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: Range of topics
This manual contains procedures for performing all required service
operations. The procedures are divided into the following five basic
operations:
Removal/Installation
Disassembly/Assembly
Replacement
Inspection
Adjustment
Simple operations which can be perf ...
Mazda 6 Owners Manual: Manifold absolute pressure (map) sensor inspection
Note
Perform the following inspection only when directed.
The following vacuum values are indicated by relative pressure
from the MAP sensor.
1. Connect the SSTs (WDS or equivalent) to the DLC-2.
2. Turn the ignition switch to ON (Engine OFF).
3. Select MAP PID on the SSTs (WDS or equi ...