Adruino Uno measuring multiple voltages

Projects
1

Hi,

I have an Adruino Uno with 6 x DFR0051 Analog Voltage Dividers. I have successfully wired these up and written a sketch which correctly returns voltage readings of 12v batteries via the 6 DFR0051’s on my test bed.

All the DFR0051 are connected to the one GND pin of the Uno.

Before I hook this up to the actual equipment I plan to monitor - am I setting myself up for any problem in terms of ground loops, interference, cross-talk between the distinct batteries when I use this configuration? Wondering if I have overlooked any safety considerations.

Regards,
Roger.

2

Hi Roger

That is a good start to success. There are some in the past that have neglected this little point. All the grounds should be connected together.
Cheers Bob

3

Hi Roger,

It sounds like you’ve dotted your Is and crossed your Ts. The only other consideration I can think of is that the voltage divider modules are not isolated so if any module was exposed to a voltage beyond the 25V maximum it could potentially feed back into your Arduino. This sounds unlikely since you’re using them with 12V batteries.
You probably want a last-minute double-check of your wiring then you can power up and test the system.

4

Hi Roger
Just had a horrible thought.
These batteries are all separate 12V units aren’t they. If you have any in series to make up a larger voltage like 24, 36, 48 or anything else you will not be able to do this. For this monitoring system all the batteries have to be separate and all negatives connected together. If you have any in any series combination for any reason connecting one of these dividers across the batteries will effectively put a short across one of them and the divider will end up being a fuse.
If you could post a sketch showing how all this is connected it would be easier to pass comment.
Cheers Bob

1 Like
5

Thanks both for your responses, much appreciated.

The batteries are distinct power sources. My test bed has 6 x 12v batteries but in reality I plan to measure:

  • 12v battery
  • 12v battery
  • 5v power supply
  • 15v power supply
  • 18v power supply
  • which leaves one DFR0051 spare at the moment.

The batteries and power supplies supply power discretely to different devices. For example a Raspberry Pi, another network connected device, a PLC. The only physical connection between these devices is by way of data. For example a computer connected to the USB port of the PLC and also reading data from the Raspberry Pi. In terms of the power sources being measured those are not connected to one another.

I have attached my crude sketch which might (or might not haha) help.

2023-01-11 15_42_04-Clipboard
2023-01-11 15_42_04-Clipboard1237×622 58.1 KB

Regards,
Roger.

6

Hi Roger
Yes that does clarify things.

The negative side of all the power sources is connected together via the ground connection of the dividers. Connected as shown you should be OK. I was just concerned you might have 2 batteries in series where you would have the positive of one connected to the negative of the other. If you then connected a divider to each battery you would have a short across one of them. but you haven’t done that so you will be OK.

And the negative or ground connection.
Cheers Bob

7

Ta, thanks for double checking.

Regards,
Roger.