LCD Display gone dead (or at least I think the fault is at the display)

[savas]

Hello

Helping repair a Batribike Dash Folding Electric Bike for someone. It was left outside for a long period and stopped working, presume got water damage.

Battery was replaced, however still no luck. Using the new battery, the display seemed to go on and then go grey across the screen (that's what I was told). The battery BMS was cleaned and looked to work, but still even with a new or old battery, still no luck.

Using a multimeter I checked and the lcd/display box was getting 40v, so we are guessing the controller is OK, but the LCD is fried/the fault?

The issue we are having is we cannot find a replacement display, even an alternative one, it's 8 pin. Any suggestions or alternative methods, such as just using a different display, but if this is possible and which ones?

 

[saneagle]

The bike should work without the LCD if you hotwire it. The LCD works as a switch to join a wire from the battery to a wire that powers the controller. they're normally red and blue. you can check by opening the controller to see one wire coming from a track connected directly to the where the thick red battery wire is soldered, and the other will be joined to a track that goes directly to the big resistor, sometimes marked vcc. If you join those two wires, the controller will switch on and work at level one pedal assist and the throttle.

It would be cheaper to get a new controller and matching LCD than just a replacement LCD. It's a Bigstone C300 LCD, and costs about £100 from Aliexpress. You can get a much better KT controller and LCD for about £70, or £80 if you want a new matching throttle and pedal sensor too.

If money is tight you can use a Brainpower controller and LCD that cost about £31 that works about the same as the original. If it's your own bike and you want to keep it, it's worth spending the extra money on the KT controller.

https://www.amazon.co.uk/Brushless-Controller-24V-48V-Waterproof-Electric/dp/B08B3WGH6Q/ref=asc_df_B08B3WGH6Q/?tag=googshopuk-21&linkCode=df0&hvadid=606643286790&hvpos=&hvnetw=g&hvrand=16388686652516510252&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007151&hvtargid=pla-1404380368059&psc=1&mcid=dbb10af323b535778ae796c34bc08ecd

If you get a replacement controller, you'll have to do a bit of wiring. Nobody uses the moulded connector with the D-shaped hole anymore.

 

[savas]

Thanks.

I thought of hotwiring it to confirm if it works, but if the display is getting the 40v, but not working does it mean the controller is most likely OK, right? I guess I don't need to potentially mess it up by going in the controller.. Is that test worth it before proceeding with further replacements?

Yeah, money is a factor. Is there a simple alternative where by buying just an aftermarket lcd/display that would fit this controller?

I'm a newb when it comes to ebikes. What's the difference between controllers on in this case the KT controller versus the budget one? Why is it much better, if you could explain so that I can provide that they can make a decision.

 

[saneagle]

Thanks.

I thought of hotwiring it to confirm if it works, but if the display is getting the 40v, but not working does it mean the controller is most likely OK, right? I guess I don't need to potentially mess it up by going in the controller.. Is that test worth it before proceeding with further replacements?

Yeah, money is a factor. Is there a simple alternative where by buying just an aftermarket lcd/display that would fit this controller?

I'm a newb when it comes to ebikes. What's the difference between controllers on in this case the KT controller versus the budget one? Why is it much better, if you could explain so that I can provide that they can make a decision.

The difference between the KT controller and the others is that the 5 levels give 5 different power levels, which means that you can set the assistance, then pedal as hard or as easy as you want. if you want to go a bit faster, just turn up the power. Also, you can use a throttle legally to over-ride the pedal assist and give max power whenever you want it. Other controllers use speed control for the 5 levels, which give a different max speed in each level. the problem with that is that you get max power as soon as you start to pedal, which is not very pleasant. It's difficult to get the power you want at any time because the power is always changing, depending on your speed.

the 40v to the LCD comes straigh from the battery. The LCD works completely independently. As long as it has a ground and battery wire (red and black), it should work. You should be able to see battery voltage and change the power levels. It communicates with the controller to tell it what it should do, and the controller sends info to the LCD, like speed and other info that shows on the LCD.

