KT Torque Imitation - What To Expect?

[jkvt]

Hi,

I just put a KT 22a sinewave controller on an ebike. It's working out pretty well. I think I got most or all of the settings right. Seems significantly better than the controller I replaced. I'm trying to figure out what to expect with this "Torque Imitation" aspect of it though. I've only ridden it around the neighborhood so far but it seems like it's basically constant current. I kind of expected it to vary the output some based on cadence, but it seems like once it's ramped up, it holds the current fairly flat. Disclaimer is that I haven't taken this on any significant ride. Way too much snow to comfortably get out of the neighborhood yet so maybe it's something that is more noticeable on more of a ride, rather than around the block. Thanks very much!

 

[JES2020]

I never have used that setting. I just have it give full power off the start. From all my experience with the KT, the settings do have a marked effect, so I wouldn't expect less of the torque limitation.

One thing though , your expectations may be mis-matched with the actual power curve.
The power is limited on start up not after you are rolling. This is a safety design so that the bike doesn't jump away from you on starting your ride.

BTW you can also choose between having the PAS control not only the pedal assist, but also the throttle assist. I find this setting very useful in fine tuning power management depending on the conditions and my preferences, on the fly.

 

[jkvt]

Thanks, I *think* we are talking two different settings though. I'm talking about the P3 setting where 1 = "Imitation Torque Control" and how that works vs. I think what you might be referring to is C5 "Controller Maximum Current Adjustment Setting" since that has some settings where things start slow.

 

[JES2020]

Right , I was going off memory.
According to my manual p3 is (imitation torque control ), the PAS setting for either pedal assist or throttle assist I was mentioning before, very useful. It allows you to set your throttle power level according to what you set your PAS too. To test this function set p3 to 0 then ride your bike with varying PAS settings and use the throttle. It also still works for pedal assist.
C5 will adjust your takeoff current, which is what your were expecting from c3 , I think.

 

[AHicks]

Short answer-
Imitation Torque Control is "chinglish" for "power based" PAS. Try it both ways (on and off) so you can see the difference in "power based" vs. "speed based". Speed based is what you probably had in your old control. Most will find "power based" FAR more attractive (imitation torque control =on).....

Much longer answer-
This same option is also available in the built in Bafang controllers used in their BBSxx and Ultra mid drive motors. Same story there, given the option, most will go for the "power" based PAS.

What it amounts to is a fixed amount of power supplied to the motor, which changes according to the PAS level, and speed no longer has any affect on what's going on (none!). The amount of power available in PAS 1 is generally the critical one, and is adjustable using a combination of C5 for big changes (to get it close), then trimming with C14 for your final adjustment. Personally, I'm a big fan of low speed control for maneuvering in tight places (trails for instance) and when riding with other slower traffic (like walkers for instance). I generally set my bikes up so they pull from 75 to maybe 150 watts in PAS 1. This give me pretty good control down to where it's easy to ride 5 or 6 mph, where the bike starts getting difficult to balance.

From there, at the higher PAS values, KT uses an algorithm to supply progressively higher amounts of power as you increase PAS levels. It's all very nicely done in a pretty seamless package. IMHO, KT supplies what is likely the best designed software/firmware available.

Further, they (KT) allow crank sensitivity. This sets how far the crank must turn to turn the power on and off (using C1). Again, my personal preference (for trail riding mostly) is to set my bike up as sensitive as possible, optimized for low speed control. If your PAS is currently working OK, make sure you don't change the forward or reverse wave form (this tells the contoller about what side of the crank your PAS sensor is on)! Instead, have a look at the owner's manual at the "start sensitivity". That sensitivity is what is used to control how far the crank needs to move. Highest sensitivity = least amount of crank movement. One caution here when considering this. When set to "highest" there IS a potential for an occasional accidental "false start". This happens when the crank is bumped just far enough for a magnet to go past the crank sensor - turning the power on for just a second. Doesn't happen often in my experience (but it WILL get your attention!) and a cheap price to pay for near immediate on and off power availability for my purposes, but maybe not the best setting for everyone. Just tossing this out for consideration. Been using KT for a while now, after installing them in several different bikes. Holler if you have more questions. -Al

 

[JES2020]

What it amounts to is a fixed amount of power supplied to the motor, which changes according to the PAS level, and speed no longer has any affect on what's going on (none!)

Actually, obviously power effects speed .
I think you will find my explanation is correct. I had to figure this exact setting out 2 years ago.
A simple test ride will prove it. Or if you have a watt meter you can test it without riding , just set PAS to 1 stall the motor/w throttle, read the max watts then set PAS to 5 stall w/throttle and read watts. I have done both tests and can attest to the results.

 

[jkvt]

Thanks for the replies and all the detail. Ill give these a shot a bit later on. I'll reply back after I do that.