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: Pid/data monitor inspection
1. Connect the WDS or equivalent to the DLC-2.
2. Measure the PID value.
Note
Perform part inspection for the output device after PCM
inspection.
The PID/DATA MONITOR function monitors the calculated value of the
input/output signals in the PCM. Therefore, if a monitored value ...
Mazda 6 Owners Manual: Floor Mat
We recommend the use of Genuine Mazda floor mats.
WARNING
Make sure the floor mats are hooked on the retention pins to prevent them
from bunching up under the foot pedals: Using a floor mat that is not secured
is dangerous as it will interfere with the accelerator and brake pedal operation,
...