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: Service cautions
HANDLING INSUFFICIENT REFRIGERANT LEVEL
If an insufficient refrigerant level is detected at troubleshooting,
do not charge (add) the refrigerant. Because an accurate amount of
refrigerant cannot be determined from the pressure indicated on the manifold
gauge, never charge the refrigeran ...
Mazda 6 Owners Manual: Operating Tips for CD Player
Condensation phenomenon
Immediately after turning on the heater when the vehicle is cold, the CD or optical
components (prism and lens) in the CD player may become clouded with condensation.
At this time, the CD will eject immediately when placed in the unit. A clouded CD
can be corrected sim ...