53 ms·

Tesla adds bidirectional charging capability

172 points by Corrado 6y ago

deleted 6y ago
[deleted]
new_realist 6y ago
Vehicle to grid is only 80% efficient and prematurely wears the battery. Given that utility scale solar is much cheaper than residential solar, I wouldn’t be surprised if utility scale energy storage is also cheaper than vehicle storage. Lithium ion is optimized to be light, which is not an requirement for grid storage, which could make use of molten salt, pumped hydro, compressed air, or hydrogen electrolysis.
- slashdotdash 6y ago
  Vehicle to grid may actually improve battery health and keep them healthier for longer. > “This new research into the potentials of V2G shows that it could actually improve vehicle battery life by around ten percent over a year.” This requires intelligent usage where the battery state of charge is kept within a limited window, not fully charged or drained. [1] https://warwick.ac.uk/newsandevents/pressreleases/clean_energy_stored/ https://warwick.ac.uk/newsandevents/pressreleases/clean_ener... [2] https://www.sciencedirect.com/science/article/pii/S0360544217306825 https://www.sciencedirect.com/science/article/pii/S036054421...
  - new_realist 6y ago
    I don’t think reducing the effective range of your car to preserve battery life will be very popular; people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow. If someone does have a very predictable routine they can just not overcharge their car in the first place and save the discharge wear.
    - magicalhippo 6y ago
      > people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow For most people, if they really need to drive hundreds of miles unexpectedly, I doubt spending 15 minutes at a high-speed charger to top up the batteries will be an issue.
      - new_realist 6y ago
        As someone who drives an EV, I can tell you that it’s not the long distance trips, it’s having an unexpectedly busy day of errands in cold weather that gets you—realizing that you’re starting out at only 50% charge, which means you can’t make that last trip into the suburbs at the end of the day. There are very few fast chargers in densely populated areas and they’re often malfunctioning, or have queues. They also hurt your battery, so not to be used on a regular basis.
        speedgoose 6y ago
        In Norway where chargers are a lot more common, it's not an issue. Of course if I want to charge at 4pm at a popular place it may be a queue but most of the times many chargers are available and functional.
        magicalhippo 6y ago
        > There are very few fast chargers in densely populated areas I live in Norway so not a huge issue, and I expect it to get better. Circle K for example is pushing hard to build high-speed chargers at their stations.
    - Cthulhu_ 6y ago
      That's one use case of car driving, yes, but most people have a fixed daily / weekly routine. Plus it could be a setting, where people can tell the car to top it up overnight instead of optimize for battery life.
  - taneq 6y ago
    As I read this, it's basically saying that a battery used for V2G power would spent more time at a lower state of charge which doesn't degrade the battery as fast, to such a degree that this factor outweighs the extra cycles on the pack? Seems like an extraordinary claim - I'd want to see it demonstrated experimentally and not just assumed based on a model (no matter how many times they say the model is 'verified').
    - hwillis 6y ago
      They did run an experiment on actual batteries. It's still only one kind of cell, but they have actual experimental evidence: https://ars.els-cdn.com/content/image/1-s2.0-S0360544217306825-egi10HBXMVPXKW_lrg.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03605442173068...
- goodcanadian 6y ago
  We're involved in the first large scale V2G trial in the UK.[1] Our round trip efficiency is about 90%, which is better than pumped hydro which serves the same purpose.[2] Part of the point of the trial is to see what the impact is on the battery, but as a sibling comment mentions, there is evidence that it is actually better for the battery than just letting it sit. [1] https://www.indra.co.uk/v2g https://www.indra.co.uk/v2g, https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger https://www.ovoenergy.com/electric-cars/vehicle-to-grid-char... [2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
  - new_realist 6y ago
    How can round trip efficiency be 90%, when the one-way 240V charging losses to my Tesla alone are greater than that (at 83.61%)? Is it lack of three phase power in the US that is killing me?
    - orwin 6y ago
      You can't ask for three phase power in the US? Surely it have to be there but restricted to business, no? I remember seeing laundries and restaurant in small towns
      - selectodude 6y ago
        Large factories can get 480V 3 phase power in the US, but even laundries and restaurants get 240V “split phase” which is technically still single phase, just two power lines that would normally be going to two houses instead going to the same place. We have a very wonky power grid here due to how early on it was built. The rest of the world had the ability to see our mistakes and fix them after WW2.
        rsynnott 6y ago
        I'm not sure if it's age so much as bad (in the long run) choices at the time. European power grids have been around for a while (and some have their own oddities; the historical use of ring circuits in UK and Ireland domestic installations produced lasting weirdness, for instance).
- taneq 6y ago
  It's the battery wear that I'd be mainly worried about. I'd much rather be burning cycle life on a Powerwall than on a $100k car.
  - brianwawok 6y ago
    Model3 is more like a 40k car, and you can replace the battery in 10 years for a lot less than 40k I suspect
