Will I be able to "down-shift?" I live in the foothills above Boulder, CO and the ability to "in-effect" use a mechanism similar to shifting down in a manual transmission car will save replacing my brakes on a yearly basis. My Prius has a very poor version of this and it drives me nuts. My manual transmission Tacoma "winter-truck" is wonderful; never have to use the brakes on my 2000' decent into Boulder.
The Aptera Forum
There may be adjustable regenerative braking levels without needing to press the brake pedal.
The vehicle will probably have blended braking. So you just press the brake pedal to control it up until a point where hydraulic brakes assist
You can't down shift if it doesn't have a transmission with gears. It will certainly have regenerative braking.
Read the question carefully. I'm very familiar with a CVT as I've been driving cars with them since 2000. With that said, for example, the Toyo Rav4 Hybrid, has a CVT that "one" is able to downshift while going down hill to save on braking; which when "one" descends 2000' in about 4.5 miles is really nice; brakes don't overheat, brakes don't ware out in 50,000 miles etc.
The Prius has a CVT, that has a one size fits all and works poorly.
With that said, let me simplify the question for you: Will Aptera design a CVT that has the option to adjust its gear down?
I'll point out my operative language to focus your attention... "a mechanism similar to shifting down in a manual transmission".
@paul , CVT is a type of transmission (gear shift mechanism). Electric motors have sufficiently have very wide torque bands so electric vehicles don't need variable gear ratios.
From the Aptera FAQ:
"Aptera will offer regenerative braking...adjustable levels in 3 or 4 settings, from off to very heavy regen braking."
If you like your Tacoma going down the mountain you will love how an electric vehicle feels going down a long hill. The regen braking essentially does the same thing as downshifting with the added benefit of getting back some energy into the batteries. With the multiple levels of regen, you'll probably find a way to be able to essentially coast down the mountain using the different levels of regen almost like gears. In a light aerodynamic vehicle like the Aptera, it will probably feel almost like gliding..
On a side note, I'd love to see an analogue slider/trigger type of control for the regen where you could 'dial it in' a lot better than with just several levels of presets like Aptera is considering doing.
One issue with regenerative braking at least on Toyo's is that once the battery in the Hybrid is fully recharged the regenerative braking "stops" braking and one has to rely on the disc brakes. Out west in the mountains that kills discs and pads.
At Pikes Peak there's a road stop half way down where one has to stop and the heat of your disc brake is measured; overheated, and one is diverted for a 10 minute cool down; no exceptions. Every time I driver my Prius down even in "B" I have to pull over to let my brakes cool.
Wife's Rav4 Hybrid with the ability to select different levels of "gear-down" on the CVT not a problem.
@paul I don't think you will have these types of issues with full BEVs since the reservoir in the battery is so much larger...rarely will you be 'regenning' so much that you get close to full battery levels where the regen capability starts to diminish/disappear even in an extreme environment like Pikes Peak.
That said, one issue with current BEVs like my Chevy Bolt is the impact on battery usage for prolonged periods of uphill, high speed and/or spirited driving.. the range hit is real! My hope is that for a variety of reasons the Aptera will be less affected.
@alexluttrell "prolonged periods of uphill, high speed and/or spirited driving" I like doing that in my ML320 W163 but it kills the (already bad) mpg too...
Regen is also deactivated in a BEV that's fully charged at the top of a hill. Drivers who live/work at hilltops & commute downhill just set their home/work chargers to stop early enough that it won't be fully charged until they're at the bottom of the hill.
Aptera's high-range models make it much less difficult for if you also sometimes have to drive around at the top of the hill, or you live halfway up & sometimes go up & sometimes down. For example you could set the 1,000-mile one to charge only to 50% for:
- Full regen all the way downhill to save your brakes, OR
- 500 miles of same-altitude driving, OR
- 300 miles uphill (& coast/regen back down)
My own BEV has no regen until it's down to about 95%, & even then it's limited. It goes back to full function around 90%, where ALL braking is regen until it drops below 7mph where the friction brakes come on.
I LOVE 1-pedal driving, even in a gas car, engine-braking. I set my friend's eGolf to it's highest of 4 levels which is still a bit too light for me. My friend would like a setting between 2 & 3, so she'd like Alex' variable idea.
If the regen is primarily for recovering energy, then it makes sense for the regen to be disabled when the battery is nearly full. But it's also possible to design a car that relies on regen as the primary brake, in which case they would simply add a way to dissipate the energy when the battery is full. This could be a separate resistor, or the motor itself could dissipate heat, or the car could run the air conditioner & heater at the same time, etc.
