If you want more than 3 kWh, you can add more battery modules -- up to 10.5 kWh. The battery units themselves are slim -- just 2.8 inches wide -- and are flat, at 13 inches by 29 inches.

It might have been a long time since you last had to grapple with a flat car battery, but when it does happen it can be a major inconvenience. Unable to start your car can ruin your day ...