KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)

[stancecoke]

I'm just coming back from a longer test ride and I'm really satisfied with the setup. Everything is working properly and reliably for me. So I'll stop further development at the moment.
It's very difficult to solve other people's problems that doesn't appear at my setup...
Thank you, geofft, for your restless efforts on the project!

regards
stancecoke

 

[geofft]

I'm just coming back from a longer test ride and I'm really satisfied with the setup. Everything is working properly and reliably for me. So I'll stop further development at the moment.
It's very difficult to solve other people's problems that doesn't appear at my setup...
Thank you, geofft, for your restless efforts on the project!

regards
stancecoke

stancecoke, I am easily able to understand your feelings, trying to resolve issues you are not seeing must be very frustrating and you have shown great patience. Many thanks for all the effort and hours you (and Casainho) have put into this so far.

Just one last small question - do any of the German users (using displays) get the speed readout issue, or is it just me?

 

[stancecoke]

do any of the German users (using displays) get the speed readout issue, or is it just me?

The last feedback of two users was, that the LCD3 isn't working at all. I think that's an issue of the last XOR in the checksum. But I can't check it, as I don't know, what their displays are sending....

regards
stancecoke

 

[Hwy89]

First of all let me admit that I don't understand most of what I have read in this topic. What I have found out is that several of you have learned a lot about how these controllers operate so I will ask my question here.
I have recently put together a dual motor set up on a Big Dummy cargo bike. I've installed two Q128H 201 Rpm motors, two S12S controllers, two LCD 5 displays and a huge 38 amp hour 52 volt battery. Very nice setup, will only go 20 MPH but lots of low end power for hills and carrying loads.
The problem I'm having is that when the battery is full, above 56 volts, the motors are cutting out. Both motors seem to drop out at the same time. I tried using two separate throttles and found myself using one motor till it stopped then switching to the other till it stopped so I changed back to a single throttle. It isn't a big problem because all I have to do is momentarily release then reapply the throttle and the power comes back on for a minute or two then repeats. When the battery voltage drops below 56 V the problem stops and everything works great.
I have tried various different programing settings on the LCD 5's and also tried discharging the caps in the controllers before plugging in a full 58.8 volt battery.
Is this a high voltage cut off action? Is there a way to change the high voltage limit?
Like I mentioned earlier the topic here is way above my capabilities and I know very little about programing so the simpler the better.

 

[geofft]

Both motors seem to drop out at the same time.

I think this must be the big clue here, if both drop at the same time it must be something common to both motors and controllers. This points towards the battery, is it fitted with a BMS (battery management system)?

If it is, then logically this is the most likely culprit, maybe an overcurrent or thermal trip is cutting out at higher voltages?

 

[Hwy89]

There is no bms. I balance charge and closely monitor. I had that same thought that it must be something common to the two but found no problems with the battery or connectors. Interesting that the cut outs seem more likely to occur at fairly low speed. I actually tested this by climbing a steep hill expecting it to cut out under heavy load. It didn't but at the top of the hill when i reduced the throttle it cut out. Climbing the hill the voltage dropped to near 56 but at the top it bounced back up to 57+. This is a very big battery with little sag.
I think this is something to do with the way the controllers are programed and since they are the same model ordered at the same time and I have all the same parameters on the two LCD 5's the controllers are just responding the same.

 

[Hwy89]

Another clue is that when I ran it with two separate throttles each of the motors exibited the same cut off problem. On that occaision I thought the problem was solved but it was only because my pack voltage had dropped to below 56V. As soon as I recharged it came back.

 

[stancecoke]

a huge 38 amp hour 52 volt battery.

52V ??? How many cells in series and which kind of cells?

regards
stancecoke

 

[Hwy89]

168 recycled Tesla 18650 cells in 14s 12p configuration.

 

[stancecoke]

I think the controller doesn't know 14s batteries. Only 24, 36, 48, 60 and 72V are expected.
http://risunmotor.com/24v-36v-48v-60v-72v-ebike-intelligent-ktlcd3-panel-lcd-display-for-our-controller.html

It thinks it's an 13s (48V) and stops working for overvoltage protection.

regards
stancecoke

 

[Hwy89]

Do you think if I bleed the controller caps and initally install a 15s pack (about 63v) I could fool it into thinking it had a 60 volt pack. Then hook my 52v pack up? I know that this will mess up my battery gauge and raise the LVC by a couple of volts but I don't pay much attention to the gauge and seldom run down to LVC.

 

[stancecoke]

could work, just try it! :wink:

regards
stancecoke

 

[Hwy89]

Welding together a 15s 1p fooler pack to try that out. Will be tomorrow before I have results because both it and the main pack will need to be charged.
Am I right in thinking that once I connect a 63 volt battery the controllers will remember and I won't have to do this each time?
Thanks for the tip

 

[honya96]

Welding together a 15s 1p fooler pack to try that out. Will be tomorrow before I have results because both it and the main pack will need to be charged.
Am I right in thinking that once I connect a 63 volt battery the controllers will remember and I won't have to do this each time?
Thanks for the tip

Don't waste your time on this.. I am having this problem with 14s battery also. At high power it happens even below 50v. If you decrease max power, you will get less cutouts. C5 parameter - 00-02 is soft start. That helps too..

I was pretty sure that it's because of phase current exceeding some set limit, but bridging the hall sensor does not seem to help..

With custom FW you don't get this issue, as there is no hard cut-off phase current limit.

 

[Hwy89]

The hard part is already done. The 1P 15S battery is charged. All I have to do is top off the bike pack and try it.
It doesn't seem like it is an over current problem though. Most of the time when it happens I'm only pulling 3 or 4 amps per motor cruising on the flat at 12 to 15 mph.
I have an ampmeter and volt meter mounted on the dash.

