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Charging cars at home at night is not the way to go: study

news.stanford.edu

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Re: Charging cars at home at night is not the way to go: study

#301

Post by PaulDavisThe1st »

landemva wrote: post #201
upsidesinclude wrote: post #66

This article does a poor job of explaining why there is going to be a problem and relaying the point of the study. To model the grid and power infrastructure into the future, assumptions must be made about where the power is derived. The article fails to provide the basic factors contributing to the problem, even though the study itself does a fine job. So California wants to legislate electric cars. That means highe…

> Charge your car at work in the sun and use it to power your home at night. And fill your coffee thermos at work and drink free coffee at home all weekend. And toilet paper and pencils from work can also be taken home and maybe resold at a flea market.

Did you see anyone suggest that you receive free electricity while at work?

Re: Charging cars at home at night is not the way to go: study

#302

Post by PaulDavisThe1st »

elihu wrote: post #285
_8j50 wrote: post #228

I need ELI5: electric cars have very large and heavy batteries right? Why is it prohibitively difficult to replace them on demand? What if there were 2-3 batteries charging at home or hundreds at a "battery station", where you would park at a spot/drive-thru garage and have a hydraulic machine drop your old battery and lift in a new battery and the whole swap can take no longer than the time it takes to fill up a has…

Battery swap stations are an old idea, but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with. The packs have to be stored and charged, so you have the same electrical service requirements plus you need a place to store the batteries, and employees or robots to move them around. You nee…

> but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with.

Precisely the kind of thing government regulation is for. Don't specify what is inside the battery pack, specify the form factor, connection points and attachment mechanisms. Leave the battery companies to figure out the rest.

Re: Charging cars at home at night is not the way to go: study

#303

Post by theluketaylor »

kieranmaine wrote: post #148
ParksNet wrote: post #129

Earlier quoted context omitted.

Each car is typically driven 35 miles daily in the USA. Against a capacity of ~250 miles, this represents many days of non-charging, and thus a lot of flexibility in when charging occurs. EVs can potentially strengthen the grid: if they are charged smartly, to balance demand. We need manufacturers, regulators, grid operators to align on how to figure this out. At the least, grid conditions/pricing should be sent to t…

This is spot on. Kaluza ( https://www.kaluza.com/demand-response/ ) are working on this problem, by giving EV drivers reduced prices for EV charging as long as the Kaluza platform controls when you car is charged, with the Kaluza platform using price signals to decide when to stop/start charging. The larger impact will come from V2G (Vehicle-to-grid) charging. This will require manufacturers to add this capability to…

I’d happily let the utility decide when to charge the car for best pricing and load usage so long as I can override it when I need from time to time at prevailing price. I’d also be happy to sell power back to the grid if I can set the price floor threshold since batteries do have cycle limits.

Re: Charging cars at home at night is not the way to go: study

#304

Post by hakcermani »

to11mtm wrote: post #218
saidajigumi wrote: post #51

Earlier quoted context omitted.

This is precisely what the linked article says. From the section "Charging Incentives": “And it’s not just California and Western states. All states may need to rethink electricity pricing structures as their EV charging needs increase and their grid changes,” added Powell, who recently took a postdoctoral research position at ETH Zurich. The article also includes other interesting and more nuanced policy details tha…

> Another issue with electricity pricing design is charging commercial and industrial customers big fees based on their peak electricity use. This can disincentivize employers from installing chargers, especially once half or more of their employees have EVs. [...] Well, I don't know what to say aside from we would need a lot of work to have it 'both ways'. By that I mean, if we expect everyone to charge their cars d…

It can incentivize rooftop solar which can supply the increased charging demand.

Re: Charging cars at home at night is not the way to go: study

#305

Post by theluketaylor »

PaulDavisThe1st wrote: post #302
elihu wrote: post #285

Earlier quoted context omitted.

Battery swap stations are an old idea, but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with. The packs have to be stored and charged, so you have the same electrical service requirements plus you need a place to store the batteries, and employees or robots to move them around. You nee…

> but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with. Precisely the kind of thing government regulation is for. Don't specify what is inside the battery pack, specify the form factor, connection points and attachment mechanisms. Leave the battery companies to figure out the rest.

Way more complex than that. Different packs have very different voltage and current delivery characteristics. A bunch of motor management depends on the battery pack characteristics, including things like regen braking.

Charge times are already under 20 minutes for the best cars and will likely continue to come down. Swappable batteries would be a massively expensive undertaking that would hugely limit innovation in battery and car packaging for a pretty minimal gain.

I’ve taken my model 3 on plenty of road trips and haven’t once thought it would be better with battery swapping.

