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.6 windshield fogged
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: Tire Pressure Monitoring System Initialization
In the following cases, system initialization must be performed so that the system
operates normally.
A tire pressure is adjusted.
Tire rotation is performed.
A tire or wheel is replaced.
The battery is replaced or completely drained.
The tire pressure monitoring system warning light i ...