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Comment by thelastgallon | Hacker News Reader

Also, we can charge EVs. Grid connected batteries may or may not use the energy, but EVs will use some portion of it every day, and can be charged again the next day when there is excess energy.

Power price goes negative +200M times/year, just in the US and it is increase. It would be wonderful to get paid for charging EV. Tesla Electric customers report making as much as $150 a day[1]. Car batteries are bigger than powerwall, EV owners can make quite a bit of money by participating in VPP (Virtual Power Plant).

(1) https://electrek.co/2023/07/05/tesla-electric-customers-repo...

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It would take a great many discounted electric bills to justify the extra wear on the batteries that would result from the extra daily charge/discharges.

I'm not sure it would have much of an adverse impact. Driving the car is constantly charging / discharging it (regen braking).

I think it's more about how deep the cycles go -- just don't let the grid drain below like 30-40% battery and it likely would have no meaningful impact long term.

I'm not sure it a totally rational thing. This is effectively putting more miles on your battery, an item that costs tens of thousands of dollars to replace, if even possible years after purchase. There would have to be a substantial compensation for such use even if it only degraded the lifetime a few percent.

But at such a compensation level, one could probably just purchase deep cycle lead acid marine batteries. They could sit in one's basement charging/discharging at a much lower cost than the lithiums in a car.

The price of batteries has declined by 97% in the last three decades:https://ourworldindata.org/battery-price-decline. And it continues to go down! The chart ends at 2018, $181/KWH. 2024 forecast is $94/KWH (half of 2018 price), 2030 forecast is $62/KWH. Thats just Lithium Ion. Newer chemistries are even cheaper. CATL first-generation cells (Sodium Ion) cost $77 per kWh, expected to drop to $40/KWH.[1]

Current estimate for a battery replacement is 4K - 20K. With energy storage's learning curve, this will be soon under $3K.

1)https://www.nextbigfuture.com/2022/12/catl-will-mix-cheaper-...

https://about.bnef.com/blog/behind-scenes-take-lithium-ion-b...

> Driving the car is constantly charging / discharging it (regen braking).

My understanding is that the impact on battery longevity relates to the rate at which it is being charged/discharged. Accelerating and regenerative braking are small potatoes compared to charging over a typical level 2 system, I would think.

Level 2? Certainly not.

A typical L2 charger will provide in the range of 6-10kW (AC, marginally less ends up going to the battery after conversion losses). 10kW is only 13hp; forget acceleration - the car draws more than that at highway speeds.

(You can come at this result another way too - an L2 charge may take 6-10hr to refill the battery from empty. But the car would not be able to drive 6-10hr at highway speed starting at 100% charge! So the L2 must be delivering less power than the car consumes at cruising speed.)

When people plug in their cars:

1: They expect them to start charging.

2: They expect them be charged when they return.

Please don't let your imagination run away with schemes like this. The incentives might be nice, but they'll only attract people who understand them and are in a situation to take advantage of them.

I dispute that. Ontario Ultra-low-overnight rates let me charge my car overnight for $2 or during peak periods for $25. Not too many people are going to ignore savings like that.

I just tell my car to make sure it's charged & warmed by 7AM and it takes care of the rest.

If I had the opportunity to join VPP I'd just tell it to make sure that it was at 80% at 7AM and never below 50% any other time.

I think every EV I've driven has a charging timer - so I've been able to say "only charge overnight when prices are cheaper". Some have "Be charged to 100% by this time" so they can pick and choose when to start charging.

Please don't let your lack of experience run away concocting scenarios which don't exist.

> lack of experience

I've had electric cars for almost a decade, and I currently have two Teslas.

> concocting scenarios which don't exist

I've had plenty of situations where my car didn't charge. (Don't buy an electric Chrysler, btw.)

The most recent situations have to do with Tesla's new feature where the car will primarily charge on solar.

> "Be charged to 100% by this time"

What I hit was with my dual car charger. (Grizzle) It gets screwed up by things like timers when two cars are plugged in.

It divides the amperage up evenly until a car finishes charging, and then gives the car that is still charging most of the amperage. If the 2nd car is on a timer, the charger will never give it full amperage until you unplug and replug it.

This is a problem with Tesla's solar charging feature, because only one car will charge at a time. When car 1 finishes and car 2 starts charging, the charger doesn't adjust, and the car 2 never gets full amperage.

You'll hit the same thing if you have two cars plugged in and they are both on timers.

Granted I could probably push on Grizzle to give me a firmware update, but my experience is that they ignore support questions.

Your assumption is there is no electricity at home or work, only at charging stations far away.

But, we have electricity anywhere we have a building. In fact, thats the first utility thats hooked up before anything is even built. Now, we can think of charging an EV anytime it is parked. Residential garages have a 240V dryer outlet (or in the laundry room next to garage). That outlet can be used or an additional outlet can be added.

Cars are parked 22 - 23 hours a day. They can charge anytime they are parked.

> Your assumption is there is no electricity at home or work

I've driven electric cars for a decade and have two.

That is not my assumption at all. My assumption is that most people will consider the car defective if they plug it in, and then it doesn't have a full charge when they come back to it. (Either overnight or at work.)

> Residential garages have a 240V dryer outlet

Where I live that was a recent code change. I had to install an outlet for my first electric car. When I built my house in 2017, I had to really push on the builder to include an outlet.

If you've chosen to go to a fast charger, you're always going to get a charge and you'll just pay what it costs. That's not going to change.

But for a destination charger (e.g. shopping center), or a charger at home or work, it doesn't have to be like that. I would have a system where there's three options (can be three big light up buttons) - 1. I need the battery charged right now, 2. I'd like the battery charged over the next 6 hours, and 3. I have enough charge for now, but do charge me up if it's free or prices are negative.

Option 2 would probably be the default, because it would be able to modulate the demand and charge very cheaply, because it'd mostly only have to avoid the two-hour or so peak periods (like the solar duck curve). Option 1 is there when you need it, but you might pay a few dollars more for a charge. During the day in summer, in areas with lots of solar (like my state in Australia) you might be able to always select Option 3, and usually get a full charge (well, I'd set the 80% limit but fully up to there) every time without ever paying anything.

It doesn't have to be hard - you just tell it you want charge right now, over the next little while, or you don't care, and you pay (or don't pay) a differently depending on what you select. It can be a very small number of super simple and extremely intuitive options, not complex settings you need to think about. People scare-monger about "Governments taking away our ability to use power when we want", but it's actually going to be "Utilities will offer incentives like free electricity if you choose to shift your usage" - just offering more options, not taking away freedoms.

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