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: Engine Exhaust (Carbon monoxide)
WARNING
Do not drive your vehicle if you smell exhaust gas inside the vehicle:
Engine exhaust gas is dangerous. This gas contains carbon monoxide (CO), which is
colorless, odorless, and poisonous. When inhaled, it can cause loss of consciousness
and death. If you smell exhaust gas inside the ...
Mazda 6 Owners Manual: Engine disassembly/assembly
1. Disconnect the engine and automatic transaxle. (ATX) (See AUTOMATIC
TRANSAXLE REMOVAL/INSTALLATION.)
2. Disconnect the engine and manual transaxle. (MTX) (See MANUAL TRANSAXLE
REMOVAL/INSTALLATION.)
3. Remove the intake-air system. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
4. Remove ...