Regenerative braking reduced warning

[DanDi58]

I am at Toronto, and starts getting warnings in the cold days, but the warnings go away automatically after battery gets warmed up after about 20min driving, but regen is still at very low condition until battery get well warmed.

However, I have a problem with displayed range is getting lower and lower (MYP). 3 weeks back was 450+km, 2 weeks ago was 441km, the update did not change anything, and now keeps showing 430km, and looks like it will keep going down this way. Is any one have the same issue?

No, because I use the % reading.

 

[DanDi58]

In the latest version of the app it is at the upper left corner just to the right of the battery status. The icon is three short red horizontal wavy lines.

"Bacon"

 

[spokey]

Wait. This is associated with reduced stopping power when lifting your foot off the go-pedal? I thought it just meant the batteries won’t be recharged from said stop. I didn’t realize the driving dynamics also change as a result of this.

yes, as far as I know, the physical brakes only are applied when you actually put your foot on them. So if regen is reduced and you aren't as good (like me) you find occasionally you need to brake.

 

[DanDi58]

Price we pay for having a heat pump, since it's scavenging the heat for the cabin, which is cooling the battery.

I thought the opposite was true, that the heat pump was using LESS energy from the battery to heat the cabin, therefore you have additional range possible?

I found this to be an excellent explanation of how the heat pump works -

 

[jcanoe]

Wait. This is associated with reduced stopping power when lifting your foot off the go-pedal? I thought it just meant the batteries won’t be recharged from said stop. I didn’t realize the driving dynamics also change as a result of this.

Yes; when regenerative braking is reduced the Tesla vehicle will not perform the same when slowing as when you have full regenerative braking.

 

[torifile]

Yes; when regenerative braking is reduced the Tesla vehicle will not perform the same when slowing as when you have full regenerative braking.

yes, as far as I know, the physical brakes only are applied when you actually put your foot on them. So if regen is reduced and you aren't as good (like me) you find occasionally you need to brake.

Yes; when regenerative braking is reduced the Tesla vehicle will not perform the same when slowing as when you have full regenerative braking.

Ah. So that’s why I can’t ever get the stop on that hill next to my house timed properly.

 

[pt19713]

I thought the opposite was true, that the heat pump was using LESS energy from the battery to heat the cabin, therefore you have additional range possible?

I found this to be an excellent explanation of how the heat pump works -

You're quoting my post pre-2021.4.11 software update, which fixed the issue of the heat pump scavenging too much heat from the battery pack. This is no longer an issue.

 

[IMFletcher]

Wait. This is associated with reduced stopping power when lifting your foot off the go-pedal? I thought it just meant the batteries won’t be recharged from said stop. I didn’t realize the driving dynamics also change as a result of this.

Correct, the stopping/braking power (in my opinion) is reduced. Sometimes substantial if not preconditioned.

 

[WillwayGTO]

It's been well-documented in the Model 3 community and I've tested it myself with the Scan My Tesla app. I've posted screenshots in another thread showing the Stator motors warming up and the battery pack temp increases over 30 minutes. Here's a cut and paste:


In the attached image, I've circled in red the relevant info. This is an image, after about 1 minute, when I woke the car up and turned on the heat. Ambient temp in my garage, 58F. Battery temp 66F. Take note of the battery flow (this is the coolant running through the battery) and the Stator motor temperatures, along with the Battery inlet temp. I'll explain all this shortly in my second reply with a second image showing pre-conditioning after 30 minutes.
View attachment 607944



Here is the car after 30 minutes of pre-conditioning.

Note the battery temps are now 82F. How does all this work by turning on your heat? This is how the car pre-conditions:

By turning on the heat, the Battery Management System (aka BMS) activates a non-motive power waveform to the Stator motors. This is to generate heat. This heat is carried away by the coolant via conduction, the same way gamers use liquid cooling on their CPU and GPU, or in gas vehicles with the radiator coolant passing through the engine block. This hot coolant eventually flows through the battery packs and then back through the Stator motors and the process is repeated. You can see the Battery Flow and Powertrain flow indicated in LPM (Liters per minute). You can also see what the temperature of the coolant is before it enters the battery packs, listed as Battery Inlet.

It also works in reverse in the summer when it's hotter outside and the batteries need to be cooler. Instead of heat conduction from the Stator motors, the Radiator Bypass is closed and the coolant is routed through the radiator fans. This speed can be found with the Radiator Fan Target. Fresh air is pushed over the coolant lines to lower the temperatures.

There you have it. Battery pre-conditioning 101.
View attachment 607945

Thanks for the info. Interesting. This is what I was thinking. Live in CT. Car is outside. Been 25-30 most mornings last few weeks. Warm it almost every day. If you don’t regenerate level is low. Takes 4% battery if it’s not plugged in. A lot But I charge at work so… Sometimes you can see battery heating on the app. You will see red icon next too the icon just above the car. I like the cabin warm, windows defrosted, seats heated and better regen it’s all good.

