Endesa conducting electric vehicle battery second life study in living energy lab

Published on Friday, 5 August 2016

The electric vehicle industry is growing rapidly, with an ever-increasing number of new commercial models on the market. Nevertheless, work is still being carried out to improve one of the key issues: its main asset, batteries. The autonomy, cost and useful capacity of these batteries can be a handicap when it comes to deciding to by an electric vehicle. However, initial studies show that, after ten years of life, batteries barely lose 20% of their capacity. It is therefore worth considering the possibility of giving batteries a second life once they are removed from vehicles, since 80% of their capacity can still be extremely productive. This is the raison d’être of SUNBATT, an electric vehicle battery second life study, spearheaded by Endesa and SEAT.

SUNBATT is a living lab, a 15 m2 container where the behaviour of four second-life batteries connected to a micro-grid are being studied and monitored. The micro-grid has four components: a 14 kW solar array (generation), three electric vehicle charging points (consumption), an electricity distribution grid (distribution) and the actual batteries (storage). From here, the connection and direction of energy flows offer a whole host of possibilities. The energy produced by the solar panels can be stored in the batteries and be exported to the distribution network or consumed, directly, if there is a vehicle connected to the charging point. The aim is to make smarter decisions to save money and energy. In other words, if it is 12 at night and you want to charge an electric vehicle, even though the batteries may be prepared to do so, energy from the gird will be used, since this is when energy is cheaper.

An optimiser makes this decision – a computer installed inside the container and which works via a series of automatic learning algorithms, i.e. that acquire experience and develop, so to speak, the capacity to make smart decisions. The optimiser predicts consumption estimates throughout the day and manages the way in which these are met, taking into account weather forecasts and the price of energy at any given time, among other variables. This software decides how the electric vehicles connected to the charging point will be charged, either via solar panels, the electricity distribution grid or the batteries being studied. In addition, this system also generates indicators such as cost savings on electricity bills, CO2 emission reductions or savings equivalent in forest mass thanks to its smart management. Apart from the optimiser, two computer systems also work in the laboratory, monitoring energy generation and consumption and the condition of the batteries, respectively.

Also taking part in this study spearheaded by Endesa and SEAT, are the Polytechnic University of Catalonia (UPC), the Catalan Institute for Energy Research (IREC) and the Research Centre for Energy Resources and Consumption (CIRCE) with three clear missions:

  • Firstly, to analyse the behaviour of the batteries in a second life;
  • Secondly, as a result of the first, to show the uses that can be given to these;
  • And thirdly, to define new business models that may arise as a result of this.


SUNBATT is proving straight away, in technical terms, that the battery can continue to function in a new environment, outside of the vehicle, and from the conclusions reached in this regard, it is also clear that there are technological changes that need to be taken into account when manufacturing electric vehicle batteries, if they are to be given a second use in the future.

In terms of how this product could be used in the future, the same living lab is proof of its viability in the field of energy services, given that it is currently carrying out an active role in a smart grid. Particularly in this regard, second life batteries could be used to store renewable energies, in distribution services, providing energy to areas or regions without electricity or even for household use.  These uses would obviously lead to new potential business models, which both companies, Endesa and SEAT, are currently exploring. 

SUNBATT is, in short, a battery reuse project which brings the automobile industry and the energy industry together with the aim of converting, what at first sight could be a disadvantage, i.e. the capacity loss of electric vehicle batteries, with a useful life of 10 years, into an opportunity for both sectors. An opportunity that is capable of contributing towards a smarter energy management policy, bringing with it important benefits in terms of saving money and preserving natural resources and the environment and it is a way of turning cities into real smart cities or cities of the future.