David, have you had a chance to run the sensored system yet to see how it crawls compared to the old unsensored system?
As I haven't yet sorted the 2.2 foams, I bolted on the MX28 Badlands, and dug up the front garden for a bit.
There is a rock there with a steep face which would easily - at dead slow - stall out the unsensored rtr motor in high gear; in low gear, sensored or unsensored, this rock was easy to walk over. The difference was that I could now do it in both low and high gear.
(My yeti prior to the IRS conversion, and that rock)
Took it out onto our big back lawn, and promptly blew out the rtr front gears after a few minutes of bashing. :twisted:
Swapped in new HD gears that night, put in 500K cst diff fluid, and on Monday I took it out and ran a pack through it in the trails, on the rocks, and some speed runs, without any major incident. The power and speed were as expected (lots!).
<iframe width="560" height="315" src="https://www.youtube.com/embed/qUwrclvDiaY?rel=0" frameborder="0" allowfullscreen></iframe>
What is not apparent in the video is how controlled you have to squeeze the trigger on the way to full throttle, so as not to loose traction on this very loose and dusty surface and spin out. It's clear to me why 4wd buggies like the slash run open diffs f/c/r, to provide stability in this situation that the yeti won't have with its locked rear and lack of centre diff.
Unfortunately, I neglected to bring my infrared thermometer, and while things got toasty, it never thermalled, but then I didn't try to make it overheat. The fan on the esc kicked in promptly, and I using a castle fan on the motor.
Sensored vs the 2-speed...
In low gear, the sensored operation took the rough edges off of the low speed crawling/climbing.
In high gear, it allowed for smooth startup speeds, but didn't drop the throttle response to how it is in low gear. More importantly, I understand that it isn't a substitute for appropriate gearing; the lack of efficiency and strain on the motor and ESC is still there even if the slow speed operation is smooth, and for those same reasons full size EVs -
Teslas, for one - would be already using multi-gear transmissions, if they were able to handle the torque of the current motors.
I can see how one may be able to make (or have to make do) due without the 2-speed, by dropping the overall gearing down, and/or taking advantage of the larger (compared to the rtr equipment) ESCs' higher heat capacity which may be enough for part-time crawling. It very much depends on your overall gearing, vehicle weight, and how you intend to use it.
Since the option is available to me, and that I typically spend most of my time in low gear on the trails, and having had a chance to run this sensored system with the 2-speed, I'll say that I like how the character of the truck changes with the different ratios, with the knowledge that the motor is geared appropriately for the task at hand. The 2-speed makes the truck more versatile; sensored just makes it better.8)
Speaking of better, the ESC's aux wire function far outshines the sensored operation of this combo for me. Being able to switch between the rock-racer and crawler modes (reverse and drag brake toggles) is just the thing to add to this vehicle's versatility. While it was not an issue for me, I hope they add the reverse travel option to the firmware, to make it more accessible for others, and eliminate the (possible) need for an external servo reverser when it shares the rx channel with the shift servo. "thumbsup"