Home Energy Storage: An Encore for Electric Car Batteries?


In the upcoming generation of electric cars, the bulky battery packs will generally be the most expensive piece, but the storage capacity (and range) will seriously degrade over time. Will the battery from your old plug-in eventually find a home storing energy for your house? A group of companies and researchers in California, funded with a $992,000 grant from the University of California, Davis (h/t Green Car Congress), hope to establish some viable models for doing just that.

Led by the nonprofit California Center for Sustainable Energy , or CCSE, the group also includes utility San Diego Gas & Electric, charging infrastructure provider AeroVironment (s AVAV), UC Berkeley’s Transportation Sustainability Research Center, and Flux Power, a battery systems developer headed up by Aptera co-founder Chris Anthony.

According to a statement this week from CCSE, the year-long study will focus on repurposing electric car batteries as household energy storage devices, testing lithium batteries at sites where SDG&E can remotely control charging and discharging based on simulated and real grid grid conditions. Using three different types of batteries, the researchers plan to investigate whether a specific chemistry or battery management system proves “superior for overall lifetime battery value,” from the vehicle through secondary applications in the home.

Electric car maker Tesla Motors, expects that after seven years or approximately 100,000 miles, the battery pack in its high-end Roadster model will drop to about 60-65 percent of its “ability to hold its initial charge,” thereby reducing the car’s range, according to the company’s S-1 filing. Charging infrastructure startup Better Place, meanwhile, has told us that for lithium-ion batteries produced in the next several years, it expects them to degrade down to about 80 percent of their original capacity (marking the end of their useful life in vehicles) after eight years on the road.

That doesn’t have to be the end of the road for these batteries. But as with so many aspects of the electric vehicle market, more data is needed. CAP Motor Research, one of the UK’s biggest providers of vehicle valuation data for leasing companies, insurance firms, vehicle retail groups and financial institutions, said recently that uncertainty surrounding electric car charging systems, overall running costs and especially the battery, make it “impossible” at this point to forecast the residual value for an electric vehicle, or how much it will be worth at the end of its lease.

Photos courtesy of Nissan and Better Place

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Craig Horne

The ability to diagnose state-of-health of a used LiB at point of installation and then forward as those cells operate within their second life requires a dramatic improvement for this to ever pass muster with insurance companies. The O&M requirements could also prove challenging to the business model. Today, we expect our appliances to work for several years without a need for a service visit. Getting a pack configured of used LiB to that level of surety is not going to be trivial. In the end I think recycling the cells and harvesting out the Li, Co, P, and stainless steel cans will be the only thing that makes sense from the standpoints of liability and business model.

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