KT controller 2x Light output

[hmsg76]

Hi all,
I got this controller (KT-6S5-C 2018-1-8) recently and I'm a bit scared of plugging lights without some testing before.
There are two outputs from controller (on board these are brown and white wire).

My battery is 36v and just measured the lights with a multimeter on 200mA.
Front light is continuous 95.6mA, rear light has a stop function which doubles LED's so peaks at 19mA +/- and stays continuous on regular one led at 5.6 mA.

I'm trying to figure this out before connecting it and burning the circuit Can any one help figure out if this circuit can hold over 100mA at peak?
Would it be 100mA per output or for both?

posting pics of light pcb

Many thanks for any advice!

 

[hmsg76]

Apologies pics didn't upload a first post

 

[E-HP]

Some posts on the forum mention a 100mA limit (and frying the circuit when drawing more). I seems like the circuit is best used to operate a relay, that can support more current. You might find more info if you used the forum search for something like "kunteng light output).

 

[hmsg76]

Thanks E-HP,

so just got an answer from KT confirming the circuit handles max 70mA!!
A lot less than what I expected.

I did search a bit before and was able to find posts on the problem but not solutions for it. I'll have to think of a way as the main reason for having purchased another controller was in fact to be able to power lights on/off from display

 

[Raider]

Hello. I'm having the exact same problem here.
But the whole kid of got me stumped...
Why the heck do they even bother with a light output at all when it cant even connect to a relay???

I just tried to have that very same light controller, control a small relay but the only thing that happends are the infamous mushroom smoke..
When I think about it, isn't it so that the power to close a relay, in effect shortcircuit the control circuit when it draws the relay on? Creating the magnetic field?
That could, of course cause a problem.

But I'm just as lost as you when it comes to using the controller light function. I can't really see any way it can be done at all. Especially also since the darn thing has the same voltage output as the battery.

I have a KT48ZWSRKT controller, but the light circuit are exactly the same as your photo. Except I don't have that white cable.
Everything else is the same. And completely useless.

 

[Raider]

My light system is probably a bit different that yours. It's all set up and modified for 5v. But my head light LED's draw 1W each and there is 3 of them.
Then I have a few for tail lights and brake lights. The same LED's actually, but with differnt resistors for different brightness of tail light and brake light.

The only solution I can see is to use a completely different light source, and buy something like the switch in the picture.

Mu plan is to then use a 5v power source that has power when the controller are swithced on, to control a relay. Then take the main power from the USB out on my battery, via the relay, to the switches. Bottom switch for the main lights, top switch for high beam.
My controller has a plug for a bluetooth dongle, and one of the cables in that plug, delivers 5v. Hopefully enough mw to control the relay.

Then, just X my fingers and hope the controller don't fry gain.. :?

BTW. Here is a very informative thread:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=75171&hilit=brake+light*

I actually tried to use almost an identical relay as he is using, except I have only 5v and 3 pins in, but the same as him on the power side of the relay.
The in controller light circuit will still fry if connected to the "controller" side of the relay. Don't make sense at all.
The relay I'm trying to use are in the bottom pic.

 

[hmsg76]

I hear you. It does feel useless to have light outputs that will likely go bust.

In my case both my front and rear lights are multi voltage (5 - 36), so I think I'm going to try and add a resistor in parallel to the 510 smd.
Something like a 100ohm 5W ceramic. Hopefully this will give me around 150mA.

 

[Raider]

It should.
I have seen on the older light pcb's it used to be an old school resistor. Of course, that didn't prevent the familiar smoke, but I have read here in another thread that in stead of replacing that resistor, just solder straight over it. And that was supposed to give about 500mA.
Not sure if I would take the chance, though. since it takes for ever to get new controllers and snow is soon to be found here..

Anyway, now I have tried every relay I could get my hands on, and the same happends every darn time.. Resistor starts to overheat. Even with a relay with guaranteed 0 resistance and supposed to be a 250v relay..
So, I'll be cutting it out'a there all together.
Another thing I also thought about.. If the lights are connected to the controller, it is a good chance that you'll have no lights at all if you run out of juice and have to pedal.
With my bike, I can still have the battery power on and as long as I don't use the assist, I'll be able to keep lights on for at least a bit longer.
Still needs to use relays, though. If I can find a source in the controller that can manage to turn a relay on.
But the worst thing of all are still all the cables and wires on the bike. And no good place to hide it.
Mind you, I have a home brew with a normal MTB as the starting point.

 

[hmsg76]

It worked!! Soldered a 100 Ohm 5W ceramic resistor and soldered it in parallel with the 510 SMD resistor. Resistance lowered to 33.4Ohms! And current increased

 

[woojak]

It should.
I have seen on the older light pcb's it used to be an old school resistor. Of course, that didn't prevent the familiar smoke, but I have read here in another thread that in stead of replacing that resistor, just solder straight over it. And that was supposed to give about 500mA.
Not sure if I would take the chance, though. since it takes for ever to get new controllers and snow is soon to be found here..

Anyway, now I have tried every relay I could get my hands on, and the same happends every darn time.. Resistor starts to overheat. Even with a relay with guaranteed 0 resistance and supposed to be a 250v relay..
So, I'll be cutting it out'a there all together.
Another thing I also thought about.. If the lights are connected to the controller, it is a good chance that you'll have no lights at all if you run out of juice and have to pedal.
With my bike, I can still have the battery power on and as long as I don't use the assist, I'll be able to keep lights on for at least a bit longer.
Still needs to use relays, though. If I can find a source in the controller that can manage to turn a relay on.
But the worst thing of all are still all the cables and wires on the bike. And no good place to hide it.
Mind you, I have a home brew with a normal MTB as the starting point.

Hello.
I encountered the exact same problem as you gentlemen and I think I have a simple solution
to it which is housed in the controller housing.
So far I'm after testing and everything seems to work great, as long as we have this little working PCB. :wink:

The solution is based on the use of a mosfet, a small prototype board and 3 resistors to make a voltage divider.
Thanks to the use of a mosfet taken from the old controller, I can now pass quite a large amperage through the line of lights.
The elements needed are:
IRF1010E mosfet (I just had one)
2 x 100k resistor
1x 91k resistor
PCB prototype board
(you can also do without the "spider", then you will save some space)

VIN - This is the voltage from the battery provided by the controller with the lights on.
(I'm using it here as a signal to turn on the mosfet)
GND - you just need to remember to use the appropriate cross-section of the wire.
Light control consists in "cutting off" the ground for the lamp, i.e. we pull up any voltage to the lamps and connect the ground to the middle leg of the mosfet.
To the right I connected the main ground wire, remembering to give a thick cable.

The best thing about it is that by applying constant voltage from the battery to the circuit and giving mass through the brake handles, you can make brake light in this way.

I am also trying to make a version with the omission of a small pcb board, but I encounter a strange problem with the "second light on".

I hope I helped and didn't dig up the topic unnecessarily.

Regards.