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: Inspecting Coolant Level
WARNING
Do not use a match or live flame in the engine compartment. DO NOT ADD
COOLANT WHEN THE ENGINE IS HOT: A hot engine is dangerous. If the engine has
been running, parts of the engine compartment can become very hot. You could be
burned. Carefully inspect the engine coolant in the coola ...
Mazda 6 Owners Manual: Flasher unit inspection
1. Connect the connector to the flasher unit.
2. Connect the negative battery cable.
3. Measure the voltage at the flasher unit using voltmeter.
When inspecting terminal F for continuity, disconnect the flasher unit connector.
4. If the value are not as specified in the Terminal Voltag ...