    - taneq 6y ago
      In my part of the world even an SR+ is $81k drive-away price. An LR with no other options is over $100k.
      - natch 6y ago
        I suspect you’re counting VAT as part of the price, which makes the claim inaccurate. It’s a $40k car with a TCO equivalent to a $26k car, which in your part of the world has taxes and fees that bring your out of pocket cost up. That doesn’t make it a $100k car. It makes it a $40k car that has heavy tariffs where you are.
- Glench 6y ago
  > given that utility-scale solar is so much cheaper than residential storage... That likely isn’t given! I haven’t looked into it thoroughly but apparently most of the cost of utility solar is transmission and billing. Australian residential solar is really booming right now because it’s 6-7 cents / kwh. See Saul Griffith of Otherlab’s article: https://medium.com/otherlab-news/green-new-deal-how-much-does-fixing-climate-change-cost-the-us-d542bb9e67c8 https://medium.com/otherlab-news/green-new-deal-how-much-doe...
- pmorici 6y ago
  The probable reason that Tesla has put this in but hasn't enabled it yet is that they are on the verge of announcing new battery technology their so called "million mile battery" that is rumored to not have the issues of current technology with respect to limited charging cycles.
- jessriedel 6y ago
  What this article needs is someone numerate who can at least do an order-of-magnitude estimate of the costs and benefits. When operating at scale, what will the marginal cost in terms of battery wear-and-tear be for storing 1 kWh and returning it to the grid? And how much will that storage be worth in terms of the difference between daily high and daily low electricity prices? Very frustrating that a putatively semi-technical publication like Electra doesn't even attempt this, or ask their interviewees estimates.
- loceng 6y ago
  https://news.ycombinator.com/item?id=23249269 https://news.ycombinator.com/item?id=23249269
_ph_ 6y ago
Before we investigate complex power to grid schemes - though electric cars could have quite an impact there - it would be great if any electric car came with at least one power outlet, so that you could power critical appliances in your house during a power outage at least. Like keeping the fridge running, some lighting and heating food on a small cooker. The same would also be great for any kind of camping. Beyond that, electric cars could of course have a huge contribution to the grid, especially with high percentages of solar and wind power. The first step would be to charge the cars dependent on the power supply situation. Loading during peak production and not loading in times with low production or pausing it in times of demand peaks. The final step would be using them to feed power back to the grid, though this needs to be done carefully, as this would increase the wear on the battery.
- new_realist 6y ago
  Powering critical appliances with your car during an electricity outage is tricky: if the outage lasts for an unexpectedly long time, you end up with no power and stranded at home with a car that has no miles in the tank. Meanwhile, you can buy a generator for as little as $400.
  - mrfusion 6y ago
    Last time I bought a generator I used it once. Two years later when I needed it it wouldn’t start. You’ve got to also invest effort in taking care of the thing. Oil changes, don’t leave fuel in it, run it every two weeks.
    - selykg 6y ago
      I've personally found that leaving gas in is fine, under two conditions: 1. You use ethanol free gas. This is more expensive, but it's also the same gas I run in all my lawn equipment so I generally have some around during the summer months. 2. If you plan on letting it sit for awhile use a fuel stabilizer in it. But yea, a safe thing to do is to run it out of fuel, especially if you have ethanol in it, because that shit will kill the plastic parts in the carburetor if it sits. Once it's out of fuel, run it every month for awhile with some new gas in it just to keep it running and active. You'll want to run it long enough that you burn out any potential water in the oil, so let it get to normal operating temperature and run it for a bit longer and you should be good. This is also good for electric start models which have a battery or capacitor that will need a regular recharge.
sorenjan 6y ago
It would be nice to be able to charge a car from another car, so you can help somebody that has depleted their battery at the side of the road.
- deleted 6y ago
  [deleted]
- Tepix 6y ago
  The upcoming Sion electric car by Sono Motors offers this feature. It also has quite a few solar cells.
  - close04 6y ago
    Their maintenance policy seems great: DIY for any minor repairs, with manuals being provided to all service shops. Repairs of critical systems and high voltage parts to be done via "a well-known European service provider". Being able, and even encouraged, to fix minor things myself instead of going to a shop for everything would be more than welcome. But I don't get their "solar panel in every body panel" approach. They say it provides 1.2KW peak but at any point in time only half (or none, in indoor parking) of the car is getting any sun. A thin layer of dust or light scratches will lower the efficiency further. And it also means any side scrape or fender bender would not just scratch the paint but damage the panels, especially on the doors. This makes repairs far more expensive and lowers the charge capability even more. And it looks like it only works with black paint which increases cooling requirements. I take it more as an emergency option. I'm not sure if the electricity they provide outweighs the added cost, complexity, weight, and perhaps increased consumption. The repair policy, small battery, large cargo space, and added solar panels might make it a good fit for professionals like plumbers or electricians only driving through the city for interventions and perhaps even leaving the car on the street. [0] https://sonomotors.com/en/sion/ https://sonomotors.com/en/sion/
- netcan 6y ago
  ...especially considering that you can't just go buy them some petrol. Now that I think of it, what's the MO if you run out of juice in a tesla.. tow?
raxxorrax 6y ago
The term is pretty misleading if cars are still charged with AC current, even with a rectifier immediately after the power supply. Maybe it is a language thing. Otherwise this "technology" could indeed be quite useful to lessen load. I would have thought that maybe providing local power to your home instead of buffering the whole network would maybe be more practical.
- teraflop 6y ago
  I don't see what's misleading about it. AC vs. DC has nothing to do with which direction power is flowing, which is what they're talking about. And feeding power to the "grid" is actually quite straightforward, at least for the customer's equipment. In effect, you can think of the 60Hz oscillations of AC voltage as being like an enormous rotating crankshaft that each customer is tightly coupled to. Correctly applying a "torque" to that system automatically distributes the energy where it's needed. In contrast, de-coupling and re-coupling one house with the grid on demand is a lot more complex: you lose the stabilizing effect of the grid's enormous "inertia", and you have to carefully synchronize the phases when reestablishing the connection.
thdrdt 6y ago
The Xpeng P7 also has a 220V output. I guess this can be useful for a lot of things. https://en.xiaopeng.com/p7/configuration.html https://en.xiaopeng.com/p7/configuration.html (Also a great looking car imho)
gwbas1c 6y ago
When I plug my car in, I expect it to charge. When I get in my car, I expect it to have a full charge. I don't want to have to push a special button or dig into hidden menus just to ensure that my car actually has a full charge. This is critical for when I take a long road trip, and I expect that I have a full charge when I leave. What I think makes sense is temporally stopping charging for the 10 seconds it takes for a generator to spin up. But these kind of events should be so infrequent that they have no noticeable impact to my ability to start a road trip with a full charge.
- wcoenen 6y ago
  > When I get in my car, I expect it to have a full charge. I don't want to have to push a special button or dig into hidden menus just to ensure that my car actually has a full charge. Then don't buy a Tesla, because the default factory setting is to charge to 90% to reduce battery degradation. (Personally I like that feature, I wish I could configure my phone to make the battery last a year longer.)
  - hnarn 6y ago
    iPhones kind of do this, I was surprised when I bought one recently and noticed it. It assumes your wake up time from usage patterns and then avoids charging above 80% or something during the night until right before you wake up.
  - gwbas1c 6y ago
    I know that. I'm referring to the electric company discharging my battery without my knowledge. Just think of what will happen the first time someone plugs in their car overnight and then the battery isn't full in the morning.
lacion 6y ago
the whole point behind Vehicle to grid is not to sustain your house but to stabilize the grid at peaks, don't think as your car but as the whole fleet of electric cars able to do V2G, that means that the grid could use a bunch of cars to sustain a small peak and avoid the need altogether of very expensive peaker plants
gregwebs 6y ago
There was a recent discussion on HN about using a Tesla as a store of energy that could be tapped to help with emergency power scenarios: https://news.ycombinator.com/item?id=23178733 https://news.ycombinator.com/item?id=23178733 Apparently the capability is already there!
loceng 6y ago
I'd highly recommend this "Battery Day is Coming" 40 minute video that explains what Tesla is likely planning: https://www.youtube.com/watch?v=pP971PYzQJs https://www.youtube.com/watch?v=pP971PYzQJs In one part of it they explain that how the batteries that went to stabilize the grid in Austrailia (and saved them a lot of money immediately, their investment/cost paid back in a few months from my understanding) can be decentralized to all cities around the world with using vehicles as the storage for energy at non-peak hours and source of energy during peak hours - arguably when you've driven your vehicle to the city and where production and office space, businesses serving the area, will be needing more energy.
spectrum1234 6y ago
This is going to make electric cars extremely cheap once the million mile battery is out. Probably at least 50% cheaper given the money you can make selling off peak electricity at peak prices. Electricity costs by me since I switched to time of use are 4x as much on peak vs off. My Tesla costs about $6 for a full charge off peak. It seems like its easy to make (4-1)* 6 = $18 a day off of this the car as it home. Let's say $10 after conversion loss and battery wear, etc. Once you buy any other hardware needed (I think they are $2k-4k now), this seems like free money. Worst case, car is home during peak 2 days a week and $10/day gain, $4k system: 2.5 year payback period and then $223/month income Best case, car is home during peak 5 days a week and $15/day gain $2k system: 26 week payback period and then $322/month income. The best case over 10 years is worth $38,700. However the biggest opportunity here is probably for Tesla to lease the battery to consumers. The car will be discounted significantly if you can plug in 3 days a week near peak usage.
deleted 6y ago
[deleted]

