Regenerative braking yay/nay?

[MoneyJohn]

I am not too sure if this is a right forum for this question. Admins can feel free to move accordingly. This question is on my mind for a while. One of my vehicles has regenerative braking whereas other one does not. I personally do not like regenerative braking, esp for city driving. Many times I go from a light to the next one without my foot on an accelerator, the car just rolls. Whereas that is not possible in Forester because of regenerative braking. Sometimes I have to push pedal even on a downward slope. What do others feel about regenerative braking? What are the benefits that I have failed to realize? Many thanks in advance.

 

[Eddie]

You get away with idling from light to light? I didn't realize 2006 Foresters had regenerative braking. I thought it was used in electric and Hy-bread vehicles only. Enlighten me. Ed

 

[nthach]

Unless Subaru installed some sort of KERS or the "mild" hybrid system off the XV Crosstrek Hybrid, I doubt you have any provision for regenerative braking. The Forester's CVT control logic probably incorporates better hill sensing and will hold back a "range" or two to keep it going steady down hill. Most automatics/CVTs have grade logic control that theoretically helps going up and down hill. In my experience the system does work well in some but I've always had to manually shift the Subies I've driven to get some decent acceleration up and deceleration down.

 

[Cujet]

I think you mean that the engine is still commanded to produce some power, even while braking. Manufacturers do this to keep catalytic converters warm and effective. I prefer a vehicle that cuts fuel flow on throttle lift. Try selecting neutral when decelerating. You might find that the engine is FAR above idle with the brakes applied. I find this annoying.

 

[ag_ghost]

Originally Posted By: nthach

Unless Subaru installed some sort of KERS or the "mild" hybrid system off the XV Crosstrek Hybrid, I doubt you have any provision for regenerative braking. The Forester's CVT control logic probably incorporates better hill sensing and will hold back a "range" or two to keep it going steady down hill. Most automatics/CVTs have grade logic control that theoretically helps going up and down hill. In my experience the system does work well in some but I've always had to manually shift the Subies I've driven to get some decent acceleration up and deceleration down.

FWIW, Our 2015 Honda CR-V with a CVT exhibits this behavior coming on significant inclines in the Bay Area. My wife and I really like it. The engine tach also seems to align with this system. I've driven a friend's Tesla Model S (now departed); THAT had regnerative braking on flat surfaces ... not trivial to acclimate imho. Kevin

 

[Ethan1]

I didn't even know there was a Forester hybrid

 

[OneEyeJack]

The 3rd gen company Prius in on the original brakes ad over 200K miles. It works just fine. Once in a while, you can feel it change over at just under 10 mph but it's not a problem. You can barely feel it if at all and then only once in a great while.

 

[TheKracken]

Originally Posted By: OneEyeJack

The 3rd gen company Prius in on the original brakes ad over 200K miles. It works just fine. Once in a while, you can feel it change over at just under 10 mph but it's not a problem. You can barely feel it if at all and then only once in a great while.

My 2ed gen got it's first brake job at 238k miles. My 3ed gen is still on it's originals as well.

 

[gathermewool]

I think you mean engine-braking. One thing I LOVE about our Subies, is that they engine-brake well. Great for reducing gas consumption and brake wear. Regenerative braking turns an electrical motor into a generator, so that the production of energy to refill the batteries causes the car to slow down, vice the brakes. This allows the car to slow down AND supply juice to the battery, extending the batteries range.

 

[EdwardC]

The LEAF has two settings for the amount of regen when coasting. The newest 2018 LEAF is reported to have the capability to come to a complete stop, so you can essentially drive with just one foot on the gas pedal. In the 'D' setting on my 2016 model, it will coast freely when the gas pedal isn't pressed, with very minimal regen. in the 'B' (brake?) mode, when I let off the gas, it'll slow down a lot more, regenerating much more power. If I'm in 'B' mode and want to decelerate slower, I'll press the throttle just a little bit and it'll coast more freely. Regen doesn't have to be limited to a gas/electric hybrid, it conceptually just means that the kinetic energy is being stored for future use. Could be charging a battery, storing compressed air, spinning a flywheel, heating something up, etc. Since the Forester doesn't appear to be a hybrid, my guess is that you're feeling the engine braking. I might be wrong on this, but in the past, when coasting, the computer would have to put in some amount of throttle/fuel to keep the engine idling. Newer cars, in search of fuel economy, can completely shut down all fuel input, requiring the momentum of the car to keep the engine spinning while it effectively just compresses/pumps air. I believe this is what CuJet is saying.

 

[MCompact]

I like the regenerative braking on our i3; you can almost drive with just one pedal. It also works pretty well on the BMW iPerformance PHEVs.

 

[HangFire]

Originally Posted By: MoneyJohn

What do others feel about regenerative braking? What are the benefits that I have failed to realize?

