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: Symptom troubleshooting
Verify the symptoms, and perform troubleshooting according to the
appropriate number.
Vehicles with ABS/TCS
Vehicles with DSC
*1 : DSC system contains traction control function, DSC indicator light goes
on and off while DSC operates.
*2 : DSC indicator light goes on and off while D ...
Mazda 6 Owners Manual: Relay inspection
Relay Type
Four-terminal
Type A
1. Remove the relay.
2. Inspect for continuity between the relay terminals using an ohmmeter.
If not as specified, replace the relay.
Type B
1. Remove the relay.
2. Inspect for continuity between the relay terminals using an ohmmeter.
If not as ...