have used your battery (which may affect the BMS perception of the health of your battery - internal resistance, etc.). So even vehicles of identical vintage under identical conditions may not be the same (though I would expect that most of the time they would be very similar).

Just turn on emulated regen braking and forget about it. You can tell when it is happening because you’ll hear the telltale whining of the car creating heat from regen to dump into the battery going downhill (a whine very similar to Supercharger preheating). So you don’t need to worry about “forgetting” that you’re wasting energy.

What is emulated regen braking are you talking about “use brakes option”. Problem with that is brakes are only applied when you get the “low regen message”

As soon as you hit supposedly full regen it stops applying the brakes but the regen is highly inconsistent

It’s funny I starting experiencing these issues as soon as I reached Denver and the hilly mountains I don’t live here have only been here for a week and leaving.

Just find it crazy it’s like the car just decided to break because of some mountany hills with regards to regen…

 

[AlanSubie4Life]

Problem with that is brakes are only applied when you get the “low regen message”

In fact no message if you have the apply brakes when regen is limited is turned on.

As soon as you hit supposedly full regen it stops applying the brakes but the regen is highly inconsistent

Sounds like something wrong with your car. Bring it in for service. Regen is extremely consistent with this option.

Good luck.