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: 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 ...
Mazda 6 Owners Manual: Transaxle oil replacement
1. Remove the drain plug with the washer.
2. Drain the oil into a suitable container.
3. Install a new washer and the drain plug.
Tightening torque
40-58 N·m {4.0-6.0 kgf·m, 29-43 ft·lbf}
4. Remove the oil level plug with washer and add nthe specified amount and
type of oil through t ...