BMW charges into home battery market

BMW is looking to join the ranks of car companies like Tesla and Mercedes-Benz by offering a home energy storage solution based around its vehicle battery technology.

Announced at an electric vehicle convention in Montreal this week, BMW is examining a concept to upcycle used battery packs from its i3 for domestic energy storage.

The i3’s original battery pack, which is comprised of 96 lithium ion cells that output around 22 kilowatt hours of energy, has almost enough juice to power the average home for about a day; average usage in Australia is estimated at about 30kWhr a day.

The technology already exists for home storage systems to ‘talk’ to the energy grid, selling energy back to the grid when prices are high and buying it back when prices fall, as quickly as minute-by-minute.

Even if the system uses batteries plucked from old i3s that have lost some of their capacity, household usage is generally much less demanding than that of a vehicle, according to BMW.

Incidentally, a new, more powerful 33kWhr battery has just been announced for BMW’s small electric car, which has sold 45,000 worldwide since its launch in 2013. The new battery has the same dimensions as the old system, and could be used in a home storage array just as easily as a second-hand battery.

The i3-based energy storage system could be charged via either the regular grid at off-peak times, or via a solar panel array. The technology already exists for home storage systems to ‘talk’ to the energy grid, selling energy back to the grid when prices are high and buying it back when prices fall, as quickly as minute-by-minute.

Tesla, who is planning to open the world’s biggest battery factory in the US by 2020, launched its Powerwall system in Australia earlier this year, with a basic system, comprising of a 7kWhr battery unit as used in the Model S which then is teamed with an inverter, currently costing around $12,000. Powerwall units can be tethered together to create more storage.

The Tesla Model X and Model 3 both use a larger capacity, differently shaped battery than that of the Model S.

Mercedes-Benz, meanwhile, announced this year that it would enter the home energy storage arena, with the company already selling a 2.5kWhr battery module in Germany than can be built into a 20kWhr array.

At first glance, though, it looks to be a lot more expensive than the Telsa system, with each Merc module estimated to cost around A$15,000.

Nissan, interestingly, has developed a system for its Leaf EV that allows customers in Japan to use the battery in the car itself as an emergency energy supply.

With the cost of EV tech still prohibitively high, companies who have pulled the trigger on developing electric vehicle architectures are keen to see a return on that investment.

As electric car development picks up pace, though, battery tech will improve in both capacity and price, and integration between vehicle and home energy systems will become much more closely aligned.

Are these car companies leading the charge in an energy storage revolution? Tell us what you think in the comments below.