Sessy Home Battery

Omnibattery connects to a Sessy through the local HTTP API exposed by its dongle. The Sessy support is still looking for testers, so report any model or firmware-specific behaviour when asking for help.

Connection

The dongle must be reachable from Home Assistant. Enter the host or IP, HTTP port and the credentials printed on the dongle.

Field	Description	Default
Name	Name used for the battery device	—
Host	IP address or hostname of the Sessy dongle	—
HTTP port	Local API port	80
Username	Dongle/API username	—
Password	Dongle/API password	—

The wizard tests the local API before continuing. Keep the API local; no cloud connection is required by Omnibattery.

Limits and capacity

Sessy uses asymmetric hardware limits of 2200 W for charging and 1700 W for discharging. These values are seeded by the integration rather than entered as free-form hardware limits during setup.

The wizard requires the nominal battery capacity in kWh (0.01–100 kWh), because the Sessy API does not provide a nominal capacity counter. It also configures the common SOC limits, charge hysteresis and backup offgrid threshold. The default minimum SOC is 5% and the maximum is 100%.

Sessy does not expose Marstek's cell-voltage taper. See Battery configuration for the common runtime controls and system power limits.