diff --git a/res/layout/card_generator_sensors_accelerometer.xml b/res/layout/card_generator_sensors_accelerometer.xml
index 3f80ec3..d7766b4 100755
--- a/res/layout/card_generator_sensors_accelerometer.xml
+++ b/res/layout/card_generator_sensors_accelerometer.xml
@@ -45,14 +45,17 @@
                 android:orientation="horizontal"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
-                android:padding="0dp">
+                android:padding="0dp"
+                android:background="@android:color/black">
                 <com.github.mikephil.charting.charts.LineChart
                     android:id="@+id/accelerometer_chart"
                     android:layout_width="match_parent"
                     android:layout_height="160dp"
-                    android:layout_marginBottom="0dp"/>
+                    android:layout_marginBottom="0dp"
+                    android:background="@android:color/black" />
             </LinearLayout>
-            <TextView android:id="@+id/card_empty"
+            <TextView android:visibility="gone"
+                android:id="@+id/card_empty"
                 android:text="@string/message_generator_accelerometer_empty"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
diff --git a/res/layout/card_generator_sensors_ambient_light.xml b/res/layout/card_generator_sensors_ambient_light.xml
index 0176f72..24dd677 100755
--- a/res/layout/card_generator_sensors_ambient_light.xml
+++ b/res/layout/card_generator_sensors_ambient_light.xml
@@ -45,14 +45,17 @@
                 android:orientation="horizontal"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
-                android:padding="0dp">
+                android:padding="0dp"
+                android:background="@android:color/black">
                 <com.github.mikephil.charting.charts.LineChart
                     android:id="@+id/light_chart"
                     android:layout_width="match_parent"
                     android:layout_height="160dp"
-                    android:layout_marginBottom="0dp"/>
+                    android:layout_marginBottom="0dp"
+                    android:background="@android:color/black" />
             </LinearLayout>
-            <TextView android:id="@+id/card_empty"
+            <TextView android:visibility="gone"
+                android:id="@+id/card_empty"
                 android:text="@string/message_generator_ambient_light_empty"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
diff --git a/res/values/colors.xml b/res/values/colors.xml
index 2a12c47..8e6ea42 100755
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -3,4 +3,6 @@
     <color name="colorPrimary">#3F51B5</color>
     <color name="colorPrimaryDark">#303F9F</color>
     <color name="colorAccent">#FF4081</color>
+
+    <color name="pdk_chart_loading_color">#E0E0E0</color>
 </resources>
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 3c77eb0..0c44cc9 100755
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -29,5 +29,7 @@
 
     <string name="label_data_collection_description">Data Collection Description</string>
     <string name="label_data_collection_description_more">Tap here to learn how this app uses your data.</string>
+
+    <string name="pdk_generator_chart_loading_data">Waiting for chart data&#8230;</string>
 </resources>
 
diff --git a/src/com/audacious_software/passive_data_kit/PassiveDataKit.java b/src/com/audacious_software/passive_data_kit/PassiveDataKit.java
index 285f97e..6bff27b 100755
--- a/src/com/audacious_software/passive_data_kit/PassiveDataKit.java
+++ b/src/com/audacious_software/passive_data_kit/PassiveDataKit.java
@@ -16,12 +16,13 @@ public class PassiveDataKit {
     private boolean mStarted = false;
 
     public void start() {
-        if (!this.mStarted)
-        {
-            Generators.getInstance(this.mContext).start();
-            Logger.getInstance(this.mContext);
+        synchronized (this) {
+            if (!this.mStarted) {
+                this.mStarted = true;
 
-            this.mStarted = true;
+                Generators.getInstance(this.mContext).start();
+                Logger.getInstance(this.mContext);
+            }
         }
     }
 
diff --git a/src/com/audacious_software/passive_data_kit/generators/Generators.java b/src/com/audacious_software/passive_data_kit/generators/Generators.java
index 059b44d..fa68cd9 100755
--- a/src/com/audacious_software/passive_data_kit/generators/Generators.java
+++ b/src/com/audacious_software/passive_data_kit/generators/Generators.java
@@ -35,49 +35,46 @@ public class Generators {
     private HashMap<String, PowerManager.WakeLock> mWakeLocks = new HashMap<>();
 
     public void start() {
-        if (!this.mStarted)
-        {
-            this.mGenerators.clear();
+        synchronized (this) {
+            if (!this.mStarted) {
+                this.mStarted = true;
 
-            this.mGenerators.add(AppEvent.class.getCanonicalName());
+                this.mGenerators.clear();
 
-            for (String className : this.mContext.getResources().getStringArray(R.array.pdk_available_generators))
-            {
-                this.mGenerators.add(className);
-            }
-
-            for (String className : this.mContext.getResources().getStringArray(R.array.pdk_app_generators))
-            {
-                this.mGenerators.add(className);
-            }
-
-            for (String className : this.mGenerators)
-            {
-                try {
-                    Class<Generator> probeClass = (Class<Generator>) Class.forName(className);
+                this.mGenerators.add(AppEvent.class.getCanonicalName());
 
-                    Method isEnabled = probeClass.getDeclaredMethod("isEnabled", Context.class);
+                for (String className : this.mContext.getResources().getStringArray(R.array.pdk_available_generators)) {
+                    this.mGenerators.add(className);
+                }
 
-                    Boolean enabled = (Boolean) isEnabled.invoke(null, this.mContext);
+                for (String className : this.mContext.getResources().getStringArray(R.array.pdk_app_generators)) {
+                    this.mGenerators.add(className);
+                }
 
