Drove a 4xe sahara at work, what’s with the brake pedal?

CptFloridaMan

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Just curious as I’ve never really given thought to hybrids; I drove a sahara 4xe at work and the braking felt like it’s a brake by wire set up. Felt kinda funky in the sense that the jeep was a little hurky jerky and took getting used to. And when shut off, it still had the same feeling where it wouldn’t get stiff like a traditional brake system set up when building pressure. Does it have some voodoo specific to hybrids? And what if the jeep is totally dead, does the brake system work when engine and such are shut off?
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Dryver

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Braking is mostly handled by the electric motor acting as generator to reclaim battery charge. The friction brakes only kick in if you brake really hard, or at the very last bit of braking to come to a complete stop. If you hit the max regen button, you can come almost to a complete stop without applying the brakes at all, as long as you time it right. In other works, the original pads on the friction brakes on this vehicle could possibly last as long as you own it.
 

dan1000

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I own a 4xe, and have not noticed that the brake pedal feels noticeably different to other vehicles. At least, that's true while the vehicle is ready to drive (whether the internal combustion engine is running or not). My understanding of the braking system is similar to @Dryver, in that the friction brakes are mixed in with regenerative braking, with regenerative being preferred if there is room in the battery to store the regenerated electricity.

Interesting question about what happens when 12v battery is totally dead.


Just curious as I’ve never really given thought to hybrids; I drove a sahara 4xe at work and the braking felt like it’s a brake by wire set up. Felt kinda funky in the sense that the jeep was a little hurky jerky and took getting used to. And when shut off, it still had the same feeling where it wouldn’t get stiff like a traditional brake system set up when building pressure. Does it have some voodoo specific to hybrids? And what if the jeep is totally dead, does the brake system work when engine and such are shut off?
 

Dryver

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I own a 4xe, and have not noticed that the brake pedal feels noticeably different to other vehicles. At least, that's true while the vehicle is ready to drive (whether the internal combustion engine is running or not). My understanding of the braking system is similar to @Dryver, in that the friction brakes are mixed in with regenerative braking, with regenerative being preferred if there is room in the battery to store the regenerated electricity.

Interesting question about what happens when 12v battery is totally dead.
I would guess the friction brakes would still operate just like they do on a non-hybrid, but I do not know for sure.
 
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CptFloridaMan

CptFloridaMan

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Interesting about the friction brakes kicking in when slamming the brakes. Could it be a set up where it’s got a funky pedal where half the travel for example is solely for regen and then the last bit of travel using actual hydraulic brakes.
 

SnB4xe

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Interesting about the friction brakes kicking in when slamming the brakes. Could it be a set up where it’s got a funky pedal where half the travel for example is solely for regen and then the last bit of travel using actual hydraulic brakes.
There are a couple different methods in use.....I am not sure which one the Jeep employs. Basically the first portion of pedal travel has a mechanical device that resists the pressure from your foot to simulate tradition hydraulic brakes. However, if you depress far enough or very quickly then the plunger rod activates the hydraulic pressure in the master cylinder to apply the friction brakes.

If you lose 12v power, you can still stop.....just won't have any power assist, but you can stop.
 

Zombienation

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I have a 4xe Sahara and I agree the brakes feel different. Maybe it’s because I am coming from a Mustang GT but during the first few drives I almost plowed into the car in front of me haha. They feel like the vehicle is crazy heavy which I guess it is so it makes sense but getting used to them now.
 
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