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: Power outside mirror inspection
1. Disconnect the power outside mirror connector.
2. Apply battery positive voltage to the power outside mirror terminals and
inspect the operation of the power outside mirror.
If not as specified, replace the power outside mirror.
3. Inspect for continuity between the power outside mi ...
Mazda 6 Owners Manual: Front drain hose installation
Caution
If the front drain hose is pinched or bent anywhere, the water in the hose
may not discharge and enter the inside of the vehicle. During and after
installation of the trims and the headliner, always make sure there is no
interference with the front drain hose. Fix any problem if found ...