looking for a laptop that can work as much as possible when theres no electricity.

Some older laptops had easily replaceable batteries.
Of course, the replacement batteries needed to eventually be charged up.
Today's modern laptops have all day run times for normal work. They are more efficient.
 
Thanks.
do someone has any recomandation of a good power bank battery? does a power bank battery for laptops can charge smartphones aswell or it'll damage the smartphone?