Hello and apologies if my questions are extremely daft
I have a "toy" solar energy set up and I'd like to build a battery monitor using Raspberry Pi. The battery bank consists of 4 batteries and I'd like to monitor them independently.
I'm using the MCP3008 ADC and voltage sensors that you see in a lot of on-line tutorials on voltage sensing with Arduino and RPi (like this for instance:
The wiring is set up to use hardware SPI, as in this tutorial: http://kookye.com/2017/06/01/design-a-v ... ge-sensor/
It works beautifully with a single sensor, but when I tried to connect the second sensor to the second battery, I got some fireworks
For each of the sensors I connect the + and - terminals to Pi's 3.3V and GND respectively. The S terminal connects to the corresponding channel of ADC. My intention was then to connect VCC and GND terminals to the positive and negative terminals of the battery.
After looking into it, I found that all GND terminals are all inter-connected. I.e. there is no resistance between them and the multimeter would read the battery voltage between the VCC of terminal 1 and GND of any other terminal. So I'd like to understand why this is happening and what I'm doing wrong. And, hopefully, how to rectify it.
My understanding is that these voltage "sensors" are rather simple voltage divider with resistors selected for a 1/5 ratio. So I'd be happy to ditch the sensors altogether and build my own voltage dividers, but then I'm not sure if I understand the wiring properly. Would I stick two resistors between the positive and negative terminals of the battery and take the Vout (in the picture below) directly to the Channel pin of MCP3008? If that is the case, I don't understand what the + and - pins are doing on the sensor.
If something is missing from my description of the problem, please let me know. Otherwise, you input would be very much appreciated!