Batteries currently make up a quarter to a third of an electric vehicle's cost

As automakers shift from horsepower to kilowatts to comply with stricter environmental regulations, investors are looking for evidence that Tesla can increase its lead in electrification technology over legacy automakers who generate most of their sales and profits from gasoline-powered vehicles. Musk, who frequently launches new products in attention-grabbing, show-like announcements, has fueled expectations for Battery Day over the past months, in April calling the event "one of the most exci