A New, Green, Leaf Of Life For Nissan EV Batteries

When a conventional car reaches the end of its life through accident damage or just old age, major components are usually crushed and melted down for scrap.

The Nissan LEAF's battery is expected to be far too valuable for this fate however, and Nissan is already planning how to give the batteries a ‘second life' in the power generation industry.

Besides reusing the battery, the new use for it will allow excess power from renewable sources such as solar and wind generation to be stored and then released at peak times, reducing the need for conventional power stations to be kept on standby.

A fully charged battery in a LEAF holds enough energy to power a three-bedroom home for around three days (8kW/day). It has massive potential to store electricity generated by solar and then release it when the sun isn't shining, or give the ability to use wind power even when there is no wind.

The Nissan LEAF has only just been launched, but we have to think now about how we will dispose of the car when it comes to the end of its life, said Jerry Hardcastle, Vice President, Vehicle Design & Development, Nissan Technical Centre Europe. Although the LEAF is designed to last as long as any conventional car, some batteries will become available from accident-damaged cars sooner and we must manage the use of the parts now.

While a used engine has limited scope to be reused, the battery second life usage is expected to give them - and therefore the LEAF - a significant resale value.

The first large-scale demonstration of renewable generation and battery storage using LEAF batteries has been built at Nissan's global headquarters. A joint venture established by Nissan and Sumitomo Corporation, called 4R Energy, has started tests using solar panels and second-life lithium ion batteries previously used in Nissan LEAFs.

Electricity for the new storage system is generated through solar cells (photovoltaic panels) installed at Nissan's offices, and is stored in the lithium-ion batteries. The power is then used to charge electric vehicles.

With seven charging stations (three quick charge, four normal charge) connected to the solar grid at Nissan's HQ, the total electricity that can be generated and stored is the equivalent to fully charging approximately 1,800 Nissan LEAFs annually.

That's equivalent to an annual reduction of 15.4 tons of CO2 emissions and will enable electric vehicles to be charged through a completely renewable energy source. The electricity can also be supplied to EVs regardless of the time of day or weather.

Nissan LEAF is already zero emission from a vehicle point of view, says Hideaki Watanabe, Corporate Vice President for Global Zero Emission at Nissan. Now, in order to maximise that potential, if we utilise the renewable energy on the electriciy side, it would really be zero emisison.

Demonstration test outline

Solar cell: Maximum power output: 40kW (Solar Frontier)
Power conditioner: Rated power output: 40kW (10kW×4) (Sanyo Denki Co., Ltd.)
Storage battery capacity: 96kWh (Automotive Energy Supply Corporation)
Grid management unit: Rated power output: 200kW (Sanyo Denki Co., Ltd.)
EV charging equipment: Quick charger: 3 (50kW×3) Regular charger:4 (3.3kW×14)