KT display overheating issues?? Help!

[Daan]

Hi community,

I have build over 60+ e-bikes with a 48V, 22A KT controller, almost all of them with a KT LCD3 (I sell them). I now am experiencing very weird issues, which I have never had before. Three main issues:

1. Complete cut-out of power when accelerating full power with throttle from stand-still.
2. Cut of off assistance, both in PAS and throttle, display stays on. Once I stop pedalling or throttle, and reangage again, it works again. Happens randomly, 99/100 time it works fine, then 1/100 it randomly does this.
3. When full throttle, the KT LCD3 switches through the menu, the same way if you would single press the power button. So the throttle is controlling the display, without touching any display buttons. Only happens when in highest Assist and using full power, otherwise it does not happen.

All there three issues are not happening consistent and all the time, some times those issues do not appear, sometimes they do.

I have a suspicion of overheating causing these issues. Currently it is very hot in my country, and I left my bikes in the sun, so all black components were quite hot of the sun. So also battery and display. I just did a test run with a bike that had all cool components, during that test, no issues. But that could also just be random/luck.

Could all these issues be overheating related? Does the KT controller have some sort of protection for that?

Apart from that, completely clueless, I never had issues with KT controllers like this before.

Any help would be much appreciated!

 

[Hwy89]

Sounds like the battery is out of balance and the BMS is shutting it off under load. The display will stay on for a short period of time until the capacitors bleed off. When you let off the throttle the BMS resets.

 

[amberwolf]

Ditto.

Alternately, for the times the display doesn't shut off, the battery might be dropping in voltage so low that the controller's LVC kicks in and prevents motor operation.

 

[Daan]

Sounds like the battery is out of balance and the BMS is shutting it off under load. The display will stay on for a short period of time until the capacitors bleed off. When you let off the throttle the BMS resets.

Yes, I was also thinking this, however it's a new battery, with Bluetooth BMS. I monitored each cell, definitely not unbalanced, and does not seem to cut out.

 

[Daan]

Ditto.

Alternately, for the times the display doesn't shut off, the battery might be dropping in voltage so low that the controller's LVC kicks in and prevents motor operation.

Voltage doesn't drop too low, I tested with 100% full battery and could monitor the BMS, since it's a Bluetooth BMS. All balanced, no crazy drops.

You really don't think it's temperature related?

 

[amberwolf]

I haven't read of that happening yet, and haven't seen it happen here in Phoenix even on the worst days back when I was testing a display-based controller similar to the KT (lishui/KM). Doesn't mean it can't happen, though.

If you think it is temperature related, what measurements have you made when it happens vs when it does not, and what testing other than the one time with a cooler system to confirm or eliminate it have you tried (like shading the display vs not shading it, etc).

Does it happen on other builds with the same setup? If not, it's probably specific to the one system that does it. If it happens to more than one, but not all, what is common between them? If it happens to all, what is common between those?

If many things are common, eliminate them one by one; if it's suspected to be heat, test the same system under the same conditions except keep cool or shade one part of the system at a time and retest.

Systematically testing things you will find the cause; at that point you can decide how to correct it.

 

[Daan]

Ditto.

Alternately, for the times the display doesn't shut off, the battery might be dropping in voltage so low that the controller's LVC kicks in and prevents motor operation.

Voltage doesn't drop too low, I tested with 100% full battery and could monitor the BMS, since it's a Bluetooth BMS. All balanced, no crazy drops.

You really don't think it's temperature related? It was very hot,

I haven't read of that happening yet, and haven't seen it happen here in Phoenix even on the worst days back when I was testing a display-based controller similar to the KT (lishui/KM). Doesn't mean it can't happen, though.

If you think it is temperature related, what measurements have you made when it happens vs when it does not, and what testing other than the one time with a cooler system to confirm or eliminate it have you tried (like shading the display vs not shading it, etc).

Does it happen on other builds with the same setup? If not, it's probably specific to the one system that does it. If it happens to more than one, but not all, what is common between them? If it happens to all, what is common between those?

If many things are common, eliminate them one by one; if it's suspected to be heat, test the same system under the same conditions except keep cool or shade one part of the system at a time and retest.

Systematically testing things you will find the cause; at that point you can decide how to correct it.

It happens on all builds, but it doesn't seem to happen when I put them in the shade. But since it is so random, it's hard to 100% confirm.

Seemed to happen when I left them in the full sun, and then immediately pushed it to the limit. When I then started riding for a bit, and let the air cool the bike, it doesn't seem to happen as often anymore.

My KT controller is build into the battery deck, so with 22A, it only has that metal plate for cooling, and it does seem to get very hot if you push it.

But is there a temperature sensor build into the controller? Is it smart enough to know when the controller overheats?

 

[AHicks]

Voltage doesn't drop too low, I tested with 100% full battery and could monitor the BMS, since it's a Bluetooth BMS. All balanced, no crazy drops.

You really don't think it's temperature related? It was very hot,

It happens on all builds, but it doesn't seem to happen when I put them in the shade. But since it is so random, it's hard to 100% confirm.

