Hopefully someone has some insight for me. I came across this post which addressed my exact problem, except my situation needs different threshold voltages for the battery. I created a KiCad schematic, got the Spice model for the TLV431, and did a simulation. It "works", but the issue I'm finding is the threshold for reference voltage is much lower than 1.24V, more like 1.01V. Could this be something specific to Kicad, or is there something else I'm missing?

 

I'm finding is the threshold for reference voltage is much lower than 1.24V, more like 1.01V. Could this be something specific to Kicad, or is there something else I'm missing?

Hard to tell with such little info.
My crystal ball is a little cloudy, so could you post a screen-grab of your KiCad schematic?

What battery threshold do you want?

 

Hard to tell with such little info.
My crystal ball is a little cloudy, so could you post a screen-grab of your KiCad schematic?

What battery threshold do you want?

Thanks. Here's the screenshots of the schematic, and simulation results showing V(ref) in red and I(R_Sim1) in green. I'm trying to get an off threshold of 12.4V and an on threshold of 12.6V, but if I can figure out what's the issue I can probably figure out the resistor values to do that. Thanks!

 

https://www.onsemi.com/download/data-sheet/pdf/tlv431a-d.pdf has an equivalent circuit schematic = you can attempt composing your own model with minimally-characterized/near-ideal transistors (outcome might be more prone to spurious oscillations than when using a "fully" parametrized BJT models)

 

Your TLV431 model does appear to be faulty.

But I just realized the TLV431's cathode voltage is seriously exceeding its 7V max value in that circuit, so a TL431 needs to be used instead, which has 37V max rating and a 2.5V Ref value.
LTspice sim below:

 

Your TLV431 model does appear to be faulty.

But I just realized the TLV431's cathode voltage is seriously exceeding its 7V max value in that circuit, so a TL431 needs to be used instead, which has 37V max rating and a 2.5V Ref value.
LTspice sim below:

View attachment 352442

Yes, the TL431 gives the expected results. Thanks!.