 

[rjpjnk]

The ability to preheat while plugged in is becoming very valuable as the days get colder here. I like using the house power rather than the battery. Slightly more efficient and less wear on the battery.

 

[DanDi58]

The ability to preheat while plugged in is becoming very valuable as the days get colder here. I like using the house power rather than the battery. Slightly more efficient and less wear on the battery.

The only kink with this is if you have the car scheduled to charge at night, like I do. Then it won't use 'house' power but just energy from the battery. But I precon'd for about 15 minutes this am - it was about 30 degrees in the garage - and it used about 2% so NBD.

 

[spokey]

The only kink with this is if you have the car scheduled to charge at night, like I do. Then it won't use 'house' power but just energy from the battery. But I precon'd for about 15 minutes this am - it was about 30 degrees in the garage - and it used about 2% so NBD.

I set the departure time and then the schedule charge for a couple hours before but actually I intentionally set it so I don't quite get done. So if I need say 2 1/2 hours of charge and want to leave at 9:15, I start charging at 7 and the deaprture for 9:15. Sometimes I set departure later as it always seem to get up to temp in the cabin about 15 min before I want to leave.

 

[rjpjnk]

The only kink with this is if you have the car scheduled to charge at night, like I do. Then it won't use 'house' power but just energy from the battery. But I precon'd for about 15 minutes this am - it was about 30 degrees in the garage - and it used about 2% so NBD.

Are you saying that if the car is plugged in but the battery is done charging the preconditioning will use battery power? I was expecting it would use the house power. I also charge at night. I preconditioned this morning and the battery was still at the target charge level afterwards. In fact, I’m pretty sure I saw the charge cable light up green during precondition on the app. I’ll have to check again tomorrow.

 

[DanDi58]

Are you saying that if the car is plugged in but the battery is done charging the preconditioning will use battery power? I was expecting it would use the house power. I also charge at night. I preconditioned this morning and the battery was still at the target charge level afterwards. In fact, I’m pretty sure I saw the charge cable light up green during precondition on the app. I’ll have to check again tomorrow.

My experience has been that if the car is set to charge at a certain time then once it finishes charging, the Scheduled Charging time overrides the ability of the car to use 'house' power to precondition. For example, I charge my car to 80% every night. This morning, when I got in the car after preconditioning it read 78%. And I know it was at 80% because that's what the app indicated before I started preconditioning. If you're not using Scheduled Charging or Scheduled Departure, then yes, it should use house power. That's my experience, at least.

 

[Big Earl]

My experience has been that if the car is set to charge at a certain time then once it finishes charging, the Scheduled Charging time overrides the ability of the car to use 'house' power to precondition. For example, I charge my car to 80% every night. This morning, when I got in the car after preconditioning it read 78%. And I know it was at 80% because that's what the app indicated before I started preconditioning. If you're not using Scheduled Charging or Scheduled Departure, then yes, it should use house power. That's my experience, at least.

What size circuit are you using to charge? A dual motor car takes about 10 kW to both heat the battery and the cabin. If you're charging at 32 amps, that leaves a 2.5 kW deficit that must come from the battery pack. If you're charging at 24 amps, it's more like a 5 kW deficit. If you're only charging on a regular wall plug, almost all of the energy to precondition will come from the battery pack.

 

[rjpjnk]

My experience has been that if the car is set to charge at a certain time then once it finishes charging, the Scheduled Charging time overrides the ability of the car to use 'house' power to precondition. For example, I charge my car to 80% every night. This morning, when I got in the car after preconditioning it read 78%. And I know it was at 80% because that's what the app indicated before I started preconditioning. If you're not using Scheduled Charging or Scheduled Departure, then yes, it should use house power. That's my experience, at least.

Maybe that’s the difference. I am not using scheduled charging. I plug in when I get home an charge right away. Then in the morning it seems to draw from the house current to precondition.

 

[rjpjnk]

What size circuit are you using to charge? A dual motor car takes about 10 kW to both heat the battery and the cabin. If you're charging at 32 amps, that leaves a 2.5 kW deficit that must come from the battery pack. If you're charging at 24 amps, it's more like a 5 kW deficit. If you're only charging on a regular wall plug, almost all of the energy to precondition will come from the battery pack.

Interesting. Maybe this happens and then once target temp is reached the battery is topped off?

 

[DanDi58]

Maybe that’s the difference. I am not using scheduled charging. I plug in when I get home an charge right away. Then in the morning it seems to draw from the house current to precondition.

Yes, I imagine that's the reason why.

 

[DanDi58]

What size circuit are you using to charge? A dual motor car takes about 10 kW to both heat the battery and the cabin. If you're charging at 32 amps, that leaves a 2.5 kW deficit that must come from the battery pack. If you're charging at 24 amps, it's more like a 5 kW deficit. If you're only charging on a regular wall plug, almost all of the energy to precondition will come from the battery pack.

I use a NEMA 14-50 outlet and mobile connector. But again, I am also using scheduled charging so it won't start charging until 10:30 pm.

 

[torifile]

How do you precondition without scheduled departure?