172 points by Corrado 6y ago

deleted 6y ago

[deleted]

Vehicle to grid is only 80% efficient and prematurely wears the battery. Given that utility scale solar is much cheaper than residential solar, I wouldn’t be surprised if utility scale energy storage is also cheaper than vehicle storage. Lithium ion is optimized to be light, which is not an requirement for grid storage, which could make use of molten salt, pumped hydro, compressed air, or hydrogen electrolysis.

slashdotdash 6y ago
Vehicle to grid may actually improve battery health and keep them healthier for longer. > “This new research into the potentials of V2G shows that it could actually improve vehicle battery life by around ten percent over a year.” This requires intelligent usage where the battery state of charge is kept within a limited window, not fully charged or drained. [1] https://warwick.ac.uk/newsandevents/pressreleases/clean_energy_stored/ https://warwick.ac.uk/newsandevents/pressreleases/clean_ener... [2] https://www.sciencedirect.com/science/article/pii/S0360544217306825 https://www.sciencedirect.com/science/article/pii/S036054421...
- new_realist 6y ago
  I don’t think reducing the effective range of your car to preserve battery life will be very popular; people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow. If someone does have a very predictable routine they can just not overcharge their car in the first place and save the discharge wear.
  - magicalhippo 6y ago
    > people want the freedom to drive as far as they can, because it’s hard to predict when they will need that capability, and charging is very slow For most people, if they really need to drive hundreds of miles unexpectedly, I doubt spending 15 minutes at a high-speed charger to top up the batteries will be an issue.
    - new_realist 6y ago
      As someone who drives an EV, I can tell you that it’s not the long distance trips, it’s having an unexpectedly busy day of errands in cold weather that gets you—realizing that you’re starting out at only 50% charge, which means you can’t make that last trip into the suburbs at the end of the day. There are very few fast chargers in densely populated areas and they’re often malfunctioning, or have queues. They also hurt your battery, so not to be used on a regular basis.
      - speedgoose 6y ago
        In Norway where chargers are a lot more common, it's not an issue. Of course if I want to charge at 4pm at a popular place it may be a queue but most of the times many chargers are available and functional.
      - magicalhippo 6y ago
        > There are very few fast chargers in densely populated areas I live in Norway so not a huge issue, and I expect it to get better. Circle K for example is pushing hard to build high-speed chargers at their stations.
  - Cthulhu_ 6y ago
    That's one use case of car driving, yes, but most people have a fixed daily / weekly routine. Plus it could be a setting, where people can tell the car to top it up overnight instead of optimize for battery life.
- taneq 6y ago
  As I read this, it's basically saying that a battery used for V2G power would spent more time at a lower state of charge which doesn't degrade the battery as fast, to such a degree that this factor outweighs the extra cycles on the pack? Seems like an extraordinary claim - I'd want to see it demonstrated experimentally and not just assumed based on a model (no matter how many times they say the model is 'verified').
  - hwillis 6y ago
    They did run an experiment on actual batteries. It's still only one kind of cell, but they have actual experimental evidence: https://ars.els-cdn.com/content/image/1-s2.0-S0360544217306825-egi10HBXMVPXKW_lrg.jpg https://ars.els-cdn.com/content/image/1-s2.0-S03605442173068...
goodcanadian 6y ago
