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: Transaxle range (tr) switch inspection
Operating Inspection
1. Verify that the starter operates only when the ignition switch is at the
START position with the selector lever in P or N position.
If not as specified, adjust the TR switch.
2. Verify that the back-up lights illuminate when shifted to R position with
the ignition ...
Mazda 6 Owners Manual: New standards
Following is a comparison of the previous standard and the new standard.
#1 : Diagnostic trouble codes depend on the diagnostic test mode
#2 : Controlled by the PCM
#3 : In some models, there is a fuel pump relay that controls pump speed.
That relay is now called the fuel pump relay (s ...