If you want to record a Full HD video by using a smartphone, eg: Samsung Galaxy S5 or LG G4 or other similar phones, you will be able to record for about 1 hour to 1 hour and 30 minutes.
The idea is that you won’t have that much space on your device to record for 1 hour and a half. You might want to lower the quality to HD, 720p.
Also, it is a good idea to buy an external battery charger and while you record with your phone, have the phone connected to the external battery charger.
These battery chargers are pretty cheap, especially during the Black Friday event.
A 2040 mAH battery could be drained from 100% to 0% for about 1 hour and a half of video recording in Full HD.