@ATechGuy, appreciate your discussion and really do feel your pain. I have 3 EVs (2 Tesla’s) plus some Sense-resistant (or inconsistent) 240V heating loads in my house, and for long while the detection of my 2 AC compressors was fairly dodgey. I have gotten a much better handle on most of these as Sense has improved AC detection (I give the Ecobee historic integration some credit), plus my addition of second Sense solely for DCM (I have Sense solar, so I had to commit an entire separate Sense unit to just 2 circuits of DCM) to monitor my floor heating subpanel plus the Model 3 on HPWC.
But I have also spent a fair amount of time poking my nose into trying to build my own EV detector, because it seems like it truly is the big elephant in the room. But when you get inside even that simple problem it is harder than it looks for a few reasons, especially when dealing with non-machine-learning algorithms.
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the viewing window - searching for transitions requires a defined analysis window and some notion of a trigger delta. EV charging ramps don’t register as anything within Sense’s 1 second or so standard viewing window. I used a 15 min window for my (rough) detector, because I have that data window available to me. Our brains are “wired” to be more flexible so we can “see” 1 sec and 15 min elephants in the same go, but they have very different visibility to a machine, depending on window.
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overlap - as your detection window widens, detection becomes more sensitive to overlapping transitions. Multiple on transitions and off transitions can get blended together. I had cases where two heaters turning on in the same 15 min period looked like the Model 3 charging.
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differentiation between on and off patterns - I got my detector partially working, but then had to differentiate between the 3 and the S, because eventually detection has to match up ons with corresponding offs. Even with only two patterns, it was more difficult than it seems with a 15 min window, for several reasons. How do you tell a short charge (less than 15 min) apart between the two, or both ? What happens when you miss an on or off ? And the permutations go up exponentially.
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EV charging profiles change over time - Sure, if I was Sense I could have build a more “sensitive” detector that used multiple narrower time windows and unique aspects of the Model 3 and S charging curves, but all of that gets thrown out the window when the charging profile changes, which seems to be every major software release for Tesla.
Based on my experiences, I sympathetic to Sense’s challenges, even for the detecting the elephants. If you want more details, here you go: