I see a lot of questions and misconceptions about charging and range so I wanted to have a post that I can point people to when they ask “how long does it take to charge” or “my dealer says that it costs the same!” or “does the savings in fuel pay for the higher cost of the vehicle?”. So I put together the tools that you’d need to calculate the answers to those questions yourself. I’ll edit in more FAQs if you think of any I missed.

This is all in calca syntax so you can download that for free and copy-paste this whole post into it and change the numbers for your car or electric rates. Calca is like a spreadsheet met a text editor, it’s great. I don’t work for Calca it’s just a great tool.

Charging costs

Here are the factory specs for my car:

i4 battery = 81.5 kWh
i4 range = 282 mi
i4 gets = i4 range/i4 battery => 3.4601 mi/kWh

You should know that my electric company is PG&E who charges insane electric rates. You almost certainly pay about half for electricity what I do. There are two extremes in my electricity prices: t1 offpeak is the least I can pay, t2 peak is the most.

electricity costs t1 offpeak = $0.37/kWh
t1 offpeak = electricity costs t1 offpeak/i4 gets in $/mi => $0.1069/mi
t1 offpeak fillup = electricity costs t1 offpeak*i4 battery => $30.155

electricity costs t2 peak = $0.54/kWh
t2 peak = electricity costs t2 peak/i4 gets in $/mi => $0.1561/mi
t2 peak fillup = electricity costs t2 peak*i4 battery => $44.01

So if I make sure to charge on off-peak hours, I pay about 11¢/mile. Public DC charging is currently a little bit cheaper than the higher of those but that probably won’t be true for you.

public charging costs = $0.48/kWh => $0.48/kWh
public charging = public charging costs/i4 gets in $/mi => $0.1387/mi
public charging fillup = public charging costs*i4 battery => $39.12

Compare that to my motorcycle which is my main transportation around the city:

gas costs = $6.00/gal
moto gets = 62.48 mi/gal
moto costs per mile = gas costs/moto gets in $/mi => $0.096/mi
moto tank = 3.43 gal
moto range = moto tank*moto gets => 214.3064 mi
moto fillup = moto tank*gas costs => $20.58

So my very efficient motorcycle costs about the same to run per mile as my EV. Or my friend’s petrol car:

petrol car gets = 27mi/gal
petrol car tank = 15.9gal
petrol car per mile = 1/petrol car gets*gas costs in $/mi => $0.2222/mi
petrol car range = petrol car tank*petrol car gets => 429.3 mi
petrol car fillup = petrol car tank*gas costs => $95.4

So they pay a little over double what I do per mile. Speaking of, they pay way less for electricity than I do. If I charge at their house it’s less than half the price:

friend house charging costs = $0.18/kWh
friend house charging = friend house charging costs/i4 gets in $/mi => $0.052/mi
friend house fillup = friend house charging costs*i4 battery => $14.67

After 100,000 miles the different vehicles will have paid:

lifetime = 100,000mi
t1 offpeak            * lifetime => $10,693.2624
moto costs per mile   * lifetime => $9,603.073
friend house charging * lifetime => $5,202.1277
public charging       * lifetime => $13,872.3404
petrol car per mile   * lifetime => $22,222.2222

For fuel I’ll pay about $11k, my friend’s car will pay about $22k. If I didn’t have these PG&E criminals I’d pay closer to $5k.

So if you pay reasonable electric rates an EV that’s about $17k more expensive will net out to the same as a petrol car after 100,000 miles ignoring other cost differences like incentives and maintenance.

For a smaller scale perspective, a road trip from my place to Las Vegas in these vehicles would cost:

vegas = 2*597mi => 1,194 mi
public charging     * vegas => $165.6357
petrol car per mile * vegas => $265.3333

Charge time

The time to charge of course varies by the charging speed.

