[lja]

I think EV owners would need to find some level of compensation for the additional cycles they would incur. Electric vehicles are expensive because of the battery so deteriorating the life of one of the most costly parts of the car doesn't feel like a great solution.

[bryanlarsen]

Assuming Tesla prices and full cycling of battery (aka from 100->0), draining a kWh puts about 2cents wear on your battery, so compensation would need to be above that price.

In practice you'd never allow your operator to drain you to 0, so 2 cents is very much on the high side.

In the California Tesla VPP trial, they pay 50 cents per kWh.

(correction: 20cents wear, not 2cents)

[georgeg23]

I calculate about $12 per Model Y full battery cycle, how did you get 2 cents?

$12,000 (Model Y bat replace cost) * 300(miles for full drain)/300,000(total miles per pack)

= $12 per cycle

Edit: or 18 cents per kWh

[hdevalence]

The 2 cent figure is per kWh, not per cycle. Multiplying by the 75kWh pack size gives $1.50.

What about the remaining 10X? The calculation you’re doing isn’t the right one, because the battery wear isn’t directly related to miles driven; Tesla’s battery warranty is pricing in a “full stack” picture of battery degradation while actually driving.

Your computation implies that the battery has 0 value after ~1000 cycles, but battery manufacturers commonly warranty 3,000-5,000. In addition, cycle count is only one variable affecting degradation, others include the depth of discharge, the charging and discharging profiles, the thermal management, etc.

(This is one reason why a 10-year-old Tesla has noticeably different battery degradation than, say, a 10-year old Nissan Leaf, which has no thermal management and a very poor BMS)

Finally, even when battery degradation occurs, it doesn’t remove the battery’s entire capacity, so degraded batteries can still be used for stationary storage applications. While an extreme degradation like 50% is very bad for an automotive application, it doesn’t matter so much for small-scale grid storage, since space is usually not the limiting factor.

[georgeg23]

The nature paper seems to assume the car is doing a fast discharge to supply enough energy to the grid, so something like supercharging-- probably not the best on the battery. Tesla only warranties 375 cycles, so not sure what you mean? The 18 cents/kWh already assumes a more generous 1,000 cycles.

The $12,000 battery pack replacement cost is current market price, including any recycling or potential reuse of old pack.

Edit: actual battery replace including labor is $16,550 from a receipt https://www.currentautomotive.com/how-much-does-a-tesla-mode...

[hdevalence]

I don’t know about the nature paper’s assumptions, but supercharging provides far more power than could possibly be supplied to the grid via V2G — for instance, a 100A home service can draw at most 24kW (AC), while supercharging draws up to 250kW (DC). V2G would use the car’s onboard AC/DC converter, which usually tops out at 10-12kW, so it would be relatively slow discharge from the car’s perspective.

Edit: from the paper:

> We assume the home charging power as 1.92, 6.6, 22, and 1.92 kW for small, mid-size, large BEV, and PHEV, respectively

I don’t think the 22kW assumption is reasonable, but the others are comfortably within current L2 AC charging rates.

[themitigating]

If you have a high mileage car and the engine blew up would you buy a brand new engine or get a used one?

On US ebay I see model 3 batteries for $5k

A BMW engine (the b58) is about $5k used, about $10k rebuilt, and somewhere above $20k new.

[zdragnar]

1,000 cycles is only 3 years (assuming a daytime commute plus discharging to the grid plus re-charging back up counts as a cycle). Most cars are definitely still under warranty after 3 years of driving (assuming a 5 year / 50k mile warranty).

Regardless, if you do have a high mileage ICE car that you want to save, the used engine is probably the way to go, and won't suffer a crippled range of a used battery.

In general, I like the idea of electric cars, but battery packs are not on the same level as an ICE engine in terms of replacement. If you're in the unfortunate position of owning something like a Volt, odds are you literally will not even be able to get replacement battery- and if you could, it would cost more to buy and install than the car would be worth when you were done. That exact scenario hit the news at least twice in the last year.

[bryanlarsen]

Using your numbers: 300000 miles / 320 miles/cycle = 938 cycles. 938 cycles * 72kWh = 67500 kWh. $12000 / 67500 = 18 cents.

Dunno where I got my 2 cents from, that calculation was done 2 months ago.

[georgeg23]

I agree with your 18 cents/kWh. That's slightly more than the average cost of electricity in the US?..

