BAttery Efficency: kwh charge / discharge

[a.cagnetti]

Hi All,

I am a brand new Powerwall2 owner and user and for the first weeks I have been looking at the monitoring data from the powerwall and here are some first findings:

- Found discrepancy between the Gateway minisite readings (loggin with IP with browser on Gateway) and the Tesla App: % of battery left is slightly higher on gateway monitor (+2 or 3 %)

- noticed that a full charge (100% battery from 0%) takes 15kwh of charging energy and after that a full discharge gives back only 12.9 kwh (86%) which I find rather low ratio. Are other users finding same values?

- tesla app is really minimal, does not give detailed logs of passed events (charge discharge, battery %, etc...)

- It seems that when configuring the Network one cannot set fixed IP address with LAN interface but only with Wifi. Is that something normal?

looking forward to other experiences.

thx

 

[zanary]

I think what you're seeing is normal, and similar to the vehicles. The BMS reports actual numbers based on capacity and the technical limitations, while the Tesla app and the in-car system show what you have available to you as the drive.

From what I can tell, the Powerwall only allows you to consume up to 80 to 85% of the battery and not the full 100% (by design). I accidentally ran my battery down one day, and I think at around 11% it shut down completely and my entire house went offline (I was in manual ToU mode with no PV).

As for the Tesla App, you're right. It's not designed for power users, but for the average Powerwall owner. It does give you some historical data, but nothing to the same level as direct access to the APIs on the Powerwall Gateway.

I can't speak for the IP address thing, as I use DHCP over Wifi for my Powerwall.

 

[cwied]

When I ran the Wizard, it did have an option to set a static address on the Ethernet interface.

 

[Dave EV]

noticed that a full charge (100% battery from 0%) takes 15kwh of charging energy and after that a full discharge gives back only 12.9 kwh (86%) which I find rather low ratio. Are other users finding same values?

Interesting - how are you measuring? Tesla claims 90% efficiency, so if it's only 86, that's quite a bit off the mark.

 

[a.cagnetti]

Interesting - how are you measuring? Tesla claims 90% efficiency, so if it's only 86, that's quite a bit off the mark.

I have read data from the app, charge / discharge in kwh. When battery does not charge to 100% sometimes this ratio is worse, got down to 82%...

 

[a.cagnetti]

When I ran the Wizard, it did have an option to set a static address on the Ethernet interface.

Yes the option is there... but does not work. It only worked with WIFI... not sure why. I got the confirmation from the Telsa customer service.