On the 2025 Camry, we have an S mode that lets you shift virtual gears. I suspect the lower gears can act like the old B gear. From the manual : ■S mode ●You can choose from 6 levels of accelerating force and engine braking force. ●A lower shift range will provide greater accelerating force and engine braking force than a higher shift range, and the engine revolutions will also increase. ●When the shift range is S4 or lower, holding the shift lever or paddle shift switch (if equipped) toward “+” sets the shift range to S6. ●To prevent the engine from over-revving, upshifting may automatically occur when the shift range is 4 or lower.
Maybe more accurate to say "to a complete stop electrically alone"—certainly with regen almost all the way down to 0 MPH, but the way the MG's generated voltage also drops toward zero as the speed does, there's a limit to the rate of slowing you can get from regen alone in those last moments rolling to a stop. But there's no difficulty in the car supplementing that with a little bit of motor current in the reverse direction in those last moments, all transparently so you don't have to know the details. You can bring a Prius all the way to a stop that way too: just slow it by regen alone to below 6 MPH or so and then shift to R (above 6 MPH the car doesn't let you), and at the exact moment 0 MPH is hit, stab the brakes. That's my standard Prius test for brake drag, because engaging the friction brakes only at 0 MPH to keep the car stopped means they make no heat, so the test for drag isn't spoiled. A Prius reprogrammed for one-pedal driving could easily do the same, automatically. But what the standard Prius programming does instead is apply a small amount of forward motor current near 0 MPH, to emulate the behavior of a standard automatic transmission that wants to creep forward when you're not on the brake. Me, I'd be happy if I had a setting to just not apply any motor current, forward or reverse, automatically at that moment—just have a car that rolls out to a natural stop without trying to creep forward or to stop sooner. I can use the brake to stop sooner, and without the programmed-in creep, I could make nicer limo stops.
The manual language was the same with older years and between the hybrid and ICE models. Even when the Camry hybrid had B and no virtual gears, it said, "Position for engine braking" for B. Since the goal is to provide more braking force through the drive train, Toyota isn't concerned with drawing a distinction between the engine and motor in the manual. The software will use whatever it thinks is best. It is just that the size of the hybrid's battery would quickly fill with the required increase in regen. So the system goes right to increased engine revs. Got curious and looked at the bZ4X manual. There is a regen boost button next to the shifter. Press it and regen while foot off the accelerator increases the regen braking amount. Going to guess it isn't any different than shifting to B in a Prime/PHV. A button that isn't on the steering wheel makes it seem like an 'engine braking gear' was an afterthought to the rotary shifter design. Other BEVs use the lower gear positions of a traditional shifter instead of a button. The hybrid battery size was a limit on the level of regen braking. (I guess excess energy MG 2 could make could go to MG 1 to spin the engine, but that seems Goldbergesque for a drive train the connects the wheels to the engine.) I could have been conflating that to lower regen braking force. Has anyone measured the max deceleration rate before the friction brakes will be used? I'm seeing 0.2g max for a Tesla's one pedal braking. Your method of getting regen braking down to 0mph is proof that there are limits within the hybrid system. We could do it in the software, and pretend adding lines of code never messes anything up. I saw in the manual that you could do this with a Tesla. One pedal can be turned off, and the car set to coast instead of a faux auto trans creep. wouldn't surprise me if others had such setting options.
Some do. Some don't. The degree they go to one pedal driving varies. Most that do give the driver the option of using it or not.
