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: Cooling system service warnings
COOLING SYSTEM SERVICE WARNINGS
Warning
Never remove the radiator cap or loosen the radiator drain plug
while the engine is running, or when the engine and radiator are hot.
Scalding coolant and steam may shoot out and cause serious injury. It may
also damage the engine and cooling sys ...
Mazda 6 Owners Manual: Automatic Brake Operation Display (Type A Instrument Cluster)
“Smart City Brake Support activated” is indicated in the active driving display,
and “Smart City Brake Support Activated” is indicated in the multi-information display
after the SCBS brakes or the brake assist (SCBS brake assist) is operated.
NOTE
The collision warning beep sounds ...