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: Dsc system inspection
Preparation
1. Verify that the battery is fully charged.
2. With ignition switch on, verify that the ABS warning light goes out after
2.4 seconds.
3. Turn the ignition switch off.
4. On level ground, jack up the vehicle and support it evenly on safety
stands.
5. Shift the transaxle to N posi ...
Mazda 6 Owners Manual: Variable air duct (vad) control solenoid valve inspection (l3)
1. Remove the VAD control solenoid valve. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
2. Inspect airflow between the ports under the following conditions.
If not as specified, replace the VAD control solenoid valve.
If as specified, carry out the Circuit Open/Short Inspection.
Circ ...