Controller Light Output - Uses?

Bikes4two

Esteemed Pedelecer
Feb 21, 2020
892
394
Havant
OK, @MSG76 -firstly, my 'bad' - I thought the PCB resistor was 510Ω not 51Ω !

So to be clear, is your 'lights going out on applying the brakes' issue down to the controller requiring 3-wire brake sensors, or a controller fault?

And not being clued up on brake sensors, why is it not workable to use your 2-wire brake levers - looking at the circuit diagram, I'm assuming that if you wire up the red and white to your 2-wire brake levers, that might work - (an assumption which needs confirming or clarifying by others as I'm a newbie at this game).
 
Last edited:

MSG76

Pedelecer
Jun 29, 2020
30
6
Hey @Bikes4two ,
yes it's down to controller requiring 3-wire brake sensor, but I thought exactly the same thing and that wiring both red and white could make it work. Although it may be a 2 way switch so when cutting off brake signal conducts 5v and vice versa. Having both wired together may just equal both power to light and brake motor signals on simultaneously.
Will have to investigate but less worried about it.
The main reason why I wanted a new controller was to have light control on both front and rear from battery/lcd to increase security. I've been riding without brake cut-off and actually don't feel a diference. Motor cuts off quite rapidly when coasting and I still haven't found myself both pedalling and braking at the same time :D
 
  • Like
Reactions: Bikes4two

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,986
Basildon
Hey @Bikes4two ,
yes it's down to controller requiring 3-wire brake sensor, but I thought exactly the same thing and that wiring both red and white could make it work. Although it may be a 2 way switch so when cutting off brake signal conducts 5v and vice versa. Having both wired together may just equal both power to light and brake motor signals on simultaneously.
Will have to investigate but less worried about it.
The main reason why I wanted a new controller was to have light control on both front and rear from battery/lcd to increase security. I've been riding without brake cut-off and actually don't feel a diference. Motor cuts off quite rapidly when coasting and I still haven't found myself both pedalling and braking at the same time :D
I'm not sure what you're saying, but if you have a three wire brake connector and you want to connect a 2-wire brake, it should be connected to the signal and ground wires, not the red 5v.

The brake signal wire is connected to the controller's CPU. It's held at 5v by a pull-up resistor, and the cpu will give power as long as it's high. When you operate the brake, the switch shorts it to ground, which pulls it down to 0v. When the cpu sees a low signal, it cuts the power. It's as simple as that - a binary signal on one of the cpu's digital inputs.
 
  • Like
Reactions: Bikes4two

MSG76

Pedelecer
Jun 29, 2020
30
6
I'm not sure what you're saying, but if you have a three wire brake connector and you want to connect a 2-wire brake, it should be connected to the signal and ground wires, not the red 5v.

The brake signal wire is connected to the controller's CPU. It's held at 5v by a pull-up resistor, and the cpu will give power as long as it's high. When you operate the brake, the switch shorts it to ground, which pulls it down to 0v. When the cpu sees a low signal, it cuts the power. It's as simple as that - a binary signal on one of the cpu's digital inputs.

Yep, it's currently only connected as ground to ground (black) and signal to signal (white). The red 5v was left off disconnected.
If I ever connect the red 5v to brake signal it won't cut off as 5v will always flow, right?
So with current 2 to 3 wiring brake works but when cutting off to 0v also cuts power to light circuit. This indicates a 2 way switch may be operating when shorting brake signal to ground by opening the 5v red connection back into the circuit thus feeding throttle and lights.
What I may do is search for a bypass in the controller at the point cables are soldered on the board. But will have to look into it
 
Last edited:

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,986
Basildon
Yep, it's currently only connected as ground to ground (black) and signal to signal (white). The red 5v was left off disconnected.
If I ever connect the red 5v to brake signal it won't cut off as 5v will always flow, right?
So with current 2 to 3 wiring brake works but when cutting off to 0v also cuts power to light circuit. This indicates a 2 way switch may be operating when shorting brake signal to ground by opening the 5v red connection back into the circuit thus feeding throttle and lights.
What I may do is search for a bypass in the controller at the point cables are soldered on the board. But will have to look into it
I don’t understand your logic. No current flows (you said voltage). Its just voltage sensing. It's very simple. The signal wire is connected directly to the cpu with a resistor between for protection. The cpu senses whether it's 5v or 0v. The switch only has 2 wires, which are ground and signal. There's a resistor between the signal and the 5v rail that holds it at 5v when the switch is off.

In all the recent controllers that I've studdied, the lighting is worked by data. Data comes down the Tx line from the LCD into the Rx on the cpu. The cpu interprets that request and switches one of its digital outputs from 0v to 5v. The 5v then switches a transistor that switches on the lights. When that output goes low, the transistor switches off and the lights go off.

