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by ophiothrix
Mon Jan 07, 2019 1:52 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

Brandon92 wrote:
Sun Jan 06, 2019 8:56 pm
A okay. So, you want something like this:
Yes, exactly. Thank you!
by ophiothrix
Sun Jan 06, 2019 6:16 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

By the way, what for kind of batteries are you using. Because 25V sound like a bit of a extraordinary one. And is it save for this type of batteries to be used in a parallel setup? They are standard 12V lead-acid batteries. So the bank is "nominally" 24 V. But 12V is only orientation. At 80% charge...
by ophiothrix
Sun Jan 06, 2019 4:55 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

Note/Tip: You can not use four the same voltage dividers. Could I bother you to clarify this last statement? I can't use the same voltage divider, i.e. connect each of the 4 batteries to the same single divider? Or does that mean that each of the voltage dividers has to have different resistances? ...
by ophiothrix
Sun Jan 06, 2019 4:48 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

Does this concept circuit give you a better idea, of what you need to do? And this is not the advance option I was talking about btw. Note/Tip: You can not use four the same voltage dividers. Thank you Brandon. This is very helpful for getting my head round it. But in the end the problem was painfu...
by ophiothrix
Sun Jan 06, 2019 3:24 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

"-" and gnd are connected together. ADC takes all measurements relative to gnd. Therefore the voltage source and ADC must have same groud potential. "-" and gnd connections help to get them onto the same potential by connecting both system gnds together. I recommend to build the voltage divider to ...
by ophiothrix
Sun Jan 06, 2019 3:06 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

As a additional to the previous post: You indeed to remember that you are measuring between the gnd and above. And the voltage need to be save for the adc. And in your case the "pseudo-differential pairs" option of the mcp* is interesting. If you are using it in a correct and connect it in the righ...
by ophiothrix
Sun Jan 06, 2019 2:54 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Re: Problem with connecting multiple voltage sensors to Pi

As GND is connected to negative input, you shorted the first battery when you wired the second voltage sensor. You must connect all sensor negative inputs to system GND, which is also Rasp GND. Positive inputs you can connect to separate solar cells as long the input voltage is below 25V. Then you ...
by ophiothrix
Fri Jan 04, 2019 9:35 pm
Forum: Automation, sensing and robotics
Topic: Problem with connecting multiple voltage sensors to Pi
Replies: 15
Views: 580

Problem with connecting multiple voltage sensors to Pi

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 ...

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