Hacker News Reader

Biggest battery on a Tesla Model Y is 81 kwh. To charge fully in 8 hours you need 10kw of power. Sounds like a lot. Central AC is about 4kw. An electric stove is 3kw, and another 3kw for the electric oven. A microwave is 1kw. Can you run your ac, oven, stove and microwave at the same time? If so, you have more than enough to charge an electric car. And that's if you drive 330 miles per day. If you drive 36 like the average driver, you can charge your car for the same amount of power as running your AC for 2 hours / day. Power just isn't an issue.

It possibly could work, but we would be pushing our system beyond its already maxed out limit. We can hardly handle AC units in the summer. Imagine your entire neighborhood has their AC systems cycling. While stoves/microwaves come on (because people come home from work and cook food), then everyone decided to run an Arc welder in their garage at full power for 2 hours. It's a big issue of timing. If you split up these actions and only do some at a time, you can make it work. Barely. But in reality these power draws are corelated.

Average commute pre-pandemic was 40mi. Two cars x 40mi round trip is a low enough draw to charge overnight with no rewiring of anything - grid draw is already much lower an night anyway. Mostly this is a grid issue of providing night time power. Ideally as storage offsets from daytime renewable generation.

For a commute of 40mi, yeah it makes sense. I've always liked the idea of EV for short commutes. But we're talking about high density batteries to fix the range issue.

An EV city would probably flip to high draw at night, when everyone charges. It would be like your whole neighborhood turning on a welder on max settings for 2 hours. You could probably turn down the fast charging to slow charging over night (so you can spare the grid) if you only commute 40mi but if they're talking about high density batteries you won't be doing a slow charge when you drain it. Especially in the case of semis/work equipment/planes, you will need that fast-fast-fast charger to charge your new high density batteries at the same rate.

40 miles is a long commute, most people commute less.

People who commute longer can still easily charge their cars overnight. Since most commutes are less than 40mi, we don't need to design the grid for an average over 40mi.

We don't need to design for the draw for fast-charging for everyone, just for those that need it. What we will likely find is that temporary storage at sites to allow for short, super high power draw will solve that problem.

And along interstates, if we build new, necessary transmission along that existing right or way, we will be able to tap into massive power easily.

What's more likely is that these sites with fleets of vehicles will become fleets of batteries, that can be charged when energy is cheap, and perhaps even feed back into the grid when it's profitable to do so.

Don't forget your gas bill. My 2013 truck gets 13 MPG. An EV plugged into my house with 100 KWH costs about $14 to fully recharge -- roughly 3 gallons (39 miles!) of gas' worth.

I'm extremely anecdotal but my trucks runs off veggie oil I get for free. It's maybe $200/year to drive for me.

That being said, it's not great how gas is very expensive. It's a much better conversion, and wastes less in the whole grand scheme.

What is your cost per mile? My 2017 Honda Accord Hybrid is running at 9 cents per mile at current gas prices ($3.30 per gallon) and that is purely city driving. Maybe 6 cents per mile on the highway.

It's premium in an expensive gas area. $4.50+ a gallon easy. So .35/mile just for the gas. Brakes, oil, and tires also not cheap.

Sorry, I meant for the EV. Ten cents per mile of electricity costs is the cheapest I've seen, and it is often higher.

I guess in my example, that's about 5 cents/mile assuming 300 miles of range.

I get about 4mi/kWh and electricity is $0.10/kWh so approximately 2.5 cents per mile

> How do we upgrade the local grids to have this amperage in each home?

Anecdote alert: The solar panels on my roof generate more power than I use driving my EV. Maybe the future is distributed.

I love the idea of solar panels, and being fully independent without reliance on government systems. Not to mention, the sun hitting your roof is energy you don't even want. Why not convert that back into electricity?

But that price tag is brutal. I assume to solar panel your roof would be around $20k+. Plus the price of an EV. These aren't items you can really buy used either. Old/weak EV batteries aren't "repairable" like an old car is.

It just comes back to my point of it being a nice luxury for rich people. I keep my budget for my vehicles at $5k max. I will never see a new/used EV & solar panel system for that price.

We do 95+% of our charging at home on 120VAC at 12 amps, which is about 1500 watts. For our mileage use we're charging perhaps 75% of the time.

