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: No. 2 all on-board diagnostic functions inoperative
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while doing the inspection to discover whether
poor contact points are the cause of any intermittent malfunctions. If there
is a problem, check to make sure connectors, terminals and wir ...
Mazda 6 Owners Manual: Uniform Tire Quality Grading System (UTQGS)
This information relates to the tire grading system developed by the U.S. National
Highway Traffic Safety Administration for grading tires by tread wear, traction,
and temperature performance.
Tread Wear
The tread wear grade is a comparative rating based on the wear rate of the tire
when tes ...