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Sometimes, character display problem.

 Hi all, I have V4 board with 40A relay with 3.11.3 firmware.

Sometime I have a display bug with my charger. You can see on the picture.
When this appears, the charger still working.
But one time last week, the charger stopped and I saw this bad things

Have you any idea about it?

This is usually caused by Noise on the AC lines. Does your Relay have an AC coil? If so is there a MOV installed across the coil?

What do you mean about MOV? yes I have a coil, could you look on the picture? this is my build.


(1.08 MB)

Okay, that is a DC coil so no MOV is needed. 

The controller looks a lot older than a v4. From the photos that looks like a v2. Is the LCD also older? There was one batch about 5 years ago that had 47k resistors on the i2c lines instead of 4.7k. This made them more sensitive to noise. Can you take a picture of the back of the LCD?

Sorry, you right, this picture is my old hardware (board), check the new picture.

Do you need the back of the LCD yet?


I put the back LCD board, could you confirm if I need to make some modification? th battery socket it was not installed originally.


Yes, R4 and R5 need to be replaced with 805 size resistors from 2.2 - 4.7K. This will make your LCD handle noise/corruption much better.


Ok thanks, If I use standard common resistors size, it will be ok?


Yes, use the second I2C threw hole connector. Remove the two 47k resistors and add one standard resistor from 5v to SDA the other 5v to SCL.

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