Find out battery charge capacity in percentage using C# or .NET

Don't have a laptop to test with, but I'm guessing you could use the WMI class Win32_Battery.

It has two fields that look interesting - DesignCapacity, which tells you

Design capacity of the battery in milliwatt-hours.

and FullChargeCapacity, which has the fascinating note that

Full charge capacity of the battery in milliwatt-hours. Comparison of the value to the DesignCapacity property determines when the battery requires replacement.

So my guess is that you can use WMI to read these two values, and then calculate FullChargeCapacity/DesignCapacity to find the battery health percentage number.

EDIT

Here's a brief example of accessing WMI information using C#. I first added a reference to the System.Management assembly. Then:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Management;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            System.Management.ObjectQuery query = new ObjectQuery("Select * FROM Win32_Battery");
            ManagementObjectSearcher searcher = new ManagementObjectSearcher(query);

            ManagementObjectCollection collection = searcher.Get();

            foreach (ManagementObject mo in collection)
            {
                foreach (PropertyData property in mo.Properties)
                {
                    Console.WriteLine("Property {0}: Value is {1}", property.Name, property.Value);
                }                   
            }
        }
    }
}

Also, note that you are basically running a SQL-like query against WMI, so you can vary that if you want. Windows Management Instrumentation Query Language, or WQL, is what you want to search for to learn more about it.

Also take a look at ahawker's answer, it may end up being more helpful if WMI isn't properly capturing the battery data, as he notes.

It seems that you are looking for the values of FullChargeCapacity, DesignCapacity and CurrentCapacity. As someone who has solved this problem before, let me make a few comments.

The first route normally taken would be through a WMI query (Win32_Battery). However, on the test laptops I ran the WMI query (Win32_Battery) against, which included multiple manufacturers, I consistently ran into the problem of FullChargeCapacity always returning zero. Since that didn't work, I re-wrote my solution using Win32 API and was successfully able to get accurate values that way.

Hopefully, WMI will work for you. However, if you experience the same issues I did, here is a summary of the steps required for Win32API.

• Use SetupDiGetClassDevs to get a device handle to the battery (GUID_DEVCLASS_BATTERY).

• Use SetupDiEnumDeviceInterfaces to get the device data (SP_DEVICE_INTERFACE_DATA).

• Use SetupDiGetDeviceInterfaceDetail to get the device path (SP_DEVICE_INTERFACE_DETAIL_DATA).

• Use CreateFile with the device path to get handle to battery.

• Use DeviceIoControl with battery handle, IOCTL_BATTERY_QUERY_TAG to retrieve battery query info (BATTERY_QUERY_INFORMATION).

• Use DeviceIoControl with battery handle, IOCTL_BATTERY_QUERY_INFORMATION and marshalled structs to to retrieve battery info (BATTERY_INFORMATION).

Also see the Enumerating Battery Devices post on MSDN as I found that quite helpful.

I can post my solution if necessary but with all the native struct definitions, it ends up around 500 lines of code.

Example source code: https://gist.github.com/ahawker/9715872

No need to unnecessary complicate things. Try something like:

using System.Management;

PowerStatus pwr = SystemInformation.PowerStatus;

String strBatteryChargingStatus;
strBatteryChargingStatus = pwr.BatteryChargeStatus.ToString();
MessageBox.Show("battery charge status : " + batterystatus);

String strBatterylife;
strBatterylife = pwr.BatteryLifePercent.ToString();
MessageBox.Show("Battery life: "+batterylife);

In this way you can get all of the battery information.