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: Joint shaft 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 and fix it to an appropriate place wh ...
Mazda 6 Owners Manual: Lane-keep Assist System (LAS) & Lane Departure Warning System (LDWS)
The Lane-keep Assist System (LAS) & Lane Departure Warning System (LDWS) alerts
the driver that the vehicle may be deviating from its lane and it provides steering
assistance to help the driver stay within the vehicle lanes.
The Forward Sensing Camera (FSC) detects the white lines (yellow l ...