Recharging in 10 minutes is less exciting than you think


Lots of folks were forwarding a story about a battery lab at Penn State that has shown a battery that can be recharged in 10 minutes. This is good (and many other labs and companies have demonstrated other ways to do that. But my key reaction is that those who think it's a huge deal are still thinking of electric cars like gasoline cars that you fill up at filing stations. They aren't. With a recent EV, not on a road trip, you charge only at home while you sleep, which takes zero time. Fast charging is not of value there. An article about this can be found in

Read more in my Forbes article Recharging in 10 minutes is less exciting than you think


Some people, like myself, do most of their travelling on long trips, when fast recharging would be interesting. Also, not everyone has the ability to charge at home. (I even have a three-phase plug at home, but can't park close enough.)

Another myth: range is important. No, once there is a minimum range, what is important is how long it takes to charge to go a given distance.

You are unusual in that, but then indeed you will care about the fast charging. Though actually, if there is hotel charging, and you have enough range to only need one mid-day recharge, you don't actually need fast charging because you charge while having lunch. This does constrain where you get your lunch, but otherwise it does little good, I have found, to have 10 minute charging instead of 40 minute once you plan to have your lunch.

Now, if you regularly go more than 600 miles in a day, you might need two charges in a day. Those can be lunch and dinner, but that gets a bit more inconvenient.

I think you are not considering all the possible scenarios. I live in a city in Germany and there is a lot of people renting their apartments and parking their cars on the street. Home charging is not an option for those people and having access to fast charge actually might persuade them to go electric.

There are no firm numbers but yes, around 25% of cars park the night on the street. I write that today, EVs are probably not for you unless you have at-work charging. Over time, this will change, with robotic charging and maybe this fast charging.

There are a huge number of cases where 10 minute charging would be great. The question is, how much more expensive will it be, both in terms of electricity cost and in terms of wear and tear on the batteries.

And then balance that against the ability maybe to buy a car with a 200 mile range instead of a 400 mile range. Or maybe even less. (I'd have little use for more than 100 miles if I could charge in 10 minutes on those rare occasions when I travel more than 40 miles from home.)

Personally, long ranges are what are unexciting to me. I'd happily buy an EV with only 100 miles of range if it were significantly less expensive in total cost of ownership to a hybrid. But the market seems to strongly disagree with me on that one.

If you don't drive that much, EVs are much more expensive than other options, especially if you're not in a high tax bracket and eligible for generous tax credits. I'm not sure if it's just not possible today from an engineering standpoint or there just aren't any companies bold enough to offer a low cost EV, but hopefully that'll change one day.

What you write sounds very much like what I thought, and most people think, before they buy an EV. Most people change their thinking after buying the EV.

Yes, you could get by with a short range car and 10 minute charging. But 10 minute charging is many years away from being everywhere in town. For a decade, it will probably involve a 10 minute round trip detour to get to, making it 20 minute charging or more. And possibly a line at the charger until it's really common.

One of the big realizations you get after getting your 200 mile EV (whose range I also rarely use around town) is the attraction of the convenience of home charging. Since it happens when you sleep, it is to many, a great surprise. It's easier than filling up with gasoline. Most people expect worrying about and finding charging to be the downside of the EV. It's the upside. I used to hunt for gas, wanting to find a good price. Deciding how low I should let it get before I fill up. Getting in line at Costco for gas when I shop there.

This is even making me debate my opposition to inductive charging, which adds cost and wastes 5-10% of the energy. I wonder if its convenience is worth it. Literally doing nothing extra for all your hometown driving, not even thinking about it.

The people reporting these fast charging technologies claim they are gentle on the battery. Of course that has to be proven in the field.

I don't have an EV. They're too damn expensive. Total waste of money for most people. The obvious explanation for why people who own EVs don't think they're a waste is that people who think they're a waste don't buy them.

I'm not sure what you're saying by "you could get by with a short range car and 10 minute charging." I didn't mean to suggest exclusively using 10 minute charging. I'd charge at home normally (using the charging infrastructure I've had to install and maintain, which doesn't come free). I'd only use 10 minute charging on those rare occasions when I'm driving far from home. Maybe 5 times a year. I'll have to check on Google Maps tonight.

By the way, supporting most people in a neighborhood all charging at their homes at night will likely require quite a bit of expensive infrastructure upgrades on the part of the power distribution companies. Unless they all have Powerwalls.

We are a very long way from whole neighbourhoods going electric. When the time comes, we'll have a way to do it. My own prediction is that that "way" will be cars which are able to safely wander off at night to charging stations (be then 10 minute stations or 2 hour stations) within a few miles, so that no new infrastructure needs to be put into the homes themselves.

Note that a 100 mile car should not do more than 60 miles on a regular basis, though that is indeed fine for many people.

However, unless we get batteries so that they last for several decades of use, it turns out that while a 200 mile battery costs more than a 100 mile battery, it also lasts twice as long in total miles, so it is only marginally more expensive over the lifetime of the car. There is also about a 3% extra cost for carrying the extra weight, and there is the space it takes up.

