Charging has a lot of confusing specs and tradeoffs. They aren't difficult, it's just that you're unfamiliar with them.

Charging has a lot of confusing specs and tradeoffs. On top of that, there are people intentionally (or through ignorance) misleading others. The concept aren't difficult, just new. So there's more to know in the shake-out period. Eventually, there will be so much capacity, and that you won't think about it. Hopefully, this will remove some of the mystery.

ℹ️ Info

~ Aristotle Sabouni
Created: 2021-07-04

Real World[edit | edit source]

🗒️ Note:
EVs are better 95% of the time (for 95% of users), and only a little worse the 5% when you're going past total range on a regular basis. But that assumes you have a home charger. Some people don't have dedicated parking (Appartment/Urban living), and that significantly reduces the convenience of EVs.

Driving/charging an EV is different than ICE (Gasoline) cars -- better most of the time, worse in a few cases. But not nearly as bad as people think:

ICE vs EV

A lot of it is people with ICE's (Internal Combustion Engines) have to go to the Gas Stations regularly, so they don't understand how extremely rare that is for EVs (and how much easier it is when you do).

In 2 years, I went to a SuperCharger (EV gas station) once, and that was just to try it out.

EV drivers start every day with a full tank of Gasoline (SoC / Stage of Charge)

Figure 4 hours of driving (300 miles) and they can top off for free when shopping or at work. Most day trips I take a couple hours away and back, and I have plenty of range. Or I can make it to just about every major city around me without having to stop.

I live in Houston, I've done Galveston and back, or College Station and back -- no problem. I can make it to Dallas, San Antonio or Austin driving straight through, and then charge overnight where I'm staying. So the only inconvenience is picking a place to stay that has a charger. (Many do).

Tripping

The car maps where you should charge on longer trips. After the first 4 hours, you'll have to stop for 30 minutes every 3 hours of driving. And it's easier to charge than to fill a gas tank.

If you're subscribed to a service (and/or have a Tesla), you just walk up, plug in, and then go get something to eat, shop, stretch your legs, or watch a movie on Netflix. You have about 30 minutes (up to an hour) to kill, but it's pretty painless. So simpler than a gas station, but a little more time consuming. There are few more steps if you're not subscribed to a service and using another network. But basically, it's just running a credit card and waiting for it to process -- or if you want, joining a charging network which is filling out normal account data and adding a credit card -- then plug and wait.

Range Anxiety

What if I run out of power? Worst case, you're out of charge, and the next Charger is 10 miles down the road. (They seem to be ever 10-20 miles, more frequent in urban/suburban). Well, there's a ton of destination chargers around or you call Roadside assistance. Destination chargers are painfully slow (say 20-40 miles per hour of charging) but you don't need a full tank, only enough to get to the next SuperCharger. Figure 30 minutes.

So it's not like you have to wait 6 hours for a full charge -- you just need the 30 minutes worth of range to get you to the next SuperCharger, then go there. This is basically the same as running out of gas or getting a Flat Tire. Nobody wants to deal with a flat tire or running out of gas -- but it happens, and is not world ending and not much worse in an EV than an ICE vehicle. And because of more complex/fragile mechanisms, you're more likely to need AAA as an ICE driver than as an EV driver. Thus a lot of the worry about range, is overstated. (a) You aren't likely to have to think about it, unless a really rare LONG driving day, and the car handles most of it for you (b) even if you screw up, it waste's an hour or so to get back on plan, so not quite as convenient as Petrol, but not nearly as bad as some think.

Charging vs SuperCharging[edit | edit source]

🗒️ Note:
Since users care more about time than tech specs (like kW, Charging Curves, etc), I generally tell users to think in sloppy napkin math approximations and average miles per hour of charge (M/H), rather than getting too worried about the specs that seem overwhelming, and don't really matter that much when a simpler mental model will do.

There's a lot of misinformation or misunderstandings about EV charging and charging times.

Basically you have home/desiation charging (slow, but just topping off), and SuperCharging (Gas Stations for EVs). They have different purposes -- but if you have a home charger, you're only going to need SuperCharging for road trips.

Power in homes/work is AC (Alternating Current) because it transmits better over distances. Batteries (and electric cars) are DC (Direct Current). Cars have an inverter that converts AC->DC, whereas SuperChargers use their own beefier inverters to go DC directly to the batteries (going around the cars inverter), and charge at much higher power (5-10x faster).

So what do you use when?

Home Charging

Most of the time, you're charging overnight at home -- and you don't really care about time, as long as you wake up with enough charge to get to work, or where you need to go (and optionally back).