Re: Charging cars at home at night is not the way to go: study

#306

Post by vinnymac »

theluketaylor wrote: post #305
PaulDavisThe1st wrote: post #302

Earlier quoted context omitted.

> but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with. Precisely the kind of thing government regulation is for. Don't specify what is inside the battery pack, specify the form factor, connection points and attachment mechanisms. Leave the battery companies to figure out the rest.

Way more complex than that. Different packs have very different voltage and current delivery characteristics. A bunch of motor management depends on the battery pack characteristics, including things like regen braking. Charge times are already under 20 minutes for the best cars and will likely continue to come down. Swappable batteries would be a massively expensive undertaking that would hugely limit innovation in…

I agree. The newer charging stations are so quick at a rest stop, that I don't even notice them anymore. Once it's down to 10 minutes, it won't even be a discussion topic imo.

Re: Charging cars at home at night is not the way to go: study

#307

Post by nicoburns »

Terretta wrote: post #152
dybber wrote: post #132

Earlier quoted context omitted.

That’s how we do it in Denmark. We have hourly prices on electricity, so for me it’s cheaper to start the dishwasher outside peak hours. In some areas they are experimenting with car chargers hooked up to this electricity price info, so it charges when it’s cheap.

Weirdly, the latest iPhone + iOS pops a dialog box saying it will do this. // Weird given tiny amount of energy for your iPhone. But perhaps reasonable in aggregate.

iPhones do it to help preserve battery health. Slower charging is better for the battery, as is being near the middle of its charging range.

Re: Charging cars at home at night is not the way to go: study

#308

Post by User23 »

qqqwerty wrote: post #166
upsidesinclude wrote: post #104

Earlier quoted context omitted.

If we're seriously going there , then legislate mandatory carpool or motorcycles for single occupants. The thing is, California isn't making great policy decisions or even efficient power decisions. They are making virtue decisions. Moving 1.5 tons of battery or 1.25 tons of battery isn't where the hairsplitting should take place

They are making politically expedient decisions that move the state towards its clean energy commitments. Yes, there may be some hiccups down the road, but that is the price to pay for putting off the transition for so long. And as one of the faster movers in this space CA will almost undoubtedly move the market in a way that will make it cheaper and easier for everyone else. Look at the "California Solar Initiative"…

And who benefits from that? Owners of single family detached housing and megalandlords. Maybe there is some positive environmental impact, but really the main motivation is wealth transfer to the politically connected classes.

Re: Charging cars at home at night is not the way to go: study

#309

Post by chipsa »

adgjlsfhk1 wrote: post #81
chipsa wrote: post #48

Earlier quoted context omitted.

Future is SAE J2954 (aka Witricity): you have a wireless charging pad under each parking spot. No screwing with power plugs, just park and go. This isn't ideal for fast charging, but for the slower charging you'd get from being somewhere for 6-8 hours, it's perfectly fine. You still need to run power to every parking spot, but now it's embedded in the ground, and you don't have to worry about someone just coming arou…

Losing 30-70% of the power and adding a bunch of cost doesn't seem like the way forward. Cables exist for a reason. They are the best way to move charge.

They claim it's 10% total loss, not 30%. And yes, it's got a cost, but depending on how things shake out, it might not be much more if any. Cables are the best way to move charge, assuming you don't have to worry about the cables. But once you factor in damage from vandalism or theft or just accidents, how hefty the cables actually are, etc, compared to having the cable buried nice and safe.

As for the difference in power loss between qi and this? Part of it is scale : they can fit a much larger diameter pad compared to a phone, which gets them much better coupling. You're essentially talking about an air core transformer, and there's plenty of transformers in the grid.

Re: Charging cars at home at night is not the way to go: study

#310

Post by ouchjars »

theluketaylor wrote: post #305
PaulDavisThe1st wrote: post #302

Earlier quoted context omitted.

> but it's really hard to actually pull it off. It requires that all the cars you service have the same battery pack, or that there are at most only a few kinds of battery pack to deal with. Precisely the kind of thing government regulation is for. Don't specify what is inside the battery pack, specify the form factor, connection points and attachment mechanisms. Leave the battery companies to figure out the rest.

Way more complex than that. Different packs have very different voltage and current delivery characteristics. A bunch of motor management depends on the battery pack characteristics, including things like regen braking. Charge times are already under 20 minutes for the best cars and will likely continue to come down. Swappable batteries would be a massively expensive undertaking that would hugely limit innovation in…

To some extent, the forced downtime is a benefit. Instantly refeullable vehicles enable fatigued driving. It's not even healthy to be sitting for that long as a passenger.
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