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: 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 ...
Mazda 6 Owners Manual: Owner Maintenance Precautions
The owner or a qualified service technician should make these vehicle inspections
at the indicated intervals to ensure safe and dependable operation.
Bring any problem to the attention of an Authorized Mazda Dealer or qualified
service technician as soon as possible.
At Least Twice a Year (For ...