I've been interested in what is actually inside the Tesla Powerwall, but we are yet to see anyone pull one down to look inside.
So I did a lot of poking around and found some information.
Firstly we have the install manual
https://www.teslamotors.com/sites/default/files/pdfs/powerwall/Powerwall%20Installation%20and%20User%27s%20Manual-online-B.pdfIt has a single DC input/output (bi-directional) .
capacity: 6.4kWh
power in/out: 3.3kW 350-450V 9.5A
cells: nickel-manganese-cobalt (5000 hours)
comms: CAN/modbus (hardware switchable)
The basic concept is to use a DC-DC converter to convert the voltage from the battery to ~400VDC which is fed directly into the inverter's main DC rail. Power can flow both ways, so during the day the batteries are charged from the same rail that feeds the H bridge in the inverter.
Now the DC-DC converter is a ?uk converter, Dr Slobodan ?uk works for Tesla, and they have access to his various patents. It's a simplified combined buck/boost converter easily converted to bi-directional operation.
I don't believe the CAN/modbus protocols are publicly available, which is a problem as they are needed to switch the Powerwall between charge and discharge mode,
According to this article
http://www.catalyticengineering.com/top-ten-facts-about-teslas-350kwh-powerwall-battery/the battery pack likely uses two modules the same design as the Model S. Each module has 6 groups, and 74 cells in parallel per group. This makes a total of almost 900 cells, with an operating voltage of about 48 VDC. I've not seen any confirmed information on the pack voltage.
The pack is packed in a coolant, as in the Model S, Tesla stated this somewhere.
Anyone else found useful information on the Powerwall ?
It's difficult to get beyond the news stories in the search results.