Home EV Charging
How has EV charging compared to trips to the gas station, 17 months in?
In January 2023, we bought an electric car. We flirted with a plug-in hybrid for our last car purchase (in 2018), but information was scarce and the sales staff at the dealer was completely unhelpful (not just about EVs), so we opted for the familiarity of a known dealer that didn’t offer any electric options. This time around, we did our research up front and knew we wanted to go electric. Admittedly, none of the Chevy, Volkswagen, or Hyundai sales staff conveyed EV expertise (an issue for another blog to tackle), but we found our way to a Hyundai Ioniq 5 nonetheless. And we couldn’t be happier.
I won’t provide a full review of the vehicle, but I do have a couple of questions to address here:
How much has home EV charging raised our electricity consumption for a year?
How much have I saved on fuel costs (gas vs. electiricity)?
Fortunately, both are answerable with accessible data.
Home Charging
We purchased an Emporia EV Charger (Level 2) and had it installed in our garage. This charger promised similar functionality (charging speed, control via app) at a much lower price, and with good reviews, so we went for it and have been satisfied so far.
After consulting electricians, we determined that our charger could not feasibly piggyback on the 240-volt outlets for either our stove or basement dryer, so we needed a new outlet in the garage. Our electrical panel had no room for additional 50 amp circuit breakers, so we needed a subpanel put in to accommodate it.
The Emporia charger provides up to 48 Amps of current. This gives us about 9.9 kW peak charging, which allows us to charge our Ioniq 5 in a couple of hours, depending on the level of charge. The full 77-kWh battery could be fully charged, 0% to 100%, in about eight hours. That said, we’ve rarely gone below 20% or over 80% in order to maintain long-term battery health, so we’re typically done charging in under four hours.
I was able to download data from my Emporia charger in intervals of days, hours, 15 minutes, minutes, and seconds(!). Unfortunately (and perhaps not unexpectedly), Emporia only retains a year of 15 minute data, about a week of minute data, and 48 hours of second by second data, so I don’t have these for the full history of my EV charger.
The hourly data looks like this:
You can see that we plugged in between 8 and 9pm on June 9, charged for three full hours, then finished a little after midnight.
15-minute intervals for the same two-day period this week:
You can see more precisely when we started charging, and you can start to see some slight variation on 15-minute intervals.
1-minute intervals:
Wow, ok. We’ve got a few quirks to explore! You can see the exact minute we started and stopped charging, but there is also a brief dip during our charging session.
After the car is charging for a while, we often get a charging failure push notification from the Hyundai app on our phones. This seems to be a documented issue and is especially common in warmer weather. For a while, our charging session would fail and stop, leaving us to wake up to a battery that was not charged as expected. After a software update from the dealer last year, these failures are now only temporary, and charging resumes by the time I log into the Emporia charger app after receiving the notification of a failure. Not ideal, but it seems like the vehicle and charger are now able to work around this. These blips explain some of the temporary dips in the midst of a charging session.
You can also see some small, follow-up charging after the vehicle was charged, in the early morning hours on June 10. We left our EV plugged in, and our charger continued to deliver small amounts of electricity every so often until we unplugged it. This could be because some small amounts from the battery were consumed overnight and the charger topped us off. Or, it could be some small measurement error in our vehicle’s or charger’s assessment of the battery that allows us to go slightly above the 80% limit we have set. Sometimes when you get in the car after charging, the battery level will read 81%, above the max charging level of 80%.
Total Energy Consumption
Over the first 17 months of ownership, we’ve driven 22,600 miles at 3.9 miles/kWh. This seems notably better than what InsideEVs reports (2.9 mi/kWh), perhaps due to our driving style and balance of city/highway driving. (Contrary to cars with internal combustion engines, electic cars benefit from regenerative breaking and thus tend to drive more efficiently when driving in the city.) A quick scan of online forums suggests others similarly top out in our range, depending on their usage of cabin heaters in the car (which, like gas cars, consumes energy and lowers efficiency).
Based on our vehicle usage, our EV has used roughly 5,800 kWh of electricity through home and public charging.
By contrast, our here is the electricity reportedly delivered to our Ioniq 5 by various charging sources:
Emporia (Level 2 home charging): ~5,700 kWh (at residential electricity rates)
Electrify America (Level 3 public charging): 750 kWh (This is largely free for the first two years thanks to Hyundai’s deal with Electrify America, saving $200 in electricity charges.)
ChargePoint (Level 2 public charging): 115 kWh (This was also free for a while thanks to Allentown’s now-expired free public charging at downtown garages. We spent $12 total.)
Total: 6,565 kWh
How is our EV using about 11.7% less electricity than is delivered by the chargers? There is some rounding error in my estimates, but the larger answer is in electricity loss while charging. It’s beyond my scope to explain the science of electricity losses, but Recurrent does a nice job explaining the impact:
According to Recurrent (as reliable a source on EV charging and batteries as there is!), we should expect 5-15% losses at a Level 2 home charger, perhaps less at Level 3 chargers. That aligns with the 11.7% loss we’ve experienced predominantly at Level 2 home charging. These losses should be added into the cost of charging the EV for our purposes.
Final Accounting
Thanks to incentives for public charging, we’ve gotten 865 kWh of public charging for a total of $12 (roughly $0.01 per kWh). Roughly, this offset the electricity losses while charging. So, most of the electricity cost will come from our home charging.
If Pennsylvania electricity rates average $0.175/kWh over the past year or two, the cost to charge 5,700 hours at home thus far amounts to $997. Add in $12 in public charging and arrive at $1,009, so we’ll round it to $1,000.
By comparison, our predecessor vehicle was a 2015 Honda CR-V, which got about 28 miles per gallon. At $3.56/gallon over the past year in PA, that adds up to $2,950 in gas fees (not to mention the inconvenience of stopping at a gas station vs. simply plugging in at home overnight), a difference of nearly $2,000.
We’ve already saved $2,000 in operating our Ioniq 5 on energy alone, or roughly $1,400 per 12 months. Add in lower maintenance costs (no oil changes!), and the win for the EV is even bigger.