# show the charging speed in kW, how long it would take to completely charge 0-100%, and how many miles of range are added per hour
charge stats(speed) = [speed in kW, 1/speed*i4 battery in hours, i4 range/(1/speed*i4 battery) in mi/hr]

# a 110v household outlet, the slowest way to charge. level 1
charge stats(110V*10A) => [1.1 kW, 74.0909 hours, 3.8061 mi/hr]

# a cheapo 16amp charger plugged into an old dryer outlet. level 2
charge stats(240V*16A) => [3.84 kW, 21.224 hours, 13.2869 mi/hr]

# a nicer home charger, more typical. also level 2
charge stats(240V*40A) => [9.6 kW, 8.4896 hours, 33.2172 mi/hr]

# an older public DC fast charger. level 3 fast charging
charge stats(50.0kW)   => [50 kW, 1.63 hours, 173.0061 mi/hr]

# a newer public DC fast charger. some are higher or lower but my car tops out at 200kW anyway
charge stats(150.0kW)  => [150 kW, 0.5433 hours, 519.0184 mi/hr]

So a typical home charger takes 8.4 hours to “fill up”, a household outlet takes 74 hours, and DC fast charging takes about 30 minutes. You’ll really only do DC fast charging on road trips, if you can you’ll want to do pretty much all of your charging at home while you sleep. Public AC chargers like in a shopping mall car park exist but aren’t super common. In my experience they range 3-7kW and are almost always taken up by a Tesla that’s been there for 4 hours.

I’d look mainly at the charging speed in miles per hour. The fill-up time itself doesn’t matter because you will rarely do a complete fill-up. For starters home charging isn’t like a petrol station where you go in when you’re empty and wait around until you’re full. If you drive 50 miles in a given day, when you plug in at the end of the day you’ll only charge up the 50 miles that you used (about 1.5hr on our typical home charger example) and be full in the morning. Secondly because you’re doing it while you sleep, it doesn’t really matter how long it takes (with perhaps the exception of a level 1 charger where more than 30 miles will take more than a single night). You take the five seconds to plug it in and walk away. Lastly, EV owners typically only use the 20%-80% range of their battery in day-to-day use because resting the battery above or below that range can shorten its lifespan. You can go outside of there occasionally without hurting it, but you’ll want your general habits to keep it in that range. Personally I only go over 80% to prepare for a road trip and under 20% on a road trip where I’m sure that I’ll be able to charge when I arrive. (I wouldn’t want to arrive empty to an Electrify America station to find out that the stalls are broken, so I try to arrive with enough to make it to the next station if I have to skip one.) In my typical day-to-day non-road-trip driving I see the battery fluctuate between 60%-80% but that will depend on your driving habits.

A note on DC fast charging on road trips. Every car has a charging curve (here’s mine, and here’s one for a Kia EV6 and a Tesla Model 3). What that means is that for battery chemistry reasons your car charges from 20%-30% way faster than it charges from 90%-100%. Tools like A Better Route Planner or your car’s in-built trip planner will do routing using that fact to get to the destination faster, usually by taking advantage of the battery range that your car charges the fastest. So even on a long road trip you probably aren’t doing 0%-100% charges, you’re probably doing more like 15%-85% between stations. That also means that the 150kW number above can’t be precisely trusted, but the range where it can’t be trusted is a range you probably won’t be using.

FAQ

Can I get by with only level 1 charging from a regular 110v home outlet?

Yes! While it’s the slowest way to charge (at 3.8mi/hr with a car like mine), if you only ever plug it in while you’re sleeping that gives:

8hr/day*(3.8mi/hr) in mi/day => 30.4 mi/day

So if 8hr/day is the only charging you can ever do then you can still average 30 mi/day of travel on just a regular household outlet. You can still occasionally go above that as long as it averages that over time, or you increase the amount of time it’s plugged in, or you top it off with a public charger when you go over it. This is what I do, I use a regular household outlet for almost all of my charging and rarely top off at a public charging station if I’m in a rush.

Can I get by on public charging alone?

The sassy answer that some EV people give to “how long does it take to charge?” is “about 5 seconds to plug it in” because when it’s charging while you sleep you don’t worry about it. But if you can’t charge at home then with the way that public charging is right now you’re likely to have to queue for the 2 out of 4 Electrify America stalls that aren’t broken then wait around for half an hour while it charges which is too long to just sit around but too short to go eat dinner. If you use the 20%-80% range of a 300mi battery that means doing all of that every 170 miles. That’s more often than a petrol car where you do use the full 0%-100% range of the tank which is more like 400mi.

There certainly are people that do it but personally I wouldn’t.

My friend says it takes 8 hours to charge?! Ain’t nobody got time for that!

If you charge at home you don’t need time for that, you just plug it in and walk away. But again you aren’t going 0-100% every day, you’re only replenishing what you actually use.

My dealer says that electricity is so expensive now that an EV doesn’t make sense

Even at the ruinous electricity prices in California my car costs $0.11/mi to run vs the pretty typical petrol car I compared to at $0.22/mi. At more reasonable electricity prices it’s more like $0.05/mi.