Portable Charging - The cars come with little portable chargers that you can plug in to either 120v outlet, or a 240v drier outlet (much faster). At 120v it's slow (say 5 miles per hour of charge), but you're usually just topping off, or getting enough range to get to a SuperCharger. And if you're communiting under 100 miles a day, people can live off this kind of charging if they want. Most people install 240v dedicated charger (or plug if you don't have a garage drier plug), as that can refill your car entirely overnight.

Destination Charging

If your work/Mall/Grocery Store/etc, has destination charging, you just plug the car in while there, and mooch free (cheap) electricity. They're willing to do it because it doesn't cost much, and if it gets you to stay longer and buy more, it's worth it. And since you're there a while, time to charge isn't that important. It's like siphoning a little free gas every time you go somewhere.

Most of these run 240v lines, but are often more like 20 miles per hour of charge, instead of Max 40-50. Still, you shop for an hour, and you got the electricity/range to get back plus a little more. At a Hotel overnight, or at work, and you're fully charged.

SuperCharging

When you're road tripping, you care more about charging rates. A 300 mile range car is going to mean you need to take a break every 3 hours for ≈30 minutes to charge. As compared to about only needing 10-15 minutes every 4 hours in an ICE car. So it's worse, but not nearly as bad as people think.

Lower range EVs require more stops, but the recharging times are usually less time as well.

Time to Charge?[edit | edit source]

120v AC

Generally, at home on 120v you can get a few miles of range per hour of charge. So 16 hours is ≈100 miles of range. Considering the average commute is <40 miles (round trip), your car will always be topped off and have full range. Add that many workplaces have free charging, so you're getting charged there, and you'll virtually never need to go to a charging station.

At 120v w/15A (normal socket) you get ≈1.8 kW. Average full size car battery is ≈80 kWh and ≈300 miles range. Thus it takes ≈40 hours to go from empty to full, or 20 hours w/30A circuit. So figure about 5-8 miles of range per hour of charge Most people are driving <40 miles a day, thus we're talking 8 hours per night is all you need to stay at break-even. And that's not counting that many workplaces have chargers, which means you're getting hours of charge per day there. So for normal commuting, even with a 120v standard plug, your EV is practical enough for most people to live with.

240v AC

Most people install a home charger, and those get wired into 240v (Drier) plug. You get ≈20 kW, or about ≈40-50 miles of range per hour. So 4-6 hours to completely fill the average EV.

But to have more buffer/practicality, most people install a home charger, and those get wired into 240v (Drier) plug: At 240v w/50A breaker (Drier type circuit) you get ≈20 kW Thus the same ≈80 kWh and ≈300 miles range car would take about 4 hours to charge from empty to full... or about 50-75 miles of range per hour of charge. In theory. In practice? I'm glossing over a bit, but figure about 40-50 miles per hour of charge.

SuperCharging

When road tripping (long distance driving), 4-6 hour recharges are impractical. SuperCharges allow for direct DC connection to the batteries, and 250-350 kW (10 x a home charger speeds), or about 500-1000 miles per hour of charge. Practically, it falls short for a variety of reason. But figure 30-40 minutes for 200+ miles of range, meaning 3 hours of drive time, then a ≈30 minute break, for like $10-30 in electricity+session costs.

Since 6 hours of charging every 3-4 hours of driving is not practical on a road trip, they created SuperChargers -- very high voltage/amperage DC Fast Charging. It allows 150-350+ kW by sending high voltage DC power directly to the batteries (skiping the inverter). Instead of adding 50 miles of range per hour of charge, you're adding 500 to 1,000. It's a little more complex than that, but basically you can get about 2/3rds+ of your battery in a little over 30 minutes, or all of it in a little over an hour. Practically, this means every 3 hours of driving, you need to take a 30 minute recharge break. And if you get a meal and take an hour, you get more like 4 hours of range before you have to take another break. This is still a little worse than an ICE (Internal Combustion Engine) car, and there aren't as many stations, but most people want a 20 minute stretch and/or meal/potty break every 3 hours of driving anyways. And the smart trip mapping software (that tells you where to stop, and where to charge) makes this pretty painless. Thus, I know many people that drive cross country in their EVs a few times a year, and they're fine with it.

Connectors[edit source]

Main article: Electric Vehicles/Connectors

🗒️ Note:
Tesla connector is superior to CCS in every way; smaller, simpler, weighs less, costs less, less moving parts, more rugged/reliable, charges faster. But Tesla only made it a standard late (2022), and CCS was already established and being popularized.

