L2 charging the Solterra

I’m continuing to get solid numbers when it comes to recharging this thing. I’m still using the Tesla Gen 2 UMC on an L6-30 outlet (240V 30A; the adapter I got automatically throttles the Tesla charger to 24A, so it’s effectively a ~5.76 kW L2 charger). I guesstimate about 7% charge per hour for the 2024 Solterra (72.8 kWh battery, per the Monroney sticker). Plugging in today at 50%, the car reported 6 hours 30 minutes to 100% charge, ~7.7%/hr, for an actual charge rate of about 5.6 kW/hour, with ~3% lost to inefficiency - which seems low, but, eh, I’ll take it.

That’s one data point. The other is that when I plugged in at 95% the other day (I had a busy weekend ahead), the car self-reported it would take 1 hour 20 minutes hours to top off. So in the mid-90% range, I can expect maybe, what, 3.8%/hr charge rate?

A few days before that, I plugged in at 82%, and the guesstimate was 2 hours 50 minutes, so the rate had dropped to ~6.4%/hr.

Before that, 47% SOC (53% to full) was expected to take 6 hours 40 minutes (almost 8%/hr).

55% SOC (45% to full), 5:40, 7.9%/hr.

74% SOC (26% to full), 4 hours, 6.5%/hr.

64% SOC (36% to full), 5:20, ~6.8%/hr.

On a Telsa supercharger, 16% to 80% was supposed to take 1 hour. 49 minutes later I’d added 44.5820 kWh (which should have been about 61%, to 77%?) but the car was reporting 85% SOC (which implies, if DCFC is 100% efficient, a battery of about 65 kWh). Rolling in with 1% on the dash (2% reported to the charger), was supposed to take 55 minutes to get to 80%, 1623; 9 minutes later it was up to 21% with 45 miles of range. 20 minutes to 47% (20.07 kWh delivered); 27 minutes to 59% (38.4 kWh); 45 minutes to 80% (51.4 kWh), which should have been about 71% if the battery really is 72.8 kWh, so like 72% SOC ... But the car and the charger were both reporting 80% SOC - also equivalent to a 65 kWh battery... 🤔 

L2 charging from 76% to 80% (a 4% bump in SOC) was guesstimated at 20 minutes (12%/hr; way too high I think, but the low percentage change likely is throwing things off). 38% to 80%, 5 hours (8.4%/hr). 20 to 80% (60%), 4:40, 12.9%/hr... If it really is that fast < 80%, I’m not sure what to think. With a 65 kWh battery, 12.9% would still be like 8.4 kW from a 24A circuit, which just ain’t happening. 

I should really, at some point, do a more disciplined analysis, do some charging where I limit it to 80% SOC, maybe have some sort of instrumentation that determines how much power is transmitted, vs. how much gets added into the batteries. But that all sounds like work, and this is more to satiate my curiosity and provide “ballpark” numbers I can use for planning purposes.

Like, I try to generally recharge when I hit 50%, no lower, because longer than that and it may not fit neatly into a day at the office. (I say, chuckling, as if I ever had normal hours at the office.) 

Also, I generally “know” that, for 99% of my driving (coastal SoCal), every 2 miles of travel will reduce my range about 1%. (That’s assuming ~3.0 kW/h or better, which I can almost always pull off, even at up to about 70 mph on the freeway. Mountains, very cold weather, or faster travel will eat into that, of course. I also rarely run the environmental controls.) Which tracks if you think about it; 100% usually equates to somewhere in the 204-208 mile reported range. (EPA says 222 miles, and I do see that occasionally. 72.8 kW at 3.05 kW/h would yield those 222 miles, in a perfect world.)

The Solterra charging