Suunto D4i User Guide
Battery replacement
Suunto D4i displays a battery symbol as a warning when the power gets too low. When this happens, your Suunto D4i should not be used for diving until the battery has been replaced.
Contact an authorized Suunto service center for battery replacement. It is imperative that the change is made in a proper manner to avoid any leakage of water into the battery compartment or computer.
Defects caused by improper battery installation are not covered by the warranty.
All history and logbook data, as well as the altitude, personal and alarm settings, remain in the dive computer memory after the battery change. Other settings revert back to default values.