LCD Display Replacement (which is it?)

[88hertz]

Hello everybody, I had approached the e-bike world about one year ago, but only now, I start to get into exciting technicalities (and issues).

Last year, I got a second-hand cargo e-bike for my girlfriend, and I successfully managed to replace a few battery cells and the BME to make the system working nicely.

Last week, some water entered in the display (I really cannot understand from where), and it stopped working. Now, after drying it, it switches on, but then it appears a probable error code 24 (at the very first, it was code 16) and quickly switches off.

I suppose that I need a replacement, but I have no idea which model it is.

In the attachments, you can find a couple of pictures.

The LCD is connected with five wires, and on from a few measurements and the labels on the board:

Black -> GND
Red -> +5V

Gray -> Batt V+ (?)
White -> ?
Yellow -> ?

I suppose that the Yellow and white are used for the data transfer.

Can somebody recognize the LCD model?

The cargo e-bike has a controller PAS with Hall sensor and hub motor. I still have to open the battery box to check which controller model is installed. There are no "googlable" labels of indications on the LCD.

Thank you very much.

Simone

 

[E-HP]

If the display came with the bike, do you have any more info about the bike (model, etc) or a picture?

 

[d8veh]

Water went in up through where the wire goes in when you leave your bike out in the rain after using it. My theory is that the LCD becomes warm in use, which expands and expels some air. When you park the bike, the air contracts inside and sucks more in along with any water that's sitting on the cable entry point. The problem is that the battery wire is sitting right next to the comms wires. water shorts them and destroys the CPU. You end up with a dumb LCD. It will switch on, but it can't communicate with the controller.

As a general rule, you can restore some function to a controller by disconnecting the LCD and shorting the two power wires and the two comms wires. Normal colours are:
1. red - battery voltage
2. black - ground (0v)
3. blue - switched battery to power the controller
4. ANO - Tx
5. ANO - Rx
optional 6. ANO - light switch. Occasionally, they give a separate ground with the switched light wire.

Your LCD has unconventional colours. It probably says on the back of the PCB which is which. I can guess that the yellow is the switched power to the controller and the two whites are Tx and Rx, so you jump the red to the yellow plus the whites to each other, but you must confirm the markings on the back of the PCB to see which is which.

With the wires jumped, the throttle should work and you get level 1 on the PAS, but it's not guaranteed.

Rather than buy a replacement LCD, it would probably be better to get a new controller and LCD as a pair. I recommend Kunteng (KT), which you can get from PSWpower.com or Topbikekit.com. That will make your bike much nicer to ride.

 

[88hertz]

Thanks a lot for your answers.

Unfortunately, yesterday I couldn't investigate more. The cargo bike is quite old, I think It could have between 5 and 10 years... No brand on it and it seems a very common model used here in the Netherlands.

It may be a Cangoo. I found on their site a display with the same interface:

http://cangoo.nl/shop/display-lcd-panel-cangoo-2016/

but, the user manual says KT-LCD3 and it seems completely different :?

Tonight, I am going to take more pics and give a try to the d8veh method.

 

[E-HP]

Any chance you can post a picture of the controller label and the connector on the controller end? Based on the product page, it looks like they offer your display or the LCD3 as options, which could indicate it's a KT controller. Looking at Kunteng's website, they don't show your display among the dozen or so listed, so it may be something custom for that bike; but other KT displays may work.

 

[obcd]

At first glance, you would expect black to be gnd and red to be the display supply.
You could measure continuity between black and the gnd of the capacitors on the pcb to confirm that theory.
(Most bigger capacitors are connected to gnd on their minus side)
If the first assumption is correct, it means that the controller is feeding 5V to the display as supply.
The KT-LCD3, Bafang 850C and SW102 (just to name a few) all expect the battery voltage as supply and generate their own 5V or 3V3.
(Depending upon what supply the cpu needs.)
Those displays switch trough that battery voltage to the controller to turn it on. They usually are also able to measure that battery voltage to inform you of it's charge state.
So it looks like your controller / display is something custom (non standard) and it would really suprise me if it is compatible with anything else on the market.
As an example, you can look at early sparta bikes with hub motor. They also have a custom display with it's own protocol.
The same goes for gazelle innergy systems. Those even power the system with 12V.

So your best bet is to find the same display. They could have used anything as communication protocol between the controller and the display.

Even the communication interface is a guess. Some controllers use serial on TTL (5V) level, but others use the canbus protocol or
even the one wire linbus protocol.

Q3 seems to turn the lcd backlight on. So Q2 probably turns the display on.

You can try to power the display with 5V (red and black) and see what it does when you turn it on. If the communication is serial and TTL, the display TXD should show 5V and the RXD should be floating as the motor controller will drive it.

There could be a wire to turn the controller on, but the system could also use communication to do that.
So how would you know which wire is 5V to turn controller on and which one is TXD for the communication if they are both at 5V?
And never ever rely on wire colors. SEGA for instance finds white a much better color for gnd wires instead of black. (not that I am aware of any sega e-bikes)
If a wire simply is connected to a resistor and the other end of that resistor to a pin of the smd chip, it's pretty hard to guess what it's doing, unless you can figure out what the chip is and you are able to find it's datasheet.

