INA219 incorrect reading

[marcfon]

The reading from my INA219 off by about 0.3v compared to when I read voltage with a multimeter across the battery + and -.

I've got the VIN- connected to + terminal of the battery according to this schema.

Did a miss a wire or setting somewhere?

[Smeat]

Sorry, I don't have an INA219, so my ability to help is limited.
But it seems the wiring diagram is missing something, as VIN- is unconnected. You better use Jye's PCB as a reference.
Also make sure you are measuring as close to the INA219 as possible.

[marcfon]

Thanks for thinking along Smeat. You don't have to have VIN- connect if you're just monitoring voltage. If you also want to measure current then you do so it depends. I fiddled around a bit more but couldn't find the cause. Not a dealbreaker but curious if more people ran into this.

[AlessandroAU]

What's the hardware look like? a drop of 300mv is easily explained by thin wires and a current draw of couple amps.