Is Max Regen really valid for daily use?

[Past the Pavement]

What I want to know is how the max regen would work on something like a steep grade, say 6%. Often in my grand Cherokee I put it in 3rd or 4th so I’m not riding my brakes or flying down i70 from the high country. The max regen would be nice if it provided a similar type of resistance, I’m just afraid it may provide more than desired and have an algorithm to ensure it provides enough resistance to be slowing the vehicle. IE is it smart enough to provide significantly varying levels of resistance (regen) depending on your speed and if so what are they targeting. More resistance at higher speeds still may actually slow you at a lesser rate given basic properties of physics. F=ma. which means on the surface It sounds as though it is a dynamic formula Jeep has used

I should really test this down Parleys which is a pretty steep grade part of I-80 in Utah. From my limited use so far I think it's great for this. I find it will decelerate on max regen going down moderate inclines but you just position the accelerator where it maintains the speed you want and it will still regen the difference. From a lay/anecdotal perspective at least.

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[michail]

So what happens when there is too much electricity being generated, or is that even a concern? I would not want to be going down a mountain and thinking I'm generating instead of braking.

 

[JandS]

So what happens when there is too much electricity being generated, or is that even a concern? I would not want to be going down a mountain and thinking I'm generating instead of braking.

It isn't a concern. The car will just use less of its regeneration capacity. Hybrids are 20 years old and the tech doesn't have any serious flaws, if it ever did.

In response to a lot of the replies here, I felt the same about max Regen and brake life, but the point of Chris's video is that the brake pedal doesn't necessarily engage the brake pads, unless it's required. Your brake is essentially a selective Regen option unless you demand more than the motor can resist.

Knowing this is very interesting. I like 1-pedal driving BUT having the fine control of when I start 'braking' instead of guessing when is the ideal time to let off the throttle to maximize regen is pretty nice.

I feel like my day to day commute (16 miles roundtrip) max Regen is the way to go (city/traffic). But if I'm on a longer trip, not needing to manage the throttle as much when not on cruise control is pretty appealing given when I DO brake it's still using the motor to regen over the pads.

It is amazing how many things in our vehicles (not just the 4xe, but almost all new vehicles) are controlled by the car, but feedback is given to make the user think they're in control. Electric power steering is one that comes to mind - the feedback to the wheel is almost entirely based on some software.

It is sort of like how digital pictures are entirely dependent on layers of software now. Bigger sensors made low light photos better, but the secret sauce is how the camera takes a dozen or so pics at the same time (for our perception) and then stitches those together to decide how the picture should look if there was more light. Ultimately the picture you see is some blend of the picture you took and the engineer's software deciding how that pic is supposed to look.

 

[LJ_3M121318]

Started driving mine today. Will say it will take some getting used especially on freeway vs street

When I was on the freeway, the second I let go of the pedal Regen kicks in and almost drops it to a dangerously low speed. I found that I was stepping on the pedal more with Regen on, just to maintain highway speeds. Whereas withoutax Regen, then I get to a speed and lay off the pedal and just coast and make adjustments where needed. So I'm thinking while I'll get more Regen back on freeway, I might be using more pedal to hold speeds, which would negatively affect mpg.

On streets, it didn't seem to be as much of an issue. There it just feels like a golf cart so just need to get the hang of timing so it slows at the right time.

But I'm just driving it for the first time today so don't want to rush to any rash decisions so I'll play around with max Regen a bit more

 

[beaups]

It is amazing how many things in our vehicles (not just the 4xe, but almost all new vehicles) are controlled by the car, but feedback is given to make the user think they're in control. Electric power steering is one that comes to mind - the feedback to the wheel is almost entirely based on some software.

With a couple exceptions (wrangler *not* being one of them), that is not true. Most electric power steering systems still have physically connected steering shafts.

 

[SnB4xe]

Started driving mine today. Will say it will take some getting used especially on freeway vs street

When I was on the freeway, the second I let go of the pedal Regen kicks in and almost drops it to a dangerously low speed. I found that I was stepping on the pedal more with Regen on, just to maintain highway speeds. Whereas withoutax Regen, then I get to a speed and lay off the pedal and just coast and make adjustments where needed. So I'm thinking while I'll get more Regen back on freeway, I might be using more pedal to hold speeds, which would negatively affect mpg.

On streets, it didn't seem to be as much of an issue. There it just feels like a golf cart so just need to get the hang of timing so it slows at the right time.

But I'm just driving it for the first time today so don't want to rush to any rash decisions so I'll play around with max Regen a bit more

It is just the accelerator pedal mapping that changes. You aren't actually using more power to maintain speed.

It is mostly driver preference. Same or similar levels of regen can be accomplished by using the brake pedal.

 

[funnypeter]

If you don’t already know about the blended braking system on the Wrangler 4XE, this video might make you question the validity of using Max Regen on a daily basis.

Also, did you know that the Wrangler 4XE is both a series hybrid and a parallel hybrid depending on conditions? I don’t quite understand the conditions yet but I stumbled on it happening during this video and decided to talk about it.

Also, this video contains an idea for a group project. Looking for some creative electrical engineering help.

I absolutely use it everyday. The only problem is it is made me really lazy and sometimes I wait far too long before I break when I need to. Because 90% of the time it's enough not to have to use the brake pedal.

 

[BXFXJeep]

After the recent update the Max Regen works better for me, I had stopped using it, now I use it most of the time.

However I turn off the Max Regen when using e-save, or the battery hits <1%.

To me Max Regen feels weird when the gas engine is engaged, it feels a bit like there is a battle between the ICE and the Max Regen especially in heavy traffic.

The vast majority of my driving is city centre driving, so there's usually always a fair bit of stop and go traffic.

When I'm pure electric, it works nicely.

 

[BigLebowski]

I never really used the MAX Regen before, but I have been using MAX Regen a lot lately due to the weather. I find it helps slow the Jeep down in more more controlled fashion, especially when travelling down hill. I am not braking so the wheels are still turning, but the Jeep is slowing down. Engine braking without the engine.

 

[BXFXJeep]

Yes max Regen is great on slippery surfaces

 

[Doc Bo]

Three months old. Never off. Love regen. Will never replace brakes.

 

[Dabrakeman]

The max regen mode is quite simple to understand. How much regen braking can be had at any time is a function of what the battery can handle based upon battery state (charge level and temperature) and vehicle speed. What the battery can handle does not change whether you are in max regen or not. Max regen simply sets the amount of regen braking at whatever the battery state will allow as a max as soon as you lift completely off the throttle. Theoretically you could get the exact same amount of regen using the brake pedal if you knew all this information in your head and could do all the calculations real time. Whenever you exceed the max level of possible regen braking with the brake pedal (whether in max regen mode or not) you will use the friction brakes and the friction brakes is a pure energy loss (I am a retired brake engineer so this always makes me sad). When the brake pedal is depressed the blending algorithm simply takes the driver command for total braking torque from the brake pedal input (usually combination of pedal travel and pressure) and assigns delivering that torque to the wheels first via electric motor regen braking and if torque required exceeds the torque capability from the electric motors based on their state (speed, temperature, charge level) then the friction brakes "blend" in to make up the difference to achieve total driver commanded torque. I always leave the max mode on because it provides a guidance to you as the driver of what that max level is and you can tune your driving to it to maximize total regen and minimize friction braking.

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