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: Picture Quality Adjustment
WARNING
Always adjust the picture quality of the rear view monitor while the vehicle
is stopped: Do not adjust the picture quality of the rear view monitor while
driving the vehicle. Adjusting the picture quality of the rear view monitor such
as brightness, contrast, color, and tint while dri ...
Mazda 6 Owners Manual: Refrigerant pressure switch removal/installation
1. Remove the battery.
2. Discharge the refrigerant from the system. (See RECOVERY.) (See CHARGING.)
3. Loosen the refrigerant pressure switch using two spanners.
4. Remove in the order indicated in the table.
5. Install in the reverse order of removal.
Refrigerant Pressure Switch Installat ...