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: Front door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the front door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Front Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...
Mazda 6 Owners Manual: Woofer removal/installation
4SD
1. Disconnect the negative battery cable.
2. Remove the rear package trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
5HB
1. Disconnect the negative battery cable.
2. Remove in the order indicated in the table.
3. Install in the rev ...