Index: firmware/App/Controllers/LoadCell.c
===================================================================
diff -u -r22176ce95e49213c48454f34ddf5d29b8109f2cb -r6f8565fdfd2dd958f94574bcec89f1460b2b0b11
--- firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 22176ce95e49213c48454f34ddf5d29b8109f2cb)
+++ firmware/App/Controllers/LoadCell.c	(.../LoadCell.c)	(revision 6f8565fdfd2dd958f94574bcec89f1460b2b0b11)
@@ -290,6 +290,29 @@
 
 /*********************************************************************//**
  * @brief
+ * The isLoadCellTared function returns load cell tare status
+ * for a given load cell ID.
+ * @details Inputs: none
+ * @details Outputs: load cell tare status
+ * @param loadCellID ID of load cell tare status
+ *************************************************************************/
+BOOL isLoadCellTared( LOAD_CELL_ID_T loadCellID )
+{
+    BOOL tared = FALSE;
+
+    if ( fabs( loadcells[ loadCellID ].autoCalOffset ) < NEARLY_ZERO )
+    {
+        tared = FALSE;
+    }
+    else
+    {
+        tared = TRUE;
+    }
+    return tared;
+}
+
+/*********************************************************************//**
+ * @brief
  * The tareLoadCell function sets the load cell auto calibration offset
  * for a given load cell ID.
  * @details Inputs: none
@@ -299,7 +322,6 @@
 void tareLoadCell( LOAD_CELL_ID_T loadCellID )
 {
     BOOL isWeightOutOfRange = FALSE;
-
     F32 weight = getLoadCellSmallFilteredWeight( loadCellID );
 
     // Check if the load cell is being tared for the first time
@@ -470,31 +492,38 @@
  *************************************************************************/
 static void monitorLoadCellsPrimaryBackupDriftOutOfRange( void )
 {
-    // TODO do we need this function at all?
-    F32 drift;
+    F32 drift = 0.0;
+    F32 loadCellADrift = 0.0;
+    F32 loadCellBDrift = 0.0;
+    BOOL isDriftOutOfRange = FALSE;
 
-    F32 loadCellADrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_PRIMARY ) -
+    // Test is valid after load cells are tared
+    if ( isLoadCellTared( LOAD_CELL_RESERVOIR_1_PRIMARY ) && isLoadCellTared( LOAD_CELL_RESERVOIR_1_BACKUP ) )
+    {
+        loadCellADrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_PRIMARY ) -
                                getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_1_BACKUP ) );
-
-    F32 loadCellBDrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_PRIMARY ) -
+    }
+    if ( isLoadCellTared( LOAD_CELL_RESERVOIR_2_PRIMARY ) && isLoadCellTared( LOAD_CELL_RESERVOIR_2_BACKUP ) )
+    {
+        loadCellBDrift = fabs( getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_PRIMARY ) -
                                getLoadCellSmallFilteredWeight( LOAD_CELL_RESERVOIR_2_BACKUP ) );
+    }
 
-    BOOL isDriftOutOfRange = ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) ||
-                             ( loadCellBDrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
-
-    if ( TRUE == isDriftOutOfRange )
+    if ( ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) ||
+            ( loadCellBDrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ) )
     {
+        isDriftOutOfRange = TRUE;
         drift = ( loadCellADrift > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS ? loadCellADrift : loadCellBDrift );
     }
     else
     {
+        isDriftOutOfRange = FALSE;
         // Pick the biggest drift in between the two load cells when none of the is above range
         drift = ( loadCellADrift > loadCellBDrift ? loadCellADrift : loadCellBDrift );
     }
 
-    // TODO this alarm is disabled until a better drift algorithm is figured out. Drift check might be removed from the load cells
-    //checkPersistentAlarm( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, isDriftOutOfRange, drift,
-     //                     LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
+    checkPersistentAlarm( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, isDriftOutOfRange, drift,
+                          LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
 }