I edited this thread, since i've found a workaround for my problem, so if someone will experience something similar, here is my solution.
I must thank people from this forum who helped me find out the which was the problem; i also found a lot of help(not here) and information from another member of the forum, who provides the schematics of the ku63 controller (photos and schematics on his web page: http://www.avdweb.nl/solar-bike/electro ... oller.html
I have failure of the 5v power line, which cause the hall sensor and throttle working bad/stop working intermittently; the cause is the 12 to 5v converter 78l05, which overheat and don't work properly (you can find this component near the processor, on the ku63 board).
Possible solution are:
1- Arrange some kind of heat sink on the plastic part of the 78l05.
2- Replace it whit a 7805 converter, or another 78l05 version which does have a the heat sink connection.
3- Use an external 12 to 5v regulator to power the throttle, pas and hall sensors.
I've chosen the 3rd, because i already have a lot of cigarette lighter-to usb andapter, and it was easier to solder 2 wire on the back of the board (on ground and 14v supply), instead of unsolder the 78l05 from board and replace it.
So now i have connected just the signal wires of pas, throttle and hall sensor, while the power wires (black and red) are all connected to my external power adapter.
I tested it on road and it works just fine.
In this way the power consumption of my controller is increased a bit (because i now have two 5v power source, even if one almost unused), but it should not be a problem since the 36 to 12v converter (lm317t) inside the ku63 controller is on the long side of the board where there is the heat sink bar.
Here is my old post:
Hi guys, first of all, this is a great forum, i've found a lot of usefull info i used to build my e bike.
Then let me (try to) explain my problem, hopeing someone can give me some clue: i have a foldable bike (hoptown) i elecrified with a 250w 36v bafang QSWXH rear and a ku63 controller from bmsbattery; some week ago my bike stat to work just for few minutes (or seconds) and then no more until i disconnect from the battery and reconnect, then it work again just for a short time.
Since it seem to be a hall sensor problem (very common on bafang from what i read here) and since my controller can work without sensor i disconnected all the sensors wire, and after this my bike works for a bit longer. Anyway it do not work very well, cause the power is intermittent and often fail (i suspect because the engine's phase are powered with the wrong timing).
So i tested the sensor as described in this forum (led circuit) and found out something strange: hall sensor seems to work (do turn on and off rotating the wheel backward or using the engine) but when they are in their ON position(angle), they start blinking instead of remaining just turned on, as if the 5v power supply from the controller (red and black wire) cant provide enough current to keep the led on.
So i tried the same test, but this time i provide 5v power from an external lipo battery, and this time everything worked perfecly(no blinkin led, they stay turned on and off properly). Then i connected the yellow, green and blue wire to the controller (as usual) but i didn't connect the red and black, which instead i connected to my 5v lipo battery, and now everything works perfectly.
I think that my controller somehow fails to provide the 5v power source, even if my throttle and pas sensor work fine (they both depend on 5v power supply, but maybe they require fewer power than the hall sensor).
So here are my questions:
Any suggestion on how to solve this problem without using an indipendent power source(5v battery)?
I found out (with a multimeter) that on the controller side of the yellow, blue and green there is 5v voltage, is it normal?
Can this configuration cause damage to the external battery i'm using? Should i connect at least the black wire (on sensor side) to both the external battery and the controller black wire, maybe using a diode on the former to prevent reverse current flow?
Sorry for this long ad a bit confusing post... i hope someone can help with this.
Thanks in advance...