Canon PowerShot S1 IS User Manual page 144

It takes approximately 250 minutes for the
charger to fully recharge the batteries (as
determined by testing at Canon facilities).
Please do not charge batteries in areas where
the temperature is outside the range of 0 to
35 °C (32 to 95 °F).
Charging time varies according to ambient
temperature and to the batteries' initial charge
state.
The battery charger may emit noise while
charging. This is not a malfunction.
Battery/Charger Kit CBK100 can also be used.
Use Canon AA-size batteries NB-1AH with the
charger included in the CBK100 kit.
142 Appendix