[2023] Why can batteries NOT be daisy chained?

There are deliberate limitations to keep the calculations simple. Most notably, you can’t have multiple inputs. However, I can’t think of a reason for what you describe, if I’m understanding your setup correctly. You may be experiencing a bug.

Originally posted by Remnar: How are calculations not simple when it's just addition? Battery 1 charge + Batter 2 charge... etc.. Each battery could determine if a cable is connected and if that cable is connected to another battery allowing you read that batteries contents and so on and so forth. I maybe not be a software engineer or a dev; but damit if I can use my common sense to solve an issue so can you. Or are you going to tell me it's not possible because your code is nothing but a jumbled up ♥♥♥♥♥♥♥ mess of hacks and other peoples code?

The OP's example does sound simple. As I said, I can't think of a reason for why it wouldn't work, and it may in fact be a bug. If it bothers you, I'd encourage you to follow the steps for filing a bug report.

I was pointing out that there are multiple reasons it wouldn't make sense. One is because there's a bug. The other is because the electronics in this game are a simulation. Like all simulations (like structural integrity or water physics for instance), it is deliberately designed to be simpler than real life. The developers choose what is important enough to simulate, and to what degree of fidelity.

If switches and wires were executed totally faithfully, aka if they 'just made sense,' then the game would allow effectively limitless complexity a la Minecraft's redstone.
https://www.youtube.com/watch?v=hHCSSscy4BI
Going down this rabbit hole is too nerdy for a lot of people, but in a nutshell you can use this to build everything up to a fully functional computer within the game. Except with increased complexity comes decreased performance. So either the devs spend time optimizing the heck out of electronics, or they make the call that this won't be a game that focuses on building computers. In which case they build in artificial limits that may seem arbitrary to the layperson, but removes the possibility of the game having to perform in crazy scenarios.

That's why we can't have multiple inputs, and it's possible that's why a load apparently only draws power from some power sources in a daisy chain. Or there could be a bug. I don't know.