We're involved in the first large scale V2G trial in the UK.[1] Our round trip efficiency is about 90%, which is better than pumped hydro which serves the same purpose.[2] Part of the point of the trial is to see what the impact is on the battery, but as a sibling comment mentions, there is evidence that it is actually better for the battery than just letting it sit. [1] https://www.indra.co.uk/v2g https://www.indra.co.uk/v2g, https://www.ovoenergy.com/electric-cars/vehicle-to-grid-charger https://www.ovoenergy.com/electric-cars/vehicle-to-grid-char... [2] https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...
- new_realist 6y ago
  How can round trip efficiency be 90%, when the one-way 240V charging losses to my Tesla alone are greater than that (at 83.61%)? Is it lack of three phase power in the US that is killing me?
  - orwin 6y ago
    You can't ask for three phase power in the US? Surely it have to be there but restricted to business, no? I remember seeing laundries and restaurant in small towns
    - selectodude 6y ago
      Large factories can get 480V 3 phase power in the US, but even laundries and restaurants get 240V “split phase” which is technically still single phase, just two power lines that would normally be going to two houses instead going to the same place. We have a very wonky power grid here due to how early on it was built. The rest of the world had the ability to see our mistakes and fix them after WW2.
      - rsynnott 6y ago
        I'm not sure if it's age so much as bad (in the long run) choices at the time. European power grids have been around for a while (and some have their own oddities; the historical use of ring circuits in UK and Ireland domestic installations produced lasting weirdness, for instance).
taneq 6y ago
It's the battery wear that I'd be mainly worried about. I'd much rather be burning cycle life on a Powerwall than on a $100k car.
- brianwawok 6y ago
  Model3 is more like a 40k car, and you can replace the battery in 10 years for a lot less than 40k I suspect
  - taneq 6y ago
    In my part of the world even an SR+ is $81k drive-away price. An LR with no other options is over $100k.
    - natch 6y ago
      I suspect you’re counting VAT as part of the price, which makes the claim inaccurate. It’s a $40k car with a TCO equivalent to a $26k car, which in your part of the world has taxes and fees that bring your out of pocket cost up. That doesn’t make it a $100k car. It makes it a $40k car that has heavy tariffs where you are.
Glench 6y ago
> given that utility-scale solar is so much cheaper than residential storage... That likely isn’t given! I haven’t looked into it thoroughly but apparently most of the cost of utility solar is transmission and billing. Australian residential solar is really booming right now because it’s 6-7 cents / kwh. See Saul Griffith of Otherlab’s article: https://medium.com/otherlab-news/green-new-deal-how-much-does-fixing-climate-change-cost-the-us-d542bb9e67c8 https://medium.com/otherlab-news/green-new-deal-how-much-doe...
pmorici 6y ago
The probable reason that Tesla has put this in but hasn't enabled it yet is that they are on the verge of announcing new battery technology their so called "million mile battery" that is rumored to not have the issues of current technology with respect to limited charging cycles.
jessriedel 6y ago
What this article needs is someone numerate who can at least do an order-of-magnitude estimate of the costs and benefits. When operating at scale, what will the marginal cost in terms of battery wear-and-tear be for storing 1 kWh and returning it to the grid? And how much will that storage be worth in terms of the difference between daily high and daily low electricity prices? Very frustrating that a putatively semi-technical publication like Electra doesn't even attempt this, or ask their interviewees estimates.
loceng 6y ago
https://news.ycombinator.com/item?id=23249269 https://news.ycombinator.com/item?id=23249269

