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: Indicators
Manual shift mode indication
In manual shift mode, the “M” of the shift position indication in the instrument
panel illuminates.
Gear position indication
The numeral for the selected gear illuminates.
NOTE
If the gears cannot be shifted down when driving at higher speeds, the
gear ...
Mazda 6 Owners Manual: Purge solenoid valve inspection
Airflow Inspection
Note
Perform the following test only when directed.
1. Disconnect the negative battery cable.
2. Remove the purge solenoid valve. (See PURGE SOLENOID VALVE
REMOVAL/INSTALLATION.)
3. Inspect airflow between the ports under the following conditions.
If not as specifi ...