Battery drains too fast when device is Shut Down When I bought my brand new Macbook, it was like 9-months old (according to battery production date) and still had almost 40% charge on first turn on.

But after that, every time I charge my Macbook (to around 50%) for storage when I don't plan to use it and Shut Down the Macbook, the battery is completely drained (it won't turn on before charging) after only 2-3 months

This happens almost every time, I don't understand why (I know dropping a few percentage is normal, but not the entire battery...)

Please note:


I am sure it is turned off and not just in sleep mode.
I store it in a 18-24 (Celsius) environment.
My battery holds perfectly (around 8-10 hours) when device is on and I'm working with the laptop.
Battery Health 2 application shows the battery health is 98% (4294 mAh)
Firstly, try disabling WiFi before you sleep or power it off in case that is preventing sleep or waking it excessively.   

I would get Apple service to run a battery diagnostic. This is the sort of thing they can very rapidly diagnose and easily measure if they have it in for service. 

You should have months of stability if you charge your battery to 50% and then power it down. That’s what Apple recommends for long term storage. Something isn’t proper and warranty / AppleCare likely covers repair the bulk of them. Even if you’re out of coverage, get a quote and free diagnostic. 


https://www.apple.com/batteries/maximizing-performance/


Support is easy to get started over chat or phone - https://support.apple.com. You are doing everything right and I hope it’s not a flat battery that you end up having to pay to swap when it becomes too unfit for your needs.