That is interesting, that means for home-charging your electric cost (per mile) is about equal to the battery degradation cost.

Thats 2x cost than most think.

[bryanlarsen]

They'll only want to buy back electricity at times when demand exceeds supply. In Texas the price of electricity is $9/kWh during those times.

[elihu]

Presumably as we use more renewable energy, we'll need more temporary storage. Buffering out day/night cycles from solar generation, for instance, would be a daily occurrence not a rare event. $9/kwh might be reasonable in an emergency, but even 18 cents/kwh seems pretty high for daily use.

[bryanlarsen]

Your whole car depreciates, not just the battery. Depreciation cost for driving a mile is a lot more than the electricity cost.

[rtkwe]

For you though that cost is just part of the normal depreciation of using the vehicle. Allowing the utility to discharge your battery isn't part of the normal utilization for yourself so the cost should get included. We also don't usually think or talk about how much depreciation using a particular gallon of gas costs you so it muddies comparisons.

[dtech]

the "real" time-based prices have much more variability, if you have time-based prices you can buy for a lot less and sell for a lot more during peak. That difference can easily be double that 18 cents/kWh.

[ErikCorry]

Petrol engines get worn too.

[xyzzyz]

18 cents per kWh is something like 5-6 times the wholesale price of kWh. This means that using EV for large scale storage is highly uneconomical.

[epistasis]

That excludes the cost of transmission and distribution, which is more than half the cost of electricity prices to rate payers.

And using batteries to smooth out the leaks will allow greatly reducing the peak size of equipment for T&D.

Additionally, look at wholesale markets for electricity, such as Texas', and you will see price swings during a day far far in excess of 18 cents/kWh. This indicates that storage is extremely economical today.

[bryanlarsen]

It's only used for those periods when demand exceeds supply. In Texas, the wholesale price of electricity is $9/kWh during those periods.

[brianwawok]

During a brownout energy is worth a lot more, dollars to tens of dollars.

[readams]

But this article is not talking about brownouts this is talking about routine use.

[Tade0]

It's not per cycle, but per kWh.

In any case I'm getting 10-20 cents depending on battery pack size and chemistry.

[nkingsy]

This makes much more sense with large lifepo4 chemistry batteries that are expected to outlive the car by a wide margin.

Lifepo4 batteries > 50kwh should easily handle 500,000 miles.

Higher performance lithium ion will degrade at a rate faster than any expected return from a scheme like this.

At least in Northern California it’s now cheaper for me to run solar+battery off grid than to pay pge. Lifepo4 pushes it over the edge into profitability.

If off-grid is competitive, selling at peak prices is a no brainer.

[toomuchtodo]

I have 100k miles on my 2018 Model S having Supercharged it the majority of the time the last four years. It has only 6% battery degradation of the 100kw pack. Tesla warranties their powerwalls for 15 years when configured as part of their aggregated virtual power plants. The batteries are demonstrated to be durable.

New LFP chemistries that are heavier but more stable are ideal for stationary storage and high cycle counts, but the evidence shows in general that these packs are built for longevity (with very occasional early failures). You could probably do well buying a salvage Tesla and shucking the pack for working modules and coming out ahead economically (safety warning, do at your own risk, etc) if you don’t want or can’t get dedicated stationary storage (although it comes with generous federal, state, and utility subsidies in California).

[danans]

> if you don’t want or can’t get dedicated stationary storage (although it comes with generous federal, state, and utility subsidies in California).

I installed stationary LFP batteries (from Enphase) on my house in CA 1.5 years ago, but I then discovered that the state and utility subsidies [1] only apply if you are in a very low income (for CA) bracket, have a health condition that requires backup power, or live in a high fire risk zone.

I don't qualify for the first 2 categories, and my luck is that the high fire risk zone starts about a mile away from my house, so good from the fire risk perspective, but not for the subsidy. Still got the 26% federal tax credit (with IRA, it's now back up to 30%).

1. SGIP: https://www.cpuc.ca.gov/industries-and-topics/electrical-ene...

[mercutio2]

How do you like your Enphase batteries? I was pondering buying them, already have Enphase solar.

I'm particularly interested in whether you're doing any load-shifting with them, and if so, how easy it is to do with the software. I'm paying $.90/kWh at summer peak, so while I'm still on net-metering, I'm somewhat interested in going ahead and fully arbitraging during peak.

[danans]

> How do you like your Enphase batteries?

