Battery widget for awesome (using acpi)

bat_widget.lua

bat_widget = wibox.widget.textbox()
function set_bat(bat_widget)
    local s = ""
    local output = io.popen("acpi"):read()
    if not output then
        s = "N/A"
        bat_widget:set_text(s)
        return
    end
    local percentage = string.match(output, ".-(%d+)%%")
    local time_left = string.match(output, ".-(%d+:%d+)")
    local is_charging = string.find(output, "Charging") ~= nil
    local is_full = string.find(output, "Full") ~= nil
    s = string.format("%s%%", percentage, time_left)
    if time_left then
        s = s .. string.format("/%s", time_left)
    end
    if is_charging or is_full then
        s = s .. " ↯"
    end
    bat_widget:set_text(s)
end
set_bat(bat_widget)
bat_timer = timer({ timeout = 10 })
bat_timer:connect_signal("timeout", function()
    set_bat(bat_widget)
end)
bat_timer.start(bat_timer)

Just an experiment. You will probably want to use Vicious widget for battery.