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Regen Braking Question

GVB-81

Member
Oct 20, 2020
5
3
Connecticut
I’m about 3 weeks away from delivery. I’m aware of the effect that a cold and/or full battery have on the inability to recharge while regen braking. However, does this mean that in these situations I will be unable to use regen braking at all and will need to use the traditional pedal brake? Or will regen braking still work but just not send energy back into the battery? Thanks.
 

XLR82XS

D M C
Jul 26, 2019
3,148
1,802
SWFL | Vegas
Yes. In extreme cold temperature regen will be very limited. Regen level/ability can be monitored by the grey dots on the left of the energy bar under the speedometer.
 
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danarcha

Member
Feb 9, 2020
84
125
South Bend, IN
I’m about 3 weeks away from delivery. I’m aware of the effect that a cold and/or full battery have on the inability to recharge while regen braking. However, does this mean that in these situations I will be unable to use regen braking at all and will need to use the traditional pedal brake? Or will regen braking still work but just not send energy back into the battery? Thanks.

Yes, you will have to use the brake pedal more often to slow and stop the car. It's not an "all or nothing" response. What happens is that regen is limited and lifting the accelerator will result in the car slowing but not as quickly as it normally decelerates.
 

5150

Member
Apr 26, 2020
87
25
San Diego
Yes, you will have to use the brake pedal more often to slow and stop the car. It's not an "all or nothing" response. What happens is that regen is limited and lifting the accelerator will result in the car slowing but not as quickly as it normally decelerates.

Interesting. I've only had my M3 since March, and in San Diego inland area, so I was not aware I would lose regen braking power on colder days. I've seen the grey dots more on colder days, but haven't paid attention if I'm losing regen braking power. And, since working from home I normally am only going out on drives when warmer, for lunch or errands etc.
 

BHouse

Member
Sep 29, 2020
53
39
Victoria, BC
If you leave your car plugged in (as Tesla recommends) overnight, you can turn on the inside heat 30 min or so before you leave using your phone app at breakfast. That also warms the battery and substantially reduces the grey dots (regen limits) -- and is warmer for you too.
If I set a scheduled departure, will my car do that for me?

Like say I set a scheduled departure at 7am and it's cold outside. Would I have full use of regen or would the car still need to warm up from driving?
 

chrstna4

Member
Sep 3, 2020
206
270
Seattle
If you see the grey dots that indicate regen braking is limited, just leave a little extra time to slow down and you won’t have to use the brake pedal much. I find the limitation is only a big deal when going down a hill. If I’m leaving a little extra space to let regen braking do its magic, I don’t touch the brake pedal on flat roads - and once the car warms up a little the limitation disappears.
 
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chrstna4

Member
Sep 3, 2020
206
270
Seattle
If I set a scheduled departure, will my car do that for me?

Like say I set a scheduled departure at 7am and it's cold outside. Would I have full use of regen or would the car still need to warm up from driving?
I’ve read that sometimes the car will do most of the charging during off peak electricity rate times. Make sure your settings are such that it does the charging right before you leave. You can also set a charge limit % for overnight then bump it up using the app in the morning and have the car charge until you leave.
 

gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,606
2,137
Philadelphia, PA
BMW i3 mimics regen by automatically using the brakes when the battery is full or too cold for true regen. It makes it more seamless. The first time you drive a Tesla without regen after being used to having it, it's a little jarring when it happens.

Tesla's approach is more efficient because it forces you to coast more whereas the BMW approach makes you use the brakes which is wasteful, especially when most drivers probably don't realize it's using the brakes.
 
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ftmaybe

Member
Feb 11, 2020
230
306
San Joaquin
Yes, you will have to use the brake pedal more often to slow and stop the car. It's not an "all or nothing" response. What happens is that regen is limited and lifting the accelerator will result in the car slowing but not as quickly as it normally decelerates.

Also AFAIK this should only be an issue if the amount of deceleration you would want exceeds what the regen capability is. And that should be directly related to how much the bar goes "negative" or left of center vs how much of that is blocked off with dots.. I tend to drive pretty conservatively so I don't require a lot of regen to slow to a stop. Even with regen slightly limited due to it being a little cold or a near fully charged battery it isn't a negative impact so far for me (but I don't live in super cold climate).
 
