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: Abs (abs/tcs) hu/cm removal/installation
Caution
When replacing the ABS (ABS/TCS) HU/CM, configuration procedure
must be done before removing the ABS (ABS/TCS) HU/CM. If configuration is
not completed before removing the ABS (ABS/TCS) HU/CM, TCS will not work
properly (with TCS model).
Do not drop the ABS (ABS/TCS) HU/CM. Re ...
Mazda 6 Owners Manual: Outside Temperature Display
When the ignition is switched ON, the outside temperature is displayed.
NOTE
Under the following conditions, the outside temperature display may differ
from the actual outside temperature depending on the surroundings and vehicle conditions:
Significantly cold or hot temperatures.
Sudden ...