With a DC coupled battery (where the PV panels and battery storage only have one inverter) then to stop the zappi draining the battery during normal (ECO+) solar charging you need to set a small Export Margin.
This setting is found on Master Device on the menu Other Settings -> Advanced -> x x x x x -> Supply Grid -> Network -> Export Margin
Set the Export Margin to 50W and the battery should take priority over the zappi or eddi. (In some cases a setting of 100W or 150W is needed). Your myenergi devices will now wait until there is a small export before starting to divert power to the car.
Note: With the Export Margin set, the "Minimum Green Level" (MGL) needs to be set to 100%. If a lower MGL value is used then this has the effect of reducing the Export Margin and zappi/eddi may start fighting with the battery system again
To charge the car using a low rate tariff you then either need to set a Schedule in the myenergi online account (myaccount.myenergi.com) or via the app.
Note - during the scheduled boost the connected load (i.e. the EV or hot water heater) will take power from any source available, so unless the battery is turned off or also set to charge the car will still drain the battery.
Is there anything else I can do to make the hybrid battery work better with my myenergi devices?
Depending on where the battery and myenergi devices are connected in your electrical system it may be possible to wire them so that they work better together. This article provides examples from two myenergi customers: Hybrid Battery Installation - Alternative Connection Arrangements