Still New to Regenerative Braking, How Do I Time It At Fast Speeds (Highway Driving, Etc)?

[GoHawks29]

Hey everyone,

Basically the title is my question. How do I figure out how to time regenerative braking in fast speed scenarios like a highway?

I have a good grasp of the regenerative braking/letting go of the accelerator timing at lower speeds i.e 45 MPH areas and streetlight to streetlight traffic, although I've had to press the manual brake pedal a few times when switching into a turn lane and having to abruptly stop because others in front of me cut me off to get into the lane as well...good practice I guess lol.

My main question is - How do I figure regenerative braking timing out on the highways? I've driven the car on the highway a few times and while it's never happened to me just yet, I'm sure there'll be a time where I'm going 80 MPH and suddenly need to slow down ASAP because the regenerative braking won't do it in time. Is this just a scenario where the manual brake pedal has to be pressed? Or is there some sort of work around here?

I know a lot of people may suggest to always have TACC turned on and I agree with that but the only issue with that is how much of a distance it keeps from the car in front. I've dealt with a lot of people honking and cutting me off because there's a sizable distance between me and the car in front of me (even though I keep the follow distance at 2-3 at times). I sometimes press the accelerator pedal to go a bit faster to avoid this scenario but it defeats the whole purpose since automatic braking won't work if I have my foot on the accelerator with TACC on.

Any tips or tricks? Or is the secret to always just maintain a sizable distance between the car in front of you?

 

[dafish]

Time braking? How did you handle this before? It's not like you can't add more braking as normal if needed, otherwise if you drive the car for even a few start/stops you should quickly learn how to modulate the regen power. I guess this just feels a question of a new owner.

If you can't set TAC close enough, you're likely in traffic such that manual driving is the better plan. AEB still works, and until you learn how to use regen, a matter of hours, you just use the foot brake like any other car.

 

[E90alex]

It just takes practice to feel how much the car is decelerating and you will learn over time how much regen will slow the car down in anticipation of upcoming traffic etc.

If it’s not slowing fast enough or definitely in any quick or emergency braking situation, then add the friction brakes as necessary. Don’t be scared of the brake pedal. It’s good to use them occasionally to burn off any dirt and oxidation/rust that might accumulate.

 

[cmaster]

Just use the traffic aware cruise control, it will take care of the automatic braking. It can be used to brake for you wherever you go.

 

[GoHawks29]

Time braking? How did you handle this before? It's not like you can't add more braking as normal if needed, otherwise if you drive the car for even a few start/stops you should quickly learn how to modulate the regen power. I guess this just feels a question of a new owner.

If you can't set TAC close enough, you're likely in traffic such that manual driving is the better plan. AEB still works, and until you learn how to use regen, a matter of hours, you just use the foot brake like any other car.

If you’re referring to how I timed it with an ICE car, I had a good idea of when to apply the brakes with that. With the Tesla, it’s hard for me to estimate how long it’ll take for the car to slow down reasonably with the regenerative braking at really high speeds such as on a highway. I’m a new owner, this is my first ever EV. I guess my question was more how do regular drivers of EV utilize the regenerative braking like I’ve always heard people saying they never have to touch their brake pedal but then for circumstances like what I described, how is it done by them?

 

[GoHawks29]

It just takes practice to feel how much the car is decelerating and you will learn over time how much regen will slow the car down in anticipation of upcoming traffic etc.

If it’s not slowing fast enough or definitely in any quick or emergency braking situation, then add the friction brakes as necessary. Don’t be scared of the brake pedal. It’s good to use them occasionally to burn off any dirt and oxidation/rust that might accumulate.

That’s what I figured. I just always hear people saying how they never use the brake pedal and it got me to thinking how it’s possible for some scenarios because there’s still some delay from when you let your foot off the accelerator and the car actually stopping, especially at higher speeds.

 

[GoHawks29]

Just use the traffic aware cruise control, it will take care of the automatic braking. It can be used to brake for you wherever you go.

I tend to use this for the most part but it does get annoying when the car gives too much distance at times and I get honked at and overtaken frequently. Better safe than sorry tho!

 

[SkyDog]

With the Tesla, it’s hard for me to estimate how long it’ll take for the car to slow down reasonably with the regenerative braking at really high speeds such as on a highway. I’m a new owner, this is my first ever EV. I guess my question was more how do regular drivers of EV utilize the regenerative braking like I’ve always heard people saying they never have to touch their brake pedal but then for circumstances like what I described, how is it done by them?

The short answer is: don't worry, you'll quickly get the hang of it and develop a new instinct / reflex for when to use the brake pedal.

You can't really estimate hot long it'll take for the car to slow down because it varies a lot depending on the battery temperature, battery state of charge, and probably some other things. I don't use the brake pedal a lot, but I do need it at times, like coming to a stop sign on a cold morning when regen braking is very weak, or traveling at high speed and encountering a traffic jam. I instinctively take my foot off the accelerator to slow down, and when that's not slowing me down enough, I instinctively press the brake pedal. Really don't need to overthink it.

 

[GoHawks29]

The short answer is: don't worry, you'll quickly get the hang of it and develop a new instinct / reflex for when to use the brake pedal.

