Smart relay input voltage sensor

Hardware
1

Looking to connect a wifi relay to my gate motor and integrate into home assist, the motor is solar powered and I would like to monitor the input voltage as to check if the relay is drawing to much from the battery’s overnight.

I notice devices such as the Shelly pm 1 support power monitoring, but they all seem to only monitor the load not the input.

Is there a relay that can display the input voltage once integrated into home assist?

2

Is this 240VAC or some DC voltage? Probably need that info before anyone can recommend something.

And welcome to Home Assistant… :slight_smile:

3

24v DC input provided by the solar controller

4

Ok - for 24V DC you can simply build a voltage divider and measure the voltage using the ESP32 ADC. This assumes you are ok with soldering components etc.

Assume a max source voltage of 28V, R1 could be a 300KOhm resistor , R2 a 40KOhm resistor which means that the output voltage of the divider is 0-3.3V, which an ESP32 can read with an ADC, using ESPHome.

image

https://ohmslawcalculator.com/voltage-divider-calculator

sensor:
  - platform: adc
    pin: GPIO32
    name: "Battery Voltage"
    attenuation: auto
    update_interval: 60s
    filters:
      - multiply: 8.5
5

Wow thank you for your detailed response :+1:

6

No problem. If you build something don’t forget to test with a multimeter that you get voltages in the expected range. This will save blowing up your ESP.