Regenerative Braking Capacity

[delmi]

Whatever dude. No matter how sophisticated the electronics, the way it goes from applying power to regenerative braking is by SIMPLY CHANGING THE FLOW CURRENT THROUGH THE MOTOR.

And Musk isn't a mad genius. He is intelligent with a massively over inflated ego. And no, he isn't saving the world. Electric cars will not save us. This is why having a high IQ doesn't mean someone is smart. A smart person would actually be able to see all available evidence and recognize that emissions are a small part of our problem and that destroying are carbon sinks are the biggest part of our problem. We have destroyed nearly 1/3 of the worlds forests for crop production and grazing land for people to eat meat. If all the forests that we have destroyed still existed, it would be absorbing near 100% of our global CO2 emissions. So, in terms of people who are smart and recognize the real problem we face, then the people behind companies like Beyond Meat and Impossible Foods are far smarter than Elon Musk.

And again, making money in capitalism is more about one's willingness to exploit the unethical system in which we live, and not about overall intelligence. If you think it has anything to do with intelligence, then explain Donald Trump. Luckiest idiot alive.

Who were you quoting on the Trump comment.

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[delmi]

QUOTE="ajdelange, post: 3594, member: 481"]Now I could argue that this is of no benefit whatsoever as I charge from solar so wasted energy doesn't cost me (or the environment) anything ....

The point was that what regen is worth to someone depends on that person's perspective and, indeed, on the circumstances. During the summer I charge from hydro so there is no environmental impact if I waste energy (except for the relatively tiny losses of transmission). During the winter it's from solar so there is none there either. The utility does not need my solar. The utility does not want my solar. The only reason they accept it is that they are forced to by government and they make it as difficult as they possibly can for the homeowner and the situation is likely to get worse. And personally, I don't care about this aspect of it as I think anthropogenic global warming in probably the biggest scientific hoax ever foisted on mankind. My love affair with regen is solely based on the fact that I feel it's cool tech. You can argue, however, that I won't get paid for the solar energy I put into the car and waste and that is true. I drive about 9000 mi/yr at 300 wH/mi so that's 2700 kWh. If the regen recovery is 10% of that it amounts to 270 kWh for which the utility would pay me about $30. If regen amounts to 20% then $60. I guess I still don't care.


No. As my wife will be happy to explain to you the capital is gone whether I use the system or not and to whatever extent.[/QUOTE]
Anthropogenic what? If you left out that word, which I don't understand, I couldn't agree with you more about global warming.

 

[EyeOnRivian]

Who were you quoting on the Trump comment.

If I may, let's not stray, again, from thread's topic - Regenerative Braking Capacity.

 

[jimrichard]

Everyone likes options so make sure I have the ability to choose how much regen I want. Maybe that will change after I own the truck awhile and maybe it would change with where I am driving it like city to country or mountains to plains. We have some of all of these in Colorado. I like the 0- 5 idea on one of the existing vehicles mentioned about 100 posts ago rather than having to choose a name for the type of driving I want. Options please.

 

[ajdelange]

Everyone likes options so make sure I have the ability to choose how much regen I want. Maybe that will change after I own the truck awhile and maybe it would change...

It will. It takes a while to get used to and even longer to really understand what it does for you in terms of range (and, secondarily, on savings on brake pads).

If you are coming to an intersection in an ICE car and wait too long and slam on the brakes to the point your passengers complain about it what do you do? Start applying the brake earlier so that you don't have to stomp on it late in the game. With regen it's the same except that "stomping" on the brake is equivalent to taking your foot completely off the skinny pedal. If regen is too strong, don't back off so dramatically. You will learn to program your foot on the skinny pedal to obtain the same result you do/did with the brake pedal. That's how you determine the 'amount' of regen.

 

[DucRider]

After 7 years of driving an EV, my wife still vastly prefers a relatively low level of regen when lifting. I want about as much as they are willing to program in. There should be settings to adjust to user preference of regen level.

Don't know if it's correlated, but she's always had medium displacement 4 cylinder motorcycles with relative mild engine braking (unless the revs are higher than she uses). I've always had twins that have a bunch more.

 

[ajdelange]

I suppose regen is one of those wonderments of the BEV that can't be fully appreciated until one actually experiences it and that, therefore, "how much is enough for me" is a question that really can't be answered until one becomes acquainted with it. Why is it in these cars? It is included because it increases the range of the vehicle attainable from a given charge and it does that by recapturing energy that would otherwise be wasted in warming brake pads and discs. So the first question one needs to ask himself is whether that matters or not to him. The amount it will save him on his electric bills is miniscule and the amount it saves him on brake jobs isn't going to be that spectacular either so if he is indifferent to the range extension then he will be indifferent to regen.

There are people that don't need regen. There are people who don't like regen. There was even one guy who was trying to convince people that it was unsafe. If you are in one of these groups, turn it off.

It's part of the engineer's religion that wasting energy is a mortal sin. So much is done in these cars to save every joule that an owner with an engineering background wouldn't consider even slightly diminishing the effectiveness of regen. He thinks about ways to store the car warm in winter so that he doesn't have to give up that small amount of regen that one loses until the battery warms up (I'll come back to this). In case you all haven't figured it out yet I am one of those guys.