I'm mostly happy with them. The batteries are pretty much set-and-forget, but I change the reserve level by season (90% in winter, 30% in summer). The system automatically decides how to do load shifting to optimize for your particular rate structure. I will say the monitoring software can be janky at times. It's gotten better, but sometimes it is very slow to connect to the system.

> I'm paying $.90/kWh at summer peak

Whoa, where is that? That's 2x more expensive than California or Hawaii. You must be on a wholesale rate plan with very low off-peak rates if you are considering arbitrage. It's also good that you waited until this year, because before the IRA, the residential battery tax credit was only available if you charged it with on-site renewables, not from the grid.

I don't do any grid arbitrage in the sense of buying low and selling back to the grid from my batteries when rates are high. That's not possible for homeowners in CA, is it in your area? However, several places in Southern California already have home-battery based virtual-power-plants that you can participate in, and I think it integrates with Enphase batteries. In those programs, the arbitrage is managed by a 3rd party company which then compensates the homeowner.

However, my evening loads during the peak rate hours do draw on my battery until it hits its reserve level, so what I do is more like peak-rate avoidance than arbitrage.

My batteries also don't charge from the grid, just from my PV array. With subsidized net-metering 2.0, the difference between peak and off peak for me is only $.07/kWh, so there's really not a ton of economic value there, maybe like $70-80/year at most.

[mercutio2]

I live in Berkeley. PG&E’s peak EV-A rate for generation plus distribution was $.92 this summer. It doubled in a year or two.

My off peak rate for charging the car went from net $.15/kWh to $.36 during the summer.

It’s news to me that load shifting (if you’ve got batteries and solar) isn’t allowed by the CPUC, that does take the wind out of my sails a bit. But the peak rates are so high that just zeroing out my peak consumption is still probably worth it.

Does the system come with a “disconnect from the grid during emergencies” shunt?

I’ve heard conflicting reports about the availability and legality of those systems.

[nkingsy]

Good to hear about the S. I just got a used model X with free unlimited supercharging. Tesla doesn't recommend supercharging for around town use, which is strange considering it only goes over 1C for 5 minutes or so and only barely over, with active cooling.

The other strangeness for me is the recommendation to stay between 50 and 90 for daily use.

Studies of li-ion have shown 80-20 to be the optimal usage pattern for maximizing usable watts over the life of the battery.

[toomuchtodo]

Battery warranty is 8 years unlimited miles, so I don’t put much thought into pack health. Enjoy your spaceship.

[onlyrealcuzzo]

> If off-grid is competitive, selling at peak prices is a no brainer.

So why isn't the utility managing the storage directly then? Aren't they best suited to do this???

Or is this article just saying that EV car batteries could?

[Dylan16807]

> Aren't they best suited to do this???

They don't have a million EV batteries, purchased outside the scope of this program, sitting around idle and connected to the grid.

Their customers do.

[tuatoru]

Utilities don't yet have a million EV batteries laying around, but they (or specialist EoL battery companies) will soon.

From the abstract:-

> Participation rates fall below 10% if half of EV batteries at end-of-vehicle-life are used as stationary storage.

Half seems conservative to me. There are already lots of startups wanting your end-of-life EV battery.

[aurelwu]

end-of-life Battery usage will compete with recycling them and especially as material needed per kWh is going to keep going down it might be more economical to recycle them into a new battery - it also depends on costs of raw materials. I'd expect the share to be neither 0:100 nor 100:0 and to fluctuate quite a bit

[Dylan16807]

It makes sense to move a lot of load to older stationary batteries as those become more plentiful.

But more capacity is better, and getting things online sooner is better. And in 2030 almost all the capacity is going to be in non-retired packs in their original cars.

[fshbbdssbbgdd]

Utilities buy most of their power at wholesale rates, which are lower than the consumer rate they charge the end user. Net metering rules in some jurisdictions obligate the utilities to buy solar/battery power from users at consumer rates. That can be a good financial opportunity for homeowners and it’s driven a lot of the investment in home solar setups. But local policies can change. The rules are changing in California and it’s not going to be such a good deal anymore in the future.

[epistasis]

Utilities are, by and large, not economically rational actors. In addition to extreme bias in the C-suite towards old tech, they are highly constrained in decision making by public utility commissions, and decision making is often based on information that is 5-10 years old. It takes papers like this getting published, then publicized enough so that they PUC can't ignore it, before info can enter an IRP that plays out over 5-10 years.

