I created a SW to measure the voltage from some batteries of 12V 2.3Ah.
Sometimes (once on 10-15 )when I put the tips on the battery connectors, the display shows weird instead of normal ASCII characters.
I have tried to twist the cable power supply of the display but without any improvement.
Another funny thing is if I insert the Diode D2(see the png file), all pixel of the Display tuns on.
Thanks in advance for any advice
bat tester schema.pdf (89.8 KB)