_ph_ 6y ago

Before we investigate complex power to grid schemes - though electric cars could have quite an impact there - it would be great if any electric car came with at least one power outlet, so that you could power critical appliances in your house during a power outage at least. Like keeping the fridge running, some lighting and heating food on a small cooker. The same would also be great for any kind of camping. Beyond that, electric cars could of course have a huge contribution to the grid, especially with high percentages of solar and wind power. The first step would be to charge the cars dependent on the power supply situation. Loading during peak production and not loading in times with low production or pausing it in times of demand peaks. The final step would be using them to feed power back to the grid, though this needs to be done carefully, as this would increase the wear on the battery.

new_realist 6y ago
Powering critical appliances with your car during an electricity outage is tricky: if the outage lasts for an unexpectedly long time, you end up with no power and stranded at home with a car that has no miles in the tank. Meanwhile, you can buy a generator for as little as $400.
- mrfusion 6y ago
  Last time I bought a generator I used it once. Two years later when I needed it it wouldn’t start. You’ve got to also invest effort in taking care of the thing. Oil changes, don’t leave fuel in it, run it every two weeks.
  - selykg 6y ago
    I've personally found that leaving gas in is fine, under two conditions: 1. You use ethanol free gas. This is more expensive, but it's also the same gas I run in all my lawn equipment so I generally have some around during the summer months. 2. If you plan on letting it sit for awhile use a fuel stabilizer in it. But yea, a safe thing to do is to run it out of fuel, especially if you have ethanol in it, because that shit will kill the plastic parts in the carburetor if it sits. Once it's out of fuel, run it every month for awhile with some new gas in it just to keep it running and active. You'll want to run it long enough that you burn out any potential water in the oil, so let it get to normal operating temperature and run it for a bit longer and you should be good. This is also good for electric start models which have a battery or capacitor that will need a regular recharge.

sorenjan 6y ago

It would be nice to be able to charge a car from another car, so you can help somebody that has depleted their battery at the side of the road.

deleted 6y ago
[deleted]
Tepix 6y ago
The upcoming Sion electric car by Sono Motors offers this feature. It also has quite a few solar cells.
- close04 6y ago
  Their maintenance policy seems great: DIY for any minor repairs, with manuals being provided to all service shops. Repairs of critical systems and high voltage parts to be done via "a well-known European service provider". Being able, and even encouraged, to fix minor things myself instead of going to a shop for everything would be more than welcome. But I don't get their "solar panel in every body panel" approach. They say it provides 1.2KW peak but at any point in time only half (or none, in indoor parking) of the car is getting any sun. A thin layer of dust or light scratches will lower the efficiency further. And it also means any side scrape or fender bender would not just scratch the paint but damage the panels, especially on the doors. This makes repairs far more expensive and lowers the charge capability even more. And it looks like it only works with black paint which increases cooling requirements. I take it more as an emergency option. I'm not sure if the electricity they provide outweighs the added cost, complexity, weight, and perhaps increased consumption. The repair policy, small battery, large cargo space, and added solar panels might make it a good fit for professionals like plumbers or electricians only driving through the city for interventions and perhaps even leaving the car on the street. [0] https://sonomotors.com/en/sion/ https://sonomotors.com/en/sion/
netcan 6y ago
...especially considering that you can't just go buy them some petrol. Now that I think of it, what's the MO if you run out of juice in a tesla.. tow?

raxxorrax 6y ago

The term is pretty misleading if cars are still charged with AC current, even with a rectifier immediately after the power supply. Maybe it is a language thing. Otherwise this "technology" could indeed be quite useful to lessen load. I would have thought that maybe providing local power to your home instead of buffering the whole network would maybe be more practical.

