Ku63 controller at 12s voltage

[larsb]

I have gone full circle from 1000w to 20kW and back to 250w, i’m just building a tootling around bike with a 10 year old ku63 controller that i never used in 2014

I have a 12s battery and the ku63 is 24v/36v (on the label) - but i read here: Re: KU63 KU93 KU123 controller hacking that they have been used at 48V without any resistor mods.. that shouldn’t be possible if there’s an overvolt protection - can someone confirm?

I also found avandalens page with a lot of good info in it : Kunteng controllers

It has a description how to update the ku63 for 12s voltage, but the r1 resistor mod calculation on the page seems incorrect, it calculates the new r1 resistor value to 270ohm but the correct answer with the values in the formula is 317ohm



Any advice out there? I bet @d8veh , @avandalen or @amberwolf and a few others know this by heart

 

[larsb]

So.. patience is hard so i tried a fix..
I got an answer from avandalen and it seems the calculation of the r1 value is correct, but the resistor value was rounded down to 270ohm due to availability. Might be good to update that on the page @avandalen

The original resistor on my KU63 was 68ohm so i added 4 parallel 1k resistors to make the total 68+250=318ohm, within 1ohm tolerance (instead of within 47ohm with 270ohm resistor)
Let’s see if it works!

 

[larsb]

Ok, we have rotation! Love it when things come together as they should, even with a motor core that came from a different wheel, a controller for another voltage and a new battery made from scratch in a day. I tinned the shunt without any knowhow on what it should be so if it burns then it might just be me overpowering it.

Now to the finishing touches, first some riding, then tidying things up. I’ll report if i get issues further on

 

[glennb]

I recall you using Votol controllers. Why not cough up fifty bucks for an EM-25?

 

[larsb]

I had the KU63 already and it's dirt cheap and simple. I got tired of Votols when they started screwing up the program, guess that might or might not have improved by now but for this build a KU63 was right.

 

[glennb]

“Right” except for having to manipulate LVC and shunt resistance. Fair enough though, I’d probably have done the same. Hope it works out for you.

 

[larsb]

Actually my plan was originally to use it as intended, with a 10s battery, but the bms i had could not be configured as 10s - so i built the battery into 12s and fixed the rest

main thing was to avoid buying stuff and waiting for a three month shipping delay..

 

[larsb]

So, i did the first 100km on the bike and it’s good and bad.
The motor core i had turned out to be a high speed winding so at 12s voltage / 26” wheels the noload speed is 50kph. That gets me a power hungry system with about 21A max and 1000w of power - which is kind of fun but was not at all my goal with this build

The three speed switch doesn’t work, it’s the same power regardless. I think it might be because i don’t have a PAS so I’ll try connecting PAS red and green at the connector as per avandalen’s site info.

 

[larsb]

Connected PAS, but power is still the same between all assist levels when I use throttle. I don’t know if this is normal, might be that assist levels are only changed on the PAS input since with throttle you could just stop throttling at a lower level. Anyway, the function is not the best for my use case, i’d like to have full throttle range in three output power levels like the larger controllers do it.