# Tesla Powerwall Potential Battery Source?



## Sunking (Aug 10, 2009)

An empty false splash. They claim $3000 for the 7 Kwh grid interactive battery, and $3500 for the 10 Kwh UPS package. Both units are identical. Only difference is firmware in the controller limiting how much usable energy can be accessed by the user. The price is complete Bogus Bait and Switch tactic. Current the only distributor is Solar City which Musk owns and they must be purchased and installed by Solar City. Just for the battery is in excess of $7000. Want a 400 volt Inverter that does not exist yet to make it work. SolarEdge another Musk partnership company will have those available as well for purchase and installation at product release time later this year through Solar City

It is a nominal 400 volt 25 AH or 110SxP battery. Cells are rumored to be the same Panasonic cells the Giga Factory will produce from Panasonic license agreement.

As for using in a EV. Well as long you do not take more than C/4 discharge charge current, have at it. All you need is a 6 amp motor controller and a 400 volt 5 hp wheel chair motor to make it work for $7000.

Wanna sign up early for pre-release orders? Solar City is accepting deposits and taking orders. For the battery and Hybrid 2 Kw Inverter should not cost you a penny more than $12,000 installed. It will allow you to buy electricity from the POCO at say 9 cents and sell it back to them during peak hours for 4-cents. At least that is the way it works in TX for grid tied systems.


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## ninjanick (Oct 11, 2014)

What's the limiting factor on the cells? If they are the same Panasonic cells used in the vehicle, why would you be limited to C/4? You eluded to firmware limitation which is easy to remove if you can break down the Powerwall to discrete battery packs and recombine to suit the end user. Tying installation (cost) to the unit(s) would be problematic ...


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## Hollie Maea (Dec 9, 2009)

ninjanick said:


> Just trying to get that many cells on your own would cost near $20K.


Buying onesies on Ebay, sure. But even in modest volumes, these cells come way down in price, to well under $1 per Ah.

If you really want 18650s, there are better ways to do it than trying to salvage Tesla Power Packs.


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## Sunking (Aug 10, 2009)

ninjanick said:


> What's the limiting factor on the cells? If they are the same Panasonic cells used in the vehicle,


They are not the same cells. All Tesla will say is they have been changed to provide higher cycle life. The Specs or lack of specs do not really tell you anything. Not even the 10 year warranty has terms and limits defined. 

Only thing on output specified 350 to 450 volts @ 2 Kw continuous, and 3 Kwh burst for undefined amount of time. That is all you get for now. Surf around on Tesla Forums and Tech review sites and you can pick up a few more details leaked by the product engineers and Musk himself on Twitter and press leaks

The charger is 180 to 300 VAC line voltage 50/60 Hz from the grid or grid tied RE system on a 5 amp breaker. Actual charger is 400 volt 2 amps. Included is BMS and liquid thermal management that uses power. 

For now it is Vaporware with promises. Have to wait and see. For now looks like an exclusive product you can only buy from Solar City using Solar City supplied equipment, and installed by Solar City using SolarEdge equipment also owned by Musk. It looks to be proprietary equipment with a big price tag. Sounds like Tesla to me.


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## piotrsko (Dec 9, 2007)

And remember he has 2 more years BEFORE the giga factory is producing anything in bulk.


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## dcb (Dec 5, 2009)

please note, this is solarcity, not tesla. The title is misleading.


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## tomofreno (Mar 3, 2009)

dcb said:


> please note, this is solarcity, not tesla. The title is misleading.


 The title is fine. The battery pack is made by Tesla, has the Tesla emblem on the cover, and like Hollie said they have been selling this "vaporware" for a while:

http://www.renewableenergyworld.com...ores-attest-to-musks-energy-storage-ambitions


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## frodus (Apr 12, 2008)

If they're going to do this, I bet they'll give the replaced/recycled roadster/s/x/3 batteries second lives as backup storage.... rather than use new batteries. I mean, isn't that the smart choice for used batteries with >70% original capacity left? They're still good for storage when volume isn't really an issue.


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## Caps18 (Jun 8, 2008)

The price seems ridiculous. Maybe not for the intended operation, but for EV cells it does. I was able to buy 30kWh of batteries for around $5,000 (with a good deal) 

Assuming that you could buy 3 of the 10kWh packs, that would be $10,500.

Am I missing something?