North America has CCS1 and Tesla (NCAS), with a few left over CHAdeMO connectors
Europe has standardized on CCS2, with a few left over Tesla, CHAdeMO connectors
Japan has CHAdeMO connectors, with a few Tesla connectors for their own supercharging network
China did their own thing with GB/T -- which is about 1/2 way between Tesla and a Mennekes connector

I simplify by referring to is as CCS (either North America or European) -- but CCS is more complex and confusing than that. Tesla, GB/T and CHAdeMO handle both AC (Home/Destination charging) and DC (SuperCharging)... while each of the CCS charging connectors are two different connectors. CCS is basically 2 halves:

In North America for slower AC (Home/Destination) charging, you use the catchy named J1772 (aka Type 1) connector.
The CCS1 connector (North America) is a J1772, with a bottom half (two pins) welded on, which allows for faster DC SuperCharging
In Europe for for slower AC (Home/Destination) charging, you use the catchy named Mennekes (aka Type 2) connector.
The CCS2 connector (Europe) is a Mennekes, with a bottom half (and two pins) welded on, which allows for faster DC SuperCharging

Technically, this means that you may be using only the J1772 (Type 1) to charge your car at home, and not CCS1 (or Mennekes / Type-2 and not CCS2). But that's more detail that users care about. While technically, you're supposed to use the Plug Name (J1772 or CCS1), it's much easier to just refer to the socket name (CCS or CCS1) as you're going to use either plug in the same socket on the car, the only difference is just how big the plug is, and how fast it'll charge. Oh, and you have to open a stupid secondary flap on your charging port before the full CCS connector will dock. The same applies to CCS2.

🗒️ Note:
There are adapters (dongles) to go from pretty much any of these, to any other one. So you aren't locked out because of the wrong car/station combo, you just might need an adapter. It's a little annoying, if you're cross plugging, as you always need to carry the other one around. Or a lot annoying if you're on a roadtrip, and you find out you don't have one or lost it. Many Charging Stations have more than one cable/connector so you don't need to worry about it, some even have that on all their "pumps" (every stall). While most adapters/cars do have some locking mechanisms (or you can buy them 3rd party), and your car will alert you when it is unplugged, the dongles can be stolen. This is mostly an overnight or city-charging problem, rather than supercharging.

Evolution[edit source]

Main article: Electric Vehicles/Charging/Evolution

1996

GM's EV1 was first modern EV in 1996 with Delco developed "Magne Charge" (J1773 connector), it was an inductive charging paddle system that was slow, safe, and would work submerged in water. It never got widespread adoption and is dead tech.

It was 1.2Kw standard, or 6.6kW optional charging - it took up to 24 hours to charge the 60-mile range EV1. The Chevy Electric S-10 pickup and Toyota RAV-4 EV pilot programs also used that connector for a while. GM (Chevrolet): Press Release

2001

California (CARB) wanted to push EV's and supported the SAE designed the J1772 SAE connector in 2001... with a 2006 target for release. It wasn't really used until 2012 with the plug-in Hybrid Chevy Volt.

The 2011 Nissan Leaf did have the J1772 on their low end model, but it too 8 hours to charge to the 74 mile range Leaf. And their higher trims had a CHAdeMO connector which could charge the car in 30 minutes. It worked for the Volt as well, but that had only a 35 mile range (going up to 50 in later models), and a dimunative 16 kW battery.

2003

Tesla was founded on 2003, and they had the 2008 roadster with it's own connector. But in 2012 Tesla added the Model S. J1772's anemic 19.2 kW charging was too slow, so Tesla invented their own connector and created SuperCharging at 100 kW (that could scale up to 1,000 kW). They also implemented the first SuperCharging network for their cars, that is still the largest/fastest/most reliable out there.

Tesla roadster (Darkstar) in 2008 was a small little Lotus sized car, and only 2,450 units were made (low volume) and a 53kWh battery (good for 244 mile range). It was a good proof of concept, learning platform -- but the goal was always a practical ICE replacement. The Model S was a full sized sedan, their and up to 100 kW battery. And to increase practicality, Tesla needed to introduce a SuperCharging network to fill that battery quick enough to make it practical for road trips and inter-city travel. So they created their Connector with 150Kw DC SuperCharging.

2011

CHAdeMO - Nissan came our with their 74 mile range Leaf EV, and it had the J1772 in California and could recharge in 8 hours. Or you could use the optional CHAdeMO upgrade that allowed for 30 minute charging, and was adopted as the standard in Japan. But they're moving on to CCS as well.