You can't really estimate hot long it'll take for the car to slow down because it varies a lot depending on the battery temperature, battery state of charge, and probably some other things. I don't use the brake pedal a lot, but I do need it at times, like coming to a stop sign on a cold morning when regen braking is very weak, or traveling at high speed and encountering a traffic jam. I instinctively take my foot off the accelerator to slow down, and when that's not slowing me down enough, I instinctively press the brake pedal. Really don't need to overthink it.

That makes a lot of sense! Reading through some of these other posts about regenerative braking, it gave me the impression that using the brake pedal is strongly discouraged. This response was exactly what I was looking for, I wanted to know the style of driving people used with regards to utilization of the brake pedals, thanks!

 

[zoomer0056]

In an hour of one peddle driving it will become second nature. If not, then just get out and drive some more. If you drive open loop, like with yours eyes closed, you'll never get the hang of it ... kidding. Just get out and drive, one peddle driving is awesome.

 

[E90alex]

That makes a lot of sense! Reading through some of these other posts about regenerative braking, it gave me the impression that using the brake pedal is strongly discouraged. This response was exactly what I was looking for, I wanted to know the style of driving people used with regards to utilization of the brake pedals, thanks!

You want to eventually hone your pedal control and following distance to reduce regular brake pedal usage as much as you can in normal driving since that will be the most efficient. Don’t speed up on traffic and slam on the brakes last second. But when you need more braking power, you need to use the brake pedal and there’s no way around that. Crashing is worse than using the brake pedal.

 

[UncleCreepy]

Using TACC is not going to help OP since he wants to minimize the use of the friction brake. TACC can and will apply the friction brake if regen isn't strong enough.
It really doesn't take long to get a feel for when you need to start slowing down. Also, brakes (including regen) are not digital. You can modulate the deceleration as required. It's not that they are either on or off.
Lastly, the only technique I can think of to minimize manual braking if someone cuts you off is to drive slower, but you already know that.
There is nothing wrong with using the friction brake when needed, most people here including myself just hate it. Personally I'm at about 67k miles and I still use my original brake pads and rotors.

 

[bobw]

It helped that I had driven manual transmission cars before. They don’t coast when you let up on the gas. If you do want to coast you must put the clutch in, or actually shift into neutral. My first three cars were stick shift.

 

[Unclepaul]

Driving with regeneration is quite similar to an ICE vehicle. You let up on the throttle, and your car will begin to slow down itself from 80 mph. Move your foot to the brake and apply enought pressure to slow your car as rapidly as necessary.

Do not get caught up in wanting your regen to apply all the stopping power.

Regen is an assist to breking, not a replacement.

Comes pretty naturally with experience.

Regen slows the car, recaptures that energy to recharge your battery. The brakes are for stopping quickly.

 

[MY golf cart]

Driving an ICE vehicle vs driving an EV with regenerative braking is a bit different.

An ICE vehicle with automatic transmission, you are subconsciously varying the accelerator pressure to accommodate the engine and torque converter for vehicle speed. To move the vehicle from a standstill, you apply accelerator pressure. Once you reach the intended speed you let some pressure off the accelerator. With an ICE vehicle when you lessen the accelerator pressure, the vehicle would begin to coast. If you totally remove accelerator pressure, the vehicle will coast or begin to slow at a gradual rate. To stop, you apply brakes. The driving experience: is acceleration -> coast -> brake.

With an EV, moving from a standstill to a desired speed, you apply pressure to the accelerator but the difference is once you reach speed you continue to apply similar accelerator pressure to maintain speed. Once you remove accelerator pressure, the EV regenerative braking will kick-in and slow the vehicle. To brake faster, you apply physical brake as in an ICE vehicle otherwise regenerative braking slows you down to a stop. You don't have a coasting affect in an EV as you do in an ICE vehicle. [The affects of regenerative braking will be in many ways dependent on temperature. The cooler the temperature, the less regenerative braking power is applied to slow the vehicle.] The driving experience is: acceleration -> regenerative braking -> physical brakes.

So the acceleration and deacceleration driving experience in a EV is slightly different than in an ICE vehicle.

One of the attractive features of Tesla is the "HOLD" setting. When you're at a stop light or sign in an ICE vehicle you have to continuously apply brake pressure so that the vehicle does not creep forward. The minute you let pressure off the brake, the vehicle will move forward. We can thank the torque converter for that. With the HOLD setting activated in the Tesla EV, the vehicle will not creep forward. Therefore you can take you foot off the brake and the vehicle will not move. So you can rest your leg when the EV vehicle is at rest!

With regards to highway driving, speed is speed. Reducing the vehicle speed to below 70 mph gains you the most efficiency without boredom. I find maintaining my speed with the rest of the vehicles on the highway is the best way to go.

 

[dwest218]

If you’re referring to how I timed it with an ICE car, I had a good idea of when to apply the brakes with that. With the Tesla, it’s hard for me to estimate how long it’ll take for the car to slow down reasonably with the regenerative braking at really high speeds such as on a highway. I’m a new owner, this is my first ever EV. I guess my question was more how do regular drivers of EV utilize the regenerative braking like I’ve always heard people saying they never have to touch their brake pedal but then for circumstances like what I described, how is it done by them?

I think the easiest way for you to do this is to count the centerline stripes. If you’re going 30mph then multiply that by 100 and then divide by 7. The answer will be the number of stripes you can expect the regen breaking to take effect and bring you to a full stop in time. Same works for 50mph. 70. Etc. I have a different formula if you live outside the US in Canada. Let me know.