teraflop 6y ago
I don't see what's misleading about it. AC vs. DC has nothing to do with which direction power is flowing, which is what they're talking about. And feeding power to the "grid" is actually quite straightforward, at least for the customer's equipment. In effect, you can think of the 60Hz oscillations of AC voltage as being like an enormous rotating crankshaft that each customer is tightly coupled to. Correctly applying a "torque" to that system automatically distributes the energy where it's needed. In contrast, de-coupling and re-coupling one house with the grid on demand is a lot more complex: you lose the stabilizing effect of the grid's enormous "inertia", and you have to carefully synchronize the phases when reestablishing the connection.

thdrdt 6y ago

The Xpeng P7 also has a 220V output. I guess this can be useful for a lot of things. https://en.xiaopeng.com/p7/configuration.html https://en.xiaopeng.com/p7/configuration.html (Also a great looking car imho)

gwbas1c 6y ago

When I plug my car in, I expect it to charge. When I get in my car, I expect it to have a full charge. I don't want to have to push a special button or dig into hidden menus just to ensure that my car actually has a full charge. This is critical for when I take a long road trip, and I expect that I have a full charge when I leave. What I think makes sense is temporally stopping charging for the 10 seconds it takes for a generator to spin up. But these kind of events should be so infrequent that they have no noticeable impact to my ability to start a road trip with a full charge.

wcoenen 6y ago
> When I get in my car, I expect it to have a full charge. I don't want to have to push a special button or dig into hidden menus just to ensure that my car actually has a full charge. Then don't buy a Tesla, because the default factory setting is to charge to 90% to reduce battery degradation. (Personally I like that feature, I wish I could configure my phone to make the battery last a year longer.)
- hnarn 6y ago
  iPhones kind of do this, I was surprised when I bought one recently and noticed it. It assumes your wake up time from usage patterns and then avoids charging above 80% or something during the night until right before you wake up.
- gwbas1c 6y ago
  I know that. I'm referring to the electric company discharging my battery without my knowledge. Just think of what will happen the first time someone plugs in their car overnight and then the battery isn't full in the morning.

lacion 6y ago

the whole point behind Vehicle to grid is not to sustain your house but to stabilize the grid at peaks, don't think as your car but as the whole fleet of electric cars able to do V2G, that means that the grid could use a bunch of cars to sustain a small peak and avoid the need altogether of very expensive peaker plants

gregwebs 6y ago

There was a recent discussion on HN about using a Tesla as a store of energy that could be tapped to help with emergency power scenarios: https://news.ycombinator.com/item?id=23178733 https://news.ycombinator.com/item?id=23178733 Apparently the capability is already there!

loceng 6y ago

I'd highly recommend this "Battery Day is Coming" 40 minute video that explains what Tesla is likely planning: https://www.youtube.com/watch?v=pP971PYzQJs https://www.youtube.com/watch?v=pP971PYzQJs In one part of it they explain that how the batteries that went to stabilize the grid in Austrailia (and saved them a lot of money immediately, their investment/cost paid back in a few months from my understanding) can be decentralized to all cities around the world with using vehicles as the storage for energy at non-peak hours and source of energy during peak hours - arguably when you've driven your vehicle to the city and where production and office space, businesses serving the area, will be needing more energy.

spectrum1234 6y ago

This is going to make electric cars extremely cheap once the million mile battery is out. Probably at least 50% cheaper given the money you can make selling off peak electricity at peak prices. Electricity costs by me since I switched to time of use are 4x as much on peak vs off. My Tesla costs about $6 for a full charge off peak. It seems like its easy to make (4-1)* 6 = $18 a day off of this the car as it home. Let's say $10 after conversion loss and battery wear, etc. Once you buy any other hardware needed (I think they are $2k-4k now), this seems like free money. Worst case, car is home during peak 2 days a week and $10/day gain, $4k system: 2.5 year payback period and then $223/month income Best case, car is home during peak 5 days a week and $15/day gain $2k system: 26 week payback period and then $322/month income. The best case over 10 years is worth $38,700. However the biggest opportunity here is probably for Tesla to lease the battery to consumers. The car will be discounted significantly if you can plug in 3 days a week near peak usage.

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