KT controller. Brake sw turns off regen braking ? wtf ?

marka-ee

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Mar 24, 2020
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Is it me being dumb with the settings via lcd3 or is it dumb software in controller ? Right now, with my sine wave 500 watt kt controller I get regen braking action as i throttle down, but it turns off regen if I close the throttle all they way. I can live with this. But if I hit the brakes ( switch ), it turns off regen alltogether ! I want *more* regen if the brakes are on, not zero regen . Did I goof up the settings I did via LCD3 , or are the authors of the software , umm, stupid ?
 
marka-ee said:
Is it me being dumb with the settings via lcd3 or is it dumb software in controller ? Right now, with my sine wave 500 watt kt controller I get regen braking action as i throttle down, but it turns off regen if I close the throttle all they way. I can live with this. But if I hit the brakes ( switch ), it turns off regen alltogether ! I want *more* regen if the brakes are on, not zero regen . Did I goof up the settings I did via LCD3 , or are the authors of the software , umm, stupid ?

You didn't mention your settings. What is C13 set to?

Based on how my old KT controller worked, assuming stock firmware, regen with the brake lever is based on C13, and it provides a fixed level of regen down to around 6mph and then cuts out.

With the stock firmware, the "slide regen" that you feel with your throttle isn't a documented feature, but the throttle will act like it has slide regen down to the minimum throttle voltage, if you are precise with your throttle, and then cutout below that voltage. Similarly, below around 6mph, regen/braking will cutout.
 
I checked the C13 settings, and it was set to 1, which is documented to be max braking effect. The higher numbers are lower braking. Maybe my LCD3 user manual is out of date ? My sine wave controller is recent, within last year, but the LCD3 is old, about 4 years old.
This is actually a bit unsafe, as I try to feather the throttle to get braking, then when I pull the brake lever the regen braking is gone, in a slow corner on a recumbent it's unsetteling.
one more detail: I don't use the LCD3 while riding, as I have my own custom ebike computer to monitor things. This device does not talk to the controller, so it's not the cause of the problem.
 
marka-ee said:
I checked the C13 settings, and it was set to 1, which is documented to be max braking effect. The higher numbers are lower braking.

It's the opposite. 1 is the lowest besides 0 which is none.

The 2 setting is pretty close to the max braking you get from feathering the throttle, so matches up pretty good when applying the brakes. 3 is good on dry surfaces, but it's a little too much braking on a wet downhill curve, since the braking may be enough to make your tire slide out. 4 could keep my bike close to 20mph on a 20% down hill grade. For regen, anything greater than 2 doesn't work well, since the bike brakes too quickly to get enough regen to the battery. That's why for regen, lower settings are good, but for braking, higher is better. Depends on what you want to accomplish, and what you value most, braking or regen.
 
Thanks , I'll try that. My user manual is in error. Regen set to 1 was giving me a whooping 30 watts of regen. I'd like 400 ,
Side note for those who may not know: The LCD3 stores the settings in itself and saves these settings to whichever controller you have connected. I discovered this as i somehow got lower power than before on this bike, when I didn't even change the setting. Turns out it was becasuse i had the LCD on another bike which I did tweak the power setting on .
 
The manual isn't intuitive, you can see that less braking provides more regen (although regen amps are lower) because it doesn't stop the bike (which stops regen). More braking has higher amps, but stops the bike quickly, hence no regen (energy recover) to the battery. 2 always was a good balance for me, given the hills by my house. Enough braking to save on brake pads, but not soo much so I recover a good amount to my battery.

C13.jpg
 
I'm not understanding the 'energy recovery efficiency ' rating. Having more amps going back to the battery should be fine. Sure, batteries don't like high charge rates and there could be a slight loss due to that. More amps for less time is fine by me. The energy is the integral of amps and time . Worst case would be the controller just shorting the motor windings thereby burning the energy as heat. I hope that is not he case.
 
marka-ee said:
The energy is the integral of amps and time .

With high braking (and high amps), the time period drops to a few seconds, and as the bike slows down, so do the amps. Almost nothing goes back into the battery. On the hills I ride, I want to capture regen to the battery over the full descent, which won't happen if the bike slows way down quickly, which means hitting and releasing the brake all the way down the hill, rather than a steady speed and steady flow of amps back to the battery. Your case may be different. With variable regen, you can keep the regen and braking in the sweet spot, but the stock KT controller uses one setting (and level 2 was the sweet spot for max regen for my riding).
 
Wouldn't it be the same ?
Example:
Setting A: regen 10 amps for 2 seconds = energy 20
Setting B: regen 2 amps for 10 seconds = energy 20 , same

Maybe I'm missing something. I'm just trying to understand better.
 
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