diff --git a/app/ocpp_proto/chargepoint.py b/app/ocpp_proto/chargepoint.py
index 51e125d..8499762 100644
--- a/app/ocpp_proto/chargepoint.py
+++ b/app/ocpp_proto/chargepoint.py
@@ -145,6 +145,10 @@ class ChargePoint(cp):
         id_token_info = await self.__get_id_token_info(id_token)
         return call_result.AuthorizePayload(id_token_info)
     
+    @on(Action.MeterValues)
+    async def on_meter_values(self, **kwargs):
+        return call_result.MeterValuesPayload()
+    
     @on(Action.TransactionEvent)
     async def on_transaction_event(
         self,
diff --git a/app/util/websocket_wrapper.py b/app/util/websocket_wrapper.py
index 12eacee..9b11d25 100644
--- a/app/util/websocket_wrapper.py
+++ b/app/util/websocket_wrapper.py
@@ -12,13 +12,13 @@ class WebSocketWrapper():
     async def recv(self) -> str:
         try:
             text = await self._websocket.receive_text()
-            logger.info("Message received: {}", text)
+            logger.info("Message received: %s", text)
             return text
         except WebSocketDisconnect as e:
             raise ConnectionClosed(e.code, 'WebSocketWrapper')
 
     async def send(self, msg: str) -> None:
-        logger.info("Message sent: {}", msg)
+        logger.info("Message sent: %s", msg)
         await self._websocket.send_text(msg)
 
     async def close(self, code: int, reason: str) -> None: