MOnitoring 48 VDC when it's on & for how long

First time here to the new setup , alot has changed since I was here last . I have a 48 VDC solar system & I would like to be able to monitor when & for how long the fan's for the battery exhause/vent run . The fan in a 48 vdc . I don't care about current just want to know when the fan is running & for how long . I find lots of voltage & current measuring devices but nothing for just voltage . I would like to eventually set this up for data logging .If any of you folks know of such thing can you please point me in the direction . If I'm in the wrong spot please move to proper place .
thanks
animal

Add a relay and use the voltage free contacts as an input to Arduino, simple.

Do you have resistors? If so you can connect two in series to divide the voltage down. I would connect a 2K to ground, 22K to the 48V and maybe a 5.6 K from the input to the junction of the two resistors. This will give you 5V at a 60V supply. This gives you headroom etc for transients etc.

yea , that will work , just have voltage be hi when its on .
thanks
animal

1 Like

You are welcome and thanks for letting us know.

Another idea which might simplify things and provide extra safety would be to use an ordinary opto-isolator. Connect a 10K resistor in series with its inputs. Connect it's output from the Arduino pin to ground. This will protect the Arduino from any high spikes in the input voltage and remove the need for a common ground between the Arduino and the panel circuits.