"Lying" to the Kt LCD3 display on P1 to gain max speed OK? why?

[TwisterGripper]

(specs at bottom of post)

Hi all, i have searched and searched but could not find the answers...

Just finished this build and found top speed on flat ground approx 36kph with the motor magnets (P1) set to 50 as directed by KT Manual. I was a little disappointed - was hoping for 45kph.

But if i "lie" to the display and enter 100 (just tried it randomly, no reason for choosing 100 specifically)
then it tops out around 41kph - much better.

With the P1 set to the recommended 50, at top speed 36kph, i can feel the motor turning on and off every couple seconds to maintain the speed it seems...feels a bit unsettling really - you can tell the display is metering power and is not trying to go any faster.

With P1 set to 100, I get to ~41kph, and I can tell the motor is not being shut down ever with throttle pinned, it keeps trying to achieve its top unloaded speed of 48kph (determined with an unloaded spin test).
(Speed on display is accurate within 0.5kph and verified all the above speeds with gps speedo app on my phone). Nothing else appears to be affected by setting it to 100.

So my questions are:
1. Is there any potential harm in "lying" or entering incorrect motor magnet poles?

2. If anyone understands it, how does the display use this data for P1 setting, or how does it interpret the numbers and how does that affect the signal or commands sent to the controller?

3. my motor has stamped - RM G060.500.DC 07 - Regarding the last digit 07 - is that referencing the # of windings? or is it to specify to use a 7 spd cassette? The Grin page for the motor (190mm version) shows this number as 08 so i thought it was odd mine is different. the motor originally was sold by Grin.

4. just as an aside, would you consider these components well matched? I am wondering if I was too conservative on the controller and should have gone with a 25A or 30A controller for just a tad more power. (Battery bms is rated 40a max) But i read the battery 1 hr rating is 23a and general advice is to not exceed this rating when choosing controller. would a 25 or 30A controller give me a bit more jam and top speed? Would either put the motor or battery in harm's way? Display says i'm pushing close to 800w on initial acceleration. can i push this safely to 900w or 1080w (25a or 30a controller) for short hill climbs?
(I felt the motor after going for a 10k ride using mostly throttle and it barely got warm).
I would have chosen a 48v battery but this bike came to me non-working and included the battery...i'm not spending $800 to gain 5 kph.

Thank you in advance for your consideration with this long(ish) post.

Build Specs:
Bike: Electra Lux 7 Cruiser with 26" fat tires
Motor: Bafang RM G060.500.dc 07 _ 008F1S3270645 _ G50_STD 8.2 RPM/V
(RM=Rear Motor, G060=Geared 6th gen G0 Series, 500w, DC=Disc brake with cassette, 7= windings?)
for 26"/700c/28" wheels
https://ebikes.ca/shop/electric-bicycle-parts/motors/mg60-fatbike.html
Gear Ratio: 5:1 Magnetic Pole Pairs: 10 (50 effective) 6 speed pulses/revolution
Battery: 36v 23.5Ah, 40A BMS From Grin ebikes.ca ("BOB" ShenZhen Battery building)
Controller: KT-22A controller 22a max, rated 11a, voltage 36v/48v Squarewave version (not sine wave)
Display: KT LCD3 with SM 5 PIN FLAT connector and usb (wishing i had paid the extra $20 and got lcd8)

LCD3 Setttings used:
Speed Limit: 72kph max
Wheel size: 700c (found it to be the most accurate - within about 0.5kph of my gps speedometer.
P1= 50 (Motor 1-255 magnets - (Gear ratio x # magnets, So with G60 motor: 5:1 ratio x 10 magnets = 50 magnets) but i found increasing # to 100 gave me higher max speed...

P2 6 - MAGNET POLES IN MOTOR FOR SPEED SENSING
P3 0 - (PAS mode) Power Assist Control Mode - tried both 0 or 1, did not affect max speed.
P4 Set to 0 (throttle live on startup)
P5 Set at 15 - "Power monitoring setting" - estimates batt capacity
C1 7 (12 magnet reverse pas sensor)
C2 0 (for non sine wave controller)
C3 8 (remember last PAS mode setting)
C4 0 (full throttle live at startup)
C5 10 (max current - no limiting)
C6 3 (backlight)
C7 1 (Cruise on)
C8 0 (do not display motor temp.) - no temp sensor in this motor
C9 0 (no password)
C10 N (skip factory reset)
C11 0 (LCD3 comm protocol)
C12 4 (30v Low voltage cutoff)
C13 0 (No Regen)
C14 3 (strong power ramp up curve)

 

[E-HP]

Change P1 to whatever settings you want, then measure your speed with a GPS and report back.

