Is Max Regen really valid for daily use?

[Chris Hall]

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.

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[Past the Pavement]

I get what they're saying. I'd have to wonder, it seems like you'd be regening more but for less time so does it make a significant difference in overall Regen or just faster to get the same regen?

The other aspect is more of a personal preference but I really enjoy the 1 pedal operation that max regen affords.

I didn't realize the blended nature of the braking though, that's some good info for sure!

 

[CodyDog]

Great video Chris!

 

[GETLAF]

Good information here. Normally I religiously press the max regen every time I start my jeep. But I actually let it off today to try it and you are totally right! I did achieved couples miles more than I normally do on my daily commute. I normally commute 28.5 Miles in my rubicon and normally engine kick in when I am around 2 miles from home. Now I did it home with still 1-2% left. this is for 90% road averaging 55 MPH no hills.

 

[FLJeep1]

Chris,

Very interesting. You have been a huge help getting me to understand things this 4XE does.

I would think the actual brakes go on with the brake pedal and the electric motor with the regen button. It is very easy using the max regen button to drive and stop.

I usually start with 29 miles when fully charged. Over 30 would be a huge benefit especially when the EPA rates the 4XE at 21. I will have to get used to stopping again...

Keep it up please...

 

[sentience]

This is a good question. I see it as a total range versus longer brake life trade off.

While driving with Max regen on, I have noticed it potentially kicking in while I'm trying to coast, or keep speed. Since it's essentially braking for no "real" reason, there's an inefficiency there - and my total range is reduced. This also ties into one of my biggest pet peeves with this system: Its inability to communicate to me when it decides to activate the brake light.

On the flip side, with max regen on, I'm also using less of the actual brakes during 'normal' braking maneuvers, like rolling into a red light, and exiting off a highway. the vehicle is slowing down in a controlled manner without me applying the brakes, using what I assume are the motors, and hence 'saving' the brake pad, rotors from wear and tear.

Ideally, I would like to see a "max regen lite" option. something which engages at a set speed (e.g. 45 mph), where it does not affect coasting, but will assist in 'normal' maneuvers. That should reduce the amount of power loss from coasting, but still provide a tangible benefit to the braking system.

 

[michail]

I think it does a little of that. The braking is more gentle at faster speeds. In under 25 it gets harder.

In addition to the video chris did, I was on a dark road and could see the road reflectors reflectors lighting up when my foot came off the pedal. Up to that point, keeping a lite throttle worked like coasting and didn't activate the brake lights.

My guess would be max regen provides the braking force for optimal regeneration. The problem is to not over brake.

 

[Asterix2112]

Max regen lite? You have never driven an all electric car! The 4xe's "Max" regen braking is as wimpy as you can get (I have had a BMW i3, have a Chevy Bolt, and driven a Tesla). It BARELY comes on at all at highway speeds, and only is a little stronger at slow speeds. Coming to a stop from 50mph or so I rarely ever have to touch my brake on the Bolt. I pretty much always have to touch it some on the Jeep.

Now some is the fact that the Jeep is much heavier, so there is mass there, but I wish they would make the Max Regen a Mid Regen setting and give me a stronger, REAL Max Regen setting.

Just FYI, I never drive either car without the Regen braking set to the max you can do. Ever. It is awesome that I (almost) never have to change brake pads!

 

[Past the Pavement]

Great video Chris!

Lol I feel like an idiot, didn't realize it was YOUR video Chris ‍ Yeah great analysis and super informative!

 

[Past the Pavement]

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.

 

[SnB4xe]

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.

Exactly!
It makes no difference either way provided you have reasonable driving habits. The difference is where your foot is placed.

For those that don't know....
1 pedal driving uses the friction brakes too. The electric motor isn't able to bring the vehicle to a complete stop so the friction brakes are necessary with either method.

The max regen level is determined by the motor size, available battery capacity, battery temperature and cabling.

 

[Mgg253]

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

 

[dalema]

While driving with Max regen on, I have noticed it potentially kicking in while I'm trying to coast, or keep speed. Since it's essentially braking for no "real" reason, there's an inefficiency there - and my total range is reduced. This also ties into one of my biggest pet peeves with this system: Its inability to communicate to me when it decides to activate the brake light.

When I test drove one - this was my comment to the salesman with me. The max regen felt like a drag on acceleration or maybe better put while trying to keep a constant speed with my foot on the accelerator pedal. I was wondering how that would be helpful to overall mileage, and was kind of annoying. Click the button off and it went away.

One thought on the question you have - I wonder if the Tazer could identify this and be configured to trigger one of the lights on the dash that is typically used for something else. I imagine it's all in the code somewhere. @joe@zauto

 

[SnB4xe]

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

If you don't lift your foot off the accelerator completely then it will adjust to what you need and no more. I didn't have to touch the brake pedal when I was coming down from the mountains. If the Jeep was going too fast I just lifted off the accelerator pedal a little bit and it slowed down to the speed I wanted. It was kinda nice actually.

What I am curious about is how it works in 4L. That might be interesting.....and fun.

 

[michail]

I haven't had much chance to drive Wranglers in 4L since you typically need some extreme conditions for that.

I tested out my 4xe in a straight line and it was really hard to stop. It felt like I was driving the NASA crawler, lol.

There should come a point where there is too much electricity for the system to handle.

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