V2G compatible battery, use your car to power the grid, sounds interesting

[IanB]

Just ready this about Octopus PowerLoop

https://www.octopusev.com/powerloop

Sound really interesting, but surely all that charging and driving, discharging, charging driving etc etc will effect the life of the battery.

It states "You'll need to lease a Nissan LEAF from Octopus Electric Vehicles. The Nissan LEAF is currently the only fully-electric car with a V2G compatible battery, meaning it can export as well as import."

Are Tesla Batteries V2G, just a case of a software upgrade to unlock this feature?

 

[NorfolkMustard]

Tesla won’t support V2G while also doing free supercharging

I think only the CHAdeMO standard currently supports it?

 

[MrBadger]

Personally wouldn't touch it with a bargepole, even if Tesla was compatible, which it isn't.

There are very different requirements in batteries for a car and batteries for a home (V2H), and batteries for the grid (V2G)

Until there are years and years of data to say that V2H and V2G will not have any negative effect on a car battery, i'm out. Also, much evidence so far that early trials of home/grid offsetting kills home batteries. I wouldn't even do it for batteries that are so called designed for the home.

Home battery designed for the home, car battery designed for the car.

 

[Tattersky]

A Univerity of Warwick study found that daily V2G actually extended the lifetime of the battery and reduced degradation.

http://wrap.warwick.ac.uk/88018/13/...lifetime-lithium-ion-batteries-Marco-2017.pdf

Shame the Tesla does not support V2G. Elon once wrote that the lack of V2G would have no impact on sales, so did not offer it.

 

[Glan gluaisne]

As above by @VanillaAir_UK .

The killer is cycle life. EV batteries may have a cycle life of maybe 2000 cycles. That's fine, as for a 300 mile EV it represents around a 600,000 mile life, far more than most people will ever need.

A house battery may get cycled twice a day if it's charging from both day time PV and off-peak overnight. That same 2,000 cycles will now reduce the battery life down to may be 3 years.

Home batteries need to be designed/managed very differently to vehicle batteries. They need a very high cycle life, but never need to deliver much power (maybe 10 or 15 kW maximum for home use, versus maybe 350 kW in an EV). Most home batteries only really need to deliver maybe 3 to 5 kW in practice, as that's enough to offset pretty much all the peak grid demand.

 

[IanB]

Hmmmm, from Their own FAQ


Will this damage my battery?
The shortest, and most honest answer is that we don't know. This is one of many reasons we're running this project; to find out what works in Vehicle to Grid, and fix the things that don't.

It's important to point out that there’s no risk for Powerloop bundle customers because the cars are leased from Octopus Electric Vehicles, which means we take the risk on any battery degradation. Nissan are also the only manufacturer to include V2G operation as part of their warranty - a major factor in using the Nissan LEAF.

However, early signs from V2G "proof of concept" projects have shown good results for battery degradation.

The general principle when looking at battery degradation is that a battery likes to be used, but not at the extreme ends of the scale. Ensuring a battery doesn't sit at 0% or at 100%, and keeping it slightly warmed up may help prevent degradation from factors such as dendrite formation. A study by Warwick University even found the battery health improved under optimal conditions.

 

[Jason71]

I would happily do it....... so long as the car was leased

 

[Glan gluaisne]

I've been building EVs for the past 12 years or so as a hobby. Battery degradation from cycle life is real, can be managed, but I've yet to see any lithium chemistry cell that has its life increased by being cycled.

If the cycle depth is shallow, and kept around the mid-range of the battery capacity, the degradation is modest. However, start cycling batteries from near 100% SoC to near 0% SoC and cycle life plummets. The relationship between cycle life and depth of charge/discharge is very non-linear, so it may well be possible to use, say, 10% of the battery capacity in the 70% to 80% SoC range without having much of an impact, it depends very much on what the V2G scheme needs, in terms of energy from each connected vehicle.

There are better lithium chemistries for home battery use, LiFePO4 cells have a significantly higher cycle life, but aren't as capable of fast charge/discharge as other lithium chemistries. Their energy density is also a fair bit poorer, which isn't a problem for a home battery pack, but is for a vehicle, where weight is critical.

Overall, I'm far from convinced that V2G makes sense. I think it's a dead end as far as grid storage options are concerned, and the development money going into it might better be used getting very long life battery systems perfected. Right now, redox flow cells have a great deal of potential for grid storage, because of their very long predicted life, yet they aren't getting much investment, as pretty much all the battery investment money is going into vehicle batteries, with the emphasis on making batteries smaller and lighter, with a higher capacity.

 

[nigeldodd]

This discussion is all very interesting. I think it points to the difficulty of fully understanding and managing the lithium based technologies in battery performance. I am hoping a better technology will be developed in the next decade or so.

It is difficult to know what, though. There are disadvantages in high capacity capacitors, hydrogen based fuel cells - where at least the storage medium, hydrogen, doesn't really degrade but it does have other problems. Etc

Whatever form you have there is going to be a lot of energy stored. Hydrocarbons are flammable and all forms of energy usually want to discharge that energy given a chance.

I have pv panels on the roof and would like about 1kWh of storage to manage cloud cover and putting the kettle on. I have a new Tesla model 3 sitting on the drive. I'm hoping to get a Zappi or something similar to charge the car from the roof.

 

[Adopado]

If the cycle depth is shallow, and kept around the mid-range of the battery capacity, the degradation is modest. However, start cycling batteries from near 100% SoC to near 0% SoC and cycle life plummets. The relationship between cycle life and depth of charge/discharge is very non-linear, so it may well be possible to use, say, 10% of the battery capacity in the 70% to 80% SoC range without having much of an impact, it depends very much on what the V2G scheme needs, in terms of energy from each connected vehicle.