 

[TwisterGripper]

Change P1 to whatever settings you want, then measure your speed with a GPS and report back.

I did that already. with gps speedometer app. and mentioned in post...
p1=50=36kph p1=100=41kph.

 

[E-HP]

Change P1 to whatever settings you want, then measure your speed with a GPS and report back.

I did that already. with gps speedometer app. and mentioned in post...
p1=50=36kph p1=100=41kph.

Perhaps this may be of some help:
https://endless-sphere.com/forums/viewtopic.php?t=97237

 

[TwisterGripper]

Yes I read that post. It doesn't answer any of my questions though.

1. Is there any potential harm in "lying" or entering incorrect motor magnet poles?

2. If anyone understands it, how does the display use this data for P1 setting, or how does it interpret the numbers and how does that affect the signal or commands sent to the controller?

3. my motor has stamped - RM G060.500.DC 07 - Regarding the last digit 07 - is that referencing the # of windings? or is it to specify to use a 7 spd cassette? The Grin page for the motor (190mm version) shows this number as 08 so i thought it was odd mine is different. the motor originally was sold by Grin.

4. just as an aside, would you consider these components well matched? I am wondering if I was too conservative on the controller and should have gone with a 25A or 30A controller for just a tad more power. (Battery bms is rated 40a max) But i read the battery 1 hr rating is 23a and general advice is to not exceed this rating when choosing controller. would a 25 or 30A controller give me a bit more jam and top speed? Would either put the motor or battery in harm's way? Display says i'm pushing close to 800w on initial acceleration. can i push this safely to 900w or 1080w (25a or 30a controller) for short hill climbs?

 

[amberwolf]

I am wondering if I was too conservative on the controller and should have gone with a 25A or 30A controller for just a tad more power. (Battery bms is rated 40a max) But i read the battery 1 hr rating is 23a and general advice is to not exceed this rating when choosing controller.

This depends on the specs for the specific battery in question. There is a C-rate for each cell model that determines how much current it is capable of continously delivering. It is a number used as a multiplier of the capacity number in Ah, and usually has a continous and a burst value.

So a 1C-continuous / 3C-burst 23Ah pack can safely deliver 23A continously, and 69Ah for a burst (usually a few seconds max). A 2C / 5C pack could do 46A, with 115A bursts. A 0.5C/1C pack could do 11.5A with 23A bursts. Etc.

If they provide a rating for it, the Grin pack should be correctly rated as they're a reliable vendor, but note that it is common for sellers of cheap packs to either lie outright or "mistakenly" overrate the capabilities of their packs, so if you ever get one of those, I'd be conservative with it's usage.

would a 25 or 30A controller give me a bit more jam and top speed? Would either put the motor or battery in harm's way? Display says i'm pushing close to 800w on initial acceleration. can i push this safely to 900w or 1080w (25a or 30a controller) for short hill climbs?

I don't know what the motor itself can take safely (depends on conditions, speed, etc) but the battery can probably handle it ok. Voltage will sag more the higher the current drawn from it, so power output will be less than if it didn't, but still more than at a lower current.

The higher current the controller can pull from the battery, (meaning the higher the controller's battery current limit), generally the more torque the motor could provide under loading conditions sufficient to draw that extra current, up to the limits of the motor design.

Geared motors are limited by the gears and the clutch primarily; if torque applied is too high, or too suddenly applied, it can damage the teeth of the plastic gears, or crack the clutch housing and allow it to slip instead of engage. Heat is another problem for the plastic gears--if it gets too hot inside it will soften the plastic enough that they can take less torque and less sudden application of it before they fail. Heat from excessive loading is also a problem for the windings and hall sensors, as geared hubs are essentially double-insulated vs DD hubs.

I'm not certain that the G60 listed in the simulator is the same motor you have, but if it is, you can setup your conditions and system in the simulator here:
https://ebikes.ca/tools/simulator.html?motor=MG60_500
and see what happens, heatwise. It'll also show you the torque and speed, which will let you know what kind of acceleration it might have, and what speed you might reach under various conditions.


I don't have answers for any of the other questions, though.

 

[TwisterGripper]

Thanks Amberwolf. Your sage advice is always appreciated! I think i'd be comfortable with the 25a controller but sounds like it likely wont help much with top speed...

 

[amberwolf]

I think i'd be comfortable with the 25a controller but sounds like it likely wont help much with top speed...

Assuming no wind and flat paved roads, speed is primarily controlled by the voltage of the system vs the motor winding vs the size of the wheel and any gearing in between (if it's not a hubmotor in the wheel).

When going faster speeds than 20-25mph, air resistance becomes a more significant factor requiring power to overcome it, and so available power starts making a difference to speed, too.

That simulator will show you how that works, if you are interested and dont' already know.