KT36-SVPR-LCD + lcd7 voltage problem

[john33]

Hello people,

After 2 years of almost no problems my dit e-bike is having issues.

My diy bike is fitted with a KT36-SVPR-LCD controller and LCD7 display.
The battery is a li ion bidon shaped 36v.

Last week i saw that the display was fading (dark in the morning, head/tail Light on) so i pressed the middle button 2 times to see the voltage..... It showed 48 volts and rising up to 58 volts.
The higher the voltage the more the display was fading until nothing showed, just the backlight.

The controller kept working, but suddenly al went black.... A power down and restart gave it a restart and i could go on but that happened 2 times again later.
I took the system apart, and measured a few things.
Voltage from a fresh charged battery is about 40 volts, at the battery terminals, but also at the connector to the display.
When i connect the display and power up the system the display fades a bit, I press the middle button 2 times to see the voltage,.....
52 volts and rising.... Up to 58.
And its fluctuating, 53,7 54,2 57,8 and down to 55 etc etc ..
What the h*ll is happening here, and how do i solve this?

 

[docw009]

The voltage at the display connector is connected direct from the positive power input on the controller. It's the battery in other words, Probably your LCD7 going nuts.

 

[E-HP]

Very odd. I would check your C29 setting in the parameters. The display supports multiple voltages and the low voltage cutoff for a 48V battery is 40v, so if somehow it thinks you have a 48v battery, it would shutdown the controller. Even if slightly above, any voltage sag could cause it to shutdown. Lowering the lvc may allow the bike to operate for a while (might be something to test), but you may be able to unplug the controller battery input for a while, then connect the fully charged battery input hope the controller/display re-guesses the voltage of your battery.

 

[john33]

Very odd. I would check your C29 setting in the parameters. The display supports multiple voltages and the low voltage cutoff for a 48V battery is 40v, so if somehow it thinks you have a 48v battery, it would shutdown the controller. Even if slightly above, any voltage sag could cause it to shutdown. Lowering the lvc may allow the bike to operate for a while (might be something to test), but you may be able to unplug the controller battery input for a while, then connect the fully charged battery input hope the controller/display re-guesses the voltage of your battery.

Thank you for this idea,
I will try the C29 setting up see what that does

 

[john33]

Thank you for this idea,
I will try the C29 setting up see what that does

I've looked into the display controller, but it only goes to C14.....
The main issue is that the battery is 36 volt, but the display indicates voltage values up to 58 volts.
It looks like the display is garbage....

 

[E-HP]

I've looked into the display controller, but it only goes to C14.....
The main issue is that the battery is 36 volt, but the display indicates voltage values up to 58 volts.
It looks like the display is garbage....

Oops! C12. Not sure why I typed C29.

https://www.emotoer.com/wp-content/uploads/2020/03/KT-LCD7.pdf

Edit: it was on page 29 lol

 

[john33]

Well, i seemed to have found the problem.
Somehow, the to be watertight LCD7 controller is not so watertight.
I have opened the casing, and when i lifted the pcb it was obvious.
2 smd components and a chip are corroded, greenish stuff, so thats copper corrosion.

I'll take it to work tomorrow and see if the electronic guys have something to clean it with.

 

[john33]

Well, that didn't work.....
My colleague from the electronics Departement was a bit curious about a smd capacitor.
He did not trust the looks of the component, also when he tried to resolder it the zolder would not flow.
He resoldered the pins of a chip next to it perfectly.....

It seems that the display has to go to the bin....

 

[john33]

Anyway to anwer an end to this topic,
My display wasn`t waterproof, the dutch wheater of last year (lots of rain) was to much for the silicon seal of the display casing.
This caused corrosion on several components on the pcb, and damaged a capacitor and a small chip.

I have replaced the LCD7 with a brand new one...... all problems disappered.

I am thinking of 3D printing some sort of rain cover for the display.

 

[ak136]

You can also put a plastic bag over it

 

[john33]

You can also put a plastic bag over it

Yeah, but what`s the fun in that....?

 

[ak136]

KISS