Japan's dense cities and shorter commutes means smaller battery requirements -- thus Nissan Leaf had small batteries/range (24kWh/73 miles) than all purpose ICE replacement (what Tesla was competing with). In the U.S. the Leaf became popular as a 2nd short range commuter car, or City Car (for short urban trips). The lower requirements still needed a fast(er) charge option than anemic J1772, so the Japanese create CHAdeMO (CHArge de MOve) connector. It wasn't quite "SuperCharging" (100 kW), but it was Faster Charging; 50 kW in theory but only 22 kW by the implementation. It meant than instead of 8-hour charges, you could do 30 minute fast-charges to get home. When Tesla and others came out with SuperChargers, CHAdeMO did play specsmanship games to "keep up" with Tesla or CCS's DC SuperCharging... on paper. (v2 could do 200-400Kw, with 800Kw possible). However, they weren't implemented or deployed as widely (or at all), because few of their cars needed or took advantage of it. So CHAdeMO or short range EVs makes sense in Asia, or as a Urban get-about. But less so for any inter-city driving. And even their manufacturers are moving to CCS1 or 2 in other markets.

2012 CCS wanted SuperCharging as well, so they stuck a couple of optional DC pins on the bottom of J1772 (U.S. / Type 1) or Mennekes connector (EU / Type 2), to copy what Tesla was doing.

2015 GB/T is harder to Research. Basically, it feels like China copied the rest of the world, but wanted to be different. It's a little better than CCS in that it integrates DC and AC into one connector. Yet, it just just seems to be be different for the sake of being different.

Theory and Practice[edit source]

Main article: Electric Vehicles/Charging/Theory and Practice

❝ In theory there is no difference between theory and practice, while in practice there is. ❞
~ Benjamin Brewster ℹ️ The Yale Literary Magazine; February 1882 ^[1]

The manufacturers and advocates give you all these specs -- and they are good for relative measurement -- in that bigger is faster (or less time to charge), and that's better. However, they do NOT hold up in the real world in absolute numbers. Just add in some slop and don't worry about it. But if you want to know the math/why? Here's some answers.

A couple things are at play:

With electricity, there's rated amount, and actual amount. We generally run things about 10-20% below maximum rated amount, to keep from overheating. So a 15A circuit is best to run continuously at about 13A, just to prevent overheating the cable or tripping the circuit. We talk rated, we run actual.
There are losses. For example, the cable/batteries getting warm? That's electricity getting converted to heat and getting lost. Chargers, inverters, cables, just operating the cars computers, cooling (cabin or batteries), is all a little bit of waste (loss) on charging. Figure a few percent total.
Charging Curves (Peak versus continuous) exist. When charging at home/destination, it doesn't matter much. When SuperCharging, it matters a lot. The specs usually talk about the best case, and not the average case. As the batteries are charged, they start to heat, and the car slows the charge rate to regulate that heat/wear. Thus how fast you are charging varies by how far into the charge/heating you are -- and it is the car that controls this (based on battery temp) more than the Charger.

Rated versus actual[edit | edit source]

Losses Generally, the charging losses are only 2-3 percent. On top of that, your battery doesn't have 100% usable space. So if it's a 78 kWh battery, probably more like 74 kWh is usable, and that means the losses in charging efficiency, and losses in usable capacity, kinda cancel each other out. And the numbers are low enough to usually ignore as noise. But you might notice discrepencies between what the Charger says and the Car says on charging; that difference is usually just disipated heat, or other losses.

Level 1 charging

You might think 120v @ 20A is 2.4 kW... but in truth, a 20A rated circuit breaker, will be throttled by the charger/car to about 16A to leave headroom (for heat and not tripping by accident). Theory is 2.4 kW. Reality is 1.9 kW.

Some people will drop it on a 15A breaker, and only get 12A. New Reality is 1.4 kW. Thus by their math? They can charge their 72 kWh battery in 30 hours (2.4 kW x 30 hours is 72 kWh). In practice? 1.9 kW * 38 hours is 72 kWh.

Level 2 changing

240v @ 80A is 19 kW.... but only Ford uses an 80A home charger. Most use 60A, throttled to 50A, or about 12 kW. Thus the 4 hour charge time becomes 6 in the real world.

Some cars are worse than others -- a Chevy Volt and Spark only take about 3.3 kW on their level 2 circuitry, the Nissan Leaf does about 6.6 kW, but a Tesla can do like 20 kW (even if your charger only puts out 12 kW). So a 12 kW charger only runs at 3.3 kW on a Volt. But the Volt's tiny battery still charges pretty quickly.

