New study: V2G may not degrade EV battery life – it might actually extend it

Vehicle-to-grid (V2G) technology could turn the challenge of EVs’ power consumption into an opportunity, allowing vehicle batteries to help balance electrical grids and facilitate the use of renewable energy. Alas, a recent study from the University of Hawaii suggested that the additional cycling could harm battery performance.

Now a study from the University of Warwick suggests that using a battery in a V2G scenario does not necessarily degrade its performance – in fact, it might conceivably improve it. After running simulations on a “comprehensive battery degradation model,” the researchers developed a V2G algorithm designed to minimize degradation.

They also found that, under certain conditions, exchanging energy with the grid could actually extend battery life. “Extensive simulation results indicate that if a daily drive cycle consumes between 21% and 38% state of charge, then discharging 40%–8% of the batteries state of charge to the grid can reduce capacity fade by approximately 6% and power fade by 3% over a three month period,” wrote the researchers.

The smart-grid optimisation was used to investigate a case study of the electricity demand for a representative University office building. Results suggest that the smart-grid formulation is able to reduce the EVs’ battery pack capacity fade by up to 9.1% and power fade by up to 12.1%.

So, V2G good, or V2G bad? The jury is still out – as Vox notes, there are several pilot projects underway around the world. But if this study’s findings prove to be valid over the long term, V2G could turn out to be even more valuable than previously imagined. Currently, V2G is envisioned as a service to the grid for which utilities would pay EV owners. But if it were possible to improve a battery’s life by massaging it with just the right smart charging algorithm, payments might flow in the other direction.

 

Source: ScienceDirect via Vox

  • Al

    I just want to be able to power my house in case of an emergency. That will not cause any degradation. First maker that offers that gets my money.

  • davidwhittlesey

    “can reduce capacity fade by approximately 6% and power fade by 3% over a three month period,” wrote the researchers.”
    There should be no measurable capacity loss over a 3 month period under these conditions. This “study” sounds made up to satisfy some vested interest.

    • nordlyst

      Those are normal percentages, not percentage points! You can reduce even a small number by 6% without having to cheat in any way.

      But I do think you’re right to be skeptical, a priori. We don’t know where this really came from and it seems a very short period of time. Furthermore, as I understand it is based on simulation rather than on actual emprical trials, which makes the scope for biasing the results almost infinite.

      I do think V2G may have a place. If you’ve had a look at the experience of people with solar roofs who get a powerwall or some other home battery, you’ll see that not only does even a rather small battery pack dramatically cut the energy they need to get from the grid, it often completely eliminates demand in peak times, since solar energy availability tends to coincide in time with peak demand. Some seem to think V2G can’t do that because your car isn’t at home during the day, but except for those who want to be self-supplied and go off grid this doesn’t matter at all. It is enough to have the capacity in a distributed fashion, and we can have that even though we’re parked a little bit away from home – provided of course that we can still plug in to the grid.

      Just 5 kWh of capacity can make a huge impact on peek demand. And with 50-60 kWh looking like it will be the baseline going forward a very large percentage of the cars will easily be able to set aside that much for V2G purposes. The big question, I think, is simply if V2G will be cost efficient enough. I am absolutely convinced it is technically feasible, assuming EVs will make up a considerable part of the overall fleet.

  • Giovanni Velato

    He results depend heavily on how Electric Mobility will be used in an integrated mobility environment. If it continues with the current approach, the conflicts between the charging phase and the possibility that the electric car gives off energy make the V2G station ineffective for a network stabilization, mainly due to the management of non-programmable renewable sources

  • brenno

    Will be interested to see how this all pans out…will become a great solution to a lot of future problems.
    http://www.evse.com.au