Different battery chemistries can accept a charge at varying rates. Typically, a FLOODED battery can accept C/5, while a sealed battery, such as gel or AGM
can typically accept C/3. The XW+NA model supports Lithium battery charging (see article FA226500) and also provides a CUSTOM battery menu so charge voltages can be entered manually.
Ultimately, it is the battery manufacturer that must provide the recommendations for charge voltages and charge rate, as a sealed battery can be permanently damaged if overcharged.