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Powerwall Questions - 2 PW Backup Only System

macbeth

Member
Nov 6, 2014
73
20
United States
Hello,

I am trying to get this groups collective wisdom about my install and the Powerwall usage during outages. I have a 2 PW backup only system. I have a 400amp system, but I am only backing up 1 leg of my house with 1 GW2 and 2 PW's. This is my critical loads panel which consumes between 0.8kw - 1.4kw in normal usage (sometimes higher when I have space heaters running in the winter).

I have had 2 power outages over the last month (both 6 minutes, or the standard 300 seconds). During this time, my PW's are discharging, my app shows that I lose 7% (both times I lost exactly 7%) during this 6 minute power outage. 7% battery drain seems excessive for such a short outage. I am willing to provide more information, I am able to download the data from my most recent outage and I can share if that help. I can also simulate another outage and record the data if that helps with troubleshooting.

I have a call into Tesla as well, but their hold times can be excessive. I would be very happy to hear thoughts on my situation, or if this seems normal given the information above.
 

Laketime

Member
Dec 13, 2020
130
70
LI NY
I have noticed the same thing. I have 3 PWs and have went on 3 6-7min backups over the last 2 weeks all while under 2kW load or maybe 2.3kW worst case. On all 3 occasions the percentage drop was around 7%. I also notice a lot of parasitic losses on the walls with them losing at least 1% per day and as much as 6% on some without discharge. I asked my advisor and his response was the percentages are not exact (and I remember reading that somewhere at Tesla). I'm not ready to see if there is a problem until I have a longer outage.
 

h2ofun

Active Member
Aug 11, 2020
2,098
328
auburn, ca
I have noticed the same thing. I have 3 PWs and have went on 3 6-7min backups over the last 2 weeks all while under 2kW load or maybe 2.3kW worst case. On all 3 occasions the percentage drop was around 7%. I also notice a lot of parasitic losses on the walls with them losing at least 1% per day and as much as 6% on some without discharge. I asked my advisor and his response was the percentages are not exact (and I remember reading that somewhere at Tesla). I'm not ready to see if there is a problem until I have a longer outage.
You could always turn off your breaker and make a test power outage example.
 

macbeth

Member
Nov 6, 2014
73
20
United States
I was able to finally reach Tesla, they raised a ticket to do more trouble shooting. I will end up doing a 60 minute test later this week to see what happens.

when I download the data, I see an immediate spike in usage of 6.7kw when the power goes out, the tech on the support line said that was not usual given the pattern of usage surrounding the outage, and after some troubleshooting, said he will raise a ticket for backend support to review. The tech mentioned that they can usually fix these issues remotely, and that is should hear something in 3-5 days.
 

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