Our newly-installed dual Powerwall system seems to be working well, but I have one concern. I'd like to be able to keep the average charge in a more optimal range for battery longevity while still using the grid to charge our EVs at night. Yes, I know there's a ten year warranty, but I'd prefer to do what I reasonably can to achieve the longest possible lifetime for our Powerwalls. At present, I don't have access to the "time based control" functionality, so I've been manually putting the Powerwalls into Backup mode each night at 10 PM, just in time for "super off peak" hours during which time our electric vehicles charge up (we do too much driving to avoid using the grid). Every morning at 8 AM, I've been switching the Powerwalls back to Self Generation mode. Our cool, sunny days have been enabling great solar production, so the Powerwalls have been reaching 100% charge by mid to late morning or so. Our solar production drops greatly by mid-afternoon due to shade, and the Powerwalls end up at roughly 75-80% charge by 10 PM. This isn't terrible, as the Powerwalls are only spending a few hours per day at 100%, and there's undoubtedly a buffer so that "100%" isn't truly 100%. Still, it's not ideal for Lithium ion batteries to cycle between 75% and 95-100%; I'd prefer to cycle between, say, 55% and 80%. I'd like to see Tesla add a "maximum target charge percentage" that I could change seasonally. During the winter, particularly with storms coming, I'd leave it at 100%. The rest of the year, I'd probably set it to 70% or 80%.