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Post by robyice on Jul 12, 2017 21:34:11 GMT -8
Hi I have just received the INA3221, and just wanted to make sure I connect everything up correctly so I don't blow anything up.
I was looking to place my 100A / 75mv shunt on to the negative terminal of my battery bank and the negative of the Inverter to be connected to the shunt (read somewhere that it was safer to connect it to the negative side).
so I aim to Cut SJ3
INA1+ JP2 / 1 be connected on to the shunt on Inverter side
INA1 - JP2 /2 be connected to the shunt battery negative side
do I need to connect anything else was not sure if I needed a common ground from the battery bank to the INA3221 and if the max voltage of 29V could be a problem?
And just to clarify the connections to the Pi
Power 3.3V (GPIO/1)
GND GND (GPIO/6)
SCL I2C1_SCL (GPIO/5) + 10k Resistor to GPIO/1
SDA I2C1_SDA (GPIO/3) + 10k Resistor to GPIO/1
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Post by SDL on Jul 13, 2017 14:51:24 GMT -8
You need a common ground. Make sure you look at the specification. 26V is the absolute Maximum Voltage.
BP
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Post by robyice on Jul 13, 2017 16:28:54 GMT -8
Hi Can I add an inline resistor or something to make the voltage down to a safe level and still get fairly accurate results from it, I know I will need re calibrate the output results in code but that should not be to much of a problem.
also if I connect the shunt to the positive terminal and connect the common ground between the 2x 12v battery's with a diode this will then just give me a max of 14.5 V or will this still fry the circuit
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Post by robyice on Jul 16, 2017 17:17:07 GMT -8
if the shunt is on the negative terminal wont that mean the ina3221 will only ever see a max of 72mv?
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Post by SDL on Jul 17, 2017 4:55:23 GMT -8
Robyice,
Post a schematic of what you are doing and we will take a look at it. Not sure what you are doing.
BP
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Post by robyice on Jul 26, 2017 21:29:17 GMT -8
hi Finally the other parts I ordered have arrived and have down graded my set up to 12V so I don't break anything
but when I run
i2cdetect -y 1
I get
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
ok worked out the problem your manual is a little confusing.
where you put GPIO/5 I connected this to GPIO05 and that's pin 29 and in fact you mean pin 5
and where you have GPIO/3 I connected that to GPIO03 and that's pin 5 when I should be connecting it to pin 3, changed all this and now it all works.
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Post by SDL on Jul 31, 2017 13:14:28 GMT -8
Interesting. I see where you are confused. We really should say GPIO/Pin 5 and GPIO/Pin 3.
Thanks for the advice.
BP
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Post by robyice on Aug 27, 2017 15:54:54 GMT -8
with the shunt measuring the Negative terminal it is happily keeping an eye on the load of the 48v battery bank, obviously its not possible to see the V and watt as this would require it to be connected to the positive terminal and would put to many V into the ina3221
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Post by SDL on Aug 28, 2017 13:33:49 GMT -8
Please post a schematic so we can see what you are doing! Include the grounds (of course).
Happy to help.
BP
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