KT Controller C5 and C14 query

[Bikes4two]

So rumaging around Endless Sphere the best description of C14 is, quote, "With the LCD3, you can set C5 for 50-100% of the max current, and set C14 for weak,normal, or strong pedal strength. 'My question is what exactly does pedal strength mean e.g. does 'strong pedal strength' mean you have to pedal harder or does it mean the motor's assistance is greater?

Onto C5 - I get most of what it means as per the table below as in 03-10 determines the proportion of the controller's maximum current being made available for assistance but 00-02? As an example, I don't get what the 'three levels of slow start/ max current value' means. Does it mean that for every one of the five assist levels the power delivery ramps up to this in three steps (and if so, how quickly does this happen?

Thanks in advance.

 

[saneagle]

So rumaging around Endless Sphere the best description of C14 is, quote, "With the LCD3, you can set C5 for 50-100% of the max current, and set C14 for weak,normal, or strong pedal strength. 'My question is what exactly pedal strength mean e.g. does 'strong pedal strength' mean you have to pedal harder od does it mean the motor's assistance is greater?

Onto C5 - I get most of what it means as per the table below as in 03-10 determines the proportion of the controller's maximum current being made available for assistance but 00-02? As an example, I don't get what the 'three levels of slow start/ max current value' means. Does it mean that for every one of the five assist levels the power delivery ramps up to this in three steps (and if so, how quickly does this happen?

Thanks in advance.

View attachment 61619

C5 is the maximum power allowed. There are different versions of software in the LCDs, so you can't always go by the manuals. If you want to change the current, you might have to do a bit of trial and error with that parameter.

I thought C14 is how quickly the power ramps up when you start pedaling. The power is set on your pedal assist setting 1 to 5. When you're not pedaling, the power is zero, and after some short time interval, the power reaches whatever it is for that level. The time to reach it is C14; however, the below seems to be something similar, so I don't know how it works between the two of them.

I've never used 00, 01, 02, but it sounds like it does something weird with the current, like ramping it up. "Maximum current value" is that written on the outside of the controller.

 

[Sturmey]

I always set C14 to 3. The C14 setting only affects the scaling of power levels of PAS 1,2, 3 and 4. When C14 is set to 3, it brings up these levels. So, for example, with my LCD 3, when C14 is set to 2 (default), at PAS 4 level, I get something like 260W output and at PAS 5 get 425W, which leaves a big gap between PAS 4 and 5.
Setting C14 to 3 brings up PAS 1 to 4, with PAS 4 giving something like 310W output and PAS 5 is unaffected. I find it useful as I am a heavy user, so I can run the bike at say approx 70% of full power at PAS 4 rather than 60% at PAS 4.
I presume something opposite take place if you set C14 to 1, and this would suit a frugal user of power as the P1 to 4 setting would be scaled lower but I have never tried it.

 

[Bikes4two]

Thanks for that @Sturmey and your observations bear testimony to other post from ES that C14 is indeed a scaling factor and in your case show around a 20% increase in measured power between C14 = 2 or 3.

I've only been riding my first hub bike conversion for a couple of weeks and I have C14=2 at the mo but when I''ve got more experience of how that setting feels I'll give C14 a bit of a tinker to 1 and 3 to see what discernable difference it mkes to the ride feel and battery consumption.

How are you measuring your power output BTW?

 

[saneagle]

Thanks for that @Sturmey and your observations bear testimony to other post from ES that C14 is indeed a scaling factor and in your case show around a 20% increase in measured power between C14 = 2 or 3.

I've only been riding my first hub bike conversion for a couple of weeks and I have C14=2 at the mo but when I''ve got more experience of how that setting feels I'll give C14 a bit of a tinker to 1 and 3 to see what discernable difference it mkes to the ride feel and battery consumption.

How are you measuring your power output BTW?

Are you using a thumb throttle as an instant max power device to over-ride the PAS setting? It saves a lot of problems. You can also use a simple push button. We should have this system on all electric bikes to make them safer and more manageable.

That got me thinking about the ideal ebike system. They can keep the low power walk assist on the PAS down button, then add two more buttons on the right hand bar (assuming PAS controls on left side). One button gives max power up to 4 mph without pedaling. Call it hill start assist. The other gives max power up to 15.5mph as long as you're pedaling. Call it boost.

 

[guerney]

One button gives max power up to 4 mph without pedaling. Call it hill start assist.

