Boost Charge; Charging Processes - SMA SUNNY ISLAND 8.0H Installation Manual

SMA Solar Technology AG
9.2.2 Charging Processes
For transition to the constant voltage phase, battery management chooses one of the following three

charging processes:

• Boost charge

• Full charge
• Equalisation charge
Boost charge
For boost charge, a high charging voltage is applied to the battery. The battery is charged to 85% to
90% of the currently available battery capacity within a short period of time.
Boost charge allows for a high degree of utilisation of the generator and leads to gassing of the FLA
batteries, which in turn leads to equalisation of the electrolyte.
Full charge
The aim of full charge is to charge the battery to a state of charge of at least 95%. This should
compensate for effects caused by any insufficient charging and should also increase the service life
of the battery.
The off-grid inverter carries out full charging of the battery if one of the following conditions is met:
• The specified cycle time for full charge has elapsed (e.g. every 14 days).
• The total of all electric discharges since the last full charging corresponds to eight times the rated
capacity of the battery.
External charging device
An external charging device or a charge controller can also carry out full charge of the battery.
The Sunny Island treats this full charge as equivalent to a full charge that it carries out itself.
Equalisation Charge
With equalisation charge, the off-grid inverter neutralises differences in the states of charge of
individual battery cells that have resulted from the differing behaviour of various battery cells. In this
way, the off-grid inverter prevents the premature failure of individual battery cells and increases the
service life of the battery.
The off-grid inverter carries out an equalisation charge of the battery if the automatic equalisation
charge is activated and one of the following conditions is met:
• The specified cycle time for equalisation charge has elapsed (e.g. every 30 days).
• The total of all electric discharges since the last equalisation charge corresponds to 30 times the
rated capacity of the battery.
Installation Manual
9 Battery Management
SI80H-60H-OffGrid-IA-en-11 127