Latest Comic : Friday, March 27. 2020

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How does temperature affect Bolt EV's efficiency?

Efficiency-Temperature Correlation of Bolt EV (February 2019 to January 2020)

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.

Road Type Speed Limit
(km/h)
Minimum
% of Trip
Trip Range (km) Speed Range (km/h)
Min Max Min Max
Expressway 100 - 110 75 112.7 364.8 70.4 90.0
Intercity 70 - 90 19.6 25.3 40.6 69.0
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.

Road Type Total Trip
(km)
Average Data Count
Trip (km) Time (H:M:S) Speed (km/h)
Expressway 9,036.7 251.02 3:10:03 79.25 36
Intercity 1,593.1 22.13 0:26:20 50.41 72
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.
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Annular Solar Eclipse of 2019

My Nikon P1000 was set up on the roof of the Marina Barrage along with other cameras and telescopes

An annular solar eclipse happening on the Boxing Day in Singapore sounded like a great excuse to have a year-end family trip there, so I acted on it. As expected, multiple venues across the city-state provided spots for people to view and photograph the phenomenon. I picked Marina Barrage as it would have longer totality and snacks.

My family arrived nearly two hours before the start, but a lot of equipment were already on the roof. Once our stuff was set up, my daughters saw the Sun through the handheld protective film or binoculars while I took photos in intervals.One thing that concerned me was the weather, as it was supposed to be cloudy with a chance of rain that day. While the sky was mostly clear during the early stages, clouds began to build up as we neared the totality.

Progress of the solar eclipse observed in Singapore on December 26, 2019

The clouds were both a curse and a blessing. It became cumbersome to track and photograph the Sun through the camera on the tripod, since I needed to fiddle with the settings every now and then. But the clouds often became just thick enough for my iPhone to take the ongoing eclipse directly without any filters, letting me get these nice photos you see above. As a result, both the phone and the camera had their share of the action.

Celine was able to see the eclipse in the morning (left) but clouds obscured view in much of the afternoon (right)

The clouds that moved in about half way through the 2 minutes of totality created a breathtaking view - people could see the "ring" of Sun with naked eyes. That was quite an experience. Alas, the clouds blocking the Sun became thicker and more frequent after that, so they became much more annoying in the second half of the eclipse. I was getting a lot more gaps in the interval photos I was taking, so I finished my session about an hour early and went sightseeing around the Marina Bay with my family to much satisfaction.

Device: iPhone 11 Pro
Settings: 52mm - ISO 20-25 - 1/23810-1/564s - f/2.0
Filters: None
Time: 2019-12-26 12:09-14:25 UTC+8
Location: Marina South, Singapore

Making external storage work on iPhones with iOS 13

- or, why do I get "too much power" error with my drive and how do I fix it? -

Apple's official Lightning to USB Camera Adapter

With iOS 13, native support of USB external storage was introduced to iPhones. Files stored externally can be accessed from the Files app included in the OS. Other apps can do it as well if it can connect to this Files app. Sadly, modern iPhones' external port of choice is Lightning, which means you either buy a storage device with a Lightning port or get an adapter to connect a USB device. This is where things get complicated.

I bought a Lexar MicroSD to Lightning Reader (part # LRWMLBNL) more than three years ago. It connects directly to the Lightning port and I can open files using a dedicated app. Apple MFI certified storage can supposedly work with the iOS 13's Files app, but that wasn't the case here despite the certification. Adding insult to injury, its app had not been updated in more than two years - the screen resolution and the file sharing functions were outdated. I needed a different solution.

Apple sells many types of USB adapters, one of which is the Lightning to USB Camera Adapter you see above (US$29). It can be connected to a camera for transferring photos and videos, hence the name. Other devices could be plugged in as long as the OS recognizes it, like keyboard, MIDI equipment, or Ethernet adapter. iOS 13 expands this to general storage and mouse.

Plugging in a USB flash drive directly do the adapter results in a "Cannot Use Accessory: This accessory requires too much power" error

So I bought this adapter expecting that any low-power storage devices like USB flash drives and memory card reader could be plugged in directly for my file management uses. Boy was I so wrong. Of the multitudes of flash drives and card readers I own, all of them, save for one, caused the "too much power" error you see here. This was bizarre because they shouldn't consume enough power for this to appear. There had to be a reason and a way around this, so I decided to dig in.
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Experiencing the 2019 Daegu EV Eco Rally

Starting gate and the ceremonial stage of the 2019 Daegu EV Eco Rally

Daegu Metropolitan City is currently the most proactive regional government in the mainland Korea for promoting the adoption of electric vehicles. The city has its own sprawling charger network and the total number of EVs eligible for purchase subsidy per year is one of the largest in the nation. Also, it has been holding an EV Eco Rally since 2017 to show off the clean and efficient nature of the EVs to its citizens.

I wanted to know how efficient I was driving my car, so I attended the event last year despite being just four months into EV ownership at the time and needing a two and a half hour trip from Naju. I ended up ranking roughly in the middle. Feeling that I could do better, I honed my skills and re-entered the competition this year.

My daughter Celine rode with me on my Bolt EV, and the car was assigned to Group D, number 42

Since each car models have different characteristics, participating cars were grouped according to the model. A group needed at least four cars for efficiency ranking and four models qualified this year - Kona (Group A) and Niro (Group B) had 14 cars while Ioniq (Group C) and Bolt EV (Group D) had 9. Other models participated on a non-competitive basis, which brought the overall total to 56 cars.

To drive as efficiently as possible in the rally, convenience features like air conditioning and satellite navigation screen are turned off to save energy. This makes the ride quite uncomfortable as my family found out last year. But Celine still wanted to join her dad in the event for this year, so I assigned her the duty of a human navigator, helping me make my way around the busy Daegu downtown. I didn’t realize how significant this would affect the outcome at first.
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Assessing one full year of Bolt EV driving

My Bolt EV has travelled 24,099.4km in its first year

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.

Bolt EV's monthly statistics from June 2018 to May 2019 - distance, fuel economy, and battery capacity

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.
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