Battery Charger

• Conventional automatic chargers:
  
  These have higher charging capacities and quick charging functions. The battery must be isolated from the vehicle electrical system for charging. This is the only way to guarantee that the electronics in the vehicle are not damaged. MBUSA advises against using the starting aid feature in the larger battery chargers.
  
  The purpose of "normal charging" is to charge a discharged battery up over a longer charging period (approx. 8-12 h) to a full charge (approx. 100%) with a relatively low charging current. On chargers on which the charging current can be adjusted, the charging current (arithmetic mean) should be set to approx. 10% of the numerical value of the battery capacity (88 Ah x 0.1 = approx. 9 A). Completely or nearly completely discharged batteries must be charged with a low charging current to remove the sulphate layer. A quick increase in the battery voltage is typical for sulphated batteries. "Quick charging" should only be used to charge the battery enough to start the engine (partial charge). This can be achieved relatively quickly (approx. 20 - 30 minutes) with the appropriate charging current (not greater than 80% of the numerical value of the battery capacity, preferably 50%).
  
  Chargers require a certain battery minimum voltage to start the charging procedure. This value differs for different chargers; check with the manufacturer. If your shop frequently encounters completely discharged batteries, this feature should be taken into consideration during the purchase.
  
  
• Chargers suitable for "buffer operation":
  
  Most useful are electronically controlled chargers which are also approved for charging with the battery connected (buffer operation). The charge voltage in these chargers is free of residual ripple, current and voltage spikes. This ensures that the electronics in the vehicle are not damaged. Many of these type of chargers feature a "backup mode" function. A limited current supply to the vehicle electrical system preserves the stored codes and fault code information while the battery is replaced (alternative to quiescent current retention unit). The disadvantage of electronic chargers is their relatively low charging capacity (20A).



• Parallel circuit:
  
  All batteries are connected to the same voltage. The charging current for each battery results from the state of the battery in question. The magnitude of the charging current results from the total of the individual batteries (total of Ah values x 0.1). The prerequisite for using a parallel circuit is that the battery Ah values are nearly equal. The age and discharge state should also be comparable. For this reason a parallel circuit should only be used for charging new batteries for the first time.