[gschlact2]

It’s been discussed in various threads, but I wanted to try to consolidate a discussion on battery regeneration while driving.

I’ve only had my new 45e a day but played a bunch driving around for an hour yesterday evening. I remembered, reading some of the various hypotheses of regen charging and ‘one peddle’ driving being different depending on Drive mode (sports, hybrid, electric, adaptive).

What I observed, is that in either hybrid or electric modes, regular one foot regen seemed about the same level of charging from similar speeds on the dynamic ‘bar graph’ on the dash display. However, I had the idea to see what happened in the same modes if I down shifted with the paddle. I didn’t know what to expect and thought the ICE might pop on for the extra torque breaking.

What I observed was the more I paddled down shifting, the deeper the charge got (higher number) on the bar graph, and seat of the pants breaking measurement got stronger.

[jad03060]

Maximum regeneration on the 45e does not really support one pedal driving.

The computer can disconnect the ICE from the rest of the drivetrain as the EV motor is at the front of the transmission, so as you manually downshift, even if the ICE is on, while decelerating, the computer can decide how to slow the vehicle based on twirling the engine or the EV motor turned generator...it's much more energy efficient to use the regeneration than the engine, but it might combine the two as it reengaged the ICE.

[gschlact2]

Originally Posted by jad03060

Maximum regeneration on the 45e does not really support one pedal driving.

The computer can disconnect the ICE from the rest of the drivetrain as the EV motor is at the front of the transmission, so as you manually downshift, even if the ICE is on, while decelerating, the computer can decide how to slow the vehicle based on twirling the engine or the EV motor turned generator...it's much more energy efficient to use the regeneration than the engine, but it might combine the two as it reengaged the ICE.

If it were to have used the ice, I believe we would have seen RPM pop up on the dashboard, plus I didn’t here the engine. So, downshifting the transmission drove up revolutions of the electric motor for higher charging current and more e-breaking.

[Jrg3170]

Somewhat related - has anyone seen / read anything on regen efficiency comparisons across different BEVs/PHEVs?

I wonder how efficient the regen is for the 45e vs a motor that's implemented more directly, for example with the XC90

[jad03060]

The amount of regen is mostly a function of programming. BMW did not program it so one-pedal driving was possible. Personally, I'd like a bit more control over it and would be happy to have more.

[NoClosedDoors]

Would be great if Mission could modify regen as well..

[DRMura]

I will be picking up my 2023 45e in two days. I’ve never driven an electric vehicle before and have a couple questions on this regeneration topic. If I’m driving on the highway under electric power and I take my foot off the pedal to slow down, I assume the car then uses the electric motor to generate energy for charging both batteries while coasting. Is this correct?

If I’m driving on the highway with the ICE running, and I take my foot off the pedal to slow down, will the ICE shut off and allow the electric motor to generate energy for charging?

In either case, will the car decelerate faster than a non-electric car with the foot off the pedal, given that it is using the kinetic energy of the vehicle to charge the batteries?

Another question - if I’m driving under electric power on a cold day and get on the highway, will the ICE turn on even if it hasn’t warmed up?

I apologize if these questions are answered elsewhere in this forum. I am a little overwhelmed with all the information available. But I don’t want to not know what’s happening as I experience what is apparently a fantastic vehicle.

[gschlact2]

Standard foot off the accelerator will regenerate battery and slow more than a non e vehicle, but not significantly enough that brake lights need to auto turn on. If you want faster decel without braking, you can left paddle as a downshift and get even more regen as well. ICE will always turn in immediately under all conditions if the driver depresses accelerator enough.

[biterror]

Originally Posted by gschlact2

Standard foot off the accelerator will regenerate battery and slow more than a non e vehicle, but not significantly enough that brake lights need to auto turn on. If you want faster decel without braking, you can left paddle as a downshift and get even more regen as well. ICE will always turn in immediately under all conditions if the driver depresses accelerator enough.

If you need to decelerate faster, you can also use the brake pedal as usual. It will first increase the regen power and only if that isn't enough, it will apply real brakes. You can see this in the electric power / regen meter. In other words, using the brake pedal does not necessarily activate the real brakes.

Edit: Likewise, if the decelation is too strong, you can adjust it by gently pressing the gas pedal. Neither pedal is an on/off switch but can be used to control acceleration/deceleration smoothly.

[Apples12]

How much regen does the car actually do? I.e. if it's at 0, what sort of distance do you need to cover to recharge 5%?

I ask this as we had a 45e on demo a couple of weeks ago, no charging options available for us so tried to see how much we could regen...it wasn't much, 1-2% max. But I don't know what settings the car was set to or anything

[cellarrat]

Originally Posted by jad03060

The amount of regen is mostly a function of programming. BMW did not program it so one-pedal driving was possible. Personally, I'd like a bit more control over it and would be happy to have more.

