Possible good news for the Jeep Wrangler

OverlanderJL

Resident Smartass
Because those are the two relevant vehicles that I have experience with. What I want is something with Jeep's off-road capability and something like Tesla's motors and electronics. I just use Tesla as an example of what you can expect from an EV drivetrain in terms of range and power. And my experience driving both as it relates to how efficiency varies with speed and terrain. It's obvious that an EV drivetrain is much more efficient on the highway. And I think it's probably the case that it would be much more efficient on the trails, too. Probably much more. Which isn't a very high bar given the absolutely horrible efficiency of a Wrangler in 4Lo.

The range discussion is actually not the most interesting part of an EVJeep. More interesting, I think, especially for this forum, is what the rock-crawling experience would be like. Everyone seems to want a diesel Jeep for its better low-end torque. But an EV is far superior in that respect: it has its maximum torque at zero rpm and it has a lot of it. And thus it can get by just fine with a single-speed transmission. It seems to me that such a thing would be a lot easier to handle on the rocks.

Yeah that’s why everyone tows with electric ram 2500’s and electric ford f-350’s. I forgot.


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BillArnett

New member
Yeah that’s why everyone tows with electric ram 2500’s and electric ford f-350’s. I forgot.


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Tesla Model X towing capacity rating is 5000 pounds (more than a JLU) but that seems to be a little conservative:

https://www.youtube.com/watch?v=30TSXDMMsc0

Range is greatly decreased when towing, of course. Just like a gas vehicle. But if towing is really your thing check out the Tesla Semi:

https://www.tesla.com/semi

The point is that electric motors are really good at torque. Tesla sedans and SUVs aren't designed for towing big loads. But a Tesla pickup truck would work just fine. There are vague rumors that Tesla might actually make a pickup a few years down the road. And that might be a good starting point for an off-roader, too.
 

OverlanderJL

Resident Smartass
Tesla Model X towing capacity rating is 5000 pounds (more than a JLU) but that seems to be a little conservative:

https://www.youtube.com/watch?v=30TSXDMMsc0

Range is greatly decreased when towing, of course. Just like a gas vehicle. But if towing is really your thing check out the Tesla Semi:

https://www.tesla.com/semi

The point is that electric motors are really good at torque. Tesla sedans and SUVs aren't designed for towing big loads. But a Tesla pickup truck would work just fine. There are vague rumors that Tesla might actually make a pickup a few years down the road. And that might be a good starting point for an off-roader, too.

The point is electric vehicles are shit and worse for the environment than gasoline powered vehicles but the retarded hippie fucks that drive the EV’s are too stupid to understand that. You don’t listen to anyone but yourself and apparently you have more experience at everything than anyone else. You are a pretentious asshole.

And no, I’m not going to check out any link from Tesla and I am fully aware of what they make and sell. They also haven’t made a dime since they started.


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13_gecko_rubi

New member
Reading through all this many of your points on EVs are correct but some are not.

Torque wise you are dead on. At my previous employer we made locomotives which are electric powered. The diesel is just a huge generator that provides the electric for the motors. This is done because the alternator is 95-97% efficient at generating electricity. The engine can also by designed to run at only a few rpm for maximum efficiency which further helps. Even with the best modern transmission u are losing 30%+.

I also worked on full electric humvees for the military in the past.

Whatever on road range you assume, take 50% of that for off road range. That's not being overly conservative. It's about what it ends up being. You lose most regen off road because u don't have long sustained regen cycles like u do on road if you drive an EV correctly. Most off road events are short hard bursts and you must use the mechanical brakes. Some places like Moab etc on long down grades you could get some significant regen.

Something along Teslas battery size I'd estimate you could get 100 miles or so off road. In the future as battery technology advances this could get better.

The ideal setup in the short term would be to still have a small gas or diesel powered "ranger extender". Think of a home generator. It runs at one sustained rpm, therefore it can be optimized for fuel economy. It can be very small as it is purely a battery charger. Would kick on automatically when battery state of charge falls to a certain level, etc.

The place this all falls apart is cost. Tesla says it can make a profit on model 3s, I say they are smoking crack. I know what the hybrid powertrain costs and what a vehicle costs and even at a huge scale of magnitude they are only staying afloat because of the government subsidies and the greenhouse gas credits they sell to the other manufacturers.

If you gave me an EV JL Rubicon that had a small diesel range extender I'd have a ball in it. Torque for days. But I'm not paying 100k for one of those crazy things lol.

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BillArnett

New member
Thanks 13_gecko_rubi, it's nice to hear from someone with actual experience.

The only way to really know about the off-road range would be to build something and test it in a variety of conditions. I'm sure the efficiency would be a lot better on White Rim than Pritchett Canyon, for example. But even if we take your 50% number that's 150 or 160 miles for the big battery.

But where does all the energy go? On the highway it goes mostly to aerodynamic losses. That's not going to be much of a factor off-road. Or should I read your use of "event" as meaning "race"? EVs suck at racing (except for drag racing :) The motors are much less efficient at high output. I guess sometimes on "ordinary" off-road trails (eg Hell's Revenge) one uses a lot of power for a few seconds for climbing a big hill. But I wouldn't think that would be as big a factor as the reduced aero loss. Maybe it's going to heating up the tires and shocks? That's certainly much worse off-road, especially when aired down. But that much?

