I have two smartphones with the companion app. One shows power and current positive while charging and negative while discharging and the other the other way round. When displayed in the same entities card or history graph this is rather confusing. Is it possible to reverse the sign in the display?
Reversing it in the graph, no. But what you can do is define a template helper sensor to do the reverse, and show that. The template would look something like this, replace the sensor entity_id with yours:
{{ -(states('sensor.my_confusing_entity') | float(0)) }}
That’s what I was was afraid of. I can do it, when I define the sensor myself, be it Esphome, MQTT, Restful, or template helper. With predefined sensors from external devices I’m stuck, the frontend offers no such functionality. Fair enough, but one can hope.