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: Automatic transaxle removal/installation
1. Disconnect the negative battery cable.
2. Remove the battery and battery tray.
3. Remove the aircleaner component. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
4. Remove the front tires and splash shield.
5. Remove the under cover.
6. Remove the steering gear and power steering pipe. (See ...
Mazda 6 Owners Manual: Temporary Spare Tire
Inspect the temporary spare tire at least monthly to make sure it is properly
inflated and stored.
NOTE
The temporary spare tire condition gradually deteriorates even if it has not
been used.
The temporary spare tire is easier to handle because of its construction which
is lighter and small ...