KT controller short circuit fault on a solar trike

[romelec]

Hi,
I've finished a solar trike with 240W panel, 48V 11Ah battery, MXUS direct drive motor and 9 fet KT controller.

I was supposed to go on a trip from today but I have an issue on the controller, it occasionally shuts down with the error "Motor or controller short circuit fault". From what I've seen it's a generic issue that happens when the controller senses some current flowing when there should not.

It happens only if there is direct sunlight, there is no issue when the panels are disconnected or if it is cloudy/shady and the cells generate less power.

Since it is fine when the panels are disconnected I exclude a bad contact, overheating or too much power because I used only max 350W. I use the same battery on 2 other bikes without any issue.

I have no idea where it could come from, for now I only suspect the BMS to cut from time to time because it doesn't like to be charged and discharged at the same time.
It is the quite old smartbms from bmsbattery, I will put a PC and log the data while riding.

If someone have any idea...

 

[Hayds13]

Probably a different issue but...I've found my KT controller sometimes shuts down in 5 minutes based on the L4 parameter "delay time of automatic shutdown" when PAS is not collected and using throttle only. If this is the problem, then this can be changed to 120 minutes as a workaround.

 

[romelec]

That's strange I didn't get a notification.

Anyway, the issue was a module I added between the controller and LCD to display the motor temperature.
The code is based on this thread: https://endless-sphere.com/forums/viewtopic.php?t=73475

The issue appears when the temperature is above 40°C, I guess it modifies some data where it should not but I don't know how it could happen. I didn't debug it yet.

I just removed it and made my trip, about 110km per day during a week and all went fine.

 

[ZeroEm]

Just thinking out loud, does the battery SOC have any effect. Just wondering if the solar panels voltage gets to high during full sun.
Not that I know what i'm talking about. Have been trying to use only solar to charge batteries at home for my riding. have been using buck chargers and they don't seem to last that long. Panel voltages peak during full sun have not found a lasting solution.

Like the idea of over 200w while riding would really extent my rides and/or run a small battery.

 

[romelec]

That was my first idea but in the end it was not the issue.

You can't use a regular dc/dc converter, this MPPT/charger works really well: https://www.aliexpress.com/item/4000282022570.html
On a sunny day you can get about 1kWh for a 200W panel

 

[ZeroEm]

Had one only lasted six months, been looking for a better one that last longer.