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Extending capabilites of INA219 with a 50A 75mV Shunt.
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Extending capabilites of INA219 with a 50A 75mV Shunt.

by wildswan on Wed Feb 14, 2018 2:25 pm

Hi guys. I has been a while...

I need to monitor a 48 Volts (4 x 12v in series) battery that powers an Inverter. Data is going to be saved in an SD Card. I could not measure the current but I bet it goes beyond 30 Amps as my tester capable of measure 30 Amps got busted in an instant.

I've used INA219 so I am familiar with it. So, can I use the shunt I mentioned with INA219 to extend its capability and use it on my application? How do I go about it?

Thanks.

wildswan
 
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Re: Extending capabilites of INA219 with a 50A 75mV Shunt.

by wildswan on Sun Feb 18, 2018 8:02 am

Any ideas?

wildswan
 
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Re: Extending capabilites of INA219 with a 50A 75mV Shunt.

by adafruit_support_bill on Sun Feb 18, 2018 8:23 am

You can use an external shunt. Just remove the existing 0.1 ohm shunt and wire yours between the VIN- and VIN + terminals on the board. The INA219 measurement range is +/- 320mV, You can use Ohm/s Law (I = V/R) to determine the current measurement range for a given shunt.

0.01 ohms would give you +/- 32A
0.005 ohms would give you +/- 64A

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Re: Extending capabilites of INA219 with a 50A 75mV Shunt.

by wildswan on Tue Feb 20, 2018 5:00 am

Thank you so much Bill.

That's all there is? I don't have to change anything in the library or so?


Thanks again.

wildswan
 
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Location: Philippines

Re: Extending capabilites of INA219 with a 50A 75mV Shunt.

by adafruit_support_bill on Tue Feb 20, 2018 7:16 am

You will need to set the configuration register with the right combination of gains and ranges. There are several example functions named setCalibration_xxV_yyyymA, where xx is the voltage range and yyyy is the current range in milliamps. The calculations are extensively commented, so you should be able to derive what you need for your setup.

https://github.com/adafruit/Adafruit_IN ... INA219.cpp

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