Controller issue?

camyam73

1 µW
Joined
Sep 20, 2024
Messages
3
Location
Canada
I received a Chinese built e cargo bike in December.

Specs :

S810 four wire display
Bm1418-qhc 500w rear differential motor. 48V 13.5a On a 34" axel. 3100rpm. Load capacity 350 kg.
48v 26 a controller - brakes high model KLT006A-LD-712 - assuming it's a custom controller for kolawo / kalova bikes in china
Controller has the following connections :
Motor hall line. (4wire connector)
Motor (3 wires)
Pedal assist
Brake sensor
Throttle
Display (4 lines)
48 to 12v transformer - 3 wires - I'm guessing this is for the lights and the horn? The turn signal flasher is listed also at 12v dc.

Powered by four 12v 20ah SLA batteries in series to make it 48V 20ah.

The handlebar contains the s810 as stated, and a mini control with a slider for turn signals, as well as a horn. These are on the same power loop as the brake sensor from what I can tell (using continuity testing)

In May my bike died. I assumed I had killed the batteries by not charging it and running it dry. Took a week of trickle charging, but it eventuallly started working, though often sporadically.

I waited on new batteries from china for months (warranty replacements) In the end, they sent me money to buy my own.

Had an electrician do a wiring harness for a 48v lithium deep cycle battery. Plugged it in, and it immediately sparked. Turns out my battery harness in the bike was not ok. I believe the original batteries had sparked, and melted some of the c14 connector inside the female side, which I don't know because the connection was under the bike. The extra metal caused a spark on the new battery and essentially bricked it. Fun stuff.

I used a smart battery unit and did some repair cycles on each of the original 12v batteries. They def worked much better. But I was still seeing the bike die randomly after being turned off and refusing to start again until the batteries charged for several days.

Pulled the bike apart again (you have to dismantle the cargo bed to get at anything which is no easy task). Started testing. I'm seeing continuity from every negative line coming out of the controller to the battery negative connection (with battery not connected of course), except for the display. On the display line, I am getting an intermittent short /low ohms showing on the positive line to the negative battery line. With battery connected, I'm showing 48v across the display positive and negative connector.

The s810 display will flicker and not start. Though a few times after the bike has sat, it'll light up and run for a bit, then once turned off, will return to not starting and the display only flickering.

This is not isolated to just the 810 display. I'd hoped to attach a better display, but the communications are not compatible, but those few times I was able to get power going, the new lcd display did indeed power up, but was unable to communicate.

So. Here's my question - I'm assuming this is a blown controller? Possibly it began with bad batteries, and then a couple of sparks fried the controller? When I can get it to power up, the motor is still working, brake sensors still functioning (after some tweaking and testing), pedal assist is very aggressive, but does turn on the motor when you pedal. Currently the brake lights are not attached as they are a part of the cargo bed.

I cannot use an ebike tester in the controller as I have no way to manually switch on power.

1- I'd love some advice on whether this could be a wiring gremlin (though I have looked at most of the connectors and they seem ok?) or if this is almost def a controller issue?

2 - for anyone who has had an s810 with four wires, were you able to switch to an lcd display that allowed you more control?

3- if I sought to switch out the motor for a 750w version, would the existing housing work or do they usually come with housing? I use this cart to take kids back and forth to school, and want to be sure I'm not getting too close to the failure weight of the motor.

4 - And finally - is there a controller that would work better for me that would allow me to connect a uart lcd display? I've looked at several controllers, but because I'm new to this, I'm a bit nervous to purchase. I could potentially rewire things. I'm handy, and understand electrical basics. Or at least enough to be dangerous anyways.

If you read this far - Thanks! And I'm indebted for your help and advice!

Link to some photos of my beast, along with wiring diagrams and info the seller sent me.


Edited to add

- it's not a display issue as when it turns on, it'll turn on another display (though with an error), and when it won't turn on the other display won't turn on either.

-It's not a battery issue as the batteries are currently sitting at 53V.

I can turn it on and it'll run. But if I turn it of and on a few more times, it stops working for a while. And then randomly will work again.

I'm assuming this kind of haphazard functioning can only be a controller issue?
 
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Ebike controllers and the display units are generally paired, in that the f/w running on each needs to be compatible, and the only sure way to ensure that is buying the 2 aspects together from the same supplier. Many bike assemblers put their own f/w versions in controllers too further complicating repair/replacement.

KT brand controllers are popular aftermarket upgrades as they are very configurable and come with a selection of compatible lcd display options. and are in the basic cheap silver vbox format among others ( in tube and in battery base)

Be mindful of loads when connecting lights to a controller while some do support lights the switching transistor will be limited to a certain load which is not usually very high, high load lights can kill a controller.. check the lighting max switching load for anyy controller you buy and double check the load your lights inc brake light actually draw too. (edit - so a popular solution is to employ the controller light circuit to switch a relay with an independent battery supply to power any lighting you may want. )

RE bigger motor .. Why? just push more amps (or and volts) into the motor with your controller selection if you need more speed/power.. (Volts X Amps = Watts)

If you have hundereds of dollars in the budget there are lots of sophisticated controllers, but a 20-30Amp KT silverbox controller and display should be available for $120 ish but expect to pay more from a local supplier and next day delivery etc..
 
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Link to some photos of my beast, along with wiring diagrams and info the seller sent me.
Not sure if I'm missing something, but it sounds like all you need is a decent set of batteries and possibly to replace the display. The new battery appears to be a lifePO4, since you mentioned deep cycle. If so, you may have just tripped the BMS when you shorted the output conductors. "The extra metal caused a spark on the new battery and essentially bricked it." Perhaps the BMS is fried, but more likely it tripped and needs to reset.
I don't see anything from what you wrote that indicates a bad controller, especially since it works when the battery is charged. I doubt that the display is bad either.
 
Not sure if I'm missing something, but it sounds like all you need is a decent set of batteries and possibly to replace the display. The new battery appears to be a lifePO4, since you mentioned deep cycle. If so, you may have just tripped the BMS when you shorted the output conductors. "The extra metal caused a spark on the new battery and essentially bricked it." Perhaps the BMS is fried, but more likely it tripped and needs to reset.
I don't see anything from what you wrote that indicates a bad controller, especially since it works when the battery is charged. I doubt that the display is bad either.
It's not working with the battery charged though. It's intermittent and sometimes works and sometimes doesn't. I assumed it was a battery issue but it doesn't appear so. The display is not the issue as when the bike does turn on, a different display will fire up. But when the original display is having issues, the different display will also NOT fire up. Hence it's not a display issue either. Currently batteries are reading 53 V total which should be enough.
 
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