I have always thought that VTG would be something for the future when there are millions rather than a few thousand cars potentially charging. It would then presumably only require a small percentage, say 5%, from each vehicle to be able to contribute some useful grid balancing. But perhaps that grid balancing aim will be achieved in other ways by the time there are enough connected EVs to make it useful.

 

[tsh2]

Using scrap vehicle batteries for grid balance/standby might make sense prior to recycling them. Charging an EV overnight does make sense. Not so sure about anything else.

 

[nigeldodd]

"Using scrap vehicle batteries for grid balance/standby" or even lead acid batteries (leisure) which I have done to claim my servers are solar powered.

What we need in the uk is a link to the spot cost of electricity so we can balance our consumption and putting electricity back into the mains to reflect the need by the grid.

 

[MrBadger]

Using scrap vehicle batteries for grid balance/standby might make sense prior to recycling them. Charging an EV overnight does make sense. Not so sure about anything else.

Thats exactly what some of the home battery manufacturers already do.

Some simply reuse the cells as is, Teslas plan last I heard was to remanufacture the cells from the recycled raw materials.

Either way, when the time comes, a single knackered Tesla battery will likely end up being used to power 5-10 houses, or another car.

 

[NorfolkMustard]

good video about it here.

 

[gangzoom]

A Univerity of Warwick study found that daily V2G actually extended the lifetime of the battery and reduced degradation.

http://wrap.warwick.ac.uk/88018/13/...lifetime-lithium-ion-batteries-Marco-2017.pdf

It doesn't say that at all.

It says if you charge the battery to 100% everyday regardless, having the car battery been cycled for V2G between very specific SOC would be better than leaving it at high SOC idle.

They actually developed a very complex degradation model, which means the majority EVs connected to the smart grid didn't take part because they would have suffered worse degredation.

Of the 120 EVs connected to the electricity network only 46 participated in V2G; 74 are excluded because the smart-grid esti- mated that for those EVs V2G will degrade the battery more than if they were left idle.

We have had a Powerwall installed for a few weeks I can see just how much cycling a home storage system goes through

Our PowerWall is nearly constantly discharging or charging, unlike our EV which actually spends most of the day doing nothing.

Given the obsession people on this forum often has about even a 1-2 mile drop in SOC at 100% as a sign of early degredation am amazed anyone wants to risk the most valuable/experience component on their EV for the sake of saving a few £ on electricity.

Also don't estimate the total additional demand your putting on the battery by adding on load, we didn't go on any long trip this, but including car charging we pulled 180kWh+ from the grid. If you really want to maximize V2G your potential putting a not unsubstantial additional load on the battery, which WILL shorten its life.

 

[WannabeOwner]

We provide free chargers at work to promote sustainable EV driving.

I won't be interested in providing juice for staff to take and use at home, or take home and sell back to the grid.

 

[jimbo_hippo]

We provide free chargers at work to promote sustainable EV driving.

I won't be interested in providing juice for staff to take and use at home, or take home and sell back to the grid.

Can you add a coloured dye to your electricity? ;-)

 

[WannabeOwner]

Can you add a coloured dye to your electricity? ;-)

Good idea. I'm going to dye the stock room supply of Loo Paper this weekend

 

[ringi]

Many cars going from say 50% to 45% when they arrived homes at peak electricity demand time between 5pm and 7pm can give great benefits to the grid. There is no need for any single car to be providing power at more then say 3hw, hence very low stress on the batteries. The car can then be recharged from wind power overnight. Remember UK uses most electricity at the times of year when PV gives the lowest output, so storing PV power does not help in going totally carbon free at grid scale.

I would love to have a 3kw 240volt socket in a car, as it would be great for flexibility, hence I think the inverters used to drive the moters should be make to surport the V2G not a separate converter fixed to the home.

The issue Tesla have is that in their home macket, batteries have to be charged in the daytime to be useful to the grid and EV are not likely to be pluged in at these times.

 

[jimbo_hippo]

Many cars going from say 50% to 45% when they arrived homes at peak electricity demand time between 5pm and 7pm can give great benefits to the grid. There is no need for any single car to be providing power at more then say 3hw, hence very low stress on the batteries. The car can then be recharged from wind power overnight. Remember UK uses most electricity at the times of year when PV gives the lowest output, so storing PV power does not help in going totally carbon free at grid scale.

I would love to have a 3kw 240volt socket in a car, as it would be great for flexibility, hence I think the inverters used to drive the moters should be make to surport the V2G not a separate converter fixed to the home.

The issue Tesla have is that in their home macket, batteries have to be charged in the daytime to be useful to the grid and EV are not likely to be pluged in at these times.

I think one of the factors that will affect the feasibility of this is the speed at which a car can recharge. At the moment, the idea of dribbling a kW or ten per hour into a house or the grid for a few peak hours is sacrilege because of the time it takes to put it back in. The fear of the business call suggesting you have to drive immediately to Birmingham or a parent phoning you to say the lift they promised is off and you suddenly have to head into the city to pick up your offspring is always there. Sparing stored eleccy at chosen times is 99% fine. But it’s that constant nag that your emergency electrons are dwindling. If you knew that, in an emergency, at home, you could squirt in a pricey but useful 50% to get you back to 90% in the time it takes you to make a couple of calls and grab a coat, make a coffee cup in your favourite travel mug and feed the goldfish, (so say, 10mins?) I think this is a dog that’ll hunt. I live within 25/30 mins of Manchester City centre but there’s no supercharger that would help me quickly charge and pick up a child at short notice from a gig at the Arena without a massive detour. Sure, you probably have enough anyway but it’s still a worry. Until that, or doing rapid charger speeds locally or at home happens, human nature puts your own needs first and any other arrangement has to be risk free for it to be comfortable.