A user on this Product Hunt said that kinds of monitoring app such as iStatmenu, Menubar apps, that constantly poll the CPU for data, can drastically impact battery life. Is it true?
Battery is affected with power consuming operations; cpu, hdd, bluetooth, wireless, etc.
So, yes. Amount of the cpu usage may drastically impact battery. Battery life is proportional to the frequency of charges/discharges.
Please consult to apple page