KT Controller / LCD8H Headlight Control Question

Does anyone know how an LCD8H tells a KT controller to turn on the headlight circuit?
Here's the issue I'm trying to solve - I'd like to be able to turn the headlight off and on using the display (hold the up button until the headlight icon appears). On the probably more common LCD3 display holding the up button turns on the display backlight and the light circuit.
After burning up my previous controller I got a new, larger one that has the headlight connection. The problem is that unfreakingbelievably, the headlight circuit does not turn off and on using the display. It in fact does not turn off at all, ever. This has been verified by the seller, Chamrider, it's just on all the time which boggles my mind.
I recently installed head / tail and brake lights on another bike with a KT controller, and this is wired the exact same way using a step down transformer and relay.
Now I'm trying to figure out how the display tells a controller to turn on the light, if that controller has a switching light circuit. I've checked voltages at the 5 pin display connector with the light both on and off, and voltages are the same either way. Red and blue are battery voltage, and yellow and green are 4.5v. If I could find a difference I could use that as a signal to control the relay. Any ideas?

You probably know a lot more about this than I do. I just wanted to share that the LCD8H display IS able to turn the light on and off if everything is wired correctly and you have the right controller. From there, I'm pretty sure the data wire from display to the controller is serialized, meaning there is no direct headlight power on/off output available on the display side of the controller.

KT makes a ton of different controllers with very small differences. Square wave vs. sine wave, with light wire vs. 4 to 1 (8 pin) and 5 to 1 (9 pin) cables, etc. You have to be really careful when selecting them.....

THEN, the output of that controller switched headlight wire is tiny, and worse, it's not fused in anyway. Point being that circuit is very easily smoked due to shorts and overload. Thankfully, it doesn't take out the entire controller when the light circuit is smoked.

Best of luck getting it up and working.

AHicks said:

THEN, the output of that controller switched headlight wire is tiny, and worse, it's not fused in anyway. Point being that circuit is very easily smoked due to shorts and overload. Thankfully, it doesn't take out the entire controller when the light circuit is smoked.

Click to expand...

What's the point of running the headlight through a controller to begin with? As in, why did the designers put it in?

Comrade said:

AHicks said:

THEN, the output of that controller switched headlight wire is tiny, and worse, it's not fused in anyway. Point being that circuit is very easily smoked due to shorts and overload. Thankfully, it doesn't take out the entire controller when the light circuit is smoked.

Click to expand...

What's the point of running the headlight through a controller to begin with? As in, why did the designers put it in?

Click to expand...

Probably because it was an accountant that made the decision and not the designers, so they can sell more controllers because there is a certain segment of consumers that want their motor controller to control their lights. Try saying "Alexis, lights on" and see if that works?

If you don't need a lot of headlight power, it's pretty convenient to be able to turn the headlight and tail light on and off with the "up" button. The ability to do that without all of the associated switches and wiring required by an external switch is a bonus. It makes for a pretty clean setup.

There's just no good reason it's not fused or protected somehow.

AND

There no good reason for the circuit to be so light duty. They could increase that by a factor of 10 or 20 and still not cause an issue with the available battery storage. At that point you could start thinking some pretty decent headlight power. Not an expert by any shape of the imagination, but I'm betting that could be done with just a few upgraded components, that might increase the controller cost by a 5 cents or less....

Yes, a pet peeve......

AHicks said:

If you don't need a lot of headlight power, it's pretty convenient to be able to turn the headlight and tail light on and off with the "up" button. The ability to do that without all of the associated switches and wiring required by an external switch is a bonus. It makes for a pretty clean setup.

Click to expand...

It would be convenient if it was able to switch at least 10 watts of power, and be able to step it down to a programmed voltage, or even current. That would have added less than $1 in parts to the controller. But it doesn't sound like that is happening.

Does that light output just provide voltage straight from the battery whatever that is?

Comrade said:

AHicks said:

If you don't need a lot of headlight power, it's pretty convenient to be able to turn the headlight and tail light on and off with the "up" button. The ability to do that without all of the associated switches and wiring required by an external switch is a bonus. It makes for a pretty clean setup.

Click to expand...

It would be convenient if it was able to switch at least 10 watts of power, and be able to step it down to a programmed voltage, or even current. That would have added less than $1 in parts to the controller. But it doesn't sound like that is happening.

Does that light output just provide voltage straight from the battery whatever that is?

Click to expand...

Yes and no. Yes it's powered by the battery, but no, the power to the headlight doesn't come right from the battery. It must pass through this tiny circuit on the pc board that's using components that are WAY too light duty... Those are the ones with no protection that smoke regularly.

The ONLY way to make that circuit friendlier is to use the power now going to the headlight and use that to switch a relay - controlling a MUCH heavier circuit able to power anything you like - depending on the size of the relay.

If you opened the controller up you'll see the 2-wire headlight circuit is soldered directly to the pads the battery 48v comes in on. So it's basically hardwired to the battery. Battery on, light on. The controller isn't logically in the circuit.

If you opened the controller up you'll see the 2-wire headlight circuit is soldered directly to the pads the battery 48v comes in on. So it's basically hardwired to the battery. Battery on, light on. The controller isn't logically in the circuit.

I know this because at the weekend I opened up my recently bought Chamride KT Controller to replace the cabling mess with a LG1019 motor cable and 4in1 loom. The cruise and light circuit wires are now gone.

AHicks said:

If you don't need a lot of headlight power, it's pretty convenient to be able to turn the headlight and tail light on and off with the "up" button. The ability to do that without all of the associated switches and wiring required by an external switch is a bonus. It makes for a pretty clean setup.

There's just no good reason it's not fused or protected somehow.

