Rubicon 4xe - Surprising highway stability

Echo4papa

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Maybe, but this: The battery is charged by only two things; the regen braking and the engine. If the engine is charging the battery, or the battery is being maintained (not being used), how can electric motors which run on electricity get their power.

I know from butt dyno that hybrid has tons of torque when I hammer it, and e-save mode just has the rpms running high for less power.
Think about it like this...

Have you noticed when you're at <1% you still get the added power from the electric side when needed? You get it at slow speeds and under high load. Yes, you use more power from the ICE, but you still have battery in reserve for on demand usage.

The battery read out (<1%-100%) represents one compartment of the battery. When you run in eSave to maintain the charge (or recharge), this is the portion you're maintaining (or recharging). You still have the reserve that the system normally has at it's disposal.

You always have that extra power, even in eSave mode. It's a separate portion of battery power that (I believe) is always being charged/maintained by the ICE as needed.

Real world example... I drove from Daytona Beach to Baltimore and back. If this reserve wasn't being maintained by the ICE, there's no way I would have had any power to draw on from the battery side of the house, and yet every time I needed to pass someone, that power was there. Watch your meters, in eSave, even on an empty battery, when you floor it, you still see power from the electric motors. Yes, you get higher revs from the ICE, but you aren't without the electric side of the propulsion system.
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Maybe, but this: The battery is charged by only two things; the regen braking and the engine. If the engine is charging the battery, or the battery is being maintained (not being used), how can electric motors which run on electricity get their power.

I know from butt dyno that hybrid has tons of torque when I hammer it, and e-save mode just has the rpms running high for less power.
The electric motors are getting power from the reserve in the battery (i.e. since "0%" is actually 15%).

The system is constantly trying to figure out the most efficient means to accomplish the marching orders that you are giving it. First priority is what you are telling it to do via the pedals. I.E. if you're in e-save, but you floor it, it's going to temporarily prioritize propulsion and use electricity. Once things have settled down, it can return to prioritizing maintaining the battery charge.

Sorry I forget the official name, but that screen in the guage cluster with the circles (that show power usage/charging between the electric and ICE) is super helpful to get a sense for how the system "thinks". If you haven't checked it out on the highway in e-save, I recommend it. You can see how it will try to use a little electric briefly to avoid having to downshift if possible, but then if it does decide it has to, you'll see it try to use a bit of the extra energy from that downshift to replenish what it can of the battery.
 
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FloridaLarry

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The electric motors are getting power from the reserve in the battery (i.e. since "0%" is actually 15%).

The system is constantly trying to figure out the most efficient means to accomplish the marching orders that you are giving it. First priority is what you are telling it to do via the pedals. I.E. if you're in e-save, but you floor it, it's going to temporarily prioritize propulsion and use electricity. Once things have settled down, it can return to prioritizing maintaining the battery charge.

Sorry I forget the official name, but that screen in the guage cluster with the circles (that show power usage/charging between the electric and ICE) is super helpful to get a sense for how the system "thinks". If you haven't checked it out on the highway in e-save, I recommend it. You can see how it will try to use a little electric briefly to avoid having to downshift if possible, but then if it does decide it has to, you'll see it try to use a bit of the extra energy from that downshift to replenish what it can of the battery.

Makes sense, but about that last 15% in the "<0%" situation.... if I can burn through a batter in say 10 mins of fast highway driving and reach the "<0%" state, and the engine pops on and I continue down the highway at same speed...at some point that 15% should eventually reach true 0%. What happens then? Since energy is neither created nor lost, the only thing pushing the 5200lb brick down the highway is the ICE all by its lonesome. Correct?
 

Jocko

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Makes sense, but about that last 15% in the "<0%" situation.... if I can burn through a batter in say 10 mins of fast highway driving and reach the "<0%" state, and the engine pops on and I continue down the highway at same speed...at some point that 15% should eventually reach true 0%. What happens then? Since energy is neither created nor lost, the only thing pushing the 5200lb brick down the highway is the ICE all by its lonesome. Correct?
In <0% the system will heavily prioritize the ICE. If you're traveling at say 70MPH, it will be using the ICE to maintain that speed. If you need to punch it to pass, it will pull from the 15% reserve to give you full power with the electric motor too. But as soon as that initial burst of acceleration is over, it's going to get the ICE/transmission settled in to take full duty again. And it's going to figure out how to top that reserve back off. Most of the time, that probably means running the engine at a slightly higher RPM briefly. And it probably didn't use that much energy in this scenario anyhow as the initial acceleration probably only lasted 5-10 seconds.
 

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This is something I have been wondering about myself. I watched a video with one of the engineers and this question was specifically asked. He kinda 2 stepped around it. He said you will always have full power to accelerate on to a freeway ect, but he also admitted it would be possible to completely run it out of battery. For instance pulling a trailer. So, if I'm on a long trip running big tires into a headwind is this not similar to towing a trailer? What about if my battery is at 0 and I'm at the bottom of a long high speed moutain pass. Is that 15 percent extra gonna get me to the top? Once the battery is dead how long can I run at max power before it decides it better charge? At this point you don't actually have max power. For most with a 4xe this is probably a non issue. However a more clear picture then you will always have enough power to acellerate onto the highway would be nice.
 

