Zach Dell, son of Dell Technologies founder Michael Dell, is building Base Power into a major home battery company, with a goal of putting backup batteries in homes across the US. The Austin-based startup has installed more than 23,000 batteries, raised $1 billion in fresh funding and reached a $13 billion valuation. Its latest batteries can provide up to 36 hours of backup power and are designed to withstand extreme temperatures, from Texas summers to Chicago winters.