OP
I go back to the existence of the transmission. What is it for? Why is there a need to shift gears?
Electric Crate Motors
- Thread starter jjvw
- Start date
I go back to the existence of the transmission. What is it for? Why is there a need to shift gears?
Crawl / Wheel speed for certain obstacles. An electric motor can wing up to a pretty high RPM, but it starts to lose power as you move up in the RPM band (this is why a Tesla smokes a Ferrari from the starting line but loses in a quarter mile). Maybe you lose power at more than a linear rate so that lower RPM through less gear gives an advantage? Not sure.
He might also want to put the motor at a disadvantage in certain scenarios to not snap stuff. Neutral would also be nice to have if can't shut the power completely off. In low range, that motor would just push right through the brakes if it was hooked straight to a transfer case.
A lot of this depends on what type of motor he is running and how it is setup. I can't imagine a rock buggy like that has a very elegant motor setup like a Tesla would.
gg1
TJ Enthusiast
Yeah, they dwarf their cars in software. For example the ModelX has to be in its lowest height setting to get full power to the wheels. I'm sure when the motors become more common there will be other weak links beyond software built into the driveline so you break ujoints instead of axles.
OP
OP
Did you mean to post this in your build thread?
That's where it went! Thanks for finding it.
https://bringatrailer.com/listing/2000-porsche-boxster-18/
This ruins the value of the car, but it’s interesting nonetheless.
This ruins the value of the car, but it’s interesting nonetheless.
No, a transmission or gears is not required. A DC motor has most of its torque at lower speeds. I work in industry and we have many applications of DC and AC motors with no gearbox, then we have some that do have gearboxes. As long as you have a VFD you can control the motor however you want.
I believe Tesla has a single gear reduction just so the motor can run at rated speed at FLA and not be too much rpm for axles. I dont think they are using a VFD, but with their computer system there is no telling.
IMO I don't see gasoline ever going away completely. There are way too many classic cars out there.
I believe Tesla has a single gear reduction just so the motor can run at rated speed at FLA and not be too much rpm for axles. I dont think they are using a VFD, but with their computer system there is no telling.
IMO I don't see gasoline ever going away completely. There are way too many classic cars out there.
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OP
I know on RC cars you need to change the gearing between the motor and TC for the type of driving you want to do, even with a speed controller you burn up motors and battery run time is less if you’re trying to crawl vs hi speed runs. So my guess would be to adjust your torque to the application.
https://erevon.com/#qui-sommes-nous
"Convert your Jeep CJ, YJ or TJ to a fully Electric Vehicle
The Erevon Conversion Kits include hardware, software and installation to transform your Gas Guzzling jeep into a fully Electric Vehicle. Also available for G-Class Mercedes, Toyota Land Cruisers, and Land Rover Defenders."
Agreed for overlanding, whatever the fug that means nowadays.
An electric conversion with strong regen for downhill braking should be much, much, better for offroading. Other than cost, with a large enough battery pack its a perfect option for trailered trail rigs doing day trips. Multiple day trips should be possible with a generator carried on the tow pig or trailer.
For trailered rigs I see no issue. However, I think the majority of people I've ever been wheeling with aren't trailing their rigs.
Electric has it's place, don't get me wrong. I just think we're still along ways away from it being a serious contender for the weekend off-roader.
Of the several clubs that I wheel with probably 8 of 10 trailer. Some of the rigs aren't road legal and most prefer to have a way to haul a broken rig back to their shop.
alittleoff
TJ Addict
To me, when I see the term, "Down hill braking", I see brakes burning up and being replaced way too often.
Truckers and 4 wheelers use (in most cases) lower gears to control speed.
And generators powered by fuel, kinda defeats the purpose of an E-buggy.
Truckers and 4 wheelers use (in most cases) lower gears to control speed.
And generators powered by fuel, kinda defeats the purpose of an E-buggy.
There is a thing called regenerative braking to control downhill speed. And the point isn't to be green, its to have 100% torque the moment you touch the throttle.
OP
Electric certainly won't get anywhere with that attitude.
There is no timeframe for my curiosity surrounding this. Though I have a hunch we will all be surprised by how quickly we will begin to see things change.
A few weeks ago I toyed with the idea of building an EV Jeep and went down the rabbit hole. Conclusion - not yet feasible unless you are able to salvage, design, and or build a cutting edge 400V to 800V system using a platform other than a LJ. I figure the efficiency for a Jeep is only about 500 WH/M so to reliably travel 150 miles you want about 619 Ah capacity. The best us mortals will do off the shelf is around 160V 28,800 wh for an actual 80% range of 46 miles. That's without regen but it doesn't matter because those battery modules would weigh over 600 lbs.