How long is the life of a new EV? Tesla claims that its cars are appreciating assets and that they come with all the hardware they will ever need. You and I both are highly skeptical about that, to say the least. And other EVs don't even make that claim. A 2019 Nissan Leaf or Chevy Bolt is not going to have anywhere near the state of the art in ADAS capabilities in five years. Will it be drivable? Sure, but it will have depreciated in value by 70 or 80% or more. In the meantime, battery prices will no doubt have plummeted, and battery life will have increased. A 200-mile battery bought today might last twice as long in total miles as a 100-mile battery bought today, but a 100-mile battery bought today plus a 100-mile battery bought five years from today (at a much lower inflation-adjusted price) will last much longer than a 200-mile battery bought today. And the money you save on the less expensive battery today can be invested. At 6% interest compounded daily for five years, you'll have $135 for every $100 you've saved. And that 100-mile battery you buy today, which you replace with a new one in five years? It won't be useless after five years. It'll have a significant value for non-vehicle applications.

We probably are a very long way from whole neighborhoods going electric. But that's because EVs are too expensive, so most people aren't buying them. If we started switching over today, we'd have most car-owning households owning at least one electric car in 8 years or so. That's a lot of infrastructure improvements that would have to be made to the grid to support that, and most cars won't be self-driving in eight years. There might not even be any consumer cars that are self-driving enough to "wander off at night to charging stations" in eight years.

If cars are going to be wandering off at night to charging stations, isn't it a lot more efficient for the charging stations to support 10-minute charging rather than 2-hour charging? If the cars take 2 hours to charge rather than 10 minutes, you need 12 times as many charging stations. Yes, the charging stations will be somewhat less expensive per station, but they'll still take up the same amount of space per station, so 12 times as much space. You seem to have conceded the point that 10 minute charging is very important to your vision of the future.

My typical day of driving is under 20 miles. That's not a guess; I looked at my Google Maps Timeline for yesterday, which was higher than usual because it was a Friday, and it was under 20 miles. Of course, my driving is below average, but the average is under 30 miles.

High range batteries are a huge waste.

100 miles is more than enough. I could get away with 50, except for those 5 or so times a year when I drive about 75 miles away. There are two Tesla Supercharger stations right off the highway on that route (one fairly close to my home, and one fairly close to my destination, each no more than a mile detour from the route), several other Supercharger stations within 10 miles of the route, and a small number of level 2 chargers at the destination (which aren't guaranteed to be available). Access to 10-minute charging (5 because I'm only charging 75-100 miles?), at one of the Supercharger stations, on those occasions when the level 2 spots are full, would completely alleviate my range anxiety in making that trip.

On the other hand, the better solution would be for my destination to offer reserved-in-advance level-2 charging. Maybe combine it with valet parking, and charge $10 on top of the electricity fees. $10 should be more than enough to cover the valet service, and with the valet service they can serve multiple cars at the same station during the day.

The problem is, there's little demand for this, because not many people have EVs, because EVs are way too expensive.

Of these risks, the greatest one is indeed that the battery depreciates in value because better technology obsoletes it. This is less of a risk for taxis, which will do 250,000 miles or more in 5 years.

Even so, for people in the upper half of driving (15,000 miles/year or more) here in California with $4/gallon gasoline, if you compare an electric car at 4 cents/mile for electricity with an average 30mpg sedan you are talking about $2,000 per year in savings on gas and maintenance today, which over the 20 year life of the average car does make the electric a winner. Both will depreciate as new cars get better though, it's true.

I think that less than ten years from now, cars will be able to drive themselves at night on quiet streets to recharging stations, reducing the need for new electric infrastructure. The charging stations will be next to local transformer substations where many megawatts are readily available. This does not require full robocar ability, just low speed night driving ability.

Yes, if you do 20 miles/day, you don't want to buy that 200 mile battery. Good news -- you can get 100 mile cars for a song today because they are older generation, but unfortunately also because those older cars did not have good battery system designs and have degraded.

10 min quick charging is a *HUGE* deal - for shared fleets.

It depends on its cost, and in particular what cost it has to the life of the battery. While there are promising results, it is likely that 10 minute charging is going to come at a higher cost to battery life than 20 minute or 40 minute charging, for example. If it comes with no cost it is indeed a win.

For a robot fleet, the advantage of 10 minute charging over 20 minute is that you need only half the stalls. There is not really a big difference between having 10 minutes of downtime or 20 minutes of downtime, or even 40.

So the question will be, what costs more, 120 10-minute stalls or 200 20-minute stalls, including the cost to battery life for all the batteries used. On first blush, the 120 10 minute stalls (I am including some time for getting in and out) should cost less just because they need less land. But you want to do the full math.

Because you can't charge on the road itself. This system doesn't exist, and it would be ludicrous to build it, so it won't exist.

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