There would be three places to look for the inherent limits on regen braking: The battery capacity, which determines how long any given regen force can be sustained. Whatever maximum regen force the car will apply, a smaller battery will sooner reach the point where engine and/or friction braking must take over. The maximum torque rating of MG2. That'll set the maximum braking g force achievable through regen alone under any circumstances. The "Charge Control Limit", a PID you can read from the power management control ECU, showing the limit of charging power the car will feed into the battery. If Toyota allows more power into larger-capacity batteries based on C rate, this limit will show that. Because power is torque ✕ rpm, this means the maximum regen torque and g force available fall off at higher road speeds. It's clear that the plugins have larger batteries, and so can sustain a given level of regen for longer than the HEVs. For the gen 3 HEV (the model I know best): The MG2 torque limit is 207 Nm. Given gen 3 liftback gearing and using 314 mm for the effective tire radius, that's 5680 N (1277 pounds) of road thrust, enough to slow an unladen gen 3 (1382 kg per carspecs.org) at 0.42 g, or a fully-laden one (3980 lb GVWR sticker) at 0.32 g. As a sanity check on those numbers, this source gives examples of "Hard Braking" (0.28 g) and "Very Hard Braking" (0.51 g). So MG2's rated torque is more than enough to qualify as "Hard Braking". (Even if it can, whether the car would ever apply that much regen without also bringing the brakes into play is a matter of its programming.) The charge control limit, per the repair manual, is "−33 kW or more". (Toyota calls power from the battery positive, power to the battery negative, and by "or more" they mean "or further toward + on the number line" so, for example, −20 is "more" than −33.) The ECU adjusts this value in real time according to battery conditions, so you can't expect regen as strong as −33 kW except from a pretty young battery that isn't too charged or too hot or too cold. If CCL is the charge limit in watts at this moment and rpm the rotation of MG2, the available MG2 torque (in newton meters) is 9.5493(CCL)/rpm. That curve crosses the constant MG2 torque line, 207 Nm, at rpm = 9.5493(CCL)/−207. When CCL is −33 kW, that's rpm = 1522 (about 13 MPH road speed). At any higher speed, this limit is less than the MG2 torque rating, so the available regen g is determined by this. Those two limits lead to a plot like this as a first effort (again, I'm using gen 3 specifics here): But that plot neglects another limit, namely, whether those high regen levels at lower speeds are really achievable. A voltage higher than the battery's own voltage is needed to make a battery charge. Figure 3.6 (p. 59) from the ORNL teardown report shows the voltage out of MG2 at various speeds. The traction battery has a nominal voltage of 201.6 VDC and is even somewhat higher when charging. There is a "boost converter" that can raise that as high as 650 VDC when needed to power the MGs, and it can also buck high MG voltages back down to battery voltage during regen. That converter doesn't boost in that direction, though, so when MG2 is producing less than battery voltage, that converter can't help. The car has another trick up its sleeve, touched on further below, but an obvious question is what road speed is needed for MG2 to produce 201.6 volts? At first glance, fig. 3.6 seems to say MG2 has to rev above about 5500 rpm (47 mph road speed) to produce that voltage. Of course, we know the car can regen at lower road speeds, so the picture isn't complete yet. Two important details are in the y-axis label of the graph. The first is that it says line to neutral, and the second is that it says RMS Voltage. The three phase windings of MG2 do join at a common neutral, but that's all inside the motor where the car's inverter has no connection to it. The inverter only sees the line-to-line voltages, which (when sinusoidal) are higher by the square root of 3. (That's the same reason a building can have three-phase power that's 120 V line to neutral and 208 V line to line, or 277 V line to neutral and 480 V line to line.) Also, the way the inverter's H-bridges rectify the AC waveforms from the motor to DC, the DC voltage reflects the waves' peak, not RMS, amplitude. The peak (not peak-to-peak!) voltage of a sine wave is its RMS voltage times the square root of 2. So taking both these factors into account, the battery voltage of 201.6 VDC nominal corresponds roughly to 82 V RMS line to neutral, and fig. 3.6 shows MG2 only having to hit 2000 rpm to generate that, or 17 MPH road speed. (Wait! Doesn't that also mean the boost converter limit of 650 VDC is hit around 6500 MG2 rpm? Can't the car drive MG2 at double that speed? How can it do that? I'm pretty sure the answer involves field weakening.) 17 MPH is a lot better, but we still know the car can regen down to even lower speeds than that. That's where the other trick comes in. If the lower MG2 voltage could be boosted up to above the battery voltage, regen charging could continue. While the so-called "boost converter" doesn't boost in that direction, there is another way. The car can get a boost-converter effect by switching the IGBTs of the MG2 inverter and exploiting the inductance of MG2's own windings. There's an old thread around here somewhere with the details confirming the car does that. So the car is able to keep doing some regen even below 17 MPH and right down to single-digit speeds. But the limits at those low speeds may be lower than my g plot above suggests. Goldbergesque or not, that is exactly what's happening when a Prius is engine-braking. (There is also, though, a mechanical path through the gears. Not all of that energy is passing electrically from MG2 to MG1. More on that in this thread.) For really Goldbergesque, consider what happens when cruising along in 'overdrive' conditions (low revs at higher torque from engine, converted to high revs at low torque on the highway). Electrical power is also flowing from MG2 to MG1 then! MG2 is subtracting torque at the output, with MG1 contributing to higher output revs. The algebra works out just fine, but whoever thought it up is a weirdo.
I was surprised by how much power regen braking provides. I saw 100-200 amps from braking. The CHG mode only provides about 15 amps. I believe this is intentional, so as not to impact fuel economy too much. I am no longer able to monitor this, as the relevant feature in my OBD app has been disabled in an update.
Did you say somewhere you bought an Autel AP200? Is that what got disabled? Sure hope that doesn't happen to mine.
I have Car Scanner for Android, paid edition. I am connected wirelessly to the Vgate vLinker MC+ BluetoothOBD2 Car Diagnostic Scan Tool. In Dashboard mode, it displays windows of the protocol readings you choose on your phone screen. I had it displaying state of charge for the hybrid battery. It showed the voltage, and the current flow in and out of the battery as I drove. One day it was simply, "no longer available." More than that, I don't know.
