How many km/day can I get from my EV?

Lets do some math, and explore how far I could expect to travel in a given day in my EV. I like this statistic more than range, as range ignores the fact that you can always charge along the way. So lets take a virtual EV “roadtrip” through the sheets of Excel and see how far we can get in a 10 hour driving day.

To do this, we need to make some assumptions: Duty time, average driving speed, battery capacity, efficiency and charging speed. Lets discuss these.

Duty time. How many hours are we willing to spend per day on our virtual road driving and charging? Ontario trucking regulations set a maximum driving time per day at 13 hours (see http://www.mto.gov.on.ca/english/trucks/commercial-vehicle-operators-safety-manual/module-9.shtml). With kids in the car, I feel 8 is a practical maximum personally, but lets settle on 10 hours to keep the numbers reasonably round.

Average driving speed. This is not the same as your top driving speed, there will be some time when you are stuck in traffic, getting on and off the freeway, parking etc. So lets pick 80 km/hr as a practical number that would fit with driving near the speed-limit on most Ontario roads.

Battery capacity. Usable battery capacity is typically lower than the rated capacity, for my 2015 Nissan leaf, I find 22 kWh to be typical. For my 2018 Leaf its 36 kWh. We will discuss this further in a future post. For now, lets pick 22 kWh.

Efficiency. Most EV’s have this reported in the driving computer. I like units of km/kWh but Wh/mi or kWh/100 km can be used as well with some conversions. As we discussed in a previous post (https://electriccaradventures.ca/2021/09/01/range-how-far-can-you-go-in-that-thing/) at highway speeds, my efficiency is not as good as it might be if I drove slower, but lets pick 5.5 km/kWh.

Charging speed. My 2015 Leaf S only came with J-1772 6.6 kW charging, so lets use that for now.

The following equation shows how many driving hours we can expect during our duty day. To get here, we start by separating out our driving hours and charging hours, then we relate the charging hours to our driving hours via the other parameters.

Putting in the numbers above for my 2015 Nissan Leaf S reveals that we spend a little over 4 hours driving and a little under 6 hours charging. And in our virtual road trip day, we managed 330 km.

But here is arguably where the fun starts, as we can ponder how to best spend my extra money. Suppose I managed to snag a 2015 Leaf that had fast charging, now I get to 466 km/day, a whopping 40 % increase. How about a 2017 Leaf S with that 30 kWh battery and longer range? That’s only 348 km/day less than the 2015 that has fast charging but less range.

To really fill this in, I did some searching on Autotrader for electric cars (used and new) in the Toronto area. The table below lists my assumptions, as well as how far each virtual EV went in my virtual day and the price. Do note that these numbers are far from perfect, so do take it with a very healthy pinch of salt. Some adjustments were in order, for example, I decided to lower the charging speed of my 2018 Leaf w fast charging from the rated 50 kW to 30 kW to compensate for rapidgate (more on that in a later post).

Looking around the web for reports of EV roadtrips, these km per day numbers seem not too unreasonable (see https://www.mikesroadtrip.com/nissan-leaf-road-trip/, https://insideevs.com/reviews/338080/road-tripping-in-a-2018-nissan-leaf-is-it-capable/ and https://www.caranddriver.com/shopping-advice/a32081802/tesla-model-3-road-trip/). Lets plot distance per day as a function of cost.

There are some interesting lessons here.

• Fast charging is great value for money. Without it, you will eventually find yourself spending hours charging, eating into those limited duty hours. As EV’s are largely sold on range, not charging speed, there is lots of value in DC fast charging.
• Diminishing returns. Id have to more than double my budget to move up to a Tesla M3 compared to a used 2018 Leaf w Chademo fast charging, yet I only reap a 25% improvement in my km/day statistic.

As always, there are some limitations

• We assumed that a suitable charging station was magically available whenever we needed it, alas life is not always so kind. If you are shopping for an EV you need to look into what charging networks operate in your area and how well maintained these stations are (plugshare is great for this)
• Actual efficiencies, charging speeds and battery capacities will vary and these do change with your driving speed, the season, tire pressure, etc. Generally if I got to about factor 2 of the truth Id be pretty happy

Have fun exploring, below you can find a copy of my Excel sheet so that you may plan your own virtual road trip.