@GertSanders thanks , i think accuracy isn't a deal breaker, i believe everyone's concern is to just know when the batteries need to be replaced (hopefully that can be done without specifying the voltage correction).
Best posts made by Meshx86
RE: Presentation (S_*) and set, req (V_*) limitations
yea i ended up using V_VAR1 - V_VAR5, V_CUSTOM, V_TEXT and presenting both S_INFO and S_CUSTOM.
i am currently reading it through Wemos D1 Mini + MAX RS485 converter (working without logic converter just fine).
RE: processing incoming MQTT messages to actuate gateway local relay / variable.
This PR was merged a few days ago: