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: Turning the Engine Off
WARNINGDo not stop the engine while the vehicle is moving: Stopping the
engine while the vehicle is moving for any reason other than in an emergency is
dangerous. Stopping the engine while the vehicle is moving will result in reduced
braking ability due to the loss of power braking, which coul ...
Mazda 6 Owners Manual: Direct Mode
Direct mode can be used for temporarily switching gears by operating the steering
shift switch while the vehicle is being driven with the selector lever in the D
range.
While in direct mode, the D and M indication illuminate and the gear position
in use is illuminated. Direct mode is canceled ...