I found at 1200W panel on Amazon for less than $400.

Various realities will substantially increase that number, but it's still not too expensive just to solar charge your car at home if you don't have a substantial commute.

Do you only recharge during the day? How do you think that solar energy gets to your car at night? You rely on the network to consume your solar power during the day AND charge your car at night.

I only do that because it's stable and reliable. If it wasn't I'd get a power wall or similar.

Instability seems to happen at times of peak demand. Which is notable in that it pretty much never overlaps with times I charge my car.

These high density batteries are going to allow you to have the same range with fewer batteries. Most Americans will find an upper bound of 500 miles to be pretty reasonable for a car. Most American's don't drive 500 miles per day and thus won't be charging a full battery pack every day.

You should consider upgrading your car solely for the fact that newer cars are significantly safer in crashes.

If the biggest problem is energy distribution, then we've won. Sure, it's not an easy problem, but it's a problem we've solved in the past. Yes, EV's will require grid expansion, but it's a similar problem in terms of scale and rate as the adoption of air conditioning.

Every year you hear about the rolling black outs in California[0][1]. It gets bad with heat waves and AC systems running. An AC unit is no where near the power draw of a fast charger.

[0]https://apnews.com/article/health-california-heat-waves-stre... [1]https://www.cbsnews.com/news/california-heat-blackout-risk-p...

Average AC power use is 8-27 kWh per day. Average milage is 38 miles per day. At 4 miles per kWh, that's 9.5 kWh.

Numbers get even better if you use kW per neighborhood rather than kWh, since charging is well distributed and mostly happens off-peak and AC use is concentrated during peak periods.

Why would that be the case? When people are at work, the power usage will drop but then spike when they come back. They get home, plug in the EV, turn on the stove/microwave, lights, turn on/up the AC. The power spikes are directly corelated to people being at home. Even if you schedule your EV to charge at night, your AC doesn't stop working because youre sleeping. This applies to the entire neighborhood.

Electricity is expensive in California. Virtually all EV owners will be taking advantage of the cheaper off peak rates when air conditioners don't need to offset the sun's heat.

> Just to charge our current EV's, we need to run dedicated circuits at max capacity and it still takes a couple hours

No, you can use a standard clothes dryer hookup and charge overnight. You can even arrange it so that the car charger only consumes power when other high-powered appliances are not (e.g. water heater, dryer, stove).

> It just seems like batteries aren't the bottle neck. It's our efficiency to produce and distribute this electricity.

They may not be "the" bottleneck, but they definitely are one of them. With increased density comes either longer range or lighter vehicles. The lighter the vehicle, the more efficient it becomes.

> ICE isn't perfect, but it's an extreme dense form of energy and the output of it rotational energy. Which is exactly what our end goal is.

So you do understand why denser battery packs are useful then? Also, ICE is not a "rotational energy" and more or less than "EV" is. I don't understand why this is included.

> In electricity production we outsource it, then store it. Basically the same concept as winding up a spring loaded toy then letting it go when we want to use it. The spring isn't the source of power, it's just the energy storage. Just because we made the spring bigger and output more doesn't make it more efficient.

We didn't make the spring bigger. We made it smaller and lighter and got the same output. That is more efficient.

> We cannot even make the electric motors more efficient, we already run at 80-90% efficiency. What will we see? 1% more? 2% more?

Yes, we no longer have to improve efficiency in the motor itself. It's already many times more efficient than an ICE.

> All this electricity needs to transported but the power lines waste power, the charger wastes power, the AC-DC converters waste power, the EV motor wastes power. It's so many little losses outsourced to someone else.

And yet, after all those transformations and power losses, an EV is still a net gain in efficiency in most cases. An ICE sends about 20% of the energy to the wheels. An EV triples that in the worst case. This means the infrastructure that you get your energy from can lose a lot along the way and you still end up net positive. And it concentrates further efficiency improvements. That abstraction is huge.

> Personally, the battery pack prices are the biggest killer for me. I drive a 90s Toyota pickup. It's been problem free. I've driven it for years. Unless it rots to the ground, I'll never see a surprise bill in 10-20 years saying I need a new battery pack. My motor could entirely fail and it would be a $500 fix. Not to mention, it's entirely recyclable. People will give me money just for the metal.