[manmal]

LFP batteries can do 3k-10k cycles. Assuming a range of 500km per cycle out of an 100 kWh pack, that's 1.5 million km of total range (assuming 3k cycles). Only a small number of people will ever get that much out of a car - maybe 40% that, if maintained very very well. But we're talking Prius/Mercedes level endurance here, most cars won't make it that long. So in most cases, 70+% of the usable cycles in an LFP pack won't be done by the EV it was first installed in. Knowing that, selling cycles is actually a great way to offset purchase costs.

[throwaway894345]

Your range figures seem pretty crazy high. Pretty sure most EV batteries are smaller than 100k--my Model Y is only 75k for instance, and I'm not getting anywhere close to 500km per cycle because (1) my Model Y doesn't actually get 500km on a full charge and more importantly (2) like most EV owners, I don't charge to 100% and run my battery down to 0% but rather something closer to 80%/20%. So for my Model Y scenario, it's closer to half of your total range figure.

Also, I'm not sure what components would wear out in an EV before the battery such that it would total the car out. If the EV batteries in totaled cars can be repurposed for grid use, then great, but I would expect them to get recycled and put back into cars unless strapping them to the grid is cheaper than recycling (seems maybe plausible?).

[coryrc]

When speaking of battery cycles and lifetime, people almost always mean "full cycle equivalent". So when you say "I only go 80%->20%" then that would be considered 0.6 cycles counted against the lifetime.

[manmal]

I don't, LFP batteries are quite resilient. 80% -> 20% is a usability nightmare nobody with a $50k vehicle should accept. My Ioniq (first gen) doesn't even have an LFP battery and is optimized for 100% -> 13%, maybe even 100% -> 10% (turtle mode starts at 5%). Still at 100% SOH after three years.

Way more important for battery life is the charging rate (again, LFP are more resilient there too). Which wouldn't be an issue for grid use.

[coryrc]

I think you do. If you drove 10 miles and recharged, you wouldn't consider that a "cycle". You could do that 100k times (probably more), but no one would say the battery cycle life is 100k.

[manmal]

I mean I didn’t count in 0.6 cycles per discharge. My battery does 0.9-0.95 cycles usually.

[throwaway894345]

Is that how it works? Can I just charge every night, even if I've only driven a few miles, with no more wear on my battery than if I did full cycle charges? My vague impression is "no", but I really have no idea.

[coryrc]

It is, with lithium, basically no different to go from 80%->20%->80% once or from 80%->75%->80% twelve times.

The only complicating issue is calendar life of the battery when it is above 80%. Over time a battery loses capacity just because it exists, which I'm calling calendar life. The closer your battery is to 100% the calendar life decreases at a roughly quadratic curve (a battery at 80% has about 1/8 the calendar life loss of one at 100%). AKA you lose 8x more capacity per year at 100% than 80%. Temperature has a similar effect above room temperature or so.

So if your frequent charges keep the battery above 80%, that would reduce calendar life (increase capacity loss per year) on its own. LFP has far greater calendar life than lipo, but also cycle life too, so I think it's just as important to keep your EV at 80% or below, whenever convenient, regardless of chemistry, unless your usage will cause cycle life to end the battery usefulness before calendar life is significant; i.e. multiple full cycles per day. But also at multiple full cycles per day you probably won't spend much time above 80% even when charging to 100%.

Ah, to summarize, I'll repeat my simple advice: I think it's important to keep your EV at 80% or below, whenever convenient.

[Koemul]

If you keep the charge between 20 - 80%, your battery will last for far more cycles than when charging 0 - 100%. So you'll only get 60% of the kWh per cycle, but the battery will do 3-6 times as many cycles.

In fact, the battery management system won't even let you fully charge or discharge the battery for exactly this reason. When it shows 100%, there will still be 1-2 kWh empty and the same for a zero percent charge.

For example, a Toyota Yaris use a tiny (0.7 kWh) lithium ion battery and it gets charged/discharged constantly while breaking/accelerating, but it still last a long time because the charge is kept at about 50%.

[manmal]

There are 100kWh EVs out there, and they will quickly increase in number. For them, 500km is a rather conservative estimate.

> I would expect them to get recycled and put back into cars

In that case, you'd also get something in return for not having used those cycles. It's a matter of choice then - do I rent out my battery during use, or do I sell it after 8 years.