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## Sunking (Aug 10, 2009)

Caps18 said:


> The price seems ridiculous. Maybe not for the intended operation, but for EV cells it does. I was able to buy 30kWh of batteries for around $5,000 (with a good deal)
> 
> Assuming that you could buy 3 of the 10kWh packs, that would be $10,500.
> 
> Am I missing something?


Couple of things. First the quoted $3000 price is Bogus. You cannot just buy the battery. It has to be installed by Solar City (Musk is on the Board of Directors) or an approved Solar Contractor designated by Tesla with all the goodies that come with it as part of your solar system or UPS. $3000 turns into 7 to $15K depending on how your solar system is configured. 

Second and the show stopper is the batteries are not the same ones used in EV with high discharge rates. They are designed for cycle life, not for high Specific Power.


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## Duncan (Dec 8, 2008)

Caps18 said:


> The price seems ridiculous. Maybe not for the intended operation, but for EV cells it does. I was able to buy 30kWh of batteries for around $5,000 (with a good deal)
> 
> Assuming that you could buy 3 of the 10kWh packs, that would be $10,500.
> 
> Am I missing something?


Dunno where you got that deal but where I look cells are ~ $1.40/Ah = $0.437/Whr = $437/Kwhr
so 30Kwhr = $13,125

The Musk ones at $3500 for 10Kwhr = $350/Kwhr seem like a good deal especially as it has the temperature control and probably the BMS included


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## arklan (Dec 10, 2012)

as a thought exercise and getting off topic
lets discuss what it would take to make your own "powerwall"

the 10kwh figure is likely the total with 7-8kwh being useable but lets say we want 10kwh usuable
thats 12.5kwh at a dod of 80%

to make it easy we might use a 48v inverter so thats 260ah at 48v to get 12480wh

the mains would have to go in to our powerwall first
it would have a dpdt relay or maybe some mosfets or solid state relays
when the pack voltage is above 45 the house is powered from the inverter and batteries (which get charged from the panels)
when the batteries r low it switches to the mains and lets the batteries get back to say 80% before switching back to the inverter

it could be set up so that when the batteries get low it only runs the lights (which r on a separate circuit in australia) and if it still gets lower then full mains

260ah in prismatic is going to weigh about 130kg and at $1.4 per ah would cost $5460
a 10kw chinese inverter from eBay will cost about $800 (but i bet most people wouldnt feel comfortable with an eBay special)
relays mosfets or solid state relays to do the switching and an arduino to control it all, even add a temp controlled fan if u want, under $100

the cool looking box to make the weight of 2 people to stay on the wall, just some brackets from bunnings with a boogie board painted white in front of it


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## browncamaroz28 (May 14, 2014)

Caps18 said:


> The price seems ridiculous. Maybe not for the intended operation, but for EV cells it does. I was able to buy 30kWh of batteries for around $5,000 (with a good deal)
> 
> Assuming that you could buy 3 of the 10kWh packs, that would be $10,500.
> 
> Am I missing something?


Caps18, could you please share where you got 30kwh of batteries for $5k? I'm considering building a pack for my project and I would like to see if those batteries could work for me. Thanks!


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## Sunking (Aug 10, 2009)

arklan said:


> as a thought exercise and getting off topic
> lets discuss what it would take to make your own "powerwall"
> 
> the 10kwh figure is likely the total with 7-8kwh being useable but lets say we want 10kwh usuable
> ...


Not that easy.

First the Powerwall is to tap tax payer money for California SGIP. In an effort to put a band aide on CA failed energy policy. The battery is intended to be used to shift peak load by having citizens and large corporate users install and maintain power equipment rather than address the real problem of CA not building conventional power plants. CA imports 30% of their electrical energy up from 10% 20 years ago when they went green. 

Anyway the battery uses 240 VAC as the source of power and there is no means to charge a 400 volt battery directly from solar. To be able to interface such a battery with your home electrical system is going to require all equipment to be listed by a testing agency like UL and be installed in compliance with all electrical codes. Gorilla Installs are out of the question.

Fronius and Solar Edge announced today they are partnering with Tesla to introduce a line of Hybrid Inverters to work with the Tesla Powerwall battery operating at 400 volts. It will be an exclusive product distributed by Solar City who Musk owns a large share of and on the Board of Directors. 