Charging Curves

Supercharging gets more dramatic: Batteries heat up and wear as you charge them. The slower you charge, the better for the battery. Charging an empty battery can take full load, say 350 kW, for a short period, but they quickly start to heat, and thus they drop down draw, and by the end of a full session are down to 50 kW. Loosely 30 minutes will get you from 10-75% or so, and it will take you another 30 minutes to get to 100%, because of these charging/heating curves.

Right now, cars are not really limited by how much power you can send -- it's more about battery cooling and wear. So you can send 350kW, but the battery will heat up, and keep dropping how much power it can take over time (to prevent overheating/fire). By the end of a charge session, it might only be taking 50kW. This is called the "Charging Curve". Active cooling batteries, software, new chemistries, will improve this over time. Level 1 (120v) and Level 2 (240v) AC chargers (in homes/Grocery Stores/malls) is not going to overheat the batteries and increase charging time much. But SuperCharging will. So you'll only get near the theoretical peak performance for a few minutes, then it starts throttling (slowing) the charge. This is why it's easier to say good enough at 70-80% and drive off rather that having to wait to the extra 30 minutes just to get to 100%. This is different than ICE cars (where it doesn't take much more time to top off the tank), but the advantage of EV mapping your next charging stop for you, and once you learn to stop at 80% makes it only a little worse than an ICE. Thus, most people SuperCharging on road trips, use "Splash and Dash", they take the car as low as they can (batteries will gobble power), and they only fill it up enough to get to their charging destination or final destination (with a little bufffer) or about to 70-80%, before the curve really slows down.

V2G

Some chargers and EVs offer V2G (Vehicle to Grid). Basically, that you can drain your car battery and sell it back to the Power Company, during peak, and make some money back. It's a solution that nobody really wants, thus it doesn't really exist in the real world, and you don't probably want it if it did.

In theory, it V2G sounds good. But in practice? CHAdeMO, CCS, Tesla connector all have the theoretical capability. Tesla car inverters haven't implemented it (despite it being low cost), Ford has it on their charger, and Nissan implemented the capability, but no Power Company did anything but a minor pilot with it. The reason for the lack of interest is people's cars are out during the day (peak). And who wants to wear out their car's batteries faster, or give up range they might need/want, all to make/save a few dollars on electricity? Solar Systems (with Battery Backups) have more capacity and better battery chemistries for it. So using your EV in a power outtage for a little extra power is popular. V2G's economics (value) doesn't seem to work in the real world.

Conclusion[edit | edit source]

Electric Vehicles functionality, day-to-day, is based on it having enough range to do what you need to do. EVs are more sensitive to temperature, wind resistance, and things that affect ICE's (Internal Combustion Engines), but there's enough over-capacity in Gasoline cars, that most people don't notice. Hopefully, I can demystify a lot of the specs and what you need to know about charging.

Day-to-day? Home charging means your EV is always charged. You won't need to go to a charging station, unless road tripping or rare occasions. So you save far more time than they cost in slower charging speeds.

EV road-trippers learn how to use their cars charging, driving until their battery is low, then only charging the car enough to get to the next station (+ say 10-20% safety margin). (Called splash and dash). This is a little different, in theory to ICE's (Internal Combustion/gasoline-powered cars) because fueling times are so different. But in practice? With software telling you range to next station, you don't notice the impact much. Total time starts working out to about 30-40 minute breaks every 2.5 - 3 hours or so, maybe a little longer if you get a meal while it charges... but that is not much worse than an IC for practical road trips, unless you drive like a maniac and use a pee-can.

EVs are better day-to-day for many/most people, but that's NOT better for everyone or all use-cases. These cut into value:

If you want to go off the beaten path (too far), and/or live too rural - if you had booster gas tanks for an ICE car
If you like to tow big things for long distances
You like drive during really cold weather
If you live in an appartment/city and can't setup a home charger -- that dramatically cuts into the convenience of always being charged. Especially if you don't have work charging as well.

All of those things reduce range and start meaning the EV's (in the current generations) are not as practical as IC's for your use-case.

I'm not one that believes in pretending that better at one thing is better at everything. EV's are more economical to fuel, quieter and can be more performant and comfortable to drive -- and completely practical if you have at-home-charging, and you only occasionally road trip. But if I was doing tons of rural driving in places without a Supercharger convenient? Or towing, etc.? Or I lived in an urban apartment without my own charging stall (or without at-home charging)? I'd buy an IC and save the headaches.

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