Via Extra Battery Output Port(Xt150); Charge Your Power Station - EcoFlow DELTA 3 Plus Manual

If you need to power your device continuously, such as when storing
medicines, vaccines, or other valuable items in a refrigerator, set the power
station's AC timeout interval to "never" in the EcoFlow app. Additionally,
regularly check the power station's battery level.
Disable Grid Bypass Output
When powering up appliances in
may cause the appliance to operate improperly or be damaged. Turn on this
setting in the EcoFlow app for appliances requiring high-quality power output,
such as speakers, use only the AC output power from the power station.
Bypass mode: When you recharge and discharge the device(via AC input &
output ports) simultaneously, the device enables bypass mode
automatically.

Via Extra Battery Output Port(XT150)

After turning on the power station, connect your EcoFlow product (compatible
with the power station and supports XT150 charging) to the extra battery
output port using an EcoFlow extra battery cable.
The extra battery port supports both power input and output. Please refer to
the "Charge Your Power Station" chapter
Notice
Make sure the power station is connected to a power source when
charging an extra battery.

Charge Your Power Station

bypass mode, the instability of grid power
for more details.