Kunteng Controller Light connector issue

Hi Guys,
(sorry for my english, I'm french )

I have a Vanmoof smart S bike that I transformed to an electric bike with this Kit:
https://fr.aliexpress.com/item/4000369945271.html?spm=a2g0s.9042311.0.0.3b9f6c37XNBCR1

Originally the bike has an integrate module with light and bluetooth power by a battery charge with a Dynamo (6v, 3watts).

I replaced the wheel dynamo by the Engine.
To charge the battery, I plugged the wire directly to the light output of the controller.

It has work for a while, when switching on the light from the controller, it charged the battery... But after a few time: problem!

When opening the controller I figured out why:


How can i replace it and/or fix it?

I saw this topic but no information on how to fix it... And I'm not expert in electic stuff
https://endless-sphere.com/forums/viewtopic.php?t=97279

thank you guys for your help!!!

Nicolas

nicolas.genestar said:

Hi Guys,
(sorry for my english, I'm french )

I have a Vanmoof smart S bike that I transformed to an electric bike with this Kit:
https://fr.aliexpress.com/item/4000369945271.html?spm=a2g0s.9042311.0.0.3b9f6c37XNBCR1

Originally the bike has an integrate module with light and bluetooth power by a battery charge with a Dynamo (6v, 3watts).

I replaced the wheel dynamo by the Engine.
To charge the battery, I plugged the wire directly to the light output of the controller.

It has work for a while, when switching on the light from the controller, it charged the battery... But after a few time: problem!

When opening the controller I figured out why:
Capture d’écran 2020-09-30 à 20.27.10.png

How can i replace it and/or fix it?

I saw this topic but no information on how to fix it... And I'm not expert in electic stuff
https://endless-sphere.com/forums/viewtopic.php?t=97279

thank you guys for your help!!!

Nicolas

Click to expand...

It's a known fact that those KT light module take only around 250-300ma before blowing up. The best solution is to get rid of it, and build your own relay. You need a dc buck convert and a mosfet for that. The buck converter will be plugged directly to the battery, and set to 6V output. The mosfet will serve as switch. I had moderate success when soldering the gate of the mosfet to the KT light signal, because it's only 5V. Best go directly with the return line (blue) of the display, and use a voltage divider to get it down to 12-20V and wire it the the gate. The lights will switch on every time you swtich on the display, and stay on until you swtich it off again. Always-on lights only increase marginally the overall power consumption, and add a significant security factor. There is talk in the EU to implement mandatory always-on lights on all ebikes.

Two diagramms taken from the german forum:



Note that depending on your setup neither of thoses examples will work for you.

Also: this is not a motor related issue. It should be moved to the ebike general or ebike technical subforum.

Thanks a lot for this prompt feedback! And sorry for the mistake of group to post... I can't find how to move it unfortunately.

It seems to be what I need to be able to replace this relay by a homemade plug directly on the display signal to charge the internal bike system without turning on the light on the controller.

But to be honest I'm a bit lost concerning what to buy in terms of buck converter and mofset and how to plug it.
Any change you can give me some links about where to buy it and how to solder it?
(I guess first I need to unsolder the existing burnt relay, but then... )

Many thanks again for your help on that! Much appreciated!!!!

I found this on aliexpress that seems to be compliant for 6v and 3w (500ma) but apparently it's for 24v input maximum...
Otherwise would it be an option?
https://fr.aliexpress.com/item/33015256539.html?spm=a2g0o.productlist.0.0.28cddffcBV9Qqn&algo_pvid=921d9106-ea6e-4ca3-8015-32222e6671cf&algo_expid=921d9106-ea6e-4ca3-8015-32222e6671cf-5&btsid=0b0a187916021645975864061ec8a5&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_


Any idea on where to find a 36v one with an enable wire port?

Thanks again for your help

Up
Any idea ?
thanks again!!

nicolas.genestar said:

Up
Any idea ?
thanks again!!

Click to expand...

Don't know the voltage of your battery, so just get one of those xl7015 step down converter.

Thanks Qwerkus!

My battery is a 36v.
With one of those then if I want to use the controller signal as a switch I just need to add a mofset before the 36v + input right?