Dissapointed in the 4xe Max Regeneration mode

Asterix2112

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(Disclaimer: I had a BMW i3 that only had heavy regenerative braking, and now have a Chevy Bolt, which not only has a good max regeneration mode, but also has a paddle behind the steering wheel that when pulled gives you extra heavy regenerative braking which is great for when you're coming to a stop light and need that little extra breaking to stop without having to use the physical brake)

After a week with the 4xe I can't help but say that I am disappointed with the max regenerative braking mode. Besides the fact that it doesn't stay enabled when the car is turned off (unlike what the manual states) the actual regenerative braking itself is just way too wimpy. And this of course means I'm not getting as much charging back into the batteries as I could, and that I am using up my brake pads more than I should. (Now it is better than my friends RAV4 Prime which has no max regen mode - a dealbreaker for me)

In max regen the 4xe seems to operate differently depending on your speed. When cruising at highway speed when you lift off the pedal it barely slows the car. Compared to my Bolt I am finding situations where traffic on the interstate slows a little in front of me where on the Bolt I would just lift the gas pedal and I would slow down enough no problem, but with the 4xe it just doesn't slow enough and I find myself having to apply a little physical braking.

When going slower the 4xe does apply the regen more powerfully, but still not as much is my Bolt, even without using the paddle. I am finding that just coming to stops at traffic lights I am using my brake pedal more on the 4xe than the Bolt. Especially if you're coming in at a good clip like 50mpg, the fact that it barely slows you in the beginning and then still is not as powerful at the end means you're really using the brake pedal a lot more.

It's a shame because with such a small battery range I want as much regen braking as possible to get juice back into that battery. Plus it's awfully nice essentially not having to ever worry about changing your brake pads!

I hope this can be fixed with a software upgrade. Maybe giving us the option in the display of selecting how strong we want the max regen to be, and if we wanted to be of variable amount of regen or the same strength regardless of speed. I am sure it's all computer controlled, so should be something that can be easily implemented with a software upgrade.





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Asterix2112

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Is this your first Wrangler? If you are coming from the world of BMW or Chevy it may take some time to get adjusted to the Jeep life.
First Wrangler, but I have had a Liberty and a Cherokee Trailhawk (that I traded in to get this) (need my 4x4 for my annual Corolla beach trips and 4x4 fun in the sand!). But that really is irrelevant to how the regenerative breaking is implemented.
 

VNT

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But but but, you will get the 7500$ kickback and that is all that really matters.

Seriously if the regen is the only thing you are worried about, everything else will swamp that out.
Wait until you take the doors off and top off, then you wont give a crap about an extra mile or 2 on the battery.

with 370HP I would stomping the gas to enjoy all that HP and Tq and saluting the Kickback god for the 7500 clams the US Taxpayer gave me.
 

JeepinPete

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I suspect the reason for this is the 4xe is RWD. Weight transfer to the front tires is going to happen whether you are braking or in regen. That in turn is unloading the rear tires. Hit a slick spot on the road and the rear end is going to do unpleasant things.

I had a '14 Volt, and loved the nearly one pedal drive. I did have a few pucker moments though where it was in regen under braking, hit a slick spot, and had the ABS take what felt like an eternity to kick in. Probably only a couple tenths of a second, but if you are not expecting it, it catches you by surprise.
 

Demonic

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This doesn't seem like a significant issue. Firstly it would mean the 4xe feels more like driving a regular car. Secondly, energy recovered is based on both the mass and speed of the vehicle being slowed. So if the 4xe weighs twice as much, it doesn't have to slow as much to regenerate energy. Those who have been driving with max regen on stated the charge usually stays relatively full. Is your charge getting depleted when you're on hybrid mode in max regen?
 

jahysea

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Agree with a previous post re 2WD, are you in AWD or 2WD? 70%+ of all braking is from the front wheels in a traditional vehicle. The 4xe implementation requires the front drivetrain to be engaged to use the front for regen, without the transfer case engaged all you have are brake pads in the front. I suspect regen will be more effective in AWD and is the reason the vehicle was designed with the "4:1 Rock-Trac HD Full Time 4WD Sys" but I don't have my 4xe yet to play with.
 

BigGreen

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It might be like my Fiat 500e was where the first bit of brake pedal travel is regen before the pads start slowing the car. If that's the case, you'll be able to control regen, which I would personally like. It makes driving kind of a game, trying to regen brake instead of pad brake as much as possible.
In my 2.0t e-Torque I play a pedal game where I hold the brakes just enough to stop without triggering the ASS (auto start stop)
 

Dryver

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I've driven mine with both the max regen on and off. I find a noticeable difference with it on. Also, the amount of energy recaptured is really going to be dependent on the process of slowing down in general from a given speed, and it is a matter of timing to allow the regen function to operate fully instead of applying brakes. If I'm going x mph and slow to almost 0 on regen, the amount of energy recaptured *should* be the same whether that takes me 15 seconds or 30 seconds, disallowing for the extra friction involved in those additional 15 seconds. Just learn how to time it and lift off the pedal sooner to allow regen to bring you to almost a dead stop.
 