From this perspective, what is the "right" amount of regen? The answer is "as much as possible". I checked my X yesterday and the amount available is actually very small. It is 60 kW corresponding to 0.6C. This was with an SoC of about 65% and we have never taken note whether it goes higher when SoC is lower (regen is not available at all above 90% SoC and the cars accept more DC fast charging current at lower SoC). Assuming the X weighs about 2500 kg and that one is going 60 mph (26.82 m/s) the deceleration at 60 kW is only 60000/(2500*26.82)/9.8 = 0.09g! At 30 mph, of course, it is twice this and at 10 mph as much as 0.54g so it is appears that it is most useful at lower speeds.

There's an easy test as to whether this is sufficient or not. It is sufficient if you never have to touch the friction brake. If you do it right you never have to touch the friction brake with no regen so this should be modified to "if you never have to touch the friction brake driving as you like to drive". By this definition I suppose I'd say the X is marginally acceptable. I would like to have more for the freeway but it is adequate around town.

The thing that ostensibly limits regen is the size of the battery. Evidently my X shouldn't be charged faster than about 0.6C at 65% SoC as its battery's available discharge energy is about 95.5 kWh. The 300 mile R1T's battery's available discharge energy is supposed to be about 135 kWh so perhaps that truck will have about 35% more regen (it is probably going to be a bit heavier) and, perhaps the 400 mile R1T will have 80% more. And, perhaps, the TriMotor CT even more. I'd like that. To those who don't want that I'd say "Learn to drive with regen - you won't regret you did." but it's pretty hard to argue that the OEMs shouldn't give the customers what they think they want.

 

[Feathermerchant]

I fly electric model airplanes. Since we had NiCad batteries.
The first lithium batteries we got had all kinds of limitations. 1C charge rate, 4C (average) discharge, etc. Today just a few years later, we can charge some up to 5C and discharge up to 12C.
So I fully expect that EV batteries will also just get better and be able to receive charge at a higher rate making regen more often available. If you watched and understood Tesla's battery day, the new 4680 batteries will make us very happy. Lighter cheaper, able to charge faster, able to discharge faster, etc.
We have driven round trip DFW to Phila twice now. Once in a Model 3 and just now in a Model Y. Both trips were a breeze. I love being to precisely control my speed with regen.

 

[Gshenderson]

I have a stretch from Park City to SLC that is all downhill, at varying grades, for 10+ miles. I have my Model S on max regen and most of the trip down the canyon my energy meter is showing negative energy use (ie. regen). I generally gain about 2 miles of range by the time I hit the bottom. So, yeah, the amount of power gain is limited, but if you’re on a long trip in mountains with lots of inclines and declines it can make a difference in offsetting the extra energy used to go up hills before going down again.

That being said, I like the idea of extending the life of brakes - most likely longer than I will own the car. It seems that every brake pad replacement now also comes with a recommended rotor replacement, which can get very expensive. I think a lot of that is just shops up selling things you don’t need, but most people don’t know the difference or wait too long to change pads and actually do damage the rotors.

But what I’ve really come to like about regen is one pedal driving. I seldom use the brake pedal any more and it just makes driving easier. Yeah, it took a little while to get used to, but now that I’m used to it I much prefer it vs. the tradition two pedal operation on my 4Runner.

I agree that have it be user configurable is the right way to go. I’ll likely set mine to max regen.

 

[Hmp10]

But what I’ve really come to like about regen is one pedal driving.

This has been my experience, too. In fact, I find that the most annoying aspect of driving my ICE vehicles these days is having to get on and off the brake pedal so much more frequently when driving in heavy traffic. Until I got an EV I never realized how frequently the brake pedal is used in some traffic conditions.

I don't quite understand the lengthy discussions I've seen about getting used to regenerative braking. It took me all of about 20 minutes to adjust to it and about another 20 minutes to become addicted to it.

 

[Gshenderson]

I find that the most annoying aspect of driving my ICE vehicles these days is having to get on and off the brake pedal so much more frequently when driving in heavy traffic.

This is where AutoPilot really shines as well.

 

[Hmp10]

This is where AutoPilot really shines as well.

True, but I seldom use it. I enjoy piloting my vehicle too much, even in heavy traffic.

 

[ajdelange]

Yes, amen to that. WRT to regen, though, we have to recognize that it isn't perfect. Every time you speed up and slow down some energy is lost because while doing it with regen is more efficient than using the friction brake it isn't 100% efficient. Autopilot holds speed better than you can and so is a little more efficient than driving yourself. The difference is small. Except for the rare cases where your plan requires that you "arrive on fumes" you can use whichever you prefer at the moment.

 

[ajdelange]

I don't quite understand the lengthy discussions I've seen about getting used to regenerative braking.

I don't understand the lengthy arguments as to why the US shouldn't adopt the metric system but I've been living with their consequences all my life.

 

[skyote]

I don't understand the lengthy arguments as to why the US shouldn't adopt the metric system but I've been living with their consequences all my life.

Metric is so much better for science & math, not to mention tools! I guess if there is a positive, imperial provides plenty of practice for math proficiency.

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