I didn't understand your point about regen (unless you meant racing). It might be that the regen system would need to be designed to provide more force than Tesla's so that more energy could be recovered in steep down slopes, especially short ones. But that's easy enough. The reason Tesla doesn't do that already is that it would "fell funny" to have that much "engine braking" especially for folks used to ordinary automatic transmissions. Tesla even has an option to make the regen LESS powerful but, sadly, not one to make it more so. If I were designing it, I wouldn't have any mechanical brakes at all (if I could get past the safety regulations).

Did you actually build an electric Hummer? Sounds interesting.

Yeah, a range extender is a pretty good idea. But it's a huge amount of additional complexity. I would rather just have a bigger battery, if the cost wasn't too outrageous. Maybe the extender could be made optional somehow?

I don't want to argue about Tesla's business plan. All I'll say is that a lot of smart people are investing a lot of money in Tesla and they're not doing it just to be nice.
 

13_gecko_rubi

New member
Thanks 13_gecko_rubi, it's nice to hear from someone with actual experience.

The only way to really know about the off-road range would be to build something and test it in a variety of conditions. I'm sure the efficiency would be a lot better on White Rim than Pritchett Canyon, for example. But even if we take your 50% number that's 150 or 160 miles for the big battery.

But where does all the energy go? On the highway it goes mostly to aerodynamic losses. That's not going to be much of a factor off-road. Or should I read your use of "event" as meaning "race"? EVs suck at racing (except for drag racing :) The motors are much less efficient at high output. I guess sometimes on "ordinary" off-road trails (eg Hell's Revenge) one uses a lot of power for a few seconds for climbing a big hill. But I wouldn't think that would be as big a factor as the reduced aero loss. Maybe it's going to heating up the tires and shocks? That's certainly much worse off-road, especially when aired down. But that much?

I didn't understand your point about regen (unless you meant racing). It might be that the regen system would need to be designed to provide more force than Tesla's so that more energy could be recovered in steep down slopes, especially short ones. But that's easy enough. The reason Tesla doesn't do that already is that it would "fell funny" to have that much "engine braking" especially for folks used to ordinary automatic transmissions. Tesla even has an option to make the regen LESS powerful but, sadly, not one to make it more so. If I were designing it, I wouldn't have any mechanical brakes at all (if I could get past the safety regulations).

Did you actually build an electric Hummer? Sounds interesting.

Yeah, a range extender is a pretty good idea. But it's a huge amount of additional complexity. I would rather just have a bigger battery, if the cost wasn't too outrageous. Maybe the extender could be made optional somehow?

I don't want to argue about Tesla's business plan. All I'll say is that a lot of smart people are investing a lot of money in Tesla and they're not doing it just to be nice.

What I meant by event is traversing ledges, down small slopes, etc. the majority of regen you get on any street EV is as you are rolling up to stoplights, stop signs etc. which are long events, relative to the short bursts typically encountered wheeling. If you were coming down say a fin on hells revenge you’d get tons of regen. But normal rock crawling you don’t have long sustained events to regen. It would highly vary by terrain. Imploding something like ecoasting which the newer EVs (including Tesla have) helps a lot but it’s still hard to recover via regen in short bursts. You need long (relatively) braking zones to gain much back. You can’t have pure regen braking only. The battery can only support a certain inrush current, that’s why they don’t let you crank up regen. You cannot put that much power into the battery at once. Charging has to be controlled or you kill it real fast.

Off road a lot of the energy goes to peripheral loads. On hwy you don’t need cooling fans etc as you have the air flowing while moving and natural convection as well. Of road you basically have big heat sinks and need lots of cooling air. That, air conditioning or heating, radios, lights, etc etc are all based on time not mileage. So if you go 5 miles in 3 hours you will burn as much energy as you did on road going 350 miles at 70 mph. That 50% number isn’t just a guess, I’ll leave it at that.

The range extender isn’t really adding complexity at all. It’s literally like sticking a Honda generator beside your vehicle to charge it. Pretty simple actually. The issue with a bigger battery is weight. Jeeps are already heavy, huge batteries wouldn’t help that. That’s my issue with bigger batteries. Some day they may get lighter.

As for the humvee, we built several. Some had an electric motor attached to the tcase. That was easier conversion for an existing vehicle. We also had some with two motors, one for front and one for rear, and a couple with 4 motors. Lots of different configurations to see what worked best.




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BillArnett

New member
What I meant by event is traversing ledges, down small slopes, etc. the majority of regen you get on any street EV is as you are rolling up to stoplights, stop signs etc. which are long events, relative to the short bursts typically encountered wheeling. If you were coming down say a fin on hells revenge you’d get tons of regen. But normal rock crawling you don’t have long sustained events to regen. It would highly vary by terrain. Imploding something like ecoasting which the newer EVs (including Tesla have) helps a lot but it’s still hard to recover via regen in short bursts. You need long (relatively) braking zones to gain much back. You can’t have pure regen braking only. The battery can only support a certain inrush current, that’s why they don’t let you crank up regen. You cannot put that much power into the battery at once. Charging has to be controlled or you kill it real fast.

