Torque Limiter & Traction Issues

[cashcow]

There seems to be very noticeable traction issues with our FWD RAV4 EV and it made me wonder if a torque limiter would help keep tire losing traction on the pavement? I think all electric vehicles already have this, but it makes me wonder why, if the rav4 ev does have one, it wasn't tuned to keep the traction issue more under control?

Any other ideas on how to help with traction would be nice

 

[miimura]

The traction control on the RAV is very reactive. In other words, it only intervenes when there is excess wheel spin, which is really too late for on-road driving. Basically, physics is not on your side when you have a high-torque motor driving the front wheels. If you're driving straight, it's not too bad, but the weight transfer is still to the rear, reducing the available traction on the front tires. However, as soon as you turn the steering wheel, there will be weight transfer to the outside front wheel and the inside tire will have even less traction due to the turning and accelerating. This is why performance cars are rear wheel drive. The weight transfer on acceleration transfers more weight to the axle that is providing acceleration thrust.

 

[smkettner]

Go a little easy as you stomp on it.

You can turn traction control off. Can also enter a diagnostic mode to give unrestrained full power to the motor. But no real system to limit torque except after the fact.
Could always get better tires or turn the sport mode off....

 

[cashcow]

Thank you everyone. I have been driving now exclusively on sport mode since there were times when I was in regular mode that I suddenly needed sport and reaching down to activate it seemed to me like a hazard so I just drive in sport and try to regulate the power.

I did notice less traction when turning but I did not know that was what happened to the wheels. In a straight line I understood the weight was going back, but to the side wow I did not think about that. I will have to be more careful when making a turn with oncoming traffic .

There is space in the back for an additional motor. I wonder what the 0 to 60 times on the rav4 ev would be with an additional identical motor (From another rav4 ev?). Right now online it sounds like the rav is doing it in about 6.1 seconds though I've never timed it. With an additional motor could we hit 4s?


-e-dit-

actually it seems to be 7 seconds not sure why I thought it was 6! If that is the case them maybe... 5 seconds with a rear motor?

 

[miimura]

There is also a limit to how much power you can pull out of the battery. The front motor may already reach that limit. However, the rear motor would definitely help in lower traction situations. Even a relatively small motor like the one from the Highlander Hybrid would be useful.

 

[cashcow]

The only other solution I see is if the RAV4 EV is not speed limited on R. Kind of like how the nissan leaf is. You place it on R and floor it and the leaf speeds up to max speed. If this applies to the RAV4 EV then we will just have to drive it in R. That way it will become a RWD EV!!!

http://www.digitaltrends.com/cars/nissan-leaf-sets-world-record-for-fastest-car-in-reverse/

 

[davewill]

...
-Edit#2-

The only other solution I see is if the RAV4 EV is not speed limited on R. Kind of like how the nissan leaf is. You place it on R and floor it and the leaf speeds up to max speed. If this applies to the RAV4 EV then we will just have to drive it in R. That way it will become a RWD EV!!!

http://www.digitaltrends.com/cars/nissan-leaf-sets-world-record-for-fastest-car-in-reverse/

Actually, that car was modified to remove the reverse speed limiter.

 

[cashcow]

Looks like I was under the wrong impressions! Thanks for pointing that out. Can't believe I missed that.