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Batteries have less charging resistance under 15%. It's a dramatic lon-linear change in how the battery charging performs.

It's why that mark was chosen for the reserve and is the principal on which hybrid systems operate on.

I think there is a point where the computer protects a certain charge since going to true 0% is bad for the battery.
 

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...Once the battery is dead how long can I run at max power before it decides it better charge? At this point you don't actually have max power...
Knowing that dropping the battery to 0% (aka below voltage limit) charge would kill the battery, I'm sure the engineers built in yet another buffer beyond the "15% hybrid reserve". When the system senses the main battery get too low while in the 15% reserve range, the gas engine runs the P1 motor as a generator while assistance from the P2 main motor cuts off until the buffer is replenished. At low charge levels the main battery recharges that buffer quickly so I doubt we'd see power loss in most driving situations.

That said, the 2.0 turbo is no slouch on its own when towing. If the main battery is charging and you run at full throttle towing uphill, there should still be ~200hp available with the remainder used for running the P1 motor as a generator to charge the main battery. This is educated speculation; I have no inclination to obtain metrics for this scenario.
 
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Knowing that dropping the battery to 0% (aka below voltage limit) charge would kill the battery, I'm sure the engineers built in yet another buffer beyond the "15% hybrid reserve". When the system senses the main battery get too low while in the 15% reserve range, the gas engine runs the P1 motor as a generator while assistance from the P2 main motor cuts off until the buffer is replenished. At low charge levels the main battery recharges that buffer quickly so I doubt we'd see power loss in most driving situations.

That said, the 2.0 turbo is no slouch on its own when towing. If the main battery is charging and you run at full throttle towing uphill, there should still be ~200hp available with the remainder used for running the P1 motor as a generator to charge the main battery. This is educated speculation; I have no inclination to obtain metrics for this scenario.
Its funny, every time someone suggest a low battery makes the 4xe less efficient than a regular 2.0T, the response is always "NO, its a hybrid and hybrids always use the electric to assist power". As if you could get energy out of no energy. I took HS physics. If the gas engine is needed to charge the reserve battery, it cannot also be used to boost the 2.0T's 275HP. One day we will get this perfectly straight.
 

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Its funny, every time someone suggest a low battery makes the 4xe less efficient than a regular 2.0T, the response is always "NO, its a hybrid and hybrids always use the electric to assist power". As if you could get energy out of no energy. I took HS physics. If the gas engine is needed to charge the reserve battery, it cannot also be used to boost the 2.0T's 275HP. One day we will get this perfectly straight.
Well yes I think you are absolutely correct that it would be less efficient in that theoretical case. But I'm not sure what cases would actually get someone into that situation. I feel like it would have to be situations where more than 100% of the 2.0T's power was required consistently over an extended time. Even towing, I would imagine the ICE and transmission would get typically get settled into a good spot where it's moving the Jeep and the trailer with RPMs to spare? I guess it would have to be a situation where you have it floored and the ICE is giving all of it's torque to the towing and even that isn't enough to keep the Jeep moving? I don't tow, so I don't know how realistic that is. What would you need to be towing and at what steep of a grade and for how long for that to actually be possible?
 

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Its funny, every time someone suggest a low battery makes the 4xe less efficient than a regular 2.0T, the response is always "NO, its a hybrid and hybrids always use the electric to assist power". As if you could get energy out of no energy. I took HS physics. If the gas engine is needed to charge the reserve battery, it cannot also be used to boost the 2.0T's 275HP. One day we will get this perfectly straight.
Is the argument efficiency or available power?

If you want to compare efficiency when not plugging AT ALL, our 4xe Rubi gets the same mpg on the highway as the 2.0T JLU, the closest comparison I had, when not plugged in during a highway trip (24.3mpg, 60-70mph). On paper, it doesn't figure out, but in actual use, that's what we're measuring. Maybe the JLU Sport 2.0T just sucked?

If the argument is power availability, maybe the 4xe could momentarily use up that hybrid battery reserve if you floored it uphill continuously for a few miles while towing, sure. But, after a stint like that, the 15% battery buffer recharges quickly while cruising (then the engine stops recharging) so you've got full power for the next stint. Lithium batteries charge quick when near empty so getting back into the 15% buffer is not a worry.

Recently, we were stomping on the throttle over and over (maybe a dozen times In a few minutes) to navigate texting-zombie traffic and never, ever felt any power limits....none at all. In normal use like this it's just not even an issue and I would rant if it were.
 

yngrshr

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I mean, I think it is obvious that the battery pack is really helping with this. My Sahara 4xe is fantastic on the highway as well. Much better than my old JK. Not even close, to be honest.
 
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