I've been doing some temperature vs shunt reading deciding if I would upgrade my shunt to one with better temp-co for my B3603 DC-DC buck board.
With the stuff all set up, out of curiosity, I did a graph to see how the
Adafruit INA219's shunt reacts under the same circumstances as the shunt warms up by current and cools back down by a fan.
![](https://www.eevblog.com/forum/reviews/ina219b-reading-vs-ut61e-as-it-warms-up/?action=dlattach;attach=134489;image)
- Cooling is done by have a PC case-fan 2.5 inch blow over the PSU (and the INA219).
- Fan cycle is
8 minutes ON (cool down), 35 minutes off (warm up)- Temperature is
not temperature of the shunt but air-temperature near the PSU shunt.
- Temperature is measured by an LM35z.
- UT61E serves as the bench mark, set at the 10A range, connected in series with 2ohm 10watt
- Current is set to desired (around 1.6A) by setting the PSU voltage at the start of the run
- An empty cycle (i.e. not logged cycle) was ran before data log begin
- Room has air vent, house heat (and night cooling) is the only expected disruption to air temperature
I expected the INA219B reading to change as the current warms the shunt and as the fan cools it back down. The INA219B resisted change and tracks the UT61E's amp measurement a lot better than I expected!
Thought you may find this data interesting.
Rick