Heliaction,
I use noname 2000s in my planes.
I easily get 6 to 10 flights per charge.
A lot depends on when in the discharge curve you get nervous.
I usually quit around 4.6 volts.
I've had lots of flights by then and ready to go home.
Theoretically you should be good to 4 volts.
Some quit at 4.8, but there is still lots of power there and
it will remain at that voltage for quite awhile.
These are all loaded readings, I use a 24 ohm load, 200 mah.
Good Luck,
KW_Counter