Monitoring DC voltage on off grid solar power supply


#1

Setup:
Raspberry PI3 Model B
Raspberrian Jessie

Getting startetd on a project for remotely controling and monitoring solar and generator powered off grid cabin. Aiming to monitor indoor and outdoor temperature, remotely start and stop a Honda EU30is AC power generator and monitoring voltage on a 12 volt 1200Ah battery bank.
I think I have figured out hardware components for controling start eninge and choke for the power generator, but need hardware advice on the voltage monitoring on the battery bank. The voltage will vary from 11,5V-15.5V, depending on State of Charge and charge voltage from solar panels and generator.
Can anybody advice on necessary hardware, setup and code?
Thanks


#2

Take a look at this: https://www.youtube.com/watch?v=BgShCD7xT_A


#3

Much if this interfacing would be reasonable to do with an Arduino. If you don’t need the HDMI display, mouse and keyboard of a Pi at the remote location then Arduino would be enough.

Measuring the voltage is pretty simple: a 4:1 ratio voltage divider will scale 0…16 volts to 0…4V which is fine for the arduino. I’ve done this with four 10K resistors to the battery in series to ground, and the arduino connected from ground to the lowest 10K resistor. You could get special resistor values, but it’s easier to get these integral values with same-value resistors. If you need very high accuracy, you can put a calibration factor in your arduino code, and check the actual voltage with a good digital voltmeter.

I use these power-converter battery chargers on my home and remote cabin 12V systems:
60 Amp Charger and they can charge the batteries faster from the generator than anything else I have seen.

Let us know what you end up with!

Regards, Terry King
…In The Woods in Vermont, USA
terry@yourduino.com


#4

Very nice!


#5

-My newest Solar PV Disconnect and remote monitor uses an Esp12-e!


#6

Hey, that’s a great container for Arduino remote devices with radio antenna for Nrf24L01 or LoRa sticking out thru the top with silicone sealant…

To quote my old friend who has 100+ patents, "It’s dumb not to use a good idea… just because it wasn’t YOURS! "


#7

Raintinght! Meets NEC and UBC code specs.:slight_smile:
I (was) a licensed electrical contractor, so
everything I do gets inspected by the county…


#8

Thanks! Using a Raspberry pi, this setup seems to be the easiest way to go. Allthoug the hardware isn’t directly supported in Cayenne. Will I need the code from github mentioned in the video or can I just add it as a generic sensor to get a functioning widget displaying voltage?