Will PW prevent itself from completely discharging?

[BIC1]

When PW is set for 100% Backup Reserve, there does not appear to be any setting to not let the PW drop below, say 5% so as to retain enough power to self-start the next day. Is there a setting for this or does it have an auto stop at a certain percentage or will the battery let itself completely discharge necesitating a manual start the next sunny day? Thanks.

 

[Redhill_qik]

The percentage that you see in the app is not the actual charge percentage remaining in Powerwall. At 0% there is still 5% charge remaining, so there is nothing to worry about.

 

[BGbreeder]

While "0%" on the app means 5% in reality, Powerwlls do have a certain rate of self discharge, and if they get to true zero, they may not take a charge. It happens most often when they are stored, but not yet installed, but it does happen.

You only need the manual start if both there is no grid, and the Powerwalls have shutdown due to low power. (But not necessarily 0%, just below the app's "0%".)

Under most circumstances, as @Redhill_qik wrote, it is not an issue due to the internal reserve.

Does that make sense?

All the best,

BG

 

[BIC1]

Sorry, but I need a bit more clarification. Let's say the PW shows 0% but is actually 5%. It's midnight and the PW shuts down. Did it shut down with an actual 5% reserve so when the sun comes up, will it be able to auto-start itself back up?

If I don't want to have to manually start it back up, do I need to monitor the PW and turn the PW switch off when it hits 5%. Hopefully, it's all on autopilot. I think you're saying it's on autopilot, but not sure.

What about multiple PWs, do they drain together evenly or one go down to zero then kick over to the next one? Thanks.

 

[jjrandorin]

Sorry, but I need a bit more clarification. Let's say the PW shows 0% but is actually 5%. It's midnight and the PW shuts down. Did it shut down with an actual 5% reserve so when the sun comes up, will it be able to auto-start itself back up?

If I don't want to have to manually start it back up, do I need to monitor the PW and turn the PW switch off when it hits 5%. Hopefully, it's all on autopilot. I think you're saying it's on autopilot, but not sure.

Tesla covers this direction in their online information about powerwalls:

Best Practices During Power Outages | Tesla Support

Powerwall brings you energy independence and security, so life in your home can carry on uninterrupted when the grid goes down. Learn more about how Powerwall functions during extended power outages.

www.tesla.com

(copy / paste of relevant section from website above)

Solar Production During an Extended Outage​

If Powerwall cannot charge at its expected rate, it will signal your solar inverter to reduce or turn off to protect your home from the excessive power produced. This typically occurs when Powerwall is approaching 100% charge. Once Powerwall has the ability to accept power again, your solar inverter will be signaled to produce and will re-start after the qualification period required by your local requirements.

Running Low on Energy​

If Powerwall has less than 10% energy remaining, it will enter a standby state and stop providing power to your home. If your system is connected to the internet, you'll receive a push notification in the Tesla mobile app when Powerwall enters standby.
When in standby, and paired with a solar energy system, Powerwall will automatically attempt to recharge from solar every hour between 8 AM and 4 PM local time. If enough solar is available to charge Powerwall while still powering your home, this automatic charging will continue. Should the remaining energy decrease by more than 2.5%, Powerwall will become inactive and wait for the next hour to attempt charging again.

What about multiple PWs, do they drain together evenly or one go down to zero then kick over to the next one? Thanks.

They drain evenly together, unless there is a technical problem. They are designed to function as one storage block, together.