The battery should be 42.0v when fully charged. If it only reaches 41v, it's a bit dodgy. If only 40v, something is probably wrong with it, though it should work for testing.

 

[Nealh]

KT are the better control systems imho, we see various issues with crapwave and lishui display controller compatibility and unless one can buy them as a combo pair they seem to not work correctly or at all.
We also see various KT issues but mainly due to users not knowing how to make the correct adjustments in the settings menu, most issues simply boil down to the PAS and often using non KT type PAS that don't always play ball or the KT double Hall 12pole version that can often not play ball.

OEM bikes use Lishui a lot like the Woosh brand , cheap china bikes use no name brands so repairs are best done by replacing complete systems.
KT are unusual on OEM bikes but some do use them, for the diy market KT is #1 go to system.

 

[savas]

Thanks for the breakdown, appreciated.

the 40v to the LCD comes straigh from the battery. The LCD works completely independently. As long as it has a ground and battery wire (red and black), it should work. You should be able to see battery voltage and change the power levels. It communicates with the controller to tell it what it should do, and the controller sends info to the LCD, like speed and other info that shows on the LCD.

The battery should be 42.0v when fully charged. If it only reaches 41v, it's a bit dodgy. If only 40v, something is probably wrong with it, though it should work for testing.

Hmm, don't have the bike with me so maybe it was something like that, need to go back and double check the new battery voltage, but it's a 36v battery so I thought it was more than fine. The old battery is indicating 36v though (on the bottom) so I guess it's definitely faulty.

Here's the PCB of the display. I know that sometimes the colours are used differently on some models, so just to confirm, the red and black on this board is power and ground? I want to inject it with some power and see if I can find the troubled component to potentially replace if it's a simple cap or something.

 

[saneagle]

Thanks for the breakdown, appreciated.



Hmm, don't have the bike with me so maybe it was something like that, need to go back and double check the new battery voltage, but it's a 36v battery so I thought it was more than fine. The old battery is indicating 36v though (on the bottom) so I guess it's definitely faulty.

Here's the PCB of the display. I know that sometimes the colours are used differently on some models, so just to confirm, the red and black on this board is power and ground? I want to inject it with some power and see if I can find the troubled component to potentially replace if it's a simple cap or something.

I can't see any sign of damage, so it's probably OK.

The ground is easy to find because it's common with the battery ground. Likewise, the incoming power wire will have battery voltage on it. They're nearly always black and red.

The next important wire is the switched power wire. When you press the on button, a mosfet switches on and it connects (latches) the battery wire to one that goes back to the controller to power it, and it provides the power for the LCd pcb.

You can see the mosfet bottom right (black square thing. The middle leg and back are the output and the upper leg is input. The three capacitors are to do with the voltage reduction and power supply. One is across the battery voltage, one has somewhere between 12v and 25v and the other has 5v across it. I'm not sure if that's before or after switching on. The 5v powers the pcb and the middle voltage one powers the mosfet.

The problem might be that the problem is a short in your controller. You should test that first. Do a forum search for "mosfet test". It's very easy and quick to do. Another test would be to put a voltmeter on the battery wires while you switch on to see if the battery shuts down every time it tries to give current. Maybe do that first instead.

 

[savas]

Unfortunately I don't have the bike with me so I'll have to go back to do some of these tests. I knew I'd forgotten some things when I was looking at it.

Right now I've got the display pcb with me as I wanted to give it a clean with some alcohol as I suspected that the issue might be there, yeah it looks fine, but I think the actual screen is gone or potentially shorted. I completely forgot to test whereby seeing if turning it on via the button if it would just operate.

I wanted to ask, could you kindly link to a KT controller/display kit (I think that's all that's needed right?) if it's just a little extra for the whole set, maybe easier. So we know we got one that will work with this.

Seeing as I have the display pcb, could I just hotwire some cables to the +/- and see if I can see any life on the PCB? Using a variable PSU, injecting some voltage was my idea, but I'm not certain on which one is ground and positive. If I am not mistaken, K is the ground and B was the positive.