-                    if (enabled) {
-                        this.startGenerator(className);
+                for (String className : this.mGenerators) {
+                    try {
+                        Class<Generator> probeClass = (Class<Generator>) Class.forName(className);
+
+                        Method isEnabled = probeClass.getDeclaredMethod("isEnabled", Context.class);
+
+                        Boolean enabled = (Boolean) isEnabled.invoke(null, this.mContext);
+
+                        if (enabled) {
+                            this.startGenerator(className);
+                        } else {
+                            this.stopGenerator(className);
+                        }
+                    } catch (ClassNotFoundException e) {
+                        Logger.getInstance(this.mContext).logThrowable(e);
+                    } catch (NoSuchMethodException e) {
+                        Logger.getInstance(this.mContext).logThrowable(e);
+                    } catch (InvocationTargetException e) {
+                        Logger.getInstance(this.mContext).logThrowable(e);
+                    } catch (IllegalAccessException e) {
+                        Logger.getInstance(this.mContext).logThrowable(e);
                     }
-                    else {
-                        this.stopGenerator(className);
-                    }
-                } catch (ClassNotFoundException e) {
-                    Logger.getInstance(this.mContext).logThrowable(e);
-                } catch (NoSuchMethodException e) {
-                    Logger.getInstance(this.mContext).logThrowable(e);
-                } catch (InvocationTargetException e) {
-                    Logger.getInstance(this.mContext).logThrowable(e);
-                } catch (IllegalAccessException e) {
-                    Logger.getInstance(this.mContext).logThrowable(e);
                 }
             }
-
-            this.mStarted = true;
         }
     }
 
diff --git a/src/com/audacious_software/passive_data_kit/generators/device/Battery.java b/src/com/audacious_software/passive_data_kit/generators/device/Battery.java
index 56f7a1f..62a853f 100755
--- a/src/com/audacious_software/passive_data_kit/generators/device/Battery.java
+++ b/src/com/audacious_software/passive_data_kit/generators/device/Battery.java
@@ -114,10 +114,6 @@ public static void start(final Context context) {
     private void startGenerator() {
         final Battery me = this;
 
-        final long now = System.currentTimeMillis();
-
-        me.mLastTimestamp = now;
-
         this.mReceiver = new BroadcastReceiver() {
             @Override
             public void onReceive(final Context context, Intent intent) {
@@ -127,6 +123,10 @@ public void onReceive(final Context context, Intent intent) {
                     return;
                 }
 
+                long now = System.currentTimeMillis();
+
+                me.mLastTimestamp = now;
+
                 ContentValues values = new ContentValues();
                 values.put(Battery.HISTORY_OBSERVED, now);
 
diff --git a/src/com/audacious_software/passive_data_kit/generators/sensors/Accelerometer.java b/src/com/audacious_software/passive_data_kit/generators/sensors/Accelerometer.java
index 7f4f8a2..1930409 100755
--- a/src/com/audacious_software/passive_data_kit/generators/sensors/Accelerometer.java
+++ b/src/com/audacious_software/passive_data_kit/generators/sensors/Accelerometer.java
@@ -368,6 +368,10 @@ public static void bindViewHolder(final DataPointViewHolder holder) {
 
             dateLabel.setText(Generator.formatTimestamp(context, Accelerometer.latestPointGenerated(generator.mContext) / 1000));
 
+            LineChart chart = (LineChart) holder.itemView.findViewById(R.id.accelerometer_chart);
+            chart.setNoDataText(context.getString(R.string.pdk_generator_chart_loading_data));
+            chart.setNoDataTextColor(0xFFE0E0E0);
+
             Runnable r = new Runnable() {
                 @Override
                 public void run() {
@@ -593,6 +597,7 @@ public String getFormattedValue(float value, AxisBase axis) {
                                 chart.getDescription().setEnabled(false);
 
                                 chart.setVisibleYRange((float) Math.floor(finalMinValue) - 1, (float) Math.ceil(finalMaxValue) + 1, YAxis.AxisDependency.LEFT);
+                                chart.setNoDataText(context.getString(R.string.pdk_generator_chart_loading_data));
                                 chart.setData(chartData);
                             }
 
diff --git a/src/com/audacious_software/passive_data_kit/generators/sensors/AmbientLight.java b/src/com/audacious_software/passive_data_kit/generators/sensors/AmbientLight.java
index 5018de4..c603b9d 100755
--- a/src/com/audacious_software/passive_data_kit/generators/sensors/AmbientLight.java
+++ b/src/com/audacious_software/passive_data_kit/generators/sensors/AmbientLight.java
@@ -19,7 +19,6 @@
 import android.preference.PreferenceManager;
 import android.provider.Settings;
 import android.support.v4.content.ContextCompat;
-import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -46,10 +45,6 @@
 import java.util.Date;
 import java.util.List;
 
-/**
- * Created by cjkarr on 4/17/2017.
- */
-
 public class AmbientLight extends SensorGenerator implements SensorEventListener {
     private static final String GENERATOR_IDENTIFIER = "pdk-sensor-light";
 
@@ -286,6 +281,10 @@ public static void bindViewHolder(final DataPointViewHolder holder) {
 
             dateLabel.setText(Generator.formatTimestamp(context, AmbientLight.latestPointGenerated(context) / 1000));
 
+            LineChart chart = (LineChart) holder.itemView.findViewById(R.id.light_chart);
+            chart.setNoDataText(context.getString(R.string.pdk_generator_chart_loading_data));
+            chart.setNoDataTextColor(0xFFE0E0E0);
+
             Runnable r = new Runnable() {
                 @Override
                 public void run() {