Off road a lot of the energy goes to peripheral loads. On hwy you don’t need cooling fans etc as you have the air flowing while moving and natural convection as well. Of road you basically have big heat sinks and need lots of cooling air. That, air conditioning or heating, radios, lights, etc etc are all based on time not mileage. So if you go 5 miles in 3 hours you will burn as much energy as you did on road going 350 miles at 70 mph. That 50% number isn’t just a guess, I’ll leave it at that.

The range extender isn’t really adding complexity at all. It’s literally like sticking a Honda generator beside your vehicle to charge it. Pretty simple actually. The issue with a bigger battery is weight. Jeeps are already heavy, huge batteries wouldn’t help that. That’s my issue with bigger batteries. Some day they may get lighter.

As for the humvee, we built several. Some had an electric motor attached to the tcase. That was easier conversion for an existing vehicle. We also had some with two motors, one for front and one for rear, and a couple with 4 motors. Lots of different configurations to see what worked best.

I don't understand why one wouldn't get some regen benefit on a short event. Sure, each event wouldn't be much energy but they add up.

I did the math on eliminating the friction brakes. A 2500 kg (5500 lbs) Jeep going 30 m/sec (67 mph) equals a kinetic energy of about 0.3 kWh. Not much. But a panic stop from that speed taking say, 2 seconds equals a power level of about 500 kW. Charging a 100 kWh lithium ion battery at that rate would indeed be problematic. So I agree for the foreseeable future we're probably stuck with friction brakes. I suppose one could use a small super-capacitor but that would probably be more expensive than the brakes.

You're right about peripheral loads. But the lower speeds we see off-road are a far bigger effect. Here's a graph of range vs speed for the old Tesla Roadster and an early Model S under idea conditions with no peripheral loads:

graph1.jpg

As you can see, the range at 20 mph is just about twice that at 75 mph. On the other hand, of all the peripheral loads A/C and heating are by far the biggest users. Tesla's A/C uses about 2.5 kW when running full-blast but goes down to about 0.5 when the cabin is cooled down (this from a guy who tested it in the summer in Florida). So if we take an average of 1 kW (maybe because of stopping and opening the doors a lot) then a long day would use 10 kWh which is significant but still only about 10%. We're still coming out ahead by going slow. Or so the theory says. More experience needed!

The heaters are worse, up to 10 kW but that's for sub-zero conditions. If it's that cold, I'm staying home :)

Yeah, big batteries are heavy. But electric motors aren't. Considering all the stuff you don't need with an EV (engine, transmission, fuel and tank, etc you end up with a car that's not much different in weight either way (my Tesla weighs about 4900 lbs, a comparable MBZ or Audi comes in at around 4600-4800). And having most of the weight down beneath the floor does wonders for the handling.

I'd like to hear more about that 4-motor Hummer....
 

Ncsustats

New member
This could have been an interesting discussion, but I can’t believe how insulting and child-like some of the folks in this forum are. It’s really too bad. This was the first Jeep forum I joined, but now I wouldn’t trust any of the the advice coming out of here. I suggest some housecleaning.
 

TrailHunter

Member
This could have been an interesting discussion, but I can’t believe how insulting and child-like some of the folks in this forum are. It’s really too bad. This was the first Jeep forum I joined, but now I wouldn’t trust any of the the advice coming out of here. I suggest some housecleaning.

Seriously?? The last few posts in this thread sound like 2 Nasa employees discussing Quantum Physics of International Jeep Travel....
 

JTCO

Meme King
This could have been an interesting discussion, but I can’t believe how insulting and child-like some of the folks in this forum are. It’s really too bad. This was the first Jeep forum I joined, but now I wouldn’t trust any of the the advice coming out of here. I suggest some housecleaning.

One thread like this hurt your feelings so bad that you wouldn't trust the advice here? Housecleaning? There's the door. :standing wave:
 

wayoflife

Administrator
Staff member
This could have been an interesting discussion, but I can’t believe how insulting and child-like some of the folks in this forum are. It’s really too bad. This was the first Jeep forum I joined, but now I wouldn’t trust any of the the advice coming out of here. I suggest some housecleaning.

Funny, I still see an interesting discussion and I can't believe how incapable you are of looking past the posts that so offend you. It's really too bad. There are plenty of other Jeep forums out there and I suggest you find one that meets your sensitive needs. Certainly, trustworthy information could only come from a place where everyone is nice and agrees with each other.
 

13_gecko_rubi

New member
Funny, I still see an interesting discussion and I can't believe how incapable you are of looking past the posts that so offend you. It's really too bad. There are plenty of other Jeep forums out there and I suggest you find one that meets your sensitive needs. Certainly, trustworthy information could only come from a place where everyone is nice and agrees with each other.
If being nice equates to good advice don't listen to anything I have to say. If I'm not giving you crap I probably don't really like you.

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