I've not seen one with a separate pcb like yours has. Without being able to see where the wires go, I can't comment on it. All I can figure out from the limited info is that the transister at the bottom is switching the mosfet at the top, which is most likely powering your lights, in which case it should be able to supply all the power you need without modification, i.e. 1 amp at 36v.
 
Last edited:

RossG

Esteemed Pedelecer
Feb 12, 2019
1,628
1,646
Reading through this thread it seems as if you guys are trying to run your lights directly or indirectly through your controller which imo is a bad idea even given they may well have that function built-in.
If you have a problem or short circuit with you lights it could screw your controller, likewise a controller fault could render you lighting system useless. You'll be far better off running lights directly from the battery independent of any controller interaction.
In my own case I fitted a throttle which had one of those naff key switches not needed as I already have a separate power switch. I removed the key mechanism and replaced it with a push button switch that had the bonus of a LED inside so I could see if my lights were switched on accidently during the day. I used a thin multi-core cable doubling up the leads to handle any high current, the indicator LED works on it's own circuit direct from the battery via a dropper resistor and utilising one of the switching poles inside the switch itself.
The lighting circuit and the LED both have their own earth -v return hence the multi-core lead (don't use the negative on the throttle a mistake many make ) and it all runs completely independent of the bike control system. Works perfect.
 

MSG76

Pedelecer
Jun 29, 2020
30
6
The controller has a separate mini pcb circuit with a current regulator. It won't affect the main board. The current regulator issue was already superseded with a higher current high power capable solution
 

RossG

Esteemed Pedelecer
Feb 12, 2019
1,628
1,646
As that mini pcb board is internally connected to the controller circuits it could still cause a problem if a short were to develop. The only way to stop that happening would be by opto isolation which wouldn't be worth the trouble, besides the regulator should give short circuit protection anyway but can't be guaranteed to work.
A dedicated line from battery to lights as vfr has also pointed to is safer & more efficient all round.
 

MSG76

Pedelecer
Jun 29, 2020
30
6
A direct line to the battery is equally potentially dangerous depending on the bms and max discharge of battery. Let's say both battery max discharge and controller max current match. A cyclist, unaware, following your advice may add a power line to draw extra amperage from the battery and cause overheating or explosion of the battery cells. So in terms of potential danger we both can go as far as the imagination lets us.
In practice and looking at facts, the controller in question with a separate pcb circuit is not a liability. If for any reason get's damaged I know how to fix it, so again, it's not a liability.
 

RossG

Esteemed Pedelecer
Feb 12, 2019
1,628
1,646
I must confess I've already shorted my lighting circuit by accident and it damaged nothing, a simple fuse would of course sort out any overload problems but I haven't bothered going down that route myself.
There's no reason why having a lighting control on a separate board would be a liability but it's obvious (to me at least) that Kunteng added it as an afterthought otherwise it would be on the main board, room could be found I'm sure. Another advantage of having power from battery to light via a switch on the bars is I have full potential right to hand that I can use for any device in the cockpit as it were. One idea I had was to fit micro LED's inside my gear changers on the bars so I can see what gear I'm in when it's dark, I've seen that done before but I could do it much better with SMD LED's. Now there's a use for a lighting circuit !
 

RossG

Esteemed Pedelecer
Feb 12, 2019
1,628
1,646
When I finally get round to doing it I'll be using wire like this, it's very fine even more so in the flesh. On my bike which is a folder all the cables are covered or concealed so it doesn't matter what colour the wire is it can't be seen, I'm guessing you can get it in black and attach it to any existing cabling by wrapping or gluing. Current drawn is very low so a tiny resistor to bring the voltage down could be soldered to the LED.
Surface mount LED's are tricky to handle so I'd suggest using an LED from some of those bead lights you can get cheaply from pound stores and I would go for, red less in your face.
My bike already has a USB 5v power socket for charging a phone but that's another thing you could use a supply for.

 

jimriley

Esteemed Pedelecer
Jun 17, 2020
561
384
I've just fitted a feed from the battery output, replaced the female bullet connectors with twin ones, a 3amp micro blade fuse in rubber holder and used Wago connectors (available in 2, 3 and 5 wire, so can add accessories on the handlebars.) I've fitted a USB socket and a cheap and cheerful light/horn.
Running a bbs01b with HL battery.

I also took advantage of the British Cycling offer I came across here, join and get a free set of see.sense ace lights, I did and they are amazing. I'm not sure I'd have paid £70/£80 for them. I reckon I still need a battery-powered headlight of some sort though, for dark canal towpath etc. Hence fitting the power feed. I might splash out on one of the proper non-dazzling headlight though, anyone have any recommendations?