From what I&#x27;ve read[1] about lithium-ion batteries, it seems to me that if you don&#x27;t actually need to utilize the full capacity and don&#x27;t need to have the full capacity always available, you can get some pretty drastic improvements in battery lifespan by limiting the charge to 70-80% of maximum capacity and trying to avoid discharging below 40-50%.<p>That doesn&#x27;t mean you can&#x27;t go outside those ranges in special cases, just that it&#x27;s best for the battery to spend as much time as possible within that range. For a Powerwall, I&#x27;d take that to mean that charging it to 100% every day with solar then draining it to 10% every night recharging an electric car is going to reduce its lifespan pretty fast, but charging it to 80% daily and using it to reduce your grid draw without fully discharging may let the unit last for years with minimal decline in capacity.<p>It&#x27;s like a lot of things - if you&#x27;re constantly bouncing against hardware limitations, there&#x27;s a good chance you&#x27;re putting more stress on the hardware and are going to see shorter lifespans for it. It may not be readily visible, but effectively batteries are a moving part subject to wear so treat them as such and plan for it.<p>[1] <a href="http:&#x2F;&#x2F;batteryuniversity.com&#x2F;learn&#x2F;article&#x2F;how_to_prolong_lithium_based_batteries" rel="nofollow">http:&#x2F;&#x2F;batteryuniversity.com&#x2F;learn&#x2F;article&#x2F;how_to_prolong_li...</a>