How to send a float value from client to server

Hello, I have a problem sending values from a client to a server in unity network.
I have a class that sends the percentage of the battery in the client and that will be updating in the server but when I run client-server, the server does not receive data and the client shows me that:

Trying to send command for object without authority.
UnityEngine.Networking.NetworkBehaviour:SendCommandInternal(NetworkWriter, Int32, String)
BatteryInfo:CallCmdSendBatteryValue(Single)
BatteryInfo:Update() (at Assets/Scripts/BatteryInfo.cs:17)

this is my code:

Code (CSharp):

1. using System;
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine;
5. using UnityEngine.Networking;
6. public class BatteryInfo : NetworkBehaviour {
7.     [SyncVar]
8.     public float valorBateria;
9.     private void Update()
10.     {
11.    
12.         if (!isServer)
13.         {
14.             valorBateria = (SystemInfo.batteryLevel) * 100;
15.             CmdSendBatteryValue(valorBateria);
16.         }
17.    
18.     }
19.     [Command]
20.     public void CmdSendBatteryValue(float b)
21.     {
22.         RpcUpdateBaterry(b);
23.     }
24.     [ClientRpc]
25.     public void RpcUpdateBaterry(float b)
26.     {
27.         valorBateria = b;
28.     }
29. }

Am i using using the commands and RpcClient wrong?
I am usin unity 2017

 

A Command can only be sent by the client on either a GameObject that client has been assigned authority over, or that client's Player GameObject.

So you have 3 choices. You can move this Command to a script on the Player GameObject, assign authority of this object to that client before it needs to send the Command, or send the float using a Unet Message instead of a Command. Unet Messages are sent without association to any networked GameObject, so are ideal for instances where you don't want to be bothered with object authority.