The BMW 7 Series is equipped as standard with a maintenance-free battery. With this battery, as part of maintenance, it is no longer necessary to add distilled water, but when working with such batteries, you need to be guided by some rules.
The cover has a ventilation hole through which the battery can «breathe». To prevent electrolyte leakage, the battery must not be tilted more than 45°.
You can use a normal charger or a fast charger to charge the battery. In the latter case, the AB must be removed.
If an electronic charger is used to charge the battery, the battery can be charged in the installed and connected state. The electronics of the charger prevents voltage surges during charging.
Heavily discharged batteries should only be charged using an electronic charger. When charging with a normal charger, the initial current is too high, so the battery may be damaged or disabled.
If the electrolyte level in the battery is too low, for example, when operating a car in a hot climate, it is necessary to add distilled water to the battery.
If the vehicle is not in use, the battery must be recharged every 6 weeks.
If the car is not used for more than 6 weeks, then the battery must be removed and stored in a charged state. The storage temperature must be between 0 and +27°C, as while the battery has the lowest self-discharge. After 3 months, the battery needs to be recharged. Battery contacts must be regularly cleaned and lubricated with protective grease.
Starting devices should only be used in exceptional cases, as in this case, the battery will be subjected to a very large current.