A low level of electrolyte fluid will cause the battery to discharge quickly.

Inspect the electrolyte level at least once a week. If it is low, remove the caps and add enough distilled water to bring the level between the upper and lower level (illustration).
Do not overfill.
Examine the specific gravity of the electrolyte with a hydrometer, especially during cold weather. If it is low, recharge the battery.
Battery Maintenance
Battery RechargingMazda 6 Owners Manual: No.1 air bag system warning light does not illuminate
Diagnostic Procedure
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while doing the inspection to discover whether
poor contact points are the cause of any intermittent malfunction. If there
is a problem, check to make sure connec ...
Mazda 6 Owners Manual: Clock spring inspection
1. Remove the clock spring.
2. Inspect for continuity between the clock spring terminals using an
ohmmeter.
If not as specified, replace the clock spring.
Note
When the vehicle-side connector of clock spring is disconnected,
the terminals 1A,1B, 1C and 1D are shorted to prevent ...