KT-LCD3 shows zero battery charge while voltage is 54.5

hardW · Jun 14, 2018

Hi
I've got a following issue with my ebike: KT-LCD3 shows zero battery charge while voltage is 54.5 (according to it) and motor does not spin (both with throttle and assist). Controller is KT48ZWSRD-BSK11L, bettery Sinlion 48V 15.6Ah fully charged, motor is Bafang BF RMG06 48V500W(10). All the wiring seems to be intact. What can it be? Run out of ideas(

wturber · Jun 14, 2018

Sorry to ask the likely obvious question, but have you unplugged the battery, waited a bit, and the re-plugged it in?

hardW · Jun 14, 2018

Sure. It was first thing I've tried.
Also I want to mention that:
1) This bike was working fine for ~300Km
2) Last ride I've drained battery so that motor was not responding to both throttle and assist. But voltage was ok for display (and probably controller) to work. I've rode few miles on pedals. Then after ~10h I've plugged it in to charge.

amberwolf · Jun 14, 2018

Controller could have a problem sensing the voltage and/or sending the data to the LCD.

I have a Fusin controller / LCD (made by LiShui) set, where one controller works normally, and the other (using hte same LCD) doesn't send voltage or speed data to the LCD. The LCD does control the PAS modes/etc of the controller, either way, so I suspect something with the controller's transmit-data line, but never got to testing that (since the other controller works normally).

hardW · Jun 15, 2018

Finally I've managed to shake controller and heard something loose inside it. It was resistor :shock:

Where was it soldered I can't yet figure out. I guess I'll need photos or schematics of this controller

eee291 · Jun 15, 2018

hardW · Jun 15, 2018

Yeah those look most loose to me too. But they marked for different resistors - R63 and R64. Need to be sure.

eee291 · Jun 15, 2018

I just opened my Controller

I guess my controller is a newer version.

But when I look at your R63 solder pad it was definitely in there.

hardW · Jun 15, 2018

Thanks. Our controllers have one in common: instead of two resistors (according to drawings), they have one. Guess this can be an issue, since two small resistors can have better cooling that one big. So I'm thinking about replacing it with two small. Unfortunatelly I don't see any other way not to make it happen again (unsoldering because of overheating).

eee291 · Jun 15, 2018

I don't think it overheated. If you look at mine, the resistor looks really badly soldered. I might apply more later.

docw009 · Jun 15, 2018

Looks like you figured it out already, but here's my old PSWpower 20A controller.

Brown-black-black. What is that ..10 ohms?

yanlipavsky · Oct 1, 2020

I have same controller and you should put back your resistor here.[Look attached picture]

By the way - did you manage to find a replacement for this controller ? Did you restore your bike ? I have SAME ISSUE - Battery dropped to zero while riding and it is fully charged. Any clue ?
Model : KT48ZWSRD-JYFF04

hardW · Oct 1, 2020

I've just soldered that resistor in place. And it never failed again. Though I did not put bike in same demanding conditions again since that time: when it unsoldered I've rode very hilly landscape.

yanlipavsky · Oct 2, 2020

*update*
I found 1 faulty capacitor (470mf the big one - one out of two was bad).
replaced it and everything began working good ... but only for 5 mins - then the battery "died" again on the LCD and no torque allowed - the voltage was 51V on the battey ....

Then i took a magnifying glass and began examining the main chip - i found very slight corrosion between 2-3 legs - cleaned it with a alcohol - all the controller began working like a charm !
:bigthumb:

KT-LCD3 shows zero battery charge while voltage is 54.5

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