One thing I've learned from driving many kinds and brands of cars, is that how one manufacturer tunes one model has little/nothing to do with another. For example when I first had a GM car automatic downshift to help me compression brake, I was shocked because I had driven mostly Ford automatics (which would have upshifted just to be obnoxious, because: Ford). My Toyota likes to coast forever, but if I ease on the brakes slightly, it'll downshift too. And Hyundai... who the heck knows what that transmission was going to do next. Point being, it's not one "regenerative braking" feel across all so-equipped cars.

 

[Nick1994]

I think in your case it's a CVT thing

 

[UncleDave]

My lexus transmission has an engine braking mode - more conducive to one foot driving with stronger regeneration and engine compression braking. Interesting to note that its more efficient to practically coast under deceleration - than run in engine braking/ high regeneration mode. UD

 

[MCompact]

Originally Posted By: UncleDave

My lexus transmission has an engine braking mode - more conducive to one foot driving with stronger regeneration and engine compression braking. Interesting to note that its more efficient to practically coast under deceleration - than run in engine braking/ high regeneration mode. UD

When I put my 2 Series in Eco Pro mode the engine rpm drops to idle when coasting- down to @15 mph; I've found I can bump up my commuting fuel economy by 1-2 mpg depending on traffic.

 

[Alfred_B]

Originally Posted By: Nick1994

I think in your case it's a CVT thing

or a sticking brake caliper.

 

[MoneyJohn]

Originally Posted By: gathermewool

I think you mean engine-braking. One thing I LOVE about our Subies, is that they engine-brake well. Great for reducing gas consumption and brake wear. Regenerative braking turns an electrical motor into a generator, so that the production of energy to refill the batteries causes the car to slow down, vice the brakes. This allows the car to slow down AND supply juice to the battery, extending the batteries range.

Thank you. I didn't know this. I said regenerative braking, although its an incorrect term in this case because the car slows down the moment my foot is off the pedal. I don't know the technical terms for this. I wonder how engine braking reduces gas consumption. For me, I have to press the pedal till I reach the light, whereas for the Nissan, the kinetic energy itself propels the car to the light. That is the difference I am trying to understand. So I 'think' Subaru to use more gas as opposed to Nissan. Brake wear, yes that I can understand. Did I get that wrong?

 

[gathermewool]

Originally Posted By: MoneyJohn

Originally Posted By: gathermewool

I think you mean engine-braking. One thing I LOVE about our Subies, is that they engine-brake well. Great for reducing gas consumption and brake wear. Regenerative braking turns an electrical motor into a generator, so that the production of energy to refill the batteries causes the car to slow down, vice the brakes. This allows the car to slow down AND supply juice to the battery, extending the batteries range.

Thank you. I didn't know this. I said regenerative braking, although its an incorrect term in this case because the car slows down the moment my foot is off the pedal. I don't know the technical terms for this. I wonder how engine braking reduces gas consumption. For me, I have to press the pedal till I reach the light, whereas for the Nissan, the kinetic energy itself propels the car to the light. That is the difference I am trying to understand. So I 'think' Subaru to use more gas as opposed to Nissan. Brake wear, yes that I can understand. Did I get that wrong?

Subies are great at engine-braking, but it shouldn't slow you down drastically. Another Thing our Subaru CVT's do is raise the RPM to help with engine-braking downhill. I had a badly dragging caliper on my previous '97 Legacy, which would cause the car to slow down even more. I had let it get bad enough to do this, which wasn't good. When you stop after a long drive and put your hand on the wheel, is it hot? Can you stick your finger through the wheels pokes to touch the caliper? Be careful, because it might be very, very hot if it's sticking, but should be at most very warm to the touch after normal driving/braking.

 

[nthach]

Originally Posted By: MoneyJohn

I wonder how engine braking reduces gas consumption. For me, I have to press the pedal till I reach the light, whereas for the Nissan, the kinetic energy itself propels the car to the light. That is the difference I am trying to understand. So I 'think' Subaru to use more gas as opposed to Nissan. Brake wear, yes that I can understand. Did I get that wrong?

It depends on how the OEM programmed their deceleration algorithms. Most of the time until you step on the brake, the torque converter is locked and fuel is cut from the engine. Some OEMs will program a downshift if it senses the car is going downhill. This mimics in an automatic/CVT how a manual transmission would be driven. Since the pistons are still moving in engine braking but no fuel is being used - the engine is working against vacuum providing mechanical retardation, the minute you step on the gas the PCM/ECM will start injecting again. It works differently in a hybrid - a deceleration event turns the electric motor into a generator and the magnetic field produced by the rotor and stator creates resistance that will slow the car down but recapture energy to charge the batteries. However, shift a Toyota/Lexus/Ford hybrid into B and the power-split device will couple the gas engine and freewheel it to create more braking force since the batteries can only hold so much charge.