Apple Remote Desktop - Reports Battery Percentage or Battery Hrs Left
The "Battery Charge Remaining (mAh)" field in Apple Remote Desktop's Reports function indicates the remaining milliamp hours of the battery.

To find the battery percentage, you can use "Send UNIX Command" to remotely execute the following command:

pmset -g batt


The output is the percentage and status of the battery, including the estimated time until it will be fully discharged, for example:

51%; discharging; 3:24 remaining present: true