Ok, I just had an interesting trip. I want to make this post accessible to those who want to learn about the variability of these batteries, but I also want to include all the details. I'll start with the generalities.

I drove round-trip from Homer, Alaska to Anchorage, Alaska, yesterday, August 24th 2020. The one-way distance up to Anchorage was 229.7 miles, including running some errands, before I plugged into a charger with a middle estimate of 42 miles of range remaining and 54.8 kWh Used shown on the info screen. There is the first point: I drove nearly 230 miles without a worry about plugging in, and not coming close to using all of the battery capacity.

The temperature was around 60 degrees F the whole trip, but it was raining and the roads were wet for the second half. Wet roads produce more drag, which requires more power from the car. It is noticeable on a trip like this where you may be pushing the limits of the range, or at least think you are (!).

The trip back was more interesting and can give you an idea of the variability in not only measuring battery capacity, but how much of that capacity you need for seemingly slightly different conditions. I needed to stop for a charge.

Well- that's the big question:- Did I *need* to charge?

The temperature was a little cooler on the trip back, in the mid-upper 50's F, and the roads were wet and wipers going for the first 3/4 of it. The fan was run many times to defog the windows, but the heat was never turned on. The passenger wanted her seat a little warmer for the last 1/3 of the trip, after we charged for an hour and 20 minutes.

When I stopped to charge I was 86 miles from my house, according to Google (probably right on), and the range indicator told me my middle estimate was 88 miles of range remaining. The colored indicator bars- those yellow and green lines showing whether I was tending toward the upper or lower estimate of remaining range pointed a little in the green direction, toward the higher estimate. I had come downhill a lot recently.

So, after driving the first 165.1 miles (using 43.2 kWh), I added 39 miles of range (and 10.368 kWh = 81 minutes x 240V x 32A- measured in TorquePro). When I arrived home, the range indicator, aka the Go-O-Meter, or the GOM, showed a middle estimate of 43 miles remaining (and the info screen showed 63.6 kWh Used). So I would have made it, right? I had 4 miles to spare! Those with some experience with situations like this know that it's not so easy to decide.

Here's the second interesting part- about the variation in how much capacity the battery has at any given time under any set of conditions. I did some other calculations- ones to check the capacity of my battery pack. I measured four trips- the drive up, the whole drive back (subtracting the % charge added), and then the 165.1 mile drive to the charging station and the 86 mile drive from the charging station to home. Those of you paying inordinate attention will notice that the drive back was a bit further; I live beyond the town of Homer and ran another errand. But the trip was only 21.3 miles longer, and remember I had 42 miles remaining after driving up, and now it looked like I might only have 2 miles remaining, not 20!

The four estimates I calculated for battery capacity on this round trip were between 65.01 kWh and 65.81 kWh. The smallest estimate of battery capacity (65.01 kWh) was for the trip to Anchorage- with slightly warmer temperatures (which should cause a higher capacity estimate) and the most range remaining (using 54.8 kWh over 229.7 miles, down to 15.7% DIC battery remaining)! The largest estimate was made from the charging station to home, using the lower part of the battery's charge level, which should underestimate capacity (20.4 kWh Used over 85.9 miles from 47.1% to 16.1% DIC SoC)! Since these estimates of battery capacity, and any estimate I have made to date, were all greater than the 63.6 kWh I used to get home, I think I would have made it, in Eric (2%) Way style (aka NewsColoumb here)! The uncertainty gives me a greater appreciation for the selfless efforts that Eric puts in to informing this community about what to expect from these cars! Thanks again Eric! He sure helped me decide to buy one!

Subtracting the average of my four battery capacity estimates (65.4 kWh) under these moderately cool temperatures, and the actual use of 63.6 kWh, would have left me with 1.8 kWh left in my pack when I got home. The trip average was around 3.9 miles per kWh. Multiplying suggests I may have has as many as 7 miles of range remaining (or 2.8% of my battery). The estimate of capacity using the numbers from just the last leg- from the charging station to home was 65.81 kWh, so I may actually have had as much as 3.36% capacity left. (The smallest estimate I ever calculated was 64.51 kWh- which would have left me with 3.5 miles remaining or 1.4% !><!). Since my miles per kWh actually increased a bit for that last leg- to 4.2, I could have had as much as 10 miles of range remaining! (It wasn't raining, and the roads were mostly dry for the last leg home). Cutting it close any way you look at it, but I probably would have made it the 251 miles home through mountain passes and cool rainy weather without stopping to charge.

I have no regrets about charging! It's better for the battery to not run it down so low. The sandwich I had for lunch while waiting was delicious. And it felt great to support a local deli that has implemented good practices to limit spread of COVID, and buy a book in the adjacent bookstore. Together they both have a huge array of solar panels (16 kW?) and provide the EV charging station for free.

I hope that all of you are well!