 

[Hwy89]

So, Honya96 you were right. The experiment did not make any difference.
So tell me, how would someone like me who is basicly clueless when it comes to programing or coding, what ever it is called, be able to take advantage of this custom firm ware?

 

[geofft]

So, Honya96 you were right. The experiment did not make any difference.
So tell me, how would someone like me who is basicly clueless when it comes to programing or coding, what ever it is called, be able to take advantage of this custom firm ware?

I'm wondering if your best option would be to reconfigure your battery to 13S? You would then only need to add one more cell to make a 13s13p battery.
13s is a fairly 'standard' configuration for (nominal) 48v use and would hopefully solve your issue with just a small power reduction?

 

[honya96]

So, Honya96 you were right. The experiment did not make any difference.
So tell me, how would someone like me who is basicly clueless when it comes to programing or coding, what ever it is called, be able to take advantage of this custom firm ware?

Try to set C5 to 00.. I can't help with custom fw as I am also struggling every time I want to try it.

 

[stancecoke]

So tell me, how would someone like me who is basicly clueless when it comes to programing or coding, what ever it is called, be able to take advantage of this custom firm ware?

You can follow the tutorial chapter for chapter, see the link in my signature. This should also be feasible for inexperienced computer users. But be aware, that we have no completly positive feedback for the use of the open firmware with 12FET controllers so far. honya96 seems to be the most experienced user for these high power devices...

regards
stancecoke

 

[Hwy89]

Thanks to all of you for your suggestions.I think the simplest solution at this point is to simply charge the battery to 56 volts. Charging to 4 volts per cell is better for battery health anyway. Acording to my math this will shave about 6.6 miles off of my range but I should still be able to go around 60 miles per charge.
I have put this cargo bike together in preparation for a 2500 mile cross country camping trip starting on September 4th. I don't have much time left to make any major changes. Other than the high voltage cut out glitch the bike performs flawlessly.

 

[Hwy89]

OK, I am now officially senile or maybe just retarded. I went back and looked at the listings for the S12S comtrollers I bought from BMSB. These are 36 or 48 volt controllers. There is another model that is 72 volts. The reason my controllers don't like 56 volts and above is because they weren't ment for that high of voltage and are trying to protect themselves.
Disregard everything I have said up to this point. I should replace my bike helmet with a dunce cap.

 

[geofft]

OK, I am now officially senile or maybe just retarded. I went back and looked at the listings for the S12S comtrollers I bought from BMSB. These are 36 or 48 volt controllers. There is another model that is 72 volts. The reason my controllers don't like 56 volts and above is because they weren't ment for that high of voltage and are trying to protect themselves.
Disregard everything I have said up to this point. I should replace my bike helmet with a dunce cap.

Don't worry mate, we all make those sort of mistakes, all part of the learning process.

I don't know how the internal supplies are generated in the S12S, but in the S06S 36/48v type controllers it is done using an LM317 v. reg which is fed via a series resistor. Both these items can get bloody hot with a 12s supply, at 14s the LM317 could possibly be in shutdown territory. I've managed to fit heatsinks to these in my controllers which keeps the LM317 a little happier.

Not saying this is an issue for you, the S12S may do things differently, but maybe something to bear in mind...

 

[honya96]

OK, I am now officially senile or maybe just retarded. I went back and looked at the listings for the S12S comtrollers I bought from BMSB. These are 36 or 48 volt controllers. There is another model that is 72 volts. The reason my controllers don't like 56 volts and above is because they weren't ment for that high of voltage and are trying to protect themselves.
Disregard everything I have said up to this point. I should replace my bike helmet with a dunce cap.

Don't worry mate, we all make those sort of mistakes, all part of the learning process.

I don't know how the internal supplies are generated in the S12S, but in the S06S 36/48v type controllers it is done using an LM317 v. reg which is fed via a series resistor. Both these items can get bloody hot with a 12s supply, at 14s the LM317 could possibly be in shutdown territory. I've managed to fit heatsinks to these in my controllers which keeps the LM317 a little happier.

Not saying this is an issue for you, the S12S may do things differently, but maybe something to bear in mind...

I am running 14s with stock 18fet (48v) normally at rated 45A. It cuts out only if I beef up the shunt to 80-100A. I see no problem with voltage, sure when the battery is not fully charged, you get lower peak currents, so less cutouts.

It has the same voltage regulator as 12 and 6 fet.. It should shutdown if it gets too hot if I remember correctly from lm317 datasheet

If you consider buying different version, 48v is for 13s, 60v is for 16s, 72v is for 20s (72v display does not work under 50v) 60 and 72v version has two lm317's.

 

[reset]

Hi Folks, thanks for all of the work on this project it looks like you've been putting in a massive amount of effort. I'm a newbie to the world of coding but I've been tinkering with building e bikes for a while and I'm really keen to know if it's possible to run the s06s or the ku 63 controllers at lower voltages. I'm not looking to draw massive amps I'm happy to run the system at around 180w but I'm wondering if it's possible to use 5s or 6s batteries and setting the controller at a voltage lower than the 24v.

I've tried searching for this info through the thread but there is so much info it's been really hard to find anything on lowering the voltages.

 

[stancecoke]

I'm wondering if it's possible to use 5s or 6s batteries and setting the controller at a voltage lower than the 24v.

With our firmware you can do this, as you can set the undervoltage limit yourself.
But be aware, the motor's high speed depends on the voltage. You will get much less high speed if you run a motor that is build for 36V with 20V only.
Perhaps you have to replace the resistor R62 to get the 5V supply properly....

regards
stancecoke