Many of the "power wall" vendors that are planning to use EV form factor batteries [0] are waiting in the wings for second use batteries after EVs are done with

Many of the "power wall" vendors that are planning to use EV form factor batteries [0] are waiting in the wings for second use batteries after EVs are done with them. That was even Tesla's original plan, but then decided that it was useful to their solar efforts to sell new (first use) batteries in Tesla PowerWalls for a while to build the brand and speed solar efforts. (So far as I'm aware Tesla has not yet actually built a true second use PowerWall.) Right now first use in general (most wrecked/scrapped EV car's batteries seem to be getting reused for other cars such as conversions and upgrades, under today's statistics) is perhaps (surprisingly to some) going to turn out to be on the scale of two to three decades. Most of the EV batteries manufactured to date are still "on the road" somewhere. (Figuratively speaking of course, most of the time they are sitting in some garage somewhere, as cars spend most of their lives parked.) That status quo may last for some while longer, and we are still learning interesting things about EV battery lifetimes. (Related aside: Nissan's brand of "power wall" is older than Tesla's but I never remember the name of the brand without searching for it for the very reason that Nissan's brand is committed to only using second use batteries and so has produced very few, even fewer than they thought they would have by now given that the Leaf has been on the road longer than most models and that Nissan leased most early Leaf batteries rather than sold them. That's even with Leaf's early [lack of] battery temperature management being the biggest cause of "highly degraded" batteries of any model. Most of those "highly degraded" batteries are still in cars, which is fascinating and either says things about EV as a class of car or early adopters as a class of owner or both.) (ETA: [0] It's also fun to note that whole home batteries can use some interesting form factors that aren't good fits for cars, too. There's interesting stuff happening in Flow batteries and geothermal power generation and thermal batteries. The neat thing about thermal batteries, in theory that is slowly shaping into practice at a few interesting startups, is that they directly relate to a lot of other home appliances: a thermal battery is roughly a smarter and wilder version of your home's water heater that can help you get hot water or electricity and juggle the trade-offs appropriately, based on usage needs and time of day. In theory, too, appliances like refrigerators and ovens and HVAC could contribute to/take from a shared thermal battery and get some small efficiency advantages over converting heat to electricity and then heat again by skipping the electrical middle man. You'd probably never power a car with a thermal battery, but in any house if you could replace the water heater with something hotter and weirder and run some of your household on the left over thermal energy's electricity there's some interesting possibilities there.)