The problem with the CVT is it's still too complex and they are trying to maximize efficiency; a gasoline car might benefit from the CVT b/c of the relationship between rpm and efficiency, but an EV isn't affected by those things, so the CVT provides no visible benefits while being more complex (therefore more prone to failure, more costly). They were only forced to pick a two speed for acceleration purposes, they would have loved to not even bother with a multispeed transmission, much less a CVT, if it was possible.
Also the older motor needed 8-9k rpm to reach peak power even though peak torque comes a lot sooner (power is a factor of rpm and torque); which might play into the durability of the CVT. Also having peak torque @ 0 rpm might play into the transmission troubles too.
I would imagine it's not as easy as "strapping on" a transmission as a lot of people keep suggesting. They consulted Magna, Ricardo, x-trac (all very experienced transmission makers) and they couldn't make the 2 speed durable enough. I imagine actually the problem has more to do with insisting on lesser gears, which actually means the gap between gears will be greater, which might be causing the problem.
Anyways the details on why the 2 speed didn't work isn't as important now b/c they found a way to make the 1 speed work. You can't get more efficient or simple than a one speed, which is just basically a simple gear.
Now that we've thrown 'em off the trail, use the form below to get in touch with the people at Engadget. Please fill in all of the required fields because they're required.
The problem with the CVT is it's still too complex and they are trying to maximize efficiency; a gasoline car might benefit from the CVT b/c of the relationship between rpm and efficiency, but an EV isn't affected by those things, so the CVT provides no visible benefits while being more complex (therefore more prone to failure, more costly). They were only forced to pick a two speed for acceleration purposes, they would have loved to not even bother with a multispeed transmission, much less a CVT, if it was possible.
Also the older motor needed 8-9k rpm to reach peak power even though peak torque comes a lot sooner (power is a factor of rpm and torque); which might play into the durability of the CVT. Also having peak torque @ 0 rpm might play into the transmission troubles too.
I would imagine it's not as easy as "strapping on" a transmission as a lot of people keep suggesting. They consulted Magna, Ricardo, x-trac (all very experienced transmission makers) and they couldn't make the 2 speed durable enough. I imagine actually the problem has more to do with insisting on lesser gears, which actually means the gap between gears will be greater, which might be causing the problem.
Anyways the details on why the 2 speed didn't work isn't as important now b/c they found a way to make the 1 speed work. You can't get more efficient or simple than a one speed, which is just basically a simple gear.