The Ioniq has paddles (where the gear-change paddles on the BMW) that dial regen in and out. LOVE that idea.

[eelnoraa]

In city stop&go traffic, there will be be meaningful accumulation from regen. As soon as anything is captured, it will be used in the next acceleration from stop. Just like any hybrid I have driven before, battery is used for initial acceleration, the part where engine is most inefficient. This make sense to me.

If you are on highway, you really need some downhill to regen, flat constant speed won’t regen at all. I am driving from Paso Roble to Morro Bay today on 46. Initial stretch is uphill. The 2nd half is mild and long downhill, I got total of 3 miles back. Speed isn’t slow tho, so I don’t need ti brake to stay with traffic in front.

[eelnoraa]

Originally Posted by gschlact2

Standard foot off the accelerator will regenerate battery and slow more than a non e vehicle, but not significantly enough that brake lights need to auto turn on. If you want faster decel without braking, you can left paddle as a downshift and get even more regen as well. ICE will always turn in immediately under all conditions if the driver depresses accelerator enough.

No I don’t think down shift help in regen at all. Here is the reason. During download highway, chances are ICE is off in hybrid mode. If you down shift using paddle, ice will turn on. If anything at all, gas is being wasted here. There is no way to shift transmission manual without ice kicking in.

Regen is all about capture kinetic energy back to battery energy. ICE or engine rpm don’t play a role. If engine brake is in act, I would say regen will be less because some of the energy is taken away by engine brake.

The regen capability of 45e is there. When we hit the brake , first half is mostly regen increase. Maybe on next FW release, bmw can increase that, or have an option to increae, or best, let the setting be controlled by padding in EV mode, that will be idea.

[DRMura]

Originally Posted by eelnoraa

In city stop&go traffic, there will be be meaningful accumulation from regen. As soon as anything is captured, it will be used in the next acceleration from stop. Just like any hybrid I have driven before, battery is used for initial acceleration, the part where engine is most inefficient. This make sense to me.

If you are on highway, you really need some downhill to regen, flat constant speed won’t regen at all. I am driving from Paso Roble to Morro Bay today on 46. Initial stretch is uphill. The 2nd half is mild and long downhill, I got total of 3 miles back. Speed isn’t slow tho, so I don’t need ti brake to stay with traffic in front.

If there is no regen at constant highway speed, how does the high voltage battery not get depleted given all the sensors/electronics that are constantly using power. I have read that there is no alternator as in non-electric car, but that the 12v system is powered by the high voltage battery.

Also, thanks for the great information….

[Guy Fleegman]

I often use cruise control and reduce speed by toggling the CC speed setting on the steering wheel. For example, if I have CC set for 40mph and see the traffic light ahead turning yellow or red, I'll toggle the CC max down to 35, then 30, etc. That will slow the car down without braking more quickly than coasting alone and the regen meter indicates a high level of energy being transferred.

I don't know whether that regens more, less, or the same as coasting alone, but it gives me a little more control with little effort.

[jad03060]

When required, the computer can always turn the EV motor into a generator to maintain normal operations. All of the lights, HVAC, etc., is all run via the 12vdc systems, and that is maintained by the DC-DC converter that is powered by the HV batteries...so, the computer will never allow the HV battery to become fully discharged. You do have the option of forcing a higher minimum HV battery level with the BC button that allows 30-100% capacity. THat's primarily there for those Euro cities that have restrictions on ICE use, or price breaks for being on electric mode. On a longer trip where you may not be able to recharge, keeping 30% available will let you precondition the cabin to keep passengers comfortable if you have to make a stop somewhere.

FWIW, except in a fault situation, the braking in the 45e is brake by wire...the computer is blending regeneration and hydraulic braking by itself...you're not activating the brakes through a master cylinder directly. That does happen if the computer were to fail as a fallback situation, though.

[eelnoraa]

Originally Posted by DRMura

If there is no regen at constant highway speed, how does the high voltage battery not get depleted given all the sensors/electronics that are constantly using power. I have read that there is no alternator as in non-electric car, but that the 12v system is powered by the high voltage battery.

Also, thanks for the great information….

As far as I can tell, in highway speed with ICE, EV motor is just disconnected. In reality, speed does change a bit. There is some amount of regen when car is slow down (when you lift foot off gas paddle), maybe they does it. In fact, you remind me, I actually see EV mile reduces by 1 when I am in ICE mode for a long time. I thought it was due sudden acceleration to avoid emerging traffic. But it can also be from powering the cars electronics.