LittleDog

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(Disclaimer: I had a BMW i3 that only had heavy regenerative braking, and now have a Chevy Bolt, which not only has a good max regeneration mode, but also has a paddle behind the steering wheel that when pulled gives you extra heavy regenerative braking which is great for when you're coming to a stop light and need that little extra breaking to stop without having to use the physical brake)

After a week with the 4xe I can't help but say that I am disappointed with the max regenerative braking mode. Besides the fact that it doesn't stay enabled when the car is turned off (unlike what the manual states) the actual regenerative braking itself is just way too wimpy. And this of course means I'm not getting as much charging back into the batteries as I could, and that I am using up my brake pads more than I should. (Now it is better than my friends RAV4 Prime which has no max regen mode - a dealbreaker for me)

In max regen the 4xe seems to operate differently depending on your speed. When cruising at highway speed when you lift off the pedal it barely slows the car. Compared to my Bolt I am finding situations where traffic on the interstate slows a little in front of me where on the Bolt I would just lift the gas pedal and I would slow down enough no problem, but with the 4xe it just doesn't slow enough and I find myself having to apply a little physical braking.

When going slower the 4xe does apply the regen more powerfully, but still not as much is my Bolt, even without using the paddle. I am finding that just coming to stops at traffic lights I am using my brake pedal more on the 4xe than the Bolt. Especially if you're coming in at a good clip like 50mpg, the fact that it barely slows you in the beginning and then still is not as powerful at the end means you're really using the brake pedal a lot more.

It's a shame because with such a small battery range I want as much regen braking as possible to get juice back into that battery. Plus it's awfully nice essentially not having to ever worry about changing your brake pads!

I hope this can be fixed with a software upgrade. Maybe giving us the option in the display of selecting how strong we want the max regen to be, and if we wanted to be of variable amount of regen or the same strength regardless of speed. I am sure it's all computer controlled, so should be something that can be easily implemented with a software upgrade.

Just did a bit of quick sleuthing.

Curb weights:

Chevy Bolt - 3,500lbs
4xe various models - 5,000 - 5,200lbs

Tire/wheel weights:

Bolt - 46lbs
4xe - ~65-75lbs Too many variants.

(There's an aftermarket 17lb wheel for the Bolt!)


Depending on the input location of the regenerative braking, you also need you add the weight difference in drivetrain components being slowed.

You're going to need a better maths and physics person than me to apply that knowledge. Pretty sure there are squares and inverse squares involved. But only considering the extra 1,500lbs alone, an equal amount of braking input is going to slow a 4xe drastically less.

Wait, is the Bolt a fully electric vehicle? What the heck, there's no comparison. The regenerative braking is probably using the Bolt's entire main motor, which is much, much, larger and "stronger" in both directions than the comparatively wimpy secondary motor on the jeep, or whatever system they are even using to regen.


I've been recharging my AA batteries via the 110V plug in back. No appreciable increase in engine loading.
 

Arterius2

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Agree with a previous post re 2WD, are you in AWD or 2WD? 70%+ of all braking is from the front wheels in a traditional vehicle. The 4xe implementation requires the front drivetrain to be engaged to use the front for regen, without the transfer case engaged all you have are brake pads in the front. I suspect regen will be more effective in AWD and is the reason the vehicle was designed with the "4:1 Rock-Trac HD Full Time 4WD Sys" but I don't have my 4xe yet to play with.
um....
Regen braking on these 4xes aren’t using the brake pads for regen..
It happens in the electric motor under your engine bay. Power is diverted back through your transmission, shouldn’t make too much of a difference if it’s AWD or 2WD.
 
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jahysea

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um....
Regen braking on these 4xes aren’t using the brake pads for regen..
It happens in the electric motor under your engine bay. Power is diverted back through your transmission, shouldn’t make too much of a difference if it’s AWD or 2WD.
Yes that is my point... Brake pads are used for traditional braking. But if the transfer case is not engaged, and braking is needed in the front, you are using pads instead of recapturing that energy.
 

Arterius2

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Yes that is my point... Brake pads are used for traditional braking. But if the transfer case is not engaged, and braking is needed in the front, you are using pads instead of recapturing that energy.
That's not really how it would work under most driving scenarios.
You are reducing the inertia of the entire vehicle through your drivetrain, caused by friction of your tires and the road surface.
Unless the amount of braking overcomes the friction of your rear tires and it begins to slide, which I doubt would happen from regen.

The only scenario I could think of where AWD would aid this would be if the road surface was super slippery, and your rear tires are slipping with even the slightest resistance.
 

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