I am working on a project were I am using an INA3221 triple channel Shunt Current Power Supply Voltage Monitor. I see a few threads on here as to how it works and what mods can be applied in order to monitor three separate feeds (i.e. not using a common ground). I purchased one from ebay and it looks like it is a "new" variant of this board. Instead of VPU, GND and POW it has VPU, GND, GND. I managed to get this to work using the common ground in a simple test. My question is can this be modified to monitor three separate feeds (i.e. not shared ground) as per the other examples and if so can anyone offer some advice on how the do this?
My question is can this be modified to monitor three separate feeds (i.e. not shared ground) as per the other examples and if so can anyone offer some advice on how the do this?
It may help to provide a link to these "other examples".
BTW, the linked product page doesn't provide schematics for your board so any suggestion from our side will be (slightly educated) guessing about how the board is wired. In general: never buy hardware you don't get the schematics for or take the time to completely reverse engineer the product!
Without a schematic schematic of the board it is hard to tell. I will take a SWAG and say no, the TI data sheet shows only one ground connection, the board shows two. I would assume they are for convenience and connected together. You need to get a schematic to be sure but you can quickly test my idea by connecting an ohm meter between the two grounds.
I was trying something like you are but it won't work. Read the datasheet of the chip.
This new design versus the purple one helps you in the way you can use it to measure a solar system (solar panel/battery/load) each one with their voltages and intensities instead of three different load with same voltage as the purple one (unless you modify it like you can see here)
With this new variant you can use it to measure three different voltages, but all of them with the same ground reference. I use it in a 4S battery, subtracting the voltaje of the previous cell and another INA226 in the last one (and also the total consumption) .
I don't know if you were looking for use a kind of differential mode, but If you try to remove the resistors to use the meters of each side, you only will be able to measure */-163mV.
If you look closely at the pictures, you will notice the negative side of the three channels are not tied to ground!
Also the silk screen on the bottom shows "VIN1-,VIN1+, VIN2-,VIN2+, VIN3-,VIN3+"
So it appears the 3 independent channel variant is available.
I have not bought these yet, but I am going to buy a selection to see if they are the real deal.
Here is an example showing the ones with negative side of the three channels tied to ground:
on top you can clearly see the negative side of the three channels are tied to ground,
notice the silk screen on the bottom shows "GND,CN1, GND,CN2, GND,CN3"
Do an amazon search for "INA3221" and look closely at the pics, I a have found at least 3 listings that look like what you are looking for.
Hi , has anybody tried to change shunt resistor on that board to increase max current reading? Can you change shunt value in library "SDL_Arduino_INA3221.h" to fit with lower shunt ohm value? I´d like to increase current limit 10x to 16A , 0.01R 2,5W resistor should do the work but i need to change it´s value to get right measurements. How can i do it?
I think your safest option is to keep all systems galvanically isolated.
Unless you require the more advanced features of the INA3221, I would use three separate INA219 single channel modules, powered by three separate isolated DC/DC converters. Three I2C Isolators such as the MAX14937 or similar (depending on isolation requirements) will be needed as well. You may not be able to tie all three I2C isolators (in parallel) to the same I2C channel on your uC, so extra I2C channels may be required.
