Just like a car battery or any other battery, the more you use it, the more power it takes.
So, it's kinda understandable that Kali will take a little more power then Mac OS. Since Mac's are for personal use and Kali is more like "Work Related".
Once the systems boots, you should check the running apps on both OS's and compare them, I bet you have almost 2x more apps on Kali then on Mac.
This being said, you should try to keep checking your battery usage with some application on Kali and try to understand what is draining your battery that fast, probably a process you don't even need..
Bottom line, I have 8 Lappys at home all with Kali, some lappys are 15 years old and the battery still hangs in there for over an hour in most of them. Some of them don't have all the apps running, and others have just wireless and network sniffers (which drain the battery under an hour).
In 6 years I never had battery related issues that didn't come from application usage or any other messed up configuration.