@Ken Kobayashi I was thinking resistor for heat dissipation, but your AC and Heating idea is grandiose. Only software can take care of that. If batteries full and regen=Heat on AC on. The heat and AC is already variable, no variable resister needed.
@Ken Kobayashi Regen is already the primary brake in my 8-yr-old EV, which uses only regen, except below 7mph (or during a panic stop). eGolf, being newer design, uses only regen all the way to a full stop in normal driving.
As mentioned, regen will do what you want. With the range available, there is no reason to fully charge unless going on a long trip. This is better for batteries anyway. I believe they will be able to enable "one pedal" driving which would be excellent for this scenario.
Multiple levels of regen will certainly allow for 'one pedal driving' like what's currently available (and freakin' awesome) in BEVs like Teslas and the Chevy Bolt.
... & Kona EV, & eGolf, & Leaf 2.0, &...
The only ones I know of without it are 1st-gen Leaf & my own Fiat 500e.
The short answer is NO, you won't be able to downshift. There is no transmission, manual or automatic. What you will have is regenerative braking, where the motor becomes a generator to charge the battery. You use a practice called "one pedal driving." Press down and go fast, lift (regenerate) and you slow down. Works like a charm in our Tesla. On a recent drive up and down Mount Lemmon, Tucson, AZ, the valley floor is 2200', the top is 9000'. Never touched the brakes all the way down.
& for another part of the original question, even when you do use the brake pedal, it's still not wearing the brakes (unless you "over" charge at the top of the hill).
OH! Aptera does have a shift lever, so you may actually be able to downshift, like in an eGolf where you tap it down from "D" to get "B" (max 1-pedal regen), then tap down again to shift back to D.
can friction brakes be replaced by sending energy to the motor to move against forward movement of car? brake pads abrade away metals that dont get recycled, so if electric car has enough range to make up for energy cost of this theoretical braking, it would not only make the braking system that much more fully recyclable but it would also prevent need to buy new brake pads when they wear out. maybe the battery and motors (given their limits of lifetime) are not as recyclable as brakes, which needs to be considered.
this probably wont pay off until energy production per greenhouse gas and battery lifetime monetary cost is greatly improved from current state of things but it can be something to note in a archive for the future
Wow. Regenerative braking works by making the motor work as a generator. This is been a technology that exists for a long time. Please read this article and watch this video (7:30 onward). Electricity goes into the battery when regenerative braking is active, energy is saved.
https://en.m.wikipedia.org/wiki/Regenerative_brake
friction brakes still exist on electric cars b/c the energy in modulating the amount of toque to slow the car at some level is more than potential energy profit. my idea of spending energy into motors is to replace these friction brakes.
Right. Regenerative braking in most hybrids and EVs can only recapture energy with light to moderate braking. Aptera says that the regenerative braking is more powerful in this vehicle than most. capable of more G-forces deceleration before friction brakes have to assist. We'll have to wait for test drives to really see.
The AWD model should have the best energy recuperation.
My 8-year-old EV must be better than "most", since it can brake VERY hard on just regen. New tech should be even better than that. It's just a matter of having enough regen power available to max out the tires' traction.
Compared to my EV, Aptera has 162% more power per pound on the front (braking) tires, so I would not be at all surprised if regen could lock them (if ABS was deactivated).
In defense of Mr Discord, the very existence of friction brakes on every EV may make it appear that regen is nonexistent, or at least insufficient.
There has been recent discussion of eliminating the heavy unsprung weight of calipers, & the rotational inertia of discs, by using ONLY regen, even for emergency panic braking to a dead stop: Check out the comments starting at 27:39 of https://www.youtube.com/watch?v=IJ5sU2r-xxw
https://www.aptera.us/forum/main/comment/603c17598065de0015e2384a idea of using regenerative air pressure braking to decrease use of friction brakes and/or electrical braking to increase lifetime of battery and friction brakes. there are 2 threads, the one the link goes to and the one the link in that thread goes to
theres also another form of mechanical regenerative braking which is f imitating a wind up toy, where a metal winding is spun by forward moving wheels and the winding is released to push forward again, although gearing is used to enhance the captured energy output in a design i dont have at the moment.
I'm a fan of clockwork mechanisms and it is a shame they have gone out of favour with the advent of electric servo motors in everything. Another good technology is a Stirling engine which could perhaps be applied to utilise waste heat etc.