That kangoo display indeed looks the same. You might be able to look at the possible segments of the lcd to see if yours was able to show the same information. It looks like they changed their system at 2016 and the newer models use a KT LCD3 alike display.

So, the picture is showing the correct display, but if you click on the "handleiding" it's showing the manual of the KT LCD3 display. It's probably a mistake on their website, or they don't have the older displays anymore. It's likely best to contact them and ask about it before you buy the wrong display.

 

[88hertz]

Thanks again for the useful hints :thumb:
Indeed, I have some updates. After cleaning the LCD board with some isopropyl alcohol, it now switches on again. The display now partially works: it shows the speed, counts the kilometers (reset to 0), and allows to start the controller (and the engine) at three different assisted speeds.

Currently, only the power on/off and the up buttons work. In fact, to change the speed, now it's required to keep pressing the Up button. The Down button seems now useless (but electrically the switch works), and the mode button recalls the screen "Error 24" (see picture) with the blinking engine issue icon.

I can think only to two possibilities:

• 
  The LCD ended up in a reset mode, and it is required to reconfigure it (no idea how to);

• There are still some continuities between some electric tracks which corrupt the data messages to the controller. This point could explain why the Up button is now recognized as speed change (it decreases the setting every time is pressed for ~5 s).

I also performed some additional measures, and I can confirm:

-Black = GND
-Yellow = + Batt
-Red = +5 V, after switching on the display
-White = Data RX/TX (?)
-Gray = Data TX/TX (?)

I can recognize a periodic sync pattern in both the data lines (it seems TTL 5V), as in the picture attached.

In any case, I think it is required to change LCD/controller. My question now is: shall I look for a specific controller for my hub motor, or are all the motors standard and compatibles?

Thanks a lot.

 

[obcd]

So basically your lcd is powered by the battery voltage but only sending 5V to the controller to turn it on?

Not all hub motors are equal. Some have hall sensors to determine the rotor position and others don't.
The number of windings can differ as well.
There is an open source software project for kuteng controllers.
It uses a java program on pc for all it's settings and generates a config.h file so that these parameters make it in the final firmware.
That's probably the most flexible (cheap) approach to match a controller to a motor.
Some controllers are able to figure out the wiring of the hall sensors on their own.
On others, you need to figure out the correct wiring yourself and connect them correctly.
Some controllers drive the motor windings with a pwm signal so that it resembles a sine wave.
This makes the motor run more silent and with a higher efficiency.
Another thing to consider is the maximum current you can use to drive your motor.
On a 36V battery, 7 Amps equals 250W which is what legally is allowed in Europe.
Most motors can go higher in current, but they can overheat if they are pushed 2 much.

 

[E-HP]

-Black = GND
-Yellow = + Batt
-Red = +5 V, after switching on the display
-White = Data RX/TX (?)
-Gray = Data TX/TX (?)

I can recognize a periodic sync pattern in both the data lines (it seems TTL 5V), as in the picture attached.

In any case, I think it is required to change LCD/controller. My question now is: shall I look for a specific controller for my hub motor, or are all the motors standard and compatibles?

Thanks a lot.

IGNORE, see below - The pinout is the same as any other KT controller interface, so you probably could buy a KT-LCD3 and have it work, since it does look like an option on the bike's website. As I mentioned above, more info, or a picture of the existing controller would be helpful, but I'm guessing it's a KT.

https://www.amazon.com/Intelligent-Electric-Bicycle-Display-Bike/dp/B07KQSLY8R?th=1&psc=1

 

[obcd]

Doesn't the KT-LCD3 has +Vbat on the red wire when the display is turned on?

If the motor only expects 5V there....?

The way I interpreted the website was that they changed their system in 2016 and that the newer system uses the KT-LCD3

The manual link points to the newer KT-LCDdisplay.

It could be a problem with that display that it only has 5V on the red wire.

Maybe opening the controller ans showing pictures of it and it's connectors could clear up things.

 

[E-HP]

Doesn't the KT-LCD3 has +Vbat on the red wire when the display is turned on?

If the motor only expects 5V there....?

The way I interpreted the website was that they changed their system in 2016 and that the newer system uses the KT-LCD3

The manual link points to the newer KT-LCDdisplay.

It could be a problem with that display that it only has 5V on the red wire.

Maybe opening the controller ans showing pictures of it and it's connectors could clear up things.

you're right! looked at the wrong diagram.

 

[d8veh]

You're controller is probably an old crappy one. The modern KT ones are a lot better. They make your bike like a new one. If it were my bike, I'd replace both the controller and LCD with a a KT sine wave controller and LCD3. You can get get then from PSWPOwer.com and Topbikekit.com. delivery is quite quick and the controller is relatively cheap because there's no extra shipping cost if you're already buying the LCD. It's only about $20 extra.
http://www.pswpower.com/ven.php?cargo-s220052