White Shadow
Well-Known Member
By stall, I'm not literally meaning stall. I'm not sure what other word would describe a situation where the wheels simply will not turn. But that's exactly what I've seen in videos of other people off-roading the R1. Despite the torque, an electric motor can easily have a difficult time starting to move from being dead stopped in a upstate of high resistance. This is something that you never see when an ICE vehicle is off-roading....at least not an ICE vehicle in 4LO. The reason for that is two fold: First, the flexibility and torque curve of an engine. But much more importantly, the gearing. That's really the main thing....the amount of torque to the wheels on the average 4wd ICE vehicle is tremendous to the point that they will pretty much never get into the type of "stall" condition I described earlier. Instead, they spin all four wheels furiously in an attempt to climb. You do see that happen in ICE vehicles that don't have LO gearing though.I've not experienced this, or anything like it. I've seen it parroted. So, likely I've just not been in a position to experience it. BUT, I have some hypotheses:
Firstly, from an engineering perspective, I don't think what you're experiencing is actually 'stall' of the motor. I work with servos, steppers and drives. One of the biggest advantages to electric over anything is the near-instant torque. While there's theoretically a point where Rivian's driveline could be compromised enough to prevent the wheels from turning, it's definitely not going to be from an unladen start regardless of the incline. At 908 lbs-ft of torque, it's mathematically improbable. If you could create positive traction, so it wouldn't 'fall off,' it'd climb a vertical wall. If the characteristic between the rotor and stator were such to mean there's a 'stall torque,' we wouldn't be able to launch the 7000 lbs-mass of truck from 0-60 in 3-ish seconds. The motors won't care what vector you're taking. They'll turn.
What's more than likely happening are 1- there is a traction limit imposed by the software (likely due to safety) and 2- here's my personal experience mirrored by many others: you're trying too hard. These trucks are immensely capable. As @zefram47 mentioned above "as slow as possible, as fast as necessary" is the mantra for off-road terrain negotiation (especially rock crawling). I'm betting a LOT that if you're flooring it, Rivian's software limiting your approach (*or even canceling it in the name of safety), because it'd be dangerous as all-get-out to actually let you try to launch your truck up the side of a steep incline.
I've personally negotiated obstacles where the 'climb over' was necessary and I found that literally just sitting there and not adding ANY extra throttle, the truck figured it out. Patience. Just hold the accelerator at the same ~10% and it'll start moving again. If not, take a different approach.
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