This is also something we all need to keep in mind. You continuing to drive that truck is a benefit to the environment. I'm not trying to say you should scrap it and go get an EV. But for someone who doesn't own any vehicle, choosing an EV today is better than going with a new combustion car.

>No, you can use a standard clothes dryer hookup and charge overnight.

These are also high power, special circuits. The outlet your TV is plugged into isn't near that power level. Most appliances run off 110v.

>With increased density comes either longer range or lighter vehicles. The lighter the vehicle, the more efficient it becomes.

Yeah, that's certainly an inefficiency. Not as big of an issue to its power source inefficiency. Heavy EVs aren't it's main flaw.

>So you do understand why denser battery packs are useful then? Also, ICE is not a "rotational energy" and more or less than "EV" is. I don't understand why this is included.

I should have said "it uses an extreme dense form of energy". You can make bigger springs on a wind up car, but you need a better source of energy to wind it up. Gas goes from, "fuel -> combustion -> rotational energy". There's too many steps to go from "coal -> rotational energy" to even list. All of which, have losses.

>We didn't make the spring bigger. We made it smaller and lighter and got the same output. That is more efficient.

Sure, but doesn't fix the real issue of production and transportation. The weight is a lesser issue.

>Yes, we no longer have to improve efficiency in the motor itself. It's already many times more efficient than an ICE.

In a small scope, yes. In the whole picture, no. There's no more efficiency gain on the EV. That's it. It's at it's max efficiency and the only way to improve its efficiency is to redesign the entire system and create new technology to produce and transport electricity. Mean while, ICE is still getting improvements such as the Freevalve [0]. Not to mention how much more efficient diesel is compared to gas.

>And yet, after all those transformations and power losses, an EV is still a net gain in efficiency in most cases. An ICE sends about 20% of the energy to the wheels. An EV triples that in the worst case. This means the infrastructure that you get your energy from can lose a lot along the way and you still end up net positive. And it concentrates further efficiency improvements. That abstraction is huge.

Depends on your source. If you have wind powering your EV from a turbine, you generally don't care about the losses as much since it's all "free" anyways. Your EV is still wind powered though, it's no different than compacting that wind and using it to blow you down the street. It would take A LOT of wind to do that, so does generating electricity out of it. If your source of power is coal, you start at 66% loss, then 8-15% for powerlines, then you got charger losses, DC-AC losses, drive train losses. It's not as efficient as you think. You cannot create more power than you put in, no matter how much you try. Don't forget how much more efficient diesel is as well.

[0]https://www.freevalve.com/

> In a small scope, yes. In the whole picture, no. There's no more efficiency gain on the EV. That's it. It's at it's max efficiency and the only way to improve its efficiency is to redesign the entire system and create new technology to produce and transport electricity. Mean while, ICE is still getting improvements such as the Freevalve [0]. Not to mention how much more efficient diesel is compared to gas.

I'm focused here on tons of CO₂ per mile driven. After a century of eeking out improvements in ICE efficiency, it's still far below what we're doing with EVs. Unless you think the Freevalve is going to literally double efficiency, it's not a replacement for electric cars.

Only in the most extreme places in the US (West Virginia, Wyoming, Missouri) does the EV advantage start to wane. And even in those places, it still beats gasoline!

Burning coal for the electricity gets you 66%. Line losses and charging losses can cut that in half, and you're still beating the gasoline by a huge margin. Especially if you also ignore the costs of extracting, refining, and transporting all that fuel.

>Burning coal for the electricity gets you 66%

No no, it's 33%. 66% gets wasted as heat.

Sorry, misread. So the worst case is roughly par with an ICE, and the average case is much better.

I plugged in an old EV (2012 Model S) and a Wyoming ZIP code to the DOE's calculator¹, and I'm getting half the CO₂. 220 g/mi for the Tesla, and 410 g/mi for the new gasoline car.

I'm sure you can find an electrical outlet somewhere in the heart of coal country that fares worse for the EV, but that's not really helpful for the general analysis here. If you find yourself reliant on pure coal for your electricity, then you have a good individual use-case to remain on ICE. But for the vast majority of drivers in the U.S., EVs are tremendously more efficient than ICE when weighing CO₂ emissions per mile.

[1]: https://www.fueleconomy.gov/feg/Find.do?year=2012&vehicleId=...