when it is plugged in, the battery line increases
we notice it starts to go up first at t=8
it then goes down, then at t=16, it goes up again
so anywhere where it increases or stays constant
from t=8 to t=12 then t=16 to t=20
8+6=14, or 2pm
12+6=18, or 6pm
16+6=22, 4am
20+6=26, 2 days and 2 hours, 8am
so from 2pm to 6pm and from 4am to 8am
3pm
5pm are the answers