diff --git a/raspberry/roberto/Serial.py b/raspberry/roberto/Serial.py
index 79cb35b..944284e 100644
--- a/raspberry/roberto/Serial.py
+++ b/raspberry/roberto/Serial.py
@@ -65,11 +65,11 @@ class Serial(object):
             #self.alive = False
             #raise
 
-    def add_callback(self, cmd, callback, arg):
+    def add_callback(self, cmd, callback, arg=None):
         if not cmd in self._callbacks:
             self._callbacks[cmd] = []
         self._callbacks[cmd].append( (callback, arg) )
 
-    def del_callback(self, cmd, callback, arg):
+    def del_callback(self, cmd, callback, arg=None):
         if cmd in self._callbacks:
             self._callbacks[cmd].remove( (callback, arg) )
diff --git a/raspberry/roberto/camera/camera_gstreamer_webrtc.py b/raspberry/roberto/camera/camera_gstreamer_webrtc.py
index 0e7ed6c..9f0ce19 100644
--- a/raspberry/roberto/camera/camera_gstreamer_webrtc.py
+++ b/raspberry/roberto/camera/camera_gstreamer_webrtc.py
@@ -147,6 +147,8 @@ class WebRTCCamera(Thread):
                         self.close_global_pipeline()
                     else:
                         print("%d clients left" % self._num_clients)
+                elif item['job'] == "emit":
+                    sio.emit(item['event'], item['data'])
                 else:
                     print("unknown job: %s" % item['job'])
                 self._queue.task_done()
@@ -167,10 +169,17 @@ class WebRTCCamera(Thread):
         print('camera sid is', sio.sid)
         self.sid = sio.sid
         self.connected = True
+        from roberto import serial
+        serial.add_callback('B', self.send_battery, None)
 
     def disconnect(self):
         print("camera.disconnect()")
         self.connected = False
+        from roberto import serial
+        try:
+            serial.del_callback('B', self.send_battery, None)
+        except:
+            pass
         sio.disconnect()
 
     def connect_client(self, sid, room):
@@ -184,6 +193,13 @@ class WebRTCCamera(Thread):
             return
         self._queue.put({'job':'disconnect_client', 'sid':sid})
 
+    def emit_async(self, event, data):
+        self._queue.put({'job':'emit', 'event':event, 'data':data})
+
+    def send_battery(val, arg=None):
+        print("sending battery value %s" % val)
+        self.emit_async('battery', val)
+
     def start_global_pipeline(self):
         print("STARTING PIPELINE")
         desc = PIPELINE_DESC
diff --git a/raspberry/roberto/views/frontend/templates/index.html b/raspberry/roberto/views/frontend/templates/index.html
index b23faeb..01bcd44 100644
--- a/raspberry/roberto/views/frontend/templates/index.html
+++ b/raspberry/roberto/views/frontend/templates/index.html
@@ -215,7 +215,6 @@ function clearText() {
         ctx.font = "24px Arial";
         ctx.fillStyle = "blue";
         //ctx.fillText("Hello World", canvas.width/3, 30);
-        //socket.emit('get_stats', { "type": ["battery"] });
         
         $('form#message').submit(function(event) {
           socket.emit('text', {data: $('#message_data').val()});
diff --git a/raspberry/roberto/views/websocket/routes.py b/raspberry/roberto/views/websocket/routes.py
index bb22409..93ca791 100644
--- a/raspberry/roberto/views/websocket/routes.py
+++ b/raspberry/roberto/views/websocket/routes.py
@@ -74,12 +74,10 @@ def webrtc_message(data):
         print("unknown message type")
     socketio.emit('message', data=data, room=ROOM, skip_sid=sid)
 
-@socketio.on('get_stats')
-def get_stats(data):
+@socketio.on('battery')  # ok
+def battery_message(data):
     sid = request.sid
-    print("client %s requesting stats" % sid)
-    from roberto import serial
-    serial.add_callback('B', display_battery, sid)
+    socketio.emit('battery', data, room=ROOM, skip_sid=sid)
 
 @socketio.on('disconnect')
 def disconnect():
@@ -87,11 +85,7 @@ def disconnect():
     print("Received Disconnect message from %s" % sid)
     leave_room(ROOM)
     webrtccamera.disconnect_client(sid, ROOM)
-    from roberto import serial
-    try:
-        serial.del_callback('B', display_battery, sid)
-    except:
-        pass
+
 
 @socketio.on('connect')
 def connect():
@@ -109,7 +103,4 @@ def default_error_handler(e):
     for key in request:
         print('%s: %s' % (key, repr(request[key])))
 
-def display_battery(val, sid=ROOM):
-    print("sending battery value %s to client %s" % (val, sid))
-    socketio.emit('battery', data=val, room=sid)
-    #socketio.emit('battery', data=val)
+