How do I maximize PW2 battery life?

How do I maximize PW2 battery life?

Trying to find resources to help answer my question. Posting here to double check.

1) Looked for the answer on official Tesla documents / manuals. No luck
2) Tried to sift through the forum here. No luck.
3) Called customer support and got a couple of different (and contradictory) answers. Which tells me they don't have a script to use.

If my goal of the PW2 was to make it last - keep its maximum capacity-- for long as possible, do I just keep it in Backup-only mode all the time?


gregbrew | 28/07/2019

Lithiums tend to not like to be stored at 100% charge. Unfortunately, the PWs don't have a setting to allow you to only have them charge to, say 85%.

That being said, and ignoring the "don't leave them charged to 100%" admonition, I have two PWs myself, and have them set to "Backup Only", because I really don't have much choice in the matter. Tesla, are you listening?

DermMD | 30/07/2019

Meantime possible solution is set your backup as high as say 90% but use the advanced time based control so the battery cycles every day but with only a 10% variance. That way it won't stay charged at 100%. It turns out that using this setting the battery hardly discharges for me on the weekends when utility electricity is really cheap. Someone who sounded knowledgeable said elsewhere on this forum that it is the full discharges that will shorten the life of lithium ion battery. Hence limited partial discharges are probably the best option available to us right now.

jdaleo23 | 13/08/2019

I was told by Tesla (not sure how true it is), that when the battery shows 100% charged, it is actually around 80-85% actual capacity. I've never taken it apart or done the math to see if that is correct, but i brought it up to them when i asked if it's safe to keep it in backup mode at 100% during bad times of the year when it might stay there a while.