Keep a value during a shutdown

[SunsetRunner]

Hello the community

In my personal clockfaces I want to get the duration since last charging.

I found the solution to get the date but the value in the constante is erased during night shutdown.

Do anyone know how write a value in permanent memory and get it after reboot 

Thanks by advance.

[Gondwana · Accepted solution]

https://dev.fitbit.com/build/reference/device-api/fs/