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: Glass panel adjustment
1. Fully close the glass panel.
2. Measure the gap and height between the glass panel and body.
3. If not as specified, loosen the glass panel installation screws and
reposition the glass panel.
Clearance
a: -0.8-1.2 mm {-0.032-0.047 in}
b: 0 mm {0 in}
4. Tighten the installation scre ...
Mazda 6 Owners Manual: Panel light control switch removal/installation
1. Disconnect the negative battery cable.
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal.
Panel Light Control Switch Removal Note
1. Insert your hand from the lower side of the dashboard and squeeze the tabs
of the panel light control switch.
2. ...