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.
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You can't add a 4th wheel without a major redesign due to bumper height and other requirements for regular passenger vehicles.
You will be able to use the regenerative braking instead. Set the regen more aggressively and it will act like downshifting,it also will also recapture energy into the battery.
Yes, nearly all BEVs have one fixed drive gear without shifting, but nearly all of them also have an adjustable setting for right-pedal regen to simulate motor braking: Like the GMs above, the VW eGolf & id4 have a "low gear" shifter position called "B" (for motor Braking?), & most others have a setting in the menu or elsewhere. eGolf has a button next to the shifter, with 3 regen settings.
We drive a Renault Zoe in Switzerland the motherland of mountains. Electric cars usually have one fixed gear without shifting.
The regenerative - aka motor breaking - is plenty strong to drive down a steep mountain and enjoy the electricity it puts back into the battery.
Just one week ago we drove up to Lenzerheide 150+ turns and back down. Easy.
I owned a Chevy Volt, and now have a Cadillac ELR which are plug in hybrids (EREV) but they have an "Low-gear" shift lever position that makes regen more aggressive. Plus there are paddles that enhance regen even more. The GM traction batteries show 100% when they are 80% full, and the rest of the capacity is a battery buffer which extends the life of the battery. The actual brake pad use is very low as regen does most of the daily braking duties. Some PHEVs, EREVs, and BEVs actually use supercapacitors as a small buffer to capture and release electricity quickly for seamless regen. Aptera said that they are planning to have several levels of regen, which sounds great to me. I figure that I may only end up charging the battery to 50%-75% (with the 40kW battery) as that would comfortably leave room for regen and solar to recharge the batteries.
I'm not concerned about that at all. Most BEVs brake pads only touch the discs in a panic stop. Mine are on track to last until well after I'm dead.
Do we know exactly how the brakes work? From Clean Technica's website: "Having brakes inside the hub motor does raise other questions, like how much work will be involved if you need to change brake pads, where the brake dust will go, and how you’ll inspect brakes periodically. We are checking with Aptera and Elaphe about all of that, and will let readers know when we have more information." https://cleantechnica.com/2020/12/23/apteras-hub-motors-survive-torture-testing-other-questions-answered/
Yes, not only without brake pads that wear out, but also without heavy unsprung rotational disc weight, heavy unsprung caliper weight & the cost & complexity of all the hydraulics, which includes a high-pressure pump in the case of a BEV with no engine vacuum.
Even if the cabin is warm, diversion load could be heat AND A/C. In fact, maybe just over-spec both of those, so they could dump as much power as needed regardless of cabin & ambient temp.
In the latest Nathan Armstrong video he repeats the existence of "all braking from the motors".
It is possible to continue regen braking after the batteries are full with a diversion load. Some wind and solar charge controllers are set up with a diversion load in cases where disconnecting the source is inadvisable. The diversion load is often
a resistive water heater or similar. So your kinetic energy ends up as waste heat like friction brakes, but without brake pads that wear out. If the cabin or batteries are cold, the excess electricity could be sent there. Otherwise, you would need to dump heat through another skin cooling system. Since each motor has its own controller, using a separate diversion load for each motor would give you a mostly 3 way redundant regen braking system.
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.
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.
I have 133,000 miles on my 2014 BMW i3 with 6mm brake pad still left, so one pedal driving is pretty darned efficient.
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
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.
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
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).
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.
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.
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
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
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
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
& 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.
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.
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.
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.
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.
You can't down shift if it doesn't have a transmission with gears. It will certainly have regenerative braking.
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