Oct 28, 2019
105
66
Ridgewood NJ
We haven't had really cold weather here, yet, but on chilly days, I've gotten a warning on the screen that the regeneration is temporarily reduced. It goes away when the car warms up. And (to state the obvious) you do need to brake more.
 

SSedan

Active Member
Jul 24, 2017
2,948
2,327
Greenville Wisconsin
Let's take this moment for a teach a man to fish moment.

If the regenerative braking still functioned at full capacity but didn't recharge the battery were do you think that energy could go?
 
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android04

Member
Apr 1, 2016
449
454
Crete, Nebraska
Let's take this moment for a teach a man to fish moment.

If the regenerative braking still functioned at full capacity but didn't recharge the battery were do you think that energy could go?
It would be great (but add cost and complexity) if there were a resistive battery pack heater that the car could shunt power to when it's cold. It would kill two birds with one stone -- give consistent regen even in the cold, and warm the battery pack to where it could eventually take the regen again.
 

gavine

Petrol Head turned EV Enthusiast
Apr 1, 2014
2,606
2,137
Philadelphia, PA
It would be great (but add cost and complexity) if there were a resistive battery pack heater that the car could shunt power to when it's cold. It would kill two birds with one stone -- give consistent regen even in the cold, and warm the battery pack to where it could eventually take the regen again.

I thought about this too, but regen is like 60kW, right? That seems like too much for a pack heater.
 

puckpurnell

Member
Dec 15, 2018
352
237
Connecticut
Connecticut, eh. Well, I'm coming into my third winter with my Tesla M-3 in the land of steady habits. Yes, the regen braking drops off in the cold. On frigid New England mornings (or any cold times), my M-3 LR AWD always alerts me to the fact that regen braking will be limited. Look for the snowflake. I pay attention and notice it at the first need for braking. After a while, depending upon time driving to warm the battery and the outside temperature, the regen braking returns to normal...one pedal driving. Driving a Tesla is an art not a science although science certainly makes our driving artful. Pay attention but ne worry pas.
 

SSedan

Active Member
Jul 24, 2017
2,948
2,327
Greenville Wisconsin
It would be great (but add cost and complexity) if there were a resistive battery pack heater that the car could shunt power to when it's cold. It would kill two birds with one stone -- give consistent regen even in the cold, and warm the battery pack to where it could eventually take the regen again.
The S and X have resistance pack heaters and this still doesn't work.
 

lUtriaNt

Member
Mar 16, 2020
635
551
Los Angeles
i work usual and certain days i go in at like 4am here in LA. since its been a little cooler ( in the mid 50s)
often i will see the regen will be reduced message. still i dont use my brakes because i just modulate the pedal more. since there are no cars out i just let off the pedal and the car is coasting but once it gets to like 30 and below you feel the regen kick in and the car slows like you expect.
i dont like using the brakes because i dont want to get brake dust on the wheels :p so easing off the pedal much earlier than you normally would when coming to a stop light or needing to turn, will allow you to still use regen and one pedal braking. ive become a master at it. :)
 
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holmgang

Active Member
Sep 9, 2019
1,314
1,325
eu
If you see the grey dots that indicate regen braking is limited, just leave a little extra time to slow down and you won’t have to use the brake pedal much. I find the limitation is only a big deal when going down a hill. If I’m leaving a little extra space to let regen braking do its magic, I don’t touch the brake pedal on flat roads - and once the car warms up a little the limitation disappears.

Or just drive as normal. The flow of traffic should dictate your speed, not how much you can get away without using friction brakes
 

android04

Member
Apr 1, 2016
449
454
Crete, Nebraska
The S and X have resistance pack heaters and this still doesn't work.
The reason the dedicated battery heater in Model S/X (and the heating method used in the Model 3 where heat is captured by running the motor/s inefficiently) don't work for regen right away is that they only provide about 1/10th of the energy that can be captured by regen. A resistance battery heater that can take the full power of regen would likely not be feasible (expensive?, heavy?, more complex?), but would allow Tesla to both heat up the battery 10x faster as well as allow the heater to take up the full regen. By heating and blending regen in this way Tesla could maintain consistency year round.
 

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