Is it a problem to leave the PW at 100% Backup Reserve?

[tintop]

I have Tesla solar panels with 1 PW+, awaiting PTO.

My plan is to maintain the PW at 100% Backup Reserve mode. Net metering credits will be used to offset electrical costs during non-daylight hours.

Does maintaining the PW at 100% for an extended period of time affect the batteries' efficiency, lifespan, etc.?

Should I periodically allow the PW to run down to, say, 20% and then charge backup as part of PW "maintenance"?

I've done this with my laptop, electric razor, etc. (all lithium ion), should I do this with the PW?

Thanks.

 

[patrick40363]

My powerwalls are set at 100% for backup. I have never run them down.

 

[gpez]

My powerwalls are set at 100% for backup. I have never run them down.

Exactly the same here. I'm planning on letting Tesla's warranty do some work if that's a problem with capacity/longevity.

 

[jrweiss98020]

Test them every now & then, during a sunny-day period.

 

[el-guapin]

Test them every now & then, during a sunny-day period.

This ^^

 

[nyprepper]

i have flat rate and net-metering so there is no reason not to leave them at 100%. I have done so for the entire 3 years i've had my system.

 

[tintop]

Thanks all for the comments.

 

[Fruitcake]

You might want to investigate setting a low threshold for self-powered mode (say 90%) just to exercise the functionality of the whole system and know that everything's working properly, while still keeping a substantial reserve for outages (which for you it sounds like that is a priority - same here.)

I don't know about going as low as 20% though. Lithium-ion batteries do not like to be deeply discharged. Of course, in an emergency/outage scenario, you don't have any choice, but for everyday/sunny-day scenarios, I would avoid going that low.

Also remember that all battery chemistries (and especially Lithium-based battery chemistries) will slowly self-discharge over time, even if there is no load. Mine typically have to self-discharge down to about 95% or so before they recharge to full capacity. So you might as well use self-powered mode even a little bit as I suggest above, because your batteries are going to discharge one way or the other....

Fruitcake