Less aggressive, add comments

src/Services/Device.vala

@@ -233,17 +233,20 @@ public class Power.Services.Device : Object {
 
         var icon_name = "battery";
 
-        if (percentage >= 20) {
-            icon_name += "-%i".printf ((int) (5 * Math.round (percentage / 5)));
-        } else if (percentage >= 10) {
+        if (percentage > 10) {
+            // Round to the nearest 5 percent
+            // Clamp to 20. There is no 15. Make sure we don't have single px red line until < 10
+            var rounded_percentage = (int) (5 * Math.round (percentage / 5)).clamp (20, 100);
+            icon_name += "-%i".printf (rounded_percentage);
+        } else if (percentage > 0) {
             icon_name += "-10";
         } else {
             icon_name += "-0";
         }
 
         if (is_charging) {
             icon_name += "-charging";
-        } else if (time_to_empty > 0 && time_to_empty < 15 * 60) {
+        } else if (time_to_empty >= 0 && time_to_empty < 15 * 60) {
             icon_name = "battery-0";
         }