AND

There no good reason for the circuit to be so light duty. They could increase that by a factor of 10 or 20 and still not cause an issue with the available battery storage. At that point you could start thinking some pretty decent headlight power. Not an expert by any shape of the imagination, but I'm betting that could be done with just a few upgraded components, that might increase the controller cost by a 5 cents or less....

Yes, a pet peeve......

Click to expand...

Yes exactly, it makes for a clean setup, and you say it's serial data from the display which makes sense. So no chance of finding something there to tap into.
I couldn't agree more about a 5 cent change making a world of difference, and they should add a brake light connection while they're at it. I can't imagine what went on in that product development meeting: We're gonna put a connection on this controller to run a light, and we're gonna leave out the ability to turn it off and on even though most other ones we make have that, AND it's not going to be able to power any usefully bright light without going up in smoke.
Reminds me of a wireless phone charger I bought online. It has a very bright LED that blinks while it's charging. Who the hell wants that in their bedroom? It's like living in that 'Kenny Rogers Roasters' episode of Seinfeld. I took an ice pick to the LED since I couldn't get the charger apart without destroying it. Problem solved.

mongrol said:

If you opened the controller up you'll see the 2-wire headlight circuit is soldered directly to the pads the battery 48v comes in on. So it's basically hardwired to the battery. Battery on, light on. The controller isn't logically in the circuit.

I know this because at the weekend I opened up my recently bought Chamride KT Controller to replace the cabling mess with a LG1019 motor cable and 4in1 loom. The cruise and light circuit wires are now gone.

Click to expand...

That's interesting. I hadn't considered it would be hard wired to battery voltage since these light circuits are so notorious for going up in smoke, and every other KT controller that I've seen with a light circuit can be turned on and off. If they would just call that connection 'battery voltage' instead of 'light' the purpose would be more obvious. But it's not fused so not all that helpful.

mongrol said:

If you opened the controller up you'll see the 2-wire headlight circuit is soldered directly to the pads the battery 48v comes in on. So it's basically hardwired to the battery. Battery on, light on. The controller isn't logically in the circuit.

I know this because at the weekend I opened up my recently bought Chamride KT Controller to replace the cabling mess with a LG1019 motor cable and 4in1 loom. The cruise and light circuit wires are now gone.

Click to expand...

Struggling here a bit. Could you clarify please?

We're talking about a switched circuit using the "up" switch to turn the light on/off, right?

How are you controlling the power to the circuit you are describing?

AHicks said:

Struggling here a bit. Could you clarify please?

We're talking about a switched circuit using the "up" switch to turn the light on/off, right?
How are you controlling the power to the circuit you are describing?

Click to expand...

I think he is not. Some of my KT controllers have the light circuit on a little 1cm x 1.5 cm circuit board that stands on either 2 or 3 legs. I read there is a resistor on it that burns out. I don't use the lights either.

I also remove all the unused connectors on the KT controller. Cut the wires, pull them inside amd tape them off. So there is
-2 wires for speed limiter
-2 wires for cruise control
-3 wires for the lights
-1 extra wire for 3 wire brakes



-

docw009 said:

AHicks said:

Struggling here a bit. Could you clarify please?

We're talking about a switched circuit using the "up" switch to turn the light on/off, right?
How are you controlling the power to the circuit you are describing?

Click to expand...

I think he is not. Some of my KT controllers have the light circuit on a little 1cm x 1.5 cm circuit board that stands on either 2 or 3 legs. I read there is a resistor on it that burns out. I don't use the lights either.

I also remove all the unused connectors on the KT controller. Cut the wires, pull them inside amd tape them off. So there is
-2 wires for speed limiter
-2 wires for cruise control
-3 wires for the lights
-1 extra wire for 3 wire brakes
-

Click to expand...

On the blue, that's my thought as well, but I am all ears if he's figured out an option. Learned a long time ago to never tell somebody something can't be done. MUCH more entertaining standing aside to see what happens...

The beauty of the newer generation "waterproof" KT controllers is all of that rats nest of wiring just outside the controller is gone completely. KT conversions now WAY easier to install, and do a nice clean job of it while doing it. -Al

See pic. My light wires (orange/yellow) come straight off the incoming battery wires. No switch, no circuit board. Just raw 48V off the battery. I'm in two minds whether to keep it and make it nice as I'm replacing the whole rats nest with a 4in1 Julet loom, or be done with it as I don't like the protection (none basically).

AHicks said:

THEN, the output of that controller switched headlight wire is tiny, and worse, it's not fused in anyway. Point being that circuit is very easily smoked due to shorts and overload. Thankfully, it doesn't take out the entire controller when the light circuit is smoked.

Click to expand...

This is exactly what happened to me last weekend. I wasn't too worried about connecting 12v lights to the 48v on the headlight source of the controller. My 12v light went bad (no worry as they were cheap), but I didn't realize that the defect in the light would come back to damage the controller. There is a tiny circuit board, in the controller, that "handles" the headlight output. That little board got fried, but it saved my controller. I desoldered the damaged board and have lost that function. This is ok because, I learned a valuable lesson and am using a 12v source from a dc-dc converter with a switch to control my lights now.

mongrol said:

See pic. My light wires (orange/yellow) come straight off the incoming battery wires. No switch, no circuit board. Just raw 48V off the battery. I'm in two minds whether to keep it and make it nice as I'm replacing the whole rats nest with a 4in1 Julet loom, or be done with it as I don't like the protection (none basically).

View attachment 305273

Click to expand...

is this a KT controller if so I have the same wires yellow and orange so basically you just can't plug into the bike *i have got it correct any help, please so no plug and play.