Hi all - I’m having a strange situation that I just cannot figure out, so figured I’d float it here to see what people think.
I’m using a Boron to control a Cytron 40A motor controller. Conveniently, it provides a 5v output which I am using on VUSB to power the Boron. The system is powered by a 12v marine battery.
I want to measure the current via a shunt resistor in the 12v supply and use PWM to step down the motor controller when the shunt-current says I’m above 40A in an effort to prevent a motor stall.
So I’ve connected an INA219 to this setup, and a 100A/75mv shunt resistor, and connected this via 3.3v out (from boron) and SCA/SCL for i2c. (the on-board R100 shunt has been desoldered and removed)
The good news is, this works. I can see current and if it kicks up high, I can slow down the PWM to correct the current back and prevent a stall.
The bad news is, this works for only a very short period of time. A thermal camera shows the INA gets really hot doing this, reaching about 180deg F which just doesn’t seem right.
I’ve lost one INA due to overheating and it went spaff. I hooked up a second one, and it shows the same problem, and I’ve removed it before it died.
Question is - anybody have any idea why this is happening??