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: Canceling Operation of Blind Spot Monitoring (BSM)
The Blind Spot Monitoring (BSM) system can be set to inoperable.
When the Blind Spot Monitoring (BSM) is set to inoperable, the Blind Spot Monitoring
(BSM) and Rear Cross Traffic Alert (RCTA) systems are turned off and the Blind Spot
Monitoring (BSM) OFF indicator light in the instrument cluste ...
Mazda 6 Owners Manual: Air mix actuator inspection
1. Connect battery positive voltage to terminal D or F and ground to terminal
F or D of the air mix actuator.
2. Verify that the air mix actuator operates as shown below.
If not as specified, replace the air mix actuator.
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3. Verify that the resistance between the terminals of the ...