I think you are describing KERS (kinetic energy recovery system). It's widely used in Formula One racing cars, but not regular cars. It can absorb energy at a higher rate than regenerative brakes, but the benefit isn't worth the cost and complexity for street legal vehicles.
@Ken Kobayashi its not KERS but maybe that has potential in maximum lifetime vehicles like utility trucks etc https://www.aptera.us/forum/aptera-design-discussion/increasing-average-efficiencies-by-rental-of-usually-uneeded-things (under "RENTAL" and "TRAILER")
Existing regen already eliminates brake wear, & increases battery life by reducing discharge depth. There's no need or desire to add another system, increasing cost, mass & complexity.
You don't want to completely eliminate friction brakes. Every vehicle needs a redundant braking system. Even bicycles have them (independent front & rear brakes). And if you're going to have a friction brake, it needs to be used fairly regularly, otherwise you won't know if it's failed until you need it. It may also rust from disuse (esp. disc brake rotors).
Motorbikes use stainless discs.
eGolf's electric handbrake does NOT work while moving, so if it's the same on a gas car I wonder what its "redundant braking system" would be.
Eliminating friction brakes was NOT my idea! I, too, would have thought it unsafe or illegal, but I heard the comments starting at 27:39 of https://www.youtube.com/watch?v=IJ5sU2r-xxw
Most conventional cars have redundant hydraulic brakes. Usually the pedal is connected to two master cylinders, each of which is connected to brakes on two wheels.
Effectively correct: It's 2 semi-independent pistons in one master cylinder. The point is that fronts can fail & rears will still work. You can accomplish that even more easily with independent front & rear regen.
Redundant regenerative braking would require independent electrical systems for front and rear motors, from independent batteries (or designed to work even when disconnected from the batteries) all the way up to 2 independent sensors on the brake pedal. It's possible, but not exactly easy.
Probably easier with FWD: Regen-only on the front & disc on the rear. Still eliminates cost, weight & complexity of 2 discs, 2 calipers, 2 hoses, & lines. Dual master becomes single.
AWD is a luxury where cost is less important. I believe front & rear motors/controllers are already independent. 2 brake pedal sensors seems easy. If necessary, make each motor connect to its own section of the battery pack for regen.
Still seems easier than having 2 semi-independent hydraulic systems with 3 discs, 3 calipers, 3 hoses, lines, dual master-cylinder & an electric motor powering a brake fluid pump.
Anyway, it wasn't my idea! The experts say it's possible, starting at 27:39 of https://www.youtube.com/watch?v=IJ5sU2r-xxw
I have 133,000 miles on my 2014 BMW i3 with 6mm brake pad still left, so one pedal driving is pretty darned efficient.
Why should one pedal driving be so "pretty darned efficient"? If the regen only is activated by the brake pedal, that should not make any difference in efficiency ... for the car, not the foot. I would argue, if you take the foot of the gas AND the brake, resting your foot, there should be no energy used from the car. Provided, that there is no regen active when the gas pedal is depressed.
@Tomy J , on many EVs, one-pedal driving is more efficient because letting up on the accelerator pedal activates regen, not friction brakes. Whereas stepping on the brake pedal activates both.
One-pedal driving is also very user-friendly. If instead the car is designed as you describe (car coasts when neither pedal is pressed), driving in highway traffic would involve constantly switching your foot between the two pedals.
Right, except that in every BEV I know of, stepping on the brake pedal doesn't activate both. It only activates regen, except for panic stops, & sometimes below a certain speed (my friction brakes activate below 7mph)
@Tomy J What is "gas"? 😉
Most electric cars have settings that activate regenerative braking when the driver lets off the accelerator pedal. No need to push on the brake pedal to stop. Some do not have “full” one pedal braking stops.
https://www.aptera.us/forum/main/comment/6031daa3b24694001774f006 <devices for attaching temporary extra accerioies. i heard somone wanted a minimally existing 4th wheel b/c his local laws required it or he wanted tax credit for EV car, so i though maybe such 4th wheel could be something that in front/rear of he main rear wheel as something that doesn't touch ground unless deployed via brake pedal for more grip for more regenerative braking, and as a unintentional extra higher power acceleration(with more traction and motor), and source of more grip around turns when needed. of course such a thing can be taken off when not needed assuming it wouldn't pay off, like for when braking is not often etc.