ADC and a solar controller

Support
1

Hi there, and thanks for the help!

I have an off-grid orchard and I use the Automation Hat to let me run a well pump from a solar power system. I want to be able to read the voltage on the battery and the voltage on the panels using the ADC.

I went to a different school, so I am learning some foundational things. I am bench testing my idea using a variable power supply set to 12 volts and connecting the positive to the ADC 1 post. No ground, because I don’t know any better yet. I run this script and get the following results, different each time.

for x in range(0, 10):
value = automationhat.analog.one.read()
print(value)
3.34
9.87
0.28
11.82
11.82
11.82
-0.85
-0.85
10.74
10.74

I’ve set the supply to 12 volts and to 6 volts with similar results. All three lights on the ADC flash.

In the field, the solar panels will generate around 10 amps. This is a 12 volt system with a 100Ah battery I need to keep from dying with the panels connected least the panels pop the controller. Again.

Can you tell me how I might use the ADC properly before I break it?

Thanks again for the help!

DrewX

2

You need a common ground as a reference for the adc measurements. Connecting only the + won’t work. As long as its one of the 24v tolerant adc it should be fine.

3

Thank you, alphanumeric. Do I connect the negative from the panel and battery posts on the controller to the GRD posts on the Automation Hat or to something outside of the device. Connecting a 10a circuit through my Pi is counter-intuitive.

Seriously. Lots of school, none in electronics, but I am good at listening. Thanks again.

DrewX

4

Connecting the negative from the panel and battery posts on the controller to the GRD posts on the Automation Hat should be fine, and safe.
To measure a voltage you measure across the “+” and “-”. The “-” is in this case also the ground connection. If you check I’m pretty sure you will find that the solar panel -, battery -, and controller - are all connected together. Connecting that point to the - on the hat will let it measure the individual voltages. The Pi +5V power supply will power the Pi and Hat just fine.

Doesn’t hurt to be sure of what your doing, and double check if you have doubts.