Seemed to happen when I left them in the full sun, and then immediately pushed it to the limit. When I then started riding for a bit, and let the air cool the bike, it doesn't seem to happen as often anymore.

My KT controller is build into the battery deck, so with 22A, it only has that metal plate for cooling, and it does seem to get very hot if you push it.

But is there a temperature sensor build into the controller? Is it smart enough to know when the controller overheats?

This is where I would start. Try getting the controller out into the natural air flow to see if that changes anything. You may have to modify your design a bit to make sure the controller can dissipate some of that heat.

 

[amberwolf]

Voltage doesn't drop too low, I tested with 100% full battery and could monitor the BMS, since it's a Bluetooth BMS. All balanced, no crazy drops.

You really don't think it's temperature related? It was very hot,

I already answered that here:

KT display overheating issues?? Help!

Hi community, I have build over 60+ e-bikes with a 48V, 22A KT controller, almost all of them with a KT LCD3 (I sell them). I now am experiencing very weird issues, which I have never had before. Three main issues: 1. Complete cut-out of power when accelerating full power with throttle from...

endless-sphere.com

It happens on all builds, but it doesn't seem to happen when I put them in the shade. But since it is so random, it's hard to 100% confirm.

If it never happens when they are shaded, but does sometimes happen in the sun, then you can guess it is a heat problem.

If you shade the part of the bike you think is causing the problem, by making something to install on the bike itself to keep ti shaded all the time, so sun doesn't shine on that part of the bike, you can do long term testing of whether this is the cause, and if it's the right part.


Since it is the display that exhibits the problem, and you already verified your battery is not shutting off it's output to cut power, you would probably be best to test the shading on the display itself.


Remember--the display controls whether the controller is turned on or not. If the display isnt on and correctly operating, the controller wont' be either.


As noted before: Systematically testing things you will find the cause; at that point you can decide how to correct it.

 

[Comrade]

Maybe it's not even the display? If the voltage regulator overheats and starts dropping voltage you can have some weird things happen.

Kunteng KT-14A controller doesnt work

Hello everyone, what could be the cause of this new Kunteng KT-14A controller not communicating with my motor? I tried all sort of things, like changing the motor phase wiring with the scheme below (courtesy of Tommycat) All I wanted was to replace the original controller (see below) with...

endless-sphere.com

 

[amberwolf]

Maybe it's not even the display? If the voltage regulator overheats and starts dropping voltage you can have some weird things happen.

Since his displays go blank, it pretty much has to be something to do with the display internals or the battery's output (BMS, etc), because the controller's regulator doesn't power or control the display (the display has it's own inside it)...but the display does control the battery-voltage that goes to the controller's regulator.

So if the display's power regulator doesn't turn on (or shuts down), it's MCU doesn't get power, so it's MCU does not turn on the transistor in the display that passes it's own supplied battery voltage to the controller's regulator input, .the controller won't even turn on (it gets no power to it's own MCU).

 

[Daan]

I already answered that here:

KT display overheating issues?? Help!

Hi community, I have build over 60+ e-bikes with a 48V, 22A KT controller, almost all of them with a KT LCD3 (I sell them). I now am experiencing very weird issues, which I have never had before. Three main issues: 1. Complete cut-out of power when accelerating full power with throttle from...

endless-sphere.com

If it never happens when they are shaded, but does sometimes happen in the sun, then you can guess it is a heat problem.

If you shade the part of the bike you think is causing the problem, by making something to install on the bike itself to keep ti shaded all the time, so sun doesn't shine on that part of the bike, you can do long term testing of whether this is the cause, and if it's the right part.


Since it is the display that exhibits the problem, and you already verified your battery is not shutting off it's output to cut power, you would probably be best to test the shading on the display itself.


Remember--the display controls whether the controller is turned on or not. If the display isnt on and correctly operating, the controller wont' be either.


As noted before: Systematically testing things you will find the cause; at that point you can decide how to correct it.

Alright, little update:

Replaced the PAS sensor with one of KT, did not make a difference. Same issues.

I also put them in the shade and tested again, also did not really made a difference, still happened.

The thing that makes incredibly hard to test, is that it only happens like 1% of the time. So if you changed something and it worked, it could just be luck within the 99% it does work.

The complete power loss doesn't happen anymore for some reason, only the motor cut-out still happens sometimes.

I now do suspect the BMS, therefore I took another battery without BMS. I am testing with that now, so far so good. But I have to do hours of testing to see if I can get the issue to show up. If it does, I know it also is not BMS related.

Then the only thing that it can be will be the display/controller (firmware).

 

[richj8990]

Very first, or maybe should I say next, thing to do: look at the wires connected to the controller. If they are starting to melt or 1/2 melted, and hard to get off (like the phase wires for example), it's almost certainly the controller that's fried and on its way out. It happens. Sometimes it happens even when you don't or try not to use full power. Be gentle with your parts, respect them. Take care of them so they can take care of you. Don't full throttle off the line. Bad way to test cheap parts.