Charging Processes

When moving to the constant voltage phase, the battery management system selects one of the following charging processes:

  • Boost charge

  • Full charge

  • Equalization charge

Boost charge

With the boost charge process, a high charging voltage is applied to the battery. The battery is to be charged to between 85% and 90% of its current usable capacity in a very short time. You can adjust the charging voltage (parameter Cell charge nominal voltage for boost charge) and the duration (parameter Battery boost charge time) in accordance with the recommendations for the battery used.

Full charge

The objective of the full charge process is to recharge 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 Sunny Island performs a full charge of the battery when one of the following conditions is met:

  • The specified cycle time for the full charge has expired (parameter Cycle time full charge).

  • The sum of all discharges since the last full charge is eight times the nominal capacity of the battery.

You can adjust the charging voltage (parameter Cell charge nominal voltage for full charging) and the duration (parameter Battery full charge time) in accordance with the recommendations for the battery used.

Equalization charge

With the equalization charge process, the Sunny Island neutralizes any differences in the state of charge of individual battery cells which have arisen due to the different behaviors of the battery cells. By doing so, the Sunny Island prevents the premature failure of individual battery cells and extends the service life of the battery.

Further information on the equalization charge of lead-acid and lithium-ion batteries is contained in the Sunny Island operating manual (see www.SMA-Solar.com).

The Sunny Island performs an equalization charge of the battery if the automatic equalization charge function is activated and if one of the following conditions is met:

  • The specified cycle time for the equalization charge has expired (parameter Cycle time equalization charge).

  • The sum of all discharges since the last equalization charge is 30 times the nominal capacity of the battery.

You can adjust the charging voltage (parameter Time for equalization charge) and the duration (parameter Battery equalization charge time) in accordance with the recommendations for the battery used.

To maintain or service the battery - for example, in systems that are only operated seasonally - you can start an equalization charge manually (see the Sunny Island inverter operating manual at www.SMA-Solar.com).

    Charging Phases
    Automatic Temperature Compensation