Wesley's Tool-Box

Apple launched its first so-called spatial computing device called Vision Pro on February 2, 2024, only in the United States. As someone who had keen interest in wearable computers for quite some time, and is big fan of all things Apple, I had to get my hands on a set. So I was able to make it to Apple The Grove in Los Angeles on the launch day and do just that.

The trip wasn't easy, as the plane I took had one of the passengers falling ill mid-flight, causing an emergency landing in Tokyo Narita Int'l Airport and making the trip 6 hours longer than originally planned. Thankfully, I was able to arrive at the store before closing.

My Bolt EV has turned five this month, as it racked up more than 130 thousand kilometers on its odometer. It's fairly efficient and low maintenance, so I'll keep driving it as the primary vehicle for several more years. It definitely has some downsides like the poor fast charging performance, but I've gotten used to it. Let's see how it's been doing all this time. You can watch the YouTube video or keep reading below.

As you can see here, I generally drive about 1,500 to 2,500 km every month, for an average of 2,179.3 km. Lifetime efficiency is at 7.72 km/kWh, but it can get as high as 9 km/kWh in summer or drop to about 6.5 km/kWh in winter. As for the battery, it had been degrading stably for the first four years, then it was replaced with a new one. Interestingly enough, not only is the usable capacity larger by about 3 kWh, it's maintaining its capacity better than the original one. I'm going to be looking into this further at at later time.

On March 27, 2022, after nearly 46 months of driving, my Bolt EV's odometer hit 100,000km. Considering that it isn't used for commuting most of the time, this is a relatively quick achievement. Of the 100,734.6km driven in 46 full months, 48,588.7km was done in the city while the remaining 52,145.9km was on the expressways, so at 48:52 ratio it's got a balanced use. As for the efficiency, the car spent 13,016.1kWh, so that translates to 7.74km/kWh overall. It's well over the official numbers, so that shows how conservative I drive.

During this time, I spent KRW 5,461,940 (about US$4,440) on the car, excluding toll. Interestingly, the insurance and the tax accounted for more than half of the total. This reflects how relatively little I need to pay for the charging and maintenance. In fact, I spent just KRW 874,467 (US$710) for charging, which is less than 1/6 of the total. And other than the tires, the periodic maintenance costs were insignificant.

There's a good reason why I spent so little on charging.

GM Korea has issued a final recall for 2017-2019 Bolt EVs on June 4, 2021 which updates the battery management software to better monitor and warn against rare battery fires. I had the update applied on the first day, then drove the car around to sufficiently drain the battery. After returning, I plugged the car into a local DCFC station that I previously used for getting the detailed charging curves just over two years ago. These are the results of the new measurements.

The curved had changed significantly after the update. If you compare it with the previous data, you'll notice that the curve is no longer stepped. It's showing a gradual decline starting from about 42% SoC instead. This is close to the sort of curve that was originally seen on the 2020 and later model years of Bolt. The overall time to charge didn't change much, though.

There have been some wild changes in outside temperature during the past week. On Wednesday, February 17, it dropped to as low as about -10C (14F) and stayed consistently low. In contrast, it went up as high as 21C (70F) on Sunday, February 21. It just so happened that I needed to drive my Bolt EV from Naju to Seoul and back on those days. I did anticipate a big difference in drivable range between them, but it was still a bit jarring to experience it firsthand in such a short period.

The trips were made mostly on the same corridor of Honam / Cheonan-Nonsan / Gyeongbu expressways, which took up about 80% of the total distance and where I drove at a speed of 100 km/h (62 mph) on the dashboard. On other roads, the speed limits were always observed. I did not use any heating or air conditioning at all, as evidenced by the pie chart on the screen showing that all the energy was spent for driving.

A Naju-Seoul trip, which is roughly 320 km (200 miles) one way, can be made without a pit stop if the temperatures are above freezing. On Wednesday, I saw the drivable range drop considerably shortly after starting out. Although the battery was initially nearly full, I needed to stop and recharge mid-way, just enough so that I wouldn't be late for the schedule. The temperatures stayed between -8C and -5C (18F and 23F).

The return trip was the same - I filled up the car before starting, but had to recharge at the last service area to give myself a bit of safety margin. In the end 114.3 kWh was spent during the total trip distance of 705.5 km (438.4 miles), resulting in an efficiency of 6.17 km/kWh (3.84 mi/kWh). Given that I only try to spend a maximum of about 50 kWh on a single charge, you can see why I had to do the pit stops.

The situation on Sunday was completely different. It was exceptionally warm for Winter and I could foresee that I would reach Seoul quite comfortably on a single charge. Indeed, the temperature stayed around 20C (68F) for most of the trip until the Sun set. The dashboard showed about 100 km (62 miles) of range left when I reached the hotel.

The next day wasn't much different, although slightly cooler. I was returning to Naju with a full charge while the outside temperature was mostly in the 15C to 20C range (59F to 68F). Total distance of 706.5 km (439.0 miles) was covered using just 85.1 kWh, which gives an efficiency of 8.30 km/kWh (5.16 mi/kWh).

To put this into perspective, the efficiency was reduced by 25.7% just because the temperatures dropped by 23C (42F) and all other things remained more or less the same. Had I used heating, things would have been worse. This highlights how sensitive the electric vehicles are to outside conditions.