use widget.watch

battery-widget-v4/battery.lua

@@ -1,17 +1,19 @@
 local wibox = require("wibox")
 local awful = require("awful")
 local naughty = require("naughty")
+local watch = require("awful.widget.watch")
 
+-- Battery 0: Discharging, 75%, 01:51:38 remaining
+-- Battery 0: Charging, 53%, 00:57:43 until charged
 
-batteryIcon = wibox.widget {
-widget = wibox.widget.imagebox
-}
+batteryIcon = wibox.widget { widget = wibox.widget.imagebox }
 
-function refresh_icon()
-  awful.spawn.easy_async([[bash -c 'acpi | cut -d, -f 2 | egrep -o "[0-9]{1,3}"']], 
-    function(stdout, stderr, reason, exit_code)   
+watch(
+    "acpi", 10,
+    function(widget, stdout, stderr, exitreason, exitcode)
         local batteryType
-      local charge = tonumber(stdout)
+        local bar, status, charge, time = string.match(stdout, '(.+): (%a+), (%d%d)%%, (.+)')
+        charge = tonumber(charge)
         if (charge >= 0 and charge < 20) then 
             batteryType="battery-empty"
             show_battery_warning()
@@ -20,12 +22,15 @@ function refresh_icon()
         elseif (charge >= 60 and charge < 80) then batteryType="battery-good"
         elseif (charge >= 80 and charge <= 100) then batteryType="battery-full"
         end
-      batteryIcon.image = "/usr/share/icons/Arc-Icons/panel/22/" .. batteryType .. ".svg"
-    end)
+        if status == 'Charging' then 
+            batteryType = batteryType .. '-charging'
         end
+        batteryIcon.image = "/usr/share/icons/Arc-Icons/panel/22/" .. batteryType .. ".svg"
+    end
+)
 
 function show_battery_status()
-  awful.spawn.easy_async([[bash -c 'acpi | cut -d, -f 2,3']],
+    awful.spawn.easy_async([[bash -c 'acpi']],
         function(stdout, stderr, reason, exit_code)   
             naughty.notify{
                 text = stdout,
@@ -49,11 +54,5 @@ function show_battery_warning()
 }
 end
 
--- timer to refresh icon
-local batteryWidgetTimer = timer({ timeout = 60 })  
-batteryWidgetTimer:connect_signal("timeout",  function() refresh_icon() end)
-batteryWidgetTimer:start()
-batteryWidgetTimer:emit_signal("timeout")
-
 -- popup with battery info
 batteryIcon:connect_signal("mouse::enter", function() show_battery_status() end)