// Voltage Divider for 12-to-5 Volts
float R1 = 147000.0, R2 =  47000.0;
float ConstADC = 5.0  // Vref
float convADC = constADC / 1024.0;
  // vBatt ADC smoothing
const int iDelay = 5000;
float nReadings = 0.0, numReadings = 10.0;
float tReadings = 0.0;
  // Misc
int i, value;
float vout, vin, vind, vAC;
const float vTriggerOn = 12.45;  // below this the AC charger will turn on
const float vTriggerOff = 14.5;  // above this the AC charger will turn off

void setup() {
  Serial.begin(9600);
  digitalWrite(powerPin,HIGH); pinMode(powerPin,OUTPUT);  // Active-low
  digitalWrite(powerPin2,HIGH); pinMode(powerPin2,OUTPUT);  // Active-low
  }

void loop() {
  int val=analogRead(A2);   // Battery voltage input from voltage divider
  vout = val * convADC
  vin = vout / (R2/(R1+R2));
  tReadings = tReadings + vind;   // for smoothing
  nReadings = nReadings + 1;

  other stuff...

  if (nReadings>=numReadings) {
    vind = tReadings / nReadings;   // Smoothing
    vAC=0;
    if (vind < vTriggerOn) {    // Batt low, turn on charger
      digitalWrite(powerPin,LOW);
      digitalWrite(powerPin2,LOW);
      vAC=13.8;
      }
    if (vind > vTriggerOff) {   // Solar panels on, turn off charger
      digitalWrite(powerPin,HIGH);
      digitalWrite(powerPin2,HIGH);
      }
    if (vind>15.5) {vind=15.48; vin=15.48;}   //  <--  NEVER EXECUTES

    if (vind>vTrigger) {  // Normal - no worries
      Serial.print(vind); Serial.print("t");
      Serial.println(vAC);
      tReadings = 0.0;
      nReadings = 0.0;
      }
    else Serial.println("LOW VOLTAGE");

    delay(iDelay);
}