There is no support or plans to make the battery available to off grid crowds as there is no Tax Payer money to tap in that market. It is strictly about load shifting and some UPS applications for large businesses with Data Centers like Walmart. Its a CA thing for now.

But to your point for Off-Grid solar is not ready for Lithium batteries. There is no demand for it yet as the cost are still too high. There is no charge controllers made for lithium batteries with the exception of GenSun which targets the Marine low power 12 and 24 volt , and a golf cart booster for 48 volts. But even those controllers are not really that great because the offer no BMS or interface for BMS. For off-grid right now is a 12 volt toy market, and 24, 48, 70, and 72 volt systems. One manufacture Midnite solar offers a 1200 volt system but no Lithium support. 

One can adapt some charge controllers for lithium if they allow custom voltage settings, but you still have to figure out how to monitor and control individual cell voltages, and tell the charge controller to turn off.


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## rochesterricer (Jan 5, 2011)

Powerwall is sold out into much of 2016 with 38,000 preorders:

http://www.theverge.com/2015/5/6/8561931/tesla-38000-powerwall-preorders-announced


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## Caps18 (Jun 8, 2008)

browncamaroz28 said:


> Caps18, could you please share where you got 30kwh of batteries for $5k? I'm considering building a pack for my project and I would like to see if those batteries could work for me. Thanks!


http://hybridautocenter.com/HAC4/in...can-be-used-for-vectrix-conversion&Itemid=605

I bought 8 cells from them, but they also offer larger numbers of cells when they are in stock. You might find a wrecked Nissan Leaf, but that is not all that likely.

I got 48 of them from EVTV's flash sale last year where they sold 70 packs in 5 days at $4000. Which is about 30%-60% off. depending on what market price you use.


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## arklan (Dec 10, 2012)

Sunking said:


> Not that easy.
> 
> First the Powerwall is to tap tax payer money for California SGIP. In an effort to put a band aide on CA failed energy policy. The battery is intended to be used to shift peak load by having citizens and large corporate users install and maintain power equipment rather than address the real problem of CA not building conventional power plants. CA imports 30% of their electrical energy up from 10% 20 years ago when they went green.
> 
> ...


couple of points i want to clarify
if u were to make ur own powerwall u wouldnt have to use a 400v pack, u could use whatever because its urs
u also said that theres no way to charge a 400v battery from solar when u obviously can just by stacking panels until the voltage is higher than the batteries
if u mean there is no 400v mppt then theres the midnite one u mentioned

u also mention that all of the equipment used would have to be checked by a qualified party
if u mean the stuff in the house like fridge needs to be checked to make sure it can run off an inverter that seems kinda insane
if u mean the relays to switch between mains and inverter then yeah this would need to be installed by the proper people, in australia anything that goes in to the meter box needs to be installed by western power (new meter for solar, breakers etc)

i agree with ur point that doing all of this would be stupid money, theres people who have deep cycles with these setups (not me)

musk says on his video on the powerwall website that these can be used off grid
he also says that these can be charged during off peak and used during on peak so it would use a grid tie inverter like with the solar jobs but doesnt let the power go back in to the grid

what im thinking would be either mains or inverter so theyd be separated, to put the relays in though youd definitely want a pro, the rest id be comfortable with doing myself, if it fails it just switches to the grid so u never lose power
could put smoke alarms incase it catches fire for those hipsters out there

my house averages 16kwh a day according to the power bill so id need 2 of musks powerwalls to be self sufficient and theres only 2 people living here


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## Hollie Maea (Dec 9, 2009)

Caps18 said:


> http://hybridautocenter.com/HAC4/in...can-be-used-for-vectrix-conversion&Itemid=605
> 
> I bought 8 cells from them, but they also offer larger numbers of cells when they are in stock. You might find a wrecked Nissan Leaf, but that is not all that likely.
> 
> I got 48 of them from EVTV's flash sale last year where they sold 70 packs in 5 days at $4000. Which is about 30%-60% off. depending on what market price you use.


You can't really compare the prices of new cells with salvage or bankruptcy goods. I can get an alternator for next to nothing from the Pick and Pull, but I don't expect Napa to be selling it for that price.


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## Yabert (Feb 7, 2010)

browncamaroz28 said:


> could you please share where you got 30kwh of batteries for $5k?


car-part.com / Chevy Volt / Battery.....


You can find many complete 16 kwh battery for 2K$.


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