If the battery in your Android device keep less than 2 days you should think about switching back to GSM network and rather use WIFI connection to browse internet.

To swith to 2G GSM network go to Settings/Wireless and Network/Mobile Networks and check the option ? Use only 2G Networks?.

If in your phone there is no such options try to dial the code *#*#4636#*#* and choose Phone Information, set GSM Only in Set preferred Network Type.

Good luck