Delay with millis: unexplicable behaviour

[PaulRB]

@brice3010

  static char outvolt[7];
  static char outcurr[7];
  static char outtemp1[8];
  static char outtemp2[8];

Do you need separate string variables for each of these? Could you not have one string and re-use it?

Not sure why you made these static. They don't appear to need to be static.