Dotted line - regen

[bc1979]

So I have had my car a few weeks now and I am loving it but I do seem to get quite a few if the dotted regen dots all the time along with the message about deceleration being limited and needing to use the brake.

I understand that this is because the battery is supposedly cold but I am also getting logs of the dots even when heading out in the car when it’s about 12-13 degrees which I wouldn’t class as cold.

Is this normal? I kind of understand it but wouldn’t expect it quite as much as I am, such as on a sunny Saturday afternoon yesterday, and just want to know if I am alone in this?

 

[muster39]

If the battery is fully charged then there is nowhere for the regen electricity to go. Could this be the issue?

 

[bc1979]

It’s still when it’s not fully charged, for example yesterday I set off with the battery at 87% and had about 6 dots and it was 12 degrees?

Would people generally expect to see dots and get that message at this time of year?

It’s a two week old RWD for info.

 

[Adopado]

So I have had my car a few weeks now and I am loving it but I do seem to get quite a few if the dotted regen dots all the time along with the message about deceleration being limited and needing to use the brake.

I understand that this is because the battery is supposedly cold but I am also getting logs of the dots even when heading out in the car when it’s about 12-13 degrees which I wouldn’t class as cold.

Is this normal? I kind of understand it but wouldn’t expect it quite as much as I am, such as on a sunny Saturday afternoon yesterday, and just want to know if I am alone in this?

Yes it's normal. Cold to you as a human living in the UK is different from cold as experienced by the battery pack at the same temperature! 12-13 degrees is still "cold". You will find that if running at high states of charge ... especially 100% ... you will get some limitation of regen no matter what the temperature. If you are considering wearing a T shirt and shorts that's about the point the battery is also free from "cold" ... so 20C plus

 

[bc1979]

Yes it's normal. Cold to you as a human living in the UK is different from cold as experienced by the battery pack at the same temperature! 12-13 degrees is still "cold". You will find that if running at high states of charge ... especially 100% ... you will get some limitation of regen no matter what the temperature. If you are considering wearing a T shirt and shorts that's about the point the battery is also free from "cold" ... so 20C plus

Ok thanks for that, good to know.

 

[Adopado]

Ok thanks for that, good to know.

I should have also noted that this temperature description refers to how the battery pack is at the beginning of a trip. The pack will heat up just through normal use ... or more rapidly from spirited driving ... so the dots eventually disappear completely, though with calm driving even at 15 degrees they may never disappear completely (but to all intents and purposes you will have a level of regen not much different from no dots in my experience). Something you will find at this time of the year is that even when daytime temperatures are moderately good the battery pack could have "cold soaked" through a long cold night ... and if you haven't driven for a couple of days this night-time cold soaking will mean that the pack starts off cooler than you think, even on warm days. None of this impairs use of the car of course but for those interested in why the car reports restrictions to regen it's worth being aware of.

 

[blert]

I had this 'issue' (at 72% SoC but about 8 degrees outside) a couple of days ago as well and was wondering about it - thanks for the explanations!

 

[Cwmwd]

Think of the car as a soft southern jessie that's cold even on the warmest of spring mornings. I mean, it's British Summer Time now so offically time for shorts and sandals but still it moans...

 

[Js1977]

You can improve the the regen by preconditioning even if just for a bit before departure in the morning. The LFP battery in your car takes a fair bit longer to warm up in comparison to the previous generation cars with "older" type of battery from experience of running both. One positive you can take from this is that it gives you a natural chance of keeping your callipers in good working order and your discs clean which would otherwise take a bit more consideration depending on how you normally drive.

 

[Tigermad]

Since the latest updates I get the regen message a lot more times now. Had the car a year. It’s getting warmer outside and it still pops up. I’m convinced the firmware has caused the popup to appear even though it’s not needed at the time.

 

[WannabeOwner]

It’s getting warmer outside

Cold overnight? The battery will be "cold soaked" and take some time to warm up - spirted driving may reduce that time.

 

[Tigermad]

Cold overnight? The battery will be "cold soaked" and take some time to warm up - spirted driving may reduce that time.

nope. It even comes up when it’s warmed up after being shopping etc. it’s just the message, the regen actually works fine with lots of green. It’s obviously a bug on some cars.

 

[WannabeOwner]

It even comes up when it’s warmed up after being shopping etc.

I doubt that [i.e. a short trip] would warm the battery sufficiently (assuming it IS cold, and this isn't a bug - which, as you say, it may well be)

Scan-my-Tesla would be able to identify if battery IS cold, or not ... if anyone with this problem happens to have that.

 

[qwickshot]

It’s not a bug, you need to consider the energy involved at different speeds.

When driving around town, even with a stone cold battery, you’ll pretty much be getting full regen effect because of the amounts of energy involved are small.

Where as if you were slowing from 70mph, down a slip road with a negative gradient (down hill) with the same cold battery, you’ll max out the regen power and you’ll only be getting the same braking effect as of 30mph but because the car has so much more energy/momentum, it will barley slow down.

As the battery warms up, it can take more energy and this the regen effects are stronger up to its maximum which is limited by power and/or g-force.

In theory the car could regen much harder at lower speeds but you risk breaking traction and it’s far less comfortable for occupants because of the increased g-forces. It’s limited at lower speeds by g-force rather than power, that switches around at higher speeds which is limited by power.

I’m sure an engineer could explain that better but that’s the best I can go with my engineering hat on.

 

[Adopado]

Cold overnight? The battery will be "cold soaked" and take some time to warm up - spirted driving may reduce that time.

It's much colder at night than during the day. The days may be warming but there have been some night time frosts across the country over the past week. If it's below 10c at night then you are "cold soaking" ... in that the pack will be well below daytime ambient temps.

 

[qwickshot]

Yes, the other analogy to think about is how long it takes an ice cube to melt, now scale that up to a block of ice weighing 400kg and how long that takes. It’s a lot longer!

The same applies to a battery, it has so much mass, it requires a lot of energy to heat it up and will probably not get up to the day time temperature before that starts dropping again in the evening.