> 5.2 | Effects of Recovery Voltage

> The recovery voltage is caused by the inner chemical idleness. The battery voltage recovers almost to its old value after a heavy load is stopped as can be seen in Figure 10.
> Figure 10: Recovery voltage and voltage drops of a typical Li battery at GSM PCL5 load
> Furthermore, recovery voltage and voltage drops will rise with lower battery voltage and lower temperature. The recovery time depends on the battery and is typically in the range of 2 to 10 minutes after the end of a call or data connection. If the battery is discharged only by GSM load, the recovery voltage has no effect, because the battery has no time for recovering.
> The implemented software and battery parameters of the Siemens GSM module account for these effects to achieve best results. In Idle state the module software calculates the voltage loss (internal resistance and recovery voltage) likely to occur when a call is started. During idle mode, when the battery voltage is too low to ensure a trouble free active call, the module shuts down. The intention is to guarantee enough power left at least for a 1-minute call (e.g. an emergency call).