You shouldn't get too near me when you start talking about oddball things happening. I have a long history of coming up with the most cock-a-mamie reasons why this-or-that is happening to electronic systems. Many of those ideas often turn out wrong, but there's been times when I've hit it on the barrel head.
So: You double-checked the car's settings, made sure it was back at 48A and, lo and behold, 48A was what you got. With no discernible reason why 44A in the first place.
- Update bug. If your car has gotten a software update recently, maybe that was it. People have complained about oddball behavior out of a Tesla after a software update; this may have happened to you. Sometimes when something like this happens doing a two-scroll-wheel reset makes everything come right again as the (incorrect) limit gets overwritten by a correct limit. Or something. Likewise, adjusting the limit might overwrite some internal number and make things correct. In which case: You may die of old age before you see it again.
- Flash RAM follies. So, things like car settings are set up in non-volatile RAM, otherwise known as Flash RAM. This is the same stuff that the BIOS in your PC, the SSD on your laptop, or the storage in your cell phone, or the memory card on your camera all use these days. What isn't as well known is that Flash RAM does not last forever; all Flash RAM has a certain number of write cycles it can do on individual cells, after which a particular cell doesn't hold data so good no more. The makers of Flash RAM do something called, "wear leveling". Flash RAM looks like it has sectors and such, but there's this kind of double-indirection table where the actual Flash RAM cells are lined up in an physical array, and there's a table of pointers that line them up as seen by an external operating system. When a cell gets a certain number of wear cycles on it, the Flash RAM swaps the data in the worn cell into a cell with not nearly the same number of ops and updates pointers. The OS doesn't see this happen, and one has to have very specialized software, indeed, to figure out the wear levels of all the cells in that Flash RAM. Thing is, though, after a sufficiently long period of time, all the cells get worn to the point where storing data gets hit-or-miss. And, well, one needs a new Flash RAM. On a PC, this is usually a removable part. On a Tesla Driving Computer, it's soldered down.
As it happens, some years ago, Tesla's software people were writing logging data to a Flash RAM that was mainly full with the operating system. Repetitively writing data over and over to the same locations, with nothing else being modified, turns out to be a Bad Idea when trying to avoid wear-out and, indeed, a bunch of Teslas had driving computers that died because of this. If memory serves, a couple of people set up a cottage industry of having owners sending them their dead computers; they'd de-solder the flash; copy the flash contents onto a new flash chip of the same type; then solder the new chip in, charging, I dunno, $100 for the job. Which as a lot less than the $500 or whatever Tesla was charging. In any case, Tesla realized what was happening and rejiggered their software to Not Do That, and the complaints went away. But... you've got a four year old car, so you may have been in the middle of that. Your CPU FLASH is wearing out?
- It's well-known that an overheating Tesla Wall Connector will reduce current. Or even a Tesla Mobile Connector. On the latter, on this forum somewhere, some enterprising fellow aimed a fan at the (hot) socket in his garage and fixed his problem. The problem with this idea is that the amount of reduction is somewhere in the 50% to 80% range, I think, so your current draw should have been a lot less, not just 44A. If this happens again, look for red blinky lights around your TWC.
- Another possibility is Loose Connections. No question: If the car sees a big enough drop in the 240 VAC (which should be visible on the screen in the car), then it will drop current. The idea being that a loose connection is a dangerous connection. In a way, this is related to heat, since loose wiring joints tend to get hot. Now, if this was happening in the TWC.. or the car... I'd expect thermal sensor alarms all over the place. Hm. The car does have an "events" icon at the top of the screen; check that and see if there's an error code in the history relating to something power draw related?
However, there is one place where there's no thermal sensor, and that's the breaker box. Um. Standard breakers are thermal elements, just like light bulbs, with a bit of metal that expands as it gets hotter. Get it hot enough and it pops the breaker. But years of back-and-forth can get to these things. So a dying breaker, or a bad screw-down on that 60A breaker, might be the cause of your problem. If so, you're going to see it again because, well, Intermittents.
- There are other, screwier things, that might involve the charging systems in the car itself. Of something bizarre going on with the TWC. No idea on how to troubleshoot. However.. Once Upon A Time a co-worker of mine bought a Tesla and a Gen 2 TWC as well. He hired a local, non-Tesla certified electrician to put in the TWC. In the Gen 2 TWC manual, it clearly states that the rotary switches that set the current levels and so on Shall Not Be Moved When The TWC Is Powered. The idiot electrician did that thing, took my co-worker's money, then booked it before the co-worker realized that the TWC was fried, no joke. Now the fun part: The co-worker opened up the manual and, in there, found Tesla's support line. He called said line. And a miracle occurred: Somebody actually answered the call on the third ring. Said techie remotely logged into the car, read a bunch of stuff, then drop-shipped my co-worker a new TWC. So.. don't know if Tesla still has that level of service but, if they do, and this happens again, calling that number in your manual may get you some help. Especially if you don't change anything about the fault case when you make that call. (A bird in the hand is worth two in the bush, etc.)
So, if I were you:
- Pick a time when you can pop the main in the house. Do so. Take the front cover off the breaker box. Look at that 60A breaker carefully. (My old Chief Petty Officer once said, "90% of your problems will be with the wires." He was right.) Tug on the two wires coming off that breaker. Find the neutral wire going to the TWC (and the ground) and tug on them, too. If you find something loose, tighten it. This gets rid of any potential fire hazards, which is important.
- My motto: "I hate intermittents." Wait for the next time this happens. If it is happening, see if there's any faults being recorded in the car or on the TWC.
Good luck!