So one big advantage of EV/PHEV, paso roble is 110F today. Our hotel has EVSE, so our 45e was plugged in over night. We were able to turn on precondition when we left our room, by the time we got to the car, we would have AC on for 3-4 min. In this weather, it makes a huge difference for the kid.

[biterror]

Originally Posted by cellarrat

The Ioniq has paddles (where the gear-change paddles on the BMW) that dial regen in and out. LOVE that idea.

You can do the same using the brake and gas pedals. My wife had a Kona EV and she was constantly using the paddles when slowing down and it was VERY annoying because the ride was so jerky. I'm trying to tell her that the gas pedal is not an on/off switch but she can operate it gradually and accelerate/decelerate smoothly.

[biterror]

Originally Posted by eelnoraa

As far as I can tell, in highway speed with ICE, EV motor is just disconnected. In reality, speed does change a bit. There is some amount of regen when car is slow down (when you lift foot off gas paddle), maybe they does it. In fact, you remind me, I actually see EV mile reduces by 1 when I am in ICE mode for a long time. I thought it was due sudden acceleration to avoid emerging traffic. But it can also be from powering the cars electronics.

The electric motor can be disconnected from the ICE and the gearbox can be set to neutral, but there's no way of getting power form the ICE to the wheels without the electric motor spinning.

The AC compressor runs off the HV battery, so the battery charge will be dropping even when the ICE is running (unless the system decides to recharge the HV battery using the electric motor as a generator). The AC compressor needs far more power from the battery than the other electrical systems.

[eelnoraa]

Today, I drove back from paso roble to SF Bay. Here is a few founding. Some are quite interesting

1. Weather is hot. Ambient range from 95F-110F, most is the drive was above 100F. There are quite a bit of traffic on 101, either from construction or accidents, I only managed 24.2 EV miles before battery gauge showed “- - -“. This is the lowest I have got. I think this is due to high AC usage and time stuck in traffic. I typically can get up to 35miles without efforts.

2. I ran out is better very early. So gave me a good chance to watch how hybrid mode work by also displaying the energy flow screen. Car will use engine to charge battery in this situation (“- - -“ state) regardless of speed. The target seems to be “1 mile”. Once there, the energy flow to battery stops. I think the main purpose is to keep HV SOC to power the rest is the car. This seems to be inline with how other non Plug-in hybrid I have experience. But I am surprised the target isn’t higher, say 2-3 miles.

2. Even at “- - -“, car will try to start in EV mode. The EV power range will be up to 5%, sometime even lower. At 5%, EV mode speed last until 25-30 mph. After that ICE take over. At 1-2% at EV power gauge, EV will initial the stand still start, and once car is moving, ICE take over.

3. There are time where EV will complete not available, so car will start with ICE completely. This is the worst case and most stressful for ICE, but occasion is few. Most of the time, slow down regen will give a some EV mode on the next still start. This is a good design from ICE stand point. It avoids/eliminates the worst condition for ICE.

4. Sport mode at this “- - -“ SOC, the EV side behave the same, car will give some EV assist even when ice is enabled all the time.

5. All these time with “- - -“, bmw app shows 2-3% of battery. I wonder if this 2-3% is with the buffer included, or buffer is separate from this percentage.

Overall passive regen is small on average elevation change terrain. You cannot rely on regen to charge HV battery more than 1-2 miles. I think it will take a long stretch of majorly down hill to charge in any significant way. And even with that, the car will switch to EV mode as soon as it thinks it got enough.

I may start another thread consolidating actual MPG and kWh once I get home and open PC for excel table.

[jad03060]

The battery percentage readout is the useable amount, so does not include the buffer.

You'll almost always have some e-assist, but may not have e-boost. Similar, but different modes.

[gschlact2]

Originally Posted by eelnoraa

No I don’t think down shift help in regen at all. Here is the reason. During download highway, chances are ICE is off in hybrid mode. If you down shift using paddle, ice will turn on. If anything at all, gas is being wasted here. There is no way to shift transmission manual without ice kicking in.

Regen is all about capture kinetic energy back to battery energy. ICE or engine rpm don’t play a role. If engine brake is in act, I would say regen will be less because some of the energy is taken away by engine brake.

The regen capability of 45e is there. When we hit the brake , first half is mostly regen increase. Maybe on next FW release, bmw can increase that, or have an option to increae, or best, let the setting be controlled by padding in EV mode, that will be idea.

I have seen otherwise. If I paddle down, I still see the word eDrive displayed near/on the 0-100% bar.
Otherwise I wouldn’t see the word. My ice is not on.

EDIT-
I am wrong, with enough downshifting the ICE does turn on for engine breaking.