Index: firmware/App/Drivers/Battery.c
===================================================================
diff -u -rac636de6bf42cc4145cbd14886b616da78b3aaf8 -ra8a0f729b78556c2c58a72bad942d04a9dead3f5
--- firmware/App/Drivers/Battery.c	(.../Battery.c)	(revision ac636de6bf42cc4145cbd14886b616da78b3aaf8)
+++ firmware/App/Drivers/Battery.c	(.../Battery.c)	(revision a8a0f729b78556c2c58a72bad942d04a9dead3f5)
@@ -32,18 +32,20 @@
 #define BATTERY_STATUS_AC_PRESENT_MASK      0x8000              ///< Battery status AC present bit mask.
 #define BATTERY_COMM_TIME_OUT_MS            1                   ///< Battery communication time out in ms.
 #define BATTERY_MONITOR_INTERVAL_MS         MS_PER_SECOND       ///< Battery monitor interval in ms.
+
+#define AC_POWER_LOST_PERSISTENT_COUNT      3                   ///< AC power lost persistent count before alarming.
 
 // ********** private data **********
 
 static U16 batteryStatus = 0;                                   ///< Battery current status.
 static U32 lastBatteryMonitorTime = 0;                          ///< Previous battery monitor time.
-static BOOL isBatteryStatusReceived = FALSE;                    ///< Flag indicates battery status received.
+static U32 lostACPowerPersistentCount = 0;                      ///< Persistent count for AC power lost alarm.
 
 // ********** private function prototypes **********
 
 static void setupI2CDriver( void );
 static BOOL waitForTxReady( void );
-static void getBatteryStatus( void );
+static BOOL getBatteryStatus( void );
 
 /*********************************************************************//**
  * @brief
@@ -69,16 +71,28 @@
 {
     if ( TRUE == didTimeout( lastBatteryMonitorTime, BATTERY_MONITOR_INTERVAL_MS ) )
     {
-        isBatteryStatusReceived = FALSE;
         lastBatteryMonitorTime = getMSTimerCount();
 
 #ifndef DISABLE_BATT_COMM
-        getBatteryStatus();
-
-        if ( ( TRUE == isBatteryStatusReceived ) && ( ( batteryStatus & BATTERY_STATUS_AC_PRESENT_MASK ) == 0 ) )
+        if ( TRUE == getBatteryStatus() )
         {
-            SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_AC_POWER_LOST, (U32)batteryStatus );
+            if ( ( batteryStatus & BATTERY_STATUS_AC_PRESENT_MASK ) == 0 )
+            {
+                if ( ++lostACPowerPersistentCount > AC_POWER_LOST_PERSISTENT_COUNT )
+                {
+                    SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_AC_POWER_LOST, (U32)batteryStatus );
+                }
+            }
+            else
+            {
+                lostACPowerPersistentCount = 0;
+            }
         }
+        else
+        {
+            // Reset i2c bus if cannot communicate with battery charger
+            setupI2CDriver();
+        }
 #endif
     }
 }
@@ -121,14 +135,37 @@
 
 /*********************************************************************//**
  * @brief
+ * The waitForRxReady function checks for receive ready status from i2c
+ * driver with a timeout.
+ * @details Inputs: none
+ * @details Outputs: checked i2c receive ready status
+ * @return TRUE if timeout, otherwise FALSE
+ *************************************************************************/
+static BOOL waitForRxReady( void )
+{
+    U32 const startTime = getMSTimerCount();
+    BOOL timeout = FALSE;
+
+    while ( ( 0 == i2cIsRxReady( i2cREG1 ) ) && ( FALSE == timeout ) )
+    {
+        timeout = didTimeout( startTime, BATTERY_COMM_TIME_OUT_MS );
+    }
+
+    return timeout;
+}
+
+/*********************************************************************//**
+ * @brief
  * The getBatteryStatus function send command to smart battery charger controller
  * interface to get battery status.
  * @details Inputs: none
  * @details Outputs: get the current battery status
- * @return none
+ * @return TRUE if received battery status, otherwise FALSE
  *************************************************************************/
-static void getBatteryStatus( void )
+static BOOL getBatteryStatus( void )
 {
+    BOOL result = FALSE;
+
     if ( FALSE == i2cIsBusBusy( i2cREG1 ) )
     {
         i2cSetMode( i2cREG1, I2C_MASTER );
@@ -145,18 +182,23 @@
         {
             i2cSetDirection( i2cREG1, I2C_RECEIVER );
             i2cSetStart( i2cREG1 );
-            batteryStatus = i2cReceiveByte( i2cREG1);
-            i2cSetStop( i2cREG1 );
-            batteryStatus = ( batteryStatus | ( i2cReceiveByte( i2cREG1) << 8 ) );
 
-            isBatteryStatusReceived = TRUE;
+            if ( FALSE == waitForRxReady() )
+            {
+                // Due to the double buffer, the master must generate the stop condition after the (message size - 1)th data
+                i2cSetStop( i2cREG1 );
+                batteryStatus = i2cReceiveByte( i2cREG1);
+
+                if ( FALSE == waitForRxReady() )
+                {
+                    batteryStatus = ( batteryStatus | ( i2cReceiveByte( i2cREG1) << 8 ) );
+                    result = TRUE;
+                }
+            }
         }
-        else
-        {
-            // Reset i2c bus if comm timeout
-            setupI2CDriver();
-        }
     }
+
+    return result;
 }
 
 /**@}*/