When I limited the speed of the throttle of my BBS01B with max power to 6kph, I heard a horrible grinding of the internal nylon gears, if I pressed the throttle too sharply on a stamding start uphill, so stripping the internal nylon gears would be a worry for mid-drives with an instant max power speed limited button. Would you get the same grinding happening with a hub drive with instant max power uphill from a standing start?

Removed the throttle because I didn't want to be assailed by uninformed uniforms.

After the bit with my friend's cat.

The other gives max power up to 15.5mph as long as you're pedaling. Call it boost.

Don't you have that already via multiple PAS button presses on KT kits? I simply leave my PAS on max setting after switching the bike on and leave it there, but in the very rare scenario if using a lower PAS setting, repeated quick presses of the PAS "Up" button would get max power while pedalling up to 25kph fast.

 

[Bikes4two]

For C5 settings and in the absence of all else and given the wisdom of Amberwolf of ES (link) I'll settle on the table below:


The quote about C5 from Amberwolf:
From the wording and the typical way such things may work, I would guess that it is simply three different settings for the slow start value, with level one the least restrictive and level three the most restrictive, given that the progression of 10 to 0 in setting value decreases current for each step.

There are two likely ways the levels might work: Either the ramps are longer for each setting, but the current goes up to the same amount for each, or the ramps are the same for each setting but the current it finalizes at is less for each lower C5 value.

In general, slow start is used as you say, either to prevent shock loading on drivetrain parts, or to prevent jerkiness to the rider with sudden application of power.

With low power systems it's generally unnecessary with throttle usage because ramping can be controlled by the rider directly, but with PAS systems that are only on/off control (of whatever assist level is chosen), it can smooth out the ride.

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For the C14 settings and given @Sturmey 's observations above and until some other explanation surfaces, I'll settle on that C14 is a power-assist tuning parameter for PAS levels 1-4 and to be effective requires P3=1. The default value is 2. PAS level 5 is unaffected by this parameter.

 

[saneagle]

For C5 settings and in the absence of all else and given the wisdom of Amberwolf of ES (link) I'll settle on the table below:
View attachment 61635

The quote about C5 from Amberwolf:
From the wording and the typical way such things may work, I would guess that it is simply three different settings for the slow start value, with level one the least restrictive and level three the most restrictive, given that the progression of 10 to 0 in setting value decreases current for each step.

There are two likely ways the levels might work: Either the ramps are longer for each setting, but the current goes up to the same amount for each, or the ramps are the same for each setting but the current it finalizes at is less for each lower C5 value.

In general, slow start is used as you say, either to prevent shock loading on drivetrain parts, or to prevent jerkiness to the rider with sudden application of power.

With low power systems it's generally unnecessary with throttle usage because ramping can be controlled by the rider directly, but with PAS systems that are only on/off control (of whatever assist level is chosen), it can smooth out the ride.

-----------------------------------------------------------------------------​

For the C14 settings and given @Sturmey 's observations above and until some other explanation surfaces, I'll settle on that C14 is a power-assist tuning parameter for PAS levels 1-4 and to be effective requires P3=1. The default value is 2. PAS level 5 is unaffected by this parameter.

View attachment 61636

Whatever all that says, you should try it because I've found many different versions of the software that all affect the current differently with C14. On some, you can increase current above the standard as well as reduce it.

 

[Sturmey]

How are you measuring your power output BTW?

I am using the KT LCD 3 display which gives a power reading.

 

[Jodel]

I recently fitted a KT / LCD3 system to my solo bike. I went for the 15 amp controller at 48 volts. I previously had a 17 amp controller, but I really don't notice much loss of power. I run C5 at 10 to get full 15 amps.

I don't have enough miles on the bike to give comprehensive feedback, but there is certainly a difference in the various C14 settings.

If I use assist level 1 and C14 set to '2' (normal) then I get a reading of about 85-90 watts on the display. Assist level 2 takes that up to about 145 watts. Changing C14 to '3' means that I get about 145 watts when set to assist level 1 - I haven't checked the higher assist levels yet.

Sturmey makes the point in his post that there is quite a gap between assist level 4 and 5 if the C14 value is set to '2' and that by using '3' it makes the steps between each assist point a bit more linear. I have plans to fit a KT system to my tandem and I suspect setting C14 to '3' will be a better option for that much heavier machine. On the solo, assist level 1 feels adequate on flattish roads, assist level 2 or 3 is pretty much all I require to make decent progress.

As saneagle commented, a simple blip of throttle can be helpful to provide some extra shove when required. I think my display shows a bit over 700 watts at full power.