3G’s can shortening battery life probably because of ‘bad’ (example: 2 bars out of 5) 3G coverage, causing phones to do more work to stay connected. Currently, 2G/GPRS have an better coverage which result in a better battery lifetime.
2G/GPRS uses much less juice for voice calls, but does not support simultaneous voice + data in this mode:
Devices supporting GPRS are divided into three classes:
Can be connected to GPRS service and GSM service (voice, SMS), using both at the same time. Such devices are known to be available today.
Can be connected to GPRS service and GSM service (voice, SMS), but using only one or the other at a given time. During GSM service (voice call or SMS), GPRS service is suspended, and then resumed automatically after the GSM service (voice call or SMS) has concluded. Most GPRS mobile devices are Class B.
Are connected to either GPRS service or GSM service (voice, SMS). Must be switched manually between one or the other service.
So, to save battery power on BB 9000/9700 switch to 2G/GPRS mode only: