Apply patch by Alexander von Gluck. Fix #6951.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@39731 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/drivers/power/acpi_battery/acpi_battery.cpp

@@ -4,6 +4,7 @@
  *
  * Authors:
  *		Clemens Zeidler, [email protected]
+ *		Alexander von Gluck, [email protected]
  */
 
 #include "acpi_battery.h"
@@ -59,7 +60,7 @@ ReadBatteryStatus(battery_driver_cookie* cookie, acpi_battery_info* batteryStatu
 
 	pointer = object->data.package.objects;
 	batteryStatus->state = (pointer->object_type == ACPI_TYPE_INTEGER)
-		? pointer->data.integer : -1;
+		? pointer->data.integer : BATTERY_CRITICAL_STATE; 
 
 	pointer++;
 	batteryStatus->current_rate = (pointer->object_type == ACPI_TYPE_INTEGER)
@@ -73,6 +74,15 @@ ReadBatteryStatus(battery_driver_cookie* cookie, acpi_battery_info* batteryStatu
 	batteryStatus->voltage = (pointer->object_type == ACPI_TYPE_INTEGER)
 		? pointer->data.integer : -1;
 
+	/* If key values are all < 0, it is likely that the battery slot is empty
+	   or the battery is damaged.  Set BATTERY_CRITICAL_STATE */
+	if (batteryStatus->voltage < 0
+		&& batteryStatus->current_rate < 0
+		&& batteryStatus->capacity < 0) {
+		batteryStatus->state = BATTERY_CRITICAL_STATE;
+	}
+	
+
 exit:
 	free(buffer.pointer);
 	return status;