Further improvements:

- append a string on the control center when the device is charging
- battery status string is no more, welcome battery state enum
- the notification will not be shown when the device is charging, even if the level is below threshold

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBDeviceAdapter.java

@@ -11,6 +11,7 @@ import android.widget.TextView;
 
 import java.util.List;
 
+import nodomain.freeyourgadget.gadgetbridge.deviceevents.GBDeviceEventBatteryInfo;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
 import nodomain.freeyourgadget.gadgetbridge.R;
 
@@ -59,6 +60,11 @@ public class GBDeviceAdapter extends ArrayAdapter<GBDevice> {
         short batteryLevel = device.getBatteryLevel();
         if (batteryLevel != GBDevice.BATTERY_UNKNOWN) {
             batteryStatusLabel.setText("BAT: " + device.getBatteryLevel() + "%");
+            GBDeviceEventBatteryInfo.BatteryState batteryState = device.getBatteryState();
+            if (GBDeviceEventBatteryInfo.BatteryState.BATTERY_CHARGING.equals(batteryState) ||
+                    GBDeviceEventBatteryInfo.BatteryState.BATTERY_CHARGING_FULL.equals(batteryState)) {
+                batteryStatusLabel.append(" CHG");
+            }
         } else {
             batteryStatusLabel.setText("");
         }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/deviceevents/GBDeviceEventBatteryInfo.java

@@ -6,8 +6,6 @@ import java.util.GregorianCalendar;
 public class GBDeviceEventBatteryInfo extends GBDeviceEvent {
     public GregorianCalendar lastChargeTime= null;
     public BatteryState state = BatteryState.UNKNOWN;
-    //TODO: I think the string should be deprecated in favor of the Enum above
-    public String status;
     public short level = 50;
     public int numCharges = -1;
 
@@ -17,10 +15,11 @@ public class GBDeviceEventBatteryInfo extends GBDeviceEvent {
 
     public enum BatteryState {
         UNKNOWN,
-        CHARGE_FULL,
+        BATTERY_NORMAL,
-        CHARGE_MEDIUM,
+        BATTERY_LOW,
-        CHARGE_LOW,
+        BATTERY_CHARGING,
-        CHARGING,
+        BATTERY_CHARGING_FULL,
+        BATTERY_NOT_CHARGING_FULL
     }
 
     public boolean extendedInfoAvailable() {

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/impl/GBDevice.java

@@ -9,6 +9,7 @@ import android.support.v4.content.LocalBroadcastManager;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import nodomain.freeyourgadget.gadgetbridge.deviceevents.GBDeviceEventBatteryInfo.BatteryState;
 import nodomain.freeyourgadget.gadgetbridge.model.DeviceType;
 import nodomain.freeyourgadget.gadgetbridge.GBApplication;
 import nodomain.freeyourgadget.gadgetbridge.R;
@@ -42,6 +43,7 @@ public class GBDevice implements Parcelable {
     private short mBatteryThresholdPercent = BATTERY_THRESHOLD_PERCENT;
     //TODO: get rid of String mBatteryStatus in favor of Enum mBatteryState
     private String mBatteryStatus;
+    private BatteryState mBatteryState;
     private short mRssi = RSSI_UNKNOWN;
     private String mBusyTask;
 
@@ -180,7 +182,7 @@ public class GBDevice implements Parcelable {
 
     private void unsetDynamicState() {
         setBatteryLevel(BATTERY_UNKNOWN);
-        setBatteryStatus(null);
+        setBatteryState(BatteryState.UNKNOWN);
         setFirmwareVersion(null);
         setRssi(RSSI_UNKNOWN);
         if (mBusyTask != null) {
@@ -284,18 +286,14 @@ public class GBDevice implements Parcelable {
         }
     }
 
-    /**
+    public BatteryState getBatteryState() {
-     * Returns a string representation of the battery state.
+        return mBatteryState;
-     */
-    public String getBatteryStatus() {
-        return mBatteryStatus != null ? mBatteryStatus : GBApplication.getContext().getString(R.string._unknown_);
     }
 
-    public void setBatteryStatus(String batteryStatus) {
+    public void setBatteryState(BatteryState mBatteryState) {
-        mBatteryStatus = batteryStatus;
+        this.mBatteryState = mBatteryState;
     }
 
-
     public short getBatteryThresholdPercent() {
         return mBatteryThresholdPercent;
     }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java

@@ -228,9 +228,13 @@ public abstract class AbstractDeviceSupport implements DeviceSupport {
         Context context = getContext();
         LOG.info("Got BATTERY_INFO device event");
         gbDevice.setBatteryLevel(deviceEvent.level);
-        gbDevice.setBatteryStatus(deviceEvent.status);
+        gbDevice.setBatteryState(deviceEvent.state);
 
