Wesley's Tool-Box

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.

I keep a detailed log of my Bolt EV drives to gain insights to the questions I wanted answers to. One of them was this feeling that the drivable range was getting lower on a cold day despite the fact that I drive without having the heater on. Since my EV driving habits became consistent after driving for about half a year, I decided to analyze one full year's of driving from February 2019 to January 2020 to spot a trend between the ambient temperature and the car's efficiency ("fuel economy").

The results above speak for themselves. Even if you don't use a heater, the car's efficiency will certainly drop as the outside air gets colder. This is largely because the air itself becomes more dense, increasing resistance. Using a heater will impact efficiency on top of this. Meanwhile, driving at an average trip speed of about 50 km/h (30 mph) yielded about 1 to 1.5 km/kWh better efficiency than at about 80 km/h (50 mph). Again, less air drag meant better outcome.

If you want to know how the data points were chosen, please read on.

My two most common driving patterns happen on expressways and intercity roads. The former are usually for the long distance family trips. The latter are used in the routine errands between Naju and Gwangju for groceries or movie-going. Downtown driving is done mostly by my wife and there are no records of time or temperature, so they were not analyzed.

As all trips start and end within cities, the most significant and fastest road type used must take up at least 75% of the entire distance for a sample to be representative of a type. And to minimize impacts of traffic jams, average speed of a trip had to be at least 70 km/h for expressway and 40 km/h for intercity. Driving under rain or snow were also out in order to avoid other weather factors. Additionally, expressway trips had to be at least 100 km long and the intercity trips had to have no significant deviations from the most common 22 km-long route I take. Use of heater was completely avoided, while air conditioning was used very sparingly if needed and took up less than 1% of the battery consumption.

In the end, 108 samples spanning a total distance of more than 10,600 km were chosen out of the 27,000 km total distance covered during the period. The real life driving conditions did still create some variability, but the trends were clearly present. I can now use this analysis to better plan for future trips.

On June 1, 2019, my Bolt EV had its first birthday. As it moved around more than 24,000 kilometers, I kept a detailed log to make continuous analysis of the car's conditions and characteristics. Many people including myself are interested in how an electric vehicle fares over the years, so this should provide some good insights.


I used to drive around 1,000km per month on average before getting a Bolt EV. But you can see that it has doubled since. Cheaper fuel costs was a major factor (less than 1/10 that of gasoline), with some "new car curiosity" thrown in. Efficiency suffered in summer and winter due to the extreme temperatures, which affects battery performance and climate control use. Largely speaking though, fuel economy had been improving because I've been adjusting my driving style to be smoother in order to go further before recharging. This proved to be helpful in long-distance trips.

The three lines at the bottom of the graph depict the battery capacity as calculated by various means. The battery degradation is a major concern for many, so I kept track of this closely as well. Going by the reported values, my Bolt EV originally had 58.63kWh of usable capacity (65.14kWh raw) and had 55.98kWh usable (62.20kWh raw) by 24,099.4km. This is a degradation of 4.52%. Assuming linear progression, the battery would have exactly 70.0% of capacity left after 160,000km. This is in line with the industrial average warranty and shows that my Bolt EV's battery is in a reasonably good condition so far.

So why did I have three lines here? It stems from the fact that the Bolt EV doesn't tell you its battery health outright. One of the Parameter ID (PID) readings from the OBD-II port (#2241A3) correlates directly with battery capacity, but interpreting the number has been up for debate. So I decided to find an interpretation that I was comfortable with.