[throwaway894345]

I don't doubt they exist, I doubt that they're common enough to treat as the general case.

> In that case, you'd also get something in return for not having used those cycles. It's a matter of choice then - do I rent out my battery during use, or do I sell it after 8 years.

Yeah, but which is more economical is the salient question.

[manmal]

I agree, that’s an interesting question. You‘d need to factor in a fair bit of uncertainty due to inflation, future battery prices etc

[phkahler]

Did you know that the standard DC chargers communicate with the vehicle using PLC (Powerline communication) chips even though that communication is not over the high power conductors? I've always had the feeling the grid operators got that included because they thought they were going to communicate directly with the battery management system to control it as they wish. It never happened and now the standard is stupidly complex and they're still trying to use cars as storage without much consideration for what vehicle owners want.

Sure, offer variable rates. Offer interruptabke service. But stop wanting V2G, nobody actually wants it.

[dublinben]

>stop wanting V2G, nobody actually wants it.

Utilities really want V2G, so it's probably going to happen one way or another. It's probably less applicable to an individual homeowner, but commercial and other fleet operators are going to find this appealing at the right price.

For example: https://www.proterra.com/press-release/massachusetts-electri...

[ralph84]

School buses seem like possibly the only real use case here, since they have a very seasonal usage pattern. For other commercial vehicles, the operators buy them to operate, not sit around and power the grid. When are they envisioned to be powering the grid?

[nemomarx]

Municipal buses are parked in depots overnight, right? That would kind of make sense - they already have to own the land for that, the vehicles already have to stay there in specific conditions, etc.

[ralph84]

When are they supposed to charge if they're operating during the day and powering the grid at night?

[elihu]

I don't think that makes sense given that you'd probably want a full battery in the morning to start your day, and night-time is when you'd want to draw from the battery (assuming solar becomes a much bigger component of grid power).

It's possible I suppose that cities and school districts could have busses that have more capacity than they strictly need, and so it makes sense to use any surplus capacity for grid storage (while maintaining a reasonable margin in case a bus has to make an unexpected trip because some other bus had a flat tire or something).

[mmaurizi]

Not just seasonal, the school busses are also not in use during the day while school is in session, which is unusual for mass transit busses.

[com2kid]

Most buses do at least 4 trips a day, elementary then a middle or high school route in the morning, then repeat that in the afternoon.

There are only idle for 2 or 3 hours during the day.

(Field trips can add another usage in the middle of the day as well)

[phkahler]

Yeah, but sequential charging will eliminate that and reduce the fleet owners costs.

[jackinloadup]

Assuming V2G means Vehicle to Ground, this is something I would like to see for the following use-case.

I would like to use my car battery as a temporary home battery in the inevitable case of a grid outage. This opens the option to bring energy home from another location. Reduce or eliminates the need for a battery in a grid-tied house.

Am I crazy?

Edit: Granted that doesn't mean the energy company can use my car's battery at it's whim. I think compensation would be required and would actually make a lot of sense. It isn't like the electric company could build out a battery system for cheaper. It would need to be a higher compensation than to PV though. Batteries are more expensive and should be compensated as such.

[Reason077]

V2G = vehicle to grid. It’s quite possible for this to operate as a backup battery, but like a Powerwall it requires extra “gateway” hardware to ensure that your house is isolated from the grid when the battery is discharging.

V2L (vehicle to load) is a simpler form that lets you power 115/230V appliances directly from the vehicle. Quite a few EVs (Hyundai, Ford, etc) already support V2L.

[elihu]

There's two ways to power your house off your car battery. You could have your car act as a mobile electrical outlet that you can run extension cords off of to plug things into, or you could have it tie in directly with the wiring of the house so all your electrical outlets work.

The former is pretty straightforward. The latter would need a lot of electrical upgrades to the house. (I'd expect you'd need to do about the same thing that people do when they get solar, which is to replace the meter with something that can measure power flows in both directions, and is smart enough to disconnect the solar panels from upstream power when the power goes out, so you don't electrocute people trying to fix the power lines. If you don't have a local battery, that means basically turning the solar system off in a power failure.)

If you aren't planning on selling storage capacity to your local utility, maybe all you really need is an automatic shutoff switch to disconnect your house from the grid when the power goes out.

Either way you'd need some sort of power inverter to convert DC to AC. That could be built into the car, or it could be attached to the house.

