MacBook Pro - Battery draining fast after long-term no use.

By far the easiest way to cause poor performance, instability, overheating and crashing is to install ANY third-party speeder-uppers, Cleaners, Optimizers, or Virus scanners, Bit Torrent, or a VPN that you installed yourself.

Third-party file Sync-ers such as DropBox, BackBlaze, OneDrive, or GoogleDrive can punish performance, but are not inherently dangerous.

¿are you running any of those?

Batteries are a wear item, like the soles of your shoes and the tires on your car. Their expected lifetime depends on use (as reflected in Charge cycles) and also in the passage of time, used or not. After a while, you should expect to have to replace the battery.

Battery life also depends on two factors you may be able to control a bit better. Lithium polymer batteries deteriorate when they get too hot, and when they are subject to very deep discharge. These should be avoided when possible.

Despite using these batteries in millions of Apple devices, there is still a lot of of randomness in exactly which battery will fail when.

Apple SUGGESTS (but does not Warrant) that your battery MAY last as long as 1000 charge cycles, provided all other factors are well-controlled.

Apple uses the criterion that a battery that doesn't to hold 80 percent of its original charge capacity should be serviced, and likely replaced.

When designing systems, that 80 percent rule is intended so that, over a Very large sample of devices, almost all will be able to achieve their 'mission' -- still have at least 80 percent capacity at the three-year mark.

Your battery is now about 6 years old. 3 hours from 100 percent to 25 percent is not bad performance. That is better than many users with a 6 year old battery are getting.

I come from a background of writing in Assembler, and machines where every CPU cycle mattered. I am scrupulous about removing all start up processes, and killing the unwanted Apple News, stocks, weather and the rest applications. scrupulous to the point where I will go into deep sudo mode to disable or remove them.

Equally, every self starting video and moving JPG are to be killed.

CPU cycle = energy used, and slower processing.

Sure, I don't play games or watch videos, but batteries last as long as possible.

25% an hour is about acceptable, if you can find a recharge at lunchtime, and as has been mentioned, read up on the specific battery technology in use and how best to optimise it.

My 2015 MacBook Air still gives me excellent life from full charge - I don't have specific numbers, but I reckon on a day's worth. power down if not doping 'something' and avoid wifi and blue tooth being active

R

[Edited by Moderator]