Computercraft - Energy cell percentage calculation

-- Settings
monitorSide = "back"
consoleMonitor = "top"
modemSide = "bottom"
redstoneSide = "left"
energylow = 10 -- When the motors should be turned on (percent)
energyhigh = 95 -- When the motors should be turned off (percent)
energyCellLow = 0 -- Lowest energy cell id
energyCellHigh = 63 -- Highest energy cell id
sleepCycle = 60 -- Seconds to sleep between each loop

-- Variables
mon = peripheral.wrap(monitorSide)
monX, monY = mon.getSize()
cmon = peripheral.wrap(consoleMonitor)

-- initialization
redstone.setOutput(redstoneSide,false) -- Disabled by default
if(rednet.isOpen(modemSide) == "False") then -- Rednet
    rednet.open(modemSide)
end

-- Functions
function clear() -- Clear screen
    mon.setBackgroundColor(colors.black)
    mon.clear()
    mon.setCursorPos(1,1)
end

function drawText(x, y, text, color_txt, color_bg) -- Write text on monitor
    mon.setBackgroundColor(color_bg)
    mon.setTextColor(color_txt)
    mon.setCursorPos(x,y)
    mon.write(text)
end

function drawLine(x, y, length, size, color_bar) -- Write progress bar on monitor
    for yPos = y, y+size-1 do
        mon.setBackgroundColor(color_bar)
        mon.setCursorPos(x, yPos)
        mon.write(string.rep(" ", length))
    end
end

function drawProg(x, y, name, length, size, minVal, maxVal, color_bar, color_bg) -- Draw actual progress bar
    drawLine(x, y, length, size, color_bg)
    local barSize = math.floor((minVal/maxVal)*length)
    drawLine(x, y, barSize, size, color_bar)
    local text = name.." "..math.floor((minVal/maxVal)*100).."%"
    drawText(monX/2-#text/2+1, y+size/2, text, colors.black, color_bar)
end

function drawConsoleMon(cells, energyPercent, energyColor, invalidCells, redstoneSignal)
 cmon.clear()
 cmon.setBackgroundColor(colors.black)
 cmon.setCursorPos(1,1)
 cmon.setTextColor(colors.white)
 cmon.write("C: "..cells)
 cmon.setCursorPos(1,2)
 cmon.write("E: ")
 cmon.setTextColor(energyColor)
 cmon.write(energyPercent.."%")
 cmon.setTextColor(colors.white)
 cmon.setCursorPos(1,3)
 cmon.write("I: "..invalidCells)
 cmon.setCursorPos(1,4)
 cmon.write("R: ")
 cmon.setTextColor(colors.black)
 if redstoneSignal == "On" then
   cmon.setTextColor(colors.green)
  elseif redstoneSignal == "Off" then
   cmon.setTextColor(colors.red)
 end
 cmon.write(redstoneSignal)
end

-- Doing stuff!
while true do
    -- Check stored energy on all nodes
    storedEnergy = 0
    maxEnergy = 0
    i = energyCellLow
    invalidCells = 0
    while i <= energyCellHigh do
        local cellid = "tile_thermalexpansion_cell_resonant_name_"..math.floor(i)
        if peripheral.isPresent(cellid) == true then
            local lES = peripheral.call(cellid,"getEnergyStored","south")
            local lMES = peripheral.call(cellid,"getMaxEnergyStored","south")
            storedEnergy = storedEnergy + lES
            maxEnergy = maxEnergy + lMES
        else
            invalidCells = invalidCells + 1
        end
        i = i + 1
    end
 cellCount = i

    -- Energy controller
    energyPercent = math.floor((storedEnergy/maxEnergy)*100)
    if energyPercent < energylow then
        redstone.setOutput(redstoneSide,true)
    elseif energyPercent >= energyhigh then
        redstone.setOutput(redstoneSide,false)
    end

    -- Progress bar colour
    if energyPercent <= 10 then
        progColor = colors.red
    elseif energyPercent <= 30 then
        progColor = colors.orange
    else
        progColor = colors.green
    end

    -- vars
    if redstone.getOutput(redstoneSide) == true then
        redstoneSignal = "On"
    else
        redstoneSignal = "Off"
    end

    clear() -- Draw progress time!
 drawConsoleMon(cellCount, energyPercent, progColor, invalidCells, redstoneSignal)
    drawProg(2, 2, "Battery charge", monX-2, 3, storedEnergy, maxEnergy, progColor, colors.gray)
    datestamp = "Day: "..os.day().." - Time: "..os.time()
    term.clear()
    term.setCursorPos(1,1)
    term.write(datestamp)
    term.setCursorPos(1,2)
    term.write("Energy: "..energyPercent.."% - Invalid cells: "..math.floor(invalidCells))
    term.setCursorPos(1,3)
    term.write("Redstone signal ("..redstoneSide.."): "..redstoneSignal)
    term.setCursorPos(1,4)
    term.write("Press and hold Ctrl+T to terminate script.")
    term.setCursorPos(1,6)
    term.write("Next update in")

    i = 0
    while i <= (sleepCycle - 1) do
        term.setCursorPos(15,6)
        term.write("            ")
        term.setCursorPos(15,6)
        term.write(" "..math.floor(sleepCycle-i).." Second(s)")
        i = i + 1
        sleep(1)
    end

 term.setCursorPos(1,7)
 term.write("Updating status...")
end