[shagie]

> I would like to use my car battery as a temporary home battery in the inevitable case of a grid outage. This opens the option to bring energy home from another location. Reduce or eliminates the need for a battery in a grid-tied house.

Question is "how long?" and "how much?"

Lets take a 100 kWh battery which matches a Tesla Model S battery option and is a nice number for doing conversions from.

https://shrinkthatfootprint.com/average-household-electricit...

> The recent figures, as of 2021, show that the average annual electricity consumption for a U.S. residential utility customer is 10,632 kilowatthours (kWh). If you divide that by 12 months, the average monthly electricity consumption is 886 kWh per month. What about in a single day? That would be 10,715 KWh divided by 365, or 29 kWh. Then the average daily electricity consumption is 29 kWh.

So, hypothetically, 100 kWh would give you 3 and almost 4 days. This can be improved by unplugging things that consume more power. The other part with this is a "once that 100 kWh is drained, you're stuck stuck."

You're going to still need something between the mains power and the circuit breaker box. I'm also going to note I don't know what rate it can discharge.

You might also want to look at a system that is a dedicated whole house battery backup ( https://www.zdnet.com/home-and-office/energy/best-home-batte... )

The zdnet article links to a Lowes worksheet - https://www.lowes.com/pdf/portable_generator_wattage_chart.p...

And from that, look at the "this is what we want" and the question of "generator or battery" becomes interesting.

Then consider also, you can get a 10,000 watt generator (that does a cutover in event of a power outage in 7 seconds) for about $3000 which can provide 10 kW at 40 amps.

[dahfizz]

Anyone expecting regular 4+ day outages is already going to have a generator. What people want is for the car which is already plugged into their house to kick in when the power goes out for an hour or two.

[shagie]

At an hour or two, that's ballpark 3kWh of power you'd need. There are battery backup solutions in this range that are $3k to $6k (that are frankly quite interesting.

Those have the instant on design so that if the power is lost to the house you have a few seconds and its back up and running.

[dahfizz]

But why would I waste an extra $5k and floor space in my garage if _I already have an EV that should be able to do this_.

[toast0]

That's not crazy, it's actually a publicized optional feature on the F-150 Lightning, and the F-150 hybrid has an optional 240V 30A output that can be used as a home backup as well (although that'd be a bit more manual).

[coffeebeqn]

How could you plug a whole house into a 30A without immediately blowing the fuse?

[toast0]

Depends on your appliances. 30A @ 240V is 7.2 kW; which is plenty if you don't have AC or electric heating or cooling. If you do have those, you'll at least need to be sure not to run any two of those at once, if you can run them at all; you need to be careful with things like dryers, heaters, heat pumps, air conditioner, oven, stove, water heaters (especially tankless, but check your amps on an electric storage water heater too). Well pumps can be big loads too; mine is rated at 30A by itself, but many people have smaller pumps or utility water.

FWIW, the F-150 Lightning car to home option only goes up to 40A, which isn't that much more.

[rnk]

these are already available.

[fomine3]

it is called V2H (to Home)

[sokoloff]

Pay the right price for V2G energy supplied and a lot of people will want it.

Plenty of people are willing to drive 200 miles of Uber as a second job. V2G is a lot more appealing than that I think.

[Teknoman117]

As a semi-related side question, does anyone have good numbers on how plug-in hybrid batteries deteriorate over time? I bought a (2022) last March and I do a full charge/discharge cycle on it nearly every other day. I've averaged half my miles on electric since buying it...

I haven't noticed any range loss ... yet. I know on mine the physical capacity is 14.4 kWh but it'll only let me use a band in the middle (?) of ~11 kWh (it eats 12 kWh charging and I'm assuming a 90% charging efficiency) (I also don't know if the chargepoint chargers report delivered or stored energy). This is all what I'm presuming to be enforcing no full charge/discharge cycles to lengthen the battery life.

[kbuck]

Assuming you're using Chargepoint level 2 chargers (3.3/6.6kW AC, not DC fast chargers), they are reporting energy delivered. There is no data channel to report energy stored; only level 3 (DC fast charge) charging ports establish a data connection.

[rnk]

Varies a huge amount. I have an 8 year old tesla s 85kwh battery with 65k miles on it, known to be above average, 5 miles lost from ~272 range. Tesla has the best results for long life, it's basic matter of heating and cooling the battery. Cars without that have significant battery degredation when supercharging/fast charging because the battery gets hot. The worst is the leaf, almost every recent car except that has batt. mgmg. system. You also heat and cool battery when driving.

