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Post by Craig on Jul 12, 2017 21:36:05 GMT -8
I have 3 Ina3221's. On one of them channel 2 reports a current draw even when there is none. If i have no resistance it reports around 100 mA. If I attach about 250mA of resistance it jumps to 1300 mA. can this be fixed or adjusted somehow? On another board 2 channels give incorrect readings.
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Post by SDL on Jul 13, 2017 14:43:31 GMT -8
I'll bet a bunch of money (or let's make it beer), that you have a loose ground or don't have a common ground. Measurements go all over the place when you don't have a common ground.
To quote our beloved CTO, Dr. John C. Shovic,
BP
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craig
New Member
Posts: 1 
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Post by craig on Jul 13, 2017 17:08:43 GMT -8
I'll take an Firestone Luponic Distortion in honor of our distortion problem. They all have a common ground.
I'll try to explain but please forgive me if my terminology is incorrect. I'm using this to test 18650 battery discharge rates. I have the positives of each battery connected to the ina3221 input channels. INA1+ INA2+ INA3+
the INA 1,2,3 negative each go to a seperate resistor each grounded to a bus bar that is also grounded to the raspberry PI 3.3v negative pin and the negative of each battery. So they all have the same ground. If i switch out INA331 boards I have the same problem but on a different channel(s). Hope this helps describe the problem. Thanks for the response.
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Post by SDL on Jul 17, 2017 4:40:58 GMT -8
Craig,
This kind of behavior is almost always either a loose ground, ground loop (you are moving a lot of voltage/current) or something like that. I can't think of anything else that would cause such odd behavior. Clearly not the hardware (nice job on isolating that by the way).
BP
P.S. Beer sounds good. Very good.
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