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: Discharge headlight control unit removal/installation
Caution
Incorrect servicing of the discharge headlight control unit could
result in electrical shock. Before servicing the discharge headlight control
unit, always refer to the Discharge headlight service warnings. (See
DISCHARGE HEADLIGHT SERVICE WARNINGS)
When replacing the discharg ...
Mazda 6 Owners Manual: Trailing link removal/installation
Caution
Performing the following procedures without first removing the ABS
wheel-speed sensor may possibly cause an open circuit in the harness if it
is pulled by mistake. Before performing the following procedures, remove the
ABS wheel-speed sensor (axle side) and fix it to an appropri ...