[abracadaniel]

I've read that nearly all range reduction occurs in the first year. If you're seeing ~80% usable energy out of it, then it's probably keeping you between 10% to 90% which is probably fine. Another major factor is battery cooling. Some only air cool the batteries, and in a hot climate they will die much quicker that way. It would be nice if the details were made available as not all manufacturers will use the same limits. Even better would be if it were configurable to some degree.

[jungturk]

Not a plug-in hybrid, and not data, but I'm down 5-10% total range after 80k miles over 6 years in a plug-in (full) electric vehicle.

[vondur]

What car do you own? I’ve wondered about the Nissan leaf which apparently has no active cooling on the batteries vs others which do.

[coryrc]

Only the early model years lack active cooling.

[whazor]

Selling electricity is compensation, like with solar panels. You only need hourly energy prices to make it profitable. Plus an app that does the profitability calculation and discharging.

[ThunderSizzle]

Sounds similar to Uber using a contractor vehicle's hidden depreciation and maintenance to shift the real cost of their service.

I doubt the hourly price will ever truly be fair to individual car owners. Maybe we'll start to be asked whenever we plug in our phones to tip the owner of a car our electricity is coming from.

[cwkoss]

If there are consistent price cycles and a good API for reading price, it should be pretty easy for an EV owner to control how much they interact with the arbitrage opportunities with some simple rules. Ex. "only sell if it cost at least 15% less to charge", "always charge to X%", "charge to 70% if < $Y", charge to 100% if < $Z", "never sell below X%"

The aesthetic vibe of having an autonomous energy trading bot in my garage is attractive to me.

[rtkwe]

Part of the issue isn't the controls to do that it's that the prices to compensate wear on a battery are a) likely significantly higher than the base price and b) pretty hard to calculate.

[mhb]

That's what a market is for.

[cwkoss]

Yeah, I'd try to model the deprecation cost of the battery to some extent while tuning my magic numbers in the trading bot settings.

~1,500 cycles per $16k battery replacement. Shouldn't sell a full cycle for less than ~$15. Don't arbitrage a 1% point of battery life unless it yields at least $0.15. Might just set it at $0.20 per 1% for healthy margin/price-in hassle of battery replacement.

[jahewson]

There is no market. I can only sell electricity to PG&E and only at a flat rate.

[rlpb]

> I doubt the hourly price will ever truly be fair to individual car owners.

If it's not fair to them, then they won't participate, and the market will adjust.

[micromacrofoot]

I already get paid by my utility for the electricity my solar panels generate, and it's 1:1 with what they charge me for their generation.

[idiotsecant]

It's not likely that the pennies offered will offset the much larger loss of value in the battery, though.

[zeristor]

Surely just going between 80% to 20% would still be worthwhile, I understand this is for more amenable to a battery than a full fast discharge cycle.

Indeed as this becomes more of an option I trust that car producers could look at engineering their batteries with this in mind.

[jvanderbot]

Deferred cost is enough, just let the Tesla power the house once in a while, like the Ford Lightning can.

The extra regulatory and technological stuff to make the Tesla power the neighbors house through the city grid is just overkill.

[0cVlTeIATBs]

1. Core charge when recycling 2. Time-of-use electricity rates. Up to the customer to choose to install load shifting equipment

[micromacrofoot]

The distributor should just pay the generation fee to the car owners just like they would a power plant.

[cyanydeez]

Considering the market is moving towards pertual licensing, by the time this is a thing, you probably won't be an owner and it won't matter to anyone except some bean counters when they update lease rules.

[_yb2s]

We also need EV designs where the batteries are modular and easy to swap out. I wouldn't be interested in a deal where I was compensated financially for quickly wearing my non-replaceable car battery out, because the battery wear alters the usability of the car, e.g. I might find I can only take my family on shorter trips than planned, if my battery is now 80% of what it would have been.

I also wouldn't want the battery level timed around the grid vs my own transportation needs. What if there is suddenly a heavy demand on the grid, and now I can't take my sick family member to the hospital, because the charge was sold to the grid?

[tuatoru]

> We also need EV designs where the batteries are modular and easy to swap out.

Battery swapping is already a thing. In China. Nio[1] sells luxury cars and there are lots of more utilitarian vehicles that use battswap, but get no press outside China.

