What battery size fits inside the FX-5 cabinet, and what is the maximum Ah rating the charger can support?

The FX-5 cabinet fits up to two 7 Ah batteries (Page 109) [1], though some specifications indicate a maximum of 10 Ah can fit inside the enclosure (Page 6) [1].

The panel's charger supports a maximum capacity of 24 Ah (Page 70) [1].

If batteries larger than those fitting in the cabinet are required, an external BC-3 battery cabinet must be used (Page 109) [1].