Why is the battery draining faster?

Question

macOS

I have an old Macbook 2010 Mid 7.1 (white).
After a complete reinstallation of the system (from the old Snow Leopard to OS X El capitan) on a blank SSD, the battery began to drain quickly. Those. Previously, it was calmly and very slowly discharged, but now the charge goes away on the fly (enough for about an hour).
I’ll clarify, despite the pretty used battery and the status (soon for replacement), the battery worked quite normally before reinstalling, it lasted about 3 hours.
What could be the problem? Who is an expert in the Mac, tell me: maybe I should check some settings?
Thank you.

Answer 1

Most likely, some process loads the CPU, as a result of incorrect operation after the update. First of all, in monitoring the system, pay attention to processes that have a high percentage of CPU usage, if any, then Google is here to help in a specific case. Often this is solved by resetting smc and pram . In the same place, in the system monitoring, there is an Energy tab, where you can sort processes by energy impact.
It's unlikely that the battery dipped drastically right after the update, but to reassure yourself, you can see the current battery capacity in the System Information app on the Power tab.