In the west, Ample[2] is working with manufacturers to modularize batteries and make them swappable between vehicle brands, so a "gas station" business/industry model will work.

Edit: I believe that EV manufacturers that don't offer battswap will confine themselves to the luxury niche of the market. The mass market wants low sticker prices on its vehicles.

1. https://en.wikipedia.org/wiki/Nio_Inc.

2. https://ample.com/

[timidiceball]

NIOs are very much for sale in Europe and Oslo, Norway has two battery changing stations (more coming supposedly).

Very interesting what happens to car depreciation when decoupled from any particular battery pack.

[_yb2s]

This is really cool! Battery swap is the 'killer feature' for me that would allow an EV to replace an ICE vehicle.

[mozman]

Not to mention a bug that could drain batteries overnight and put vehicle owners at risk!

[jackmott]

cycles hurt a lot less than just time does, but of course there would need to be some incentive!

[prottog]

I agree. This further degrades the meaning of owning private property.

[wjnc]

Energy price volatility will probably increase because natural sources are more volatile and other sources have spin up / down cycles. A car battery is like 3-4 days of continuous house usage. The car battery being used to top off the top 10% in short term pricing for energy would give a very nice ROI I expect. The rest is software? Don’t overcharge, don’t go under the limit I set for continuous availability as a mode of transport. And that’s all within reach in front of the meter, thus under my ownership. Heck, without self driving becoming common a family might even have 2 EVs on the driveway, giving a week of off grid potential.

Come to think of it - a harder part is how super local the grid is and energy pricing should become. In my somewhat affluent neighborhood in high summer the voltage rises too high and the supply of solar falls. And tragedy of the commons - we are still installing solar because it’s massively incentivized (2 years before investment returns itself). To solve this with EVs requires very granular prices. There might be clouds 50 km away. But again, those are software solvable issues. (I’m not holding my breath. It’s like IoT-superplus.)

[Ajedi32]

Unless it's voluntary (which it darned well better be).

I envision a future where individual appliances (including EVs) can opt in to spot pricing for the electricity they consume (or produce). That would naturally incentivize charging during off-peak hours and discharging during peak hours, all without requiring any government incentives or coercion. It could also be useful for other major appliances which could benefit from the lower prices afforded by load shifting, such as hot water heaters.

[at-fates-hands]

>> I envision a future where individual appliances (including EVs) can opt in to spot pricing for the electricity they consume (or produce).

I remember when high speed internet was coming into being and there were a lot of pundits talking about how high speed bandwidth would be sold as a commodity on the NYSE. If someone needed say an hour of high bandwidth for a video conference, they could do what you're saying, buy an hour of high speed access. Of course, high speed internet eventually became so cheap and so readily available, those ideas faded pretty fast.

I might be remembering this wrong, but wasn't Enron doing what you're talking about?

[tguvot]

a bunch of appliances already can be aware of TOU pricing and run when it's atlowest. Many thermostats can be "auto-adjusted" based on grid load

[powerbroker]

>> I envision a future where individual appliances (including EVs) can opt in to spot pricing for the electricity they consume

When 1,000 devices jump on the grid the moment electricity hits $0.01/kWh, the demand spike will cause more generators to come back on line and increase the price back to $0.05/kWh -- thus causing the 1,000 devices to drop-off the grid.

Rinse, lather, repeat.

How do you compensate for the potential grid instability?

[Ajedi32]

Generators aren't going to spin up just to cover a brief fluctuation like that. It would cause too much wear on the system, so most likely anyone selling electricity to the grid via generators would program their system to only turn on when it predicts the price change will last more than a few seconds.

Assuming instability does actually become a problem though, that sounds like a very straightforward technical problem with many possible solutions. Just off the top of my head, the simplest market-based solution would likely be futures trading. If all these appliances reserve their electricity usage 10 seconds in advance, then sellers can know exactly how much demand there'll be and adjust their production accordingly, maybe even bidding on that capacity so they know in advance exactly how much they'll need to produce. I imagine the high-frequency trading industry probably has tons of experience with this sort of thing.

[NotYourLawyer]

Lots of now-compulsory things started out as voluntary.

[bryanlarsen]

Pretty hard to make it compulsory if you can avoid it by (at worst) unplugging your car.

[NotYourLawyer]

>bryanlarsen, we noticed that your location is at home but your car isn’t plugged in. Please plug it in and drink a verification can within the next 10 minutes to avoid a noncompliance charge