powerMon2.lua

batSide = "left"
genSide = "back"
setLevel = 1      --what % energy to turn genny on.
resetLevel = 95   --what % energy to turn genny off.

running = false
mon = peripheral.wrap("monitor_0")
bat = peripheral.wrap(batSide)
maxEnergy = bat.getMaxEnergy()
rs.setOutput(genSide, running)
mon.setBackgroundColor(colors.black)
mon.clear()
blinkState = false

function doScreen(level)
  if running then blinkColor = colors.green else blinkColor = colors.red end
  mon.setTextColor(blinkColor)
  local lvl = (math.floor((level * 10) + 0.5))/10
  mon.setCursorPos(1,3)
  mon.write("     ")
  if lvl < 10 then mon.setCursorPos(3,3) else mon.setCursorPos(2,3) end
  mon.write(string.format("%.1f", lvl).."%")

  mon.setCursorPos(7,1)
  if blinkState then mon.setBackgroundColor(colors.black) else mon.setBackgroundColor(blinkColor) end
  mon.write(" ")
  if blinkState then
    blinkState = false
  else
    blinkState = true
    mon.setBackgroundColor(colors.black)
  end
end

while true do
  energy = bat.getEnergy()
  level = (energy / maxEnergy) * 100
  if running then
    if level >= resetLevel then
      running = false
      rs.setOutput(genSide, running)
    end
  else
    if level <= setLevel then
      running = true
      rs.setOutput(genSide, running)
    end
  end

  doScreen(level)

  local lvl = (math.floor((level * 1000) + 0.5))/1000

  print("Energy: "..energy.. "/"..maxEnergy.." Level:"..string.format("%.3f", lvl).."% Running:"..tostring(running))
  sleep(1)
end