Some batteries are chosen from the Device Chooser as a unit of their own; others never appear there at all. One question decides which yours is: does the box output AC?
A smart battery — sold as an AC, AC‑coupled or all-in-one battery — has an inverter built into the case and outputs AC. Under G98/G99 that makes it a generating unit, so it must be chosen from the Device Chooser. Its register entry describes the inverter inside — the export kW, phase and protection the DNO assesses — so choosing your battery there isn’t mis-filing it as an inverter: it is an inverter too.
A DC battery outputs nothing by itself — it attaches to the DC side of an inverter and is never in the chooser. It is recorded as the Battery / Storage capacity on that inverter’s row.
The ENA register has no storage column — an entry carries the inverter’s figures only. The DNO forms do declare each unit’s storage, so the kWh is always entered by you, on the unit’s own row — whether the cells are built into the device or attached to it. (A Battery Only Inverter also takes the battery chemistry; a V2G charger takes the usable capacity of the largest vehicle it will serve.) The figure prints on the forms; routing reads only the inverter’s kW.
Not solar-connected. A Battery Only Inverter is a grid-charged battery — a smart battery, or a battery inverter with DC modules — with no PV attached: it charges cheaply during off-peak hours, then powers the premises (or exports) at peak. The Device Chooser offers the same devices under Solar Inverter and Battery Only Inverter — the register can’t tell them apart; the type records what charges the battery: solar, or the grid. Storage attached to a solar inverter is not “battery only”: it rides the Solar Inverter row as that unit’s storage figure and adds no unit of its own.