-        if (deviceEvent.level <= gbDevice.getBatteryThresholdPercent()) {
+        //show the notification if the battery level is below threshold and only if not connected to charger
+        if (deviceEvent.level <= gbDevice.getBatteryThresholdPercent() &&
+                (GBDeviceEventBatteryInfo.BatteryState.BATTERY_LOW.equals(deviceEvent.state) ||
+                        GBDeviceEventBatteryInfo.BatteryState.BATTERY_NORMAL.equals(deviceEvent.state))
+                ) {
             GB.updateBatteryNotification(context.getString(R.string.notif_battery_low_percent, gbDevice.getName(), deviceEvent.level),
                     deviceEvent.extendedInfoAvailable() ?
                             context.getString(R.string.notif_battery_low_percent, gbDevice.getName(), deviceEvent.level) + "\n" +

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/BatteryInfo.java

@@ -3,10 +3,15 @@ package nodomain.freeyourgadget.gadgetbridge.service.devices.miband;
 import java.util.Calendar;
 import java.util.GregorianCalendar;
 
-import nodomain.freeyourgadget.gadgetbridge.GBApplication;
+import nodomain.freeyourgadget.gadgetbridge.deviceevents.GBDeviceEventBatteryInfo.BatteryState;
-import nodomain.freeyourgadget.gadgetbridge.R;
 
 public class BatteryInfo extends AbstractInfo {
+    public static final byte DEVICE_BATTERY_NORMAL = 0;
+    public static final byte DEVICE_BATTERY_LOW = 1;
+    public static final byte DEVICE_BATTERY_CHARGING = 2;
+    public static final byte DEVICE_BATTERY_CHARGING_FULL = 3;
+    public static final byte DEVICE_BATTERY_CHARGE_OFF = 4;
+    
     public BatteryInfo(byte[] data) {
         super(data);
     }
@@ -18,21 +23,23 @@ public class BatteryInfo extends AbstractInfo {
         return 50; // actually unknown
     }
 
-    public String getStatus() {
+    public BatteryState getState() {
         if (mData.length >= 10) {
             int value = mData[9];
             switch (value) {
-                case 1:
+                case DEVICE_BATTERY_NORMAL:
-                    return GBApplication.getContext().getString(R.string.battery_low);
+                    return BatteryState.BATTERY_NORMAL;
-                case 2:
+                case DEVICE_BATTERY_LOW:
-                    return GBApplication.getContext().getString(R.string.battery_medium);
+                    return BatteryState.BATTERY_LOW;
-                case 3:
+                case DEVICE_BATTERY_CHARGING:
-                    return GBApplication.getContext().getString(R.string.battery_full);
+                    return BatteryState.BATTERY_CHARGING;
-                case 4:
+                case DEVICE_BATTERY_CHARGING_FULL:
-                    return GBApplication.getContext().getString(R.string.battery_not_charging);
+                    return BatteryState.BATTERY_CHARGING_FULL;
+                case DEVICE_BATTERY_CHARGE_OFF:
+                    return BatteryState.BATTERY_NOT_CHARGING_FULL;
             }
         }
-        return GBApplication.getContext().getString(R.string._unknown_);
+        return BatteryState.UNKNOWN;
     }
 
     public GregorianCalendar getLastChargeTime() {

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/MiBandSupport.java

@@ -737,6 +737,7 @@ public class MiBandSupport extends AbstractBTLEDeviceSupport {
         if (status == BluetoothGatt.GATT_SUCCESS) {
             BatteryInfo info = new BatteryInfo(value);
             batteryCmd.level = ((short) info.getLevelInPercent());
+            batteryCmd.state = info.getState();
             batteryCmd.lastChargeTime = info.getLastChargeTime();
             batteryCmd.numCharges = info.getNumCharges();
             handleGBDeviceEvent(batteryCmd);

app/src/main/res/values/strings.xml

@@ -74,10 +74,6 @@
     <string name="tap_a_device_to_connect">tap a device to connect</string>
     <string name="cannot_connect_bt_address_invalid_">Cannot connect. BT address invalid?</string>
     <string name="gadgetbridge_running">Gadgetbridge running</string>
-    <string name="battery_low">low</string>
-    <string name="battery_medium">medium</string>
-    <string name="battery_full">full</string>
-    <string name="battery_not_charging">not charging</string>
     <string name="installing_binary_d_d">installing binary %1$d/%2$d</string>
     <string name="installation_failed_">installation failed!</string>
     <string name="installation_successful">installation successful</string>