Tesla Powerwall

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weber
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Post by weber » Mon, 04 May 2015, 23:09

I've read so much hype and nonsense in the past two days about Tesla's "Powerwall", I'm sick of it. It took a major search effort to establish what was actually in it. Why are most journalists so useless?

It is an absolutely disgraceful bait-and-switch on Tesla's part. It turns out the "Powerwall" is just a battery. 10 kWh (400 V) for US$3500, and it's only good for 3 kW peak (0.33C). How pathetic is that? No inverter and no PV charge controller are included. And why does one need thermal control for a lithium battery that only does 0.2C continuous?

It's only 20% cheaper per kWh than the 9 kWh battery in Black Monolith #1 that I paid AU$4800 for 5 months ago, and of course that comparison doesn't include shipping to get the Tesla unit here. And the CALB battery in the monolith is good for much higher peak power.

The Tesla Powerwall is more expensive than the second-hand Nissan Leaf cells I'm using in Black Monolith #2, and it is shaped like a coffin for a dwarf.
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Post by offgridQLD » Mon, 04 May 2015, 23:51

I don't think it's anything revolutionary as many might have expected from Tesla. I wont be rushing out to get one.

That said it's not raw Chinese lithium cells that you get in a wooden box. You then have to assemble them with a stack of interconnects and bolts, washers. Purchase materials then fabricate pressure strapping. Purchase and install a BMS. Purchase and install contactors and the same for fusing. Purchase or build racking, shelving and protective covers. Then assembling it all as a package.

A walk in the park for us DIY battery enthusiasts. Though their is value in that for people who just want a ready to go appliance.

It's more of a consumer appliance. It might only be a lithium battery but it's ready to go from a upmarket brand (you would also expect quality components and assembly methods) and it's competitively priced.

You can think of many examples of products that are similar. Nothing special on paper (think apple products) and you can always build a PC something similar spec yourself for less.

Why would anyone expect the Tesla power wall to cost any less than a equivalent home built battery using chinese products?

The fact that it's even competitive as a fully assembled package a is a good start. Given that the units are new to the market (all first gen products are expensive) I would expect once they start producing them in numbers from that Gigafactory they might be even more competitive.

As for the 0.33C rating Perhaps that's all the cells are good for with a l0 year Warranty and or they are playing it very safe.

The Calb cells on paper say they can do way better but any 10 year tests to prove that?

Mind you if that's the true max surge rating then I would hate to try and start a pressure pump or similar from one. I guess that just confirms they are only good in unison with the grid to take up the slack.

Kurt




Last edited by offgridQLD on Mon, 04 May 2015, 14:02, edited 1 time in total.

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Post by weber » Tue, 05 May 2015, 01:19

offgridQLD wrote:That said it's not raw Chinese lithium cells that you get in a wooden box. You then have to assemble them with a stack of interconnects and bolts, washers. Purchase materials then fabricate pressure strapping. Purchase and install a BMS. Purchase and install contactors and the same for fusing.
A fair point, although how do you know it includes BMS, fuses and contactors?
Purchase or build racking, shelving and protective covers. Then assembling it all as a package.
No I don't buy that. You still have to assemble it as a package with inverter/AC charger/PV charger/system controller/switchboards.
It's more of a consumer appliance. It might only be a lithium battery but it's ready to go ...
That's what they allowed us to believe, but it is false. In what sense is a 400 volt DC battery a "ready to go consumer appliance"?
You can think of many examples of products that are similar. Nothing special on paper (think apple products) and you can always build a PC something similar spec yourself for less.

Why would anyone expect the Tesla power wall to cost any less than a equivalent home built battery using chinese products?
That's missing my point completely. They told us we could charge it from a PV array or the grid and power our house from it, all for US$3500. They completely failed to mention that to do that we'd need to add a 400 Vdc AC charger, a 400 Vdc PV charge controller and a 400 Vdc inverter (or a combination unit) and system controller and switchboards, all costing several additional thousands of dollars, and taking up lots more space on the wall with non-matching decor and conduits between.
The Calb cells on paper say they can do way better but any 10 year tests to prove that?
I don't need a 10 year test to be convinced that CALB cells can do 1C surges with no ill effect.
Mind you if that's the true max surge rating then I would hate to try and start a pressure pump or similar from one. I guess that just confirms they are only good in unison with the grid to take up the slack.
Indeed, except you're still talking like their misleading hype. The Powerwall can't work "in unison with the grid". It would have to include an inverter to do that.
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Post by lesmando » Tue, 05 May 2015, 01:41

I thought the powerwall was for people who already had solar?

From the presentation I thought you would put it in between the panels and the inverter you already own. Then it slurps up the solar power instead of the inverter until it is full. After that it goes into pass through? It is there to decrease your usage at peak times (I believe U.S.A. utilities charge different rates at different times). I gather the software turns on the battery when the cost is high (or when your solar is not producing) and it sends it to the inverter, which you then use?

I certainly like the idea I could use solar energy at night to help reduce pollution. :)

Les

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Post by weber » Tue, 05 May 2015, 01:52

In case you've forgotten, listen to Elon Musk again. I used to admire this guy. But in this case he's behaving like the slimiest used-car salesman. Utterly misleading. I've set this to start at the relevant point (8:17). Listen until 9:12.

https://youtu.be/yKORsrlN-2k?t=497

Edit: This one just seems like a straight out lie:

https://youtu.be/yKORsrlN-2k?t=618
Last edited by weber on Mon, 04 May 2015, 16:15, edited 1 time in total.
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Post by T1 Terry » Tue, 05 May 2015, 01:56

Maybe this sheds more light on the design intergration http://www.businessspectator.com.au/art ... ly&modapt= It may be more mis information but it would make sense that it is designed to link in with the solar inverter already connected to the solar system and grid

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Post by lesmando » Tue, 05 May 2015, 02:09

The only product I can find that is all in one, is this Bosch, which costs $31K installed with 8.8KWh of batteries. It has a 5 year warranty with a 5 year extension available.

http://www.enter-shop.com.au/catalogue/ ... c261/p1254

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Post by offgridQLD » Tue, 05 May 2015, 02:31

Yes I agree Weber. The video you linked to is misleading .

When has Tesla not been misleading. Didn't they say the base model tesla model S was going to be 40k US . What happened to battery swap they demonstrated. Didn't they say everything was open sorce then have block peoples write to repair there Tesla cars by shutting privately owned damaged cars down remotely .

Kurt
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Post by weber » Tue, 05 May 2015, 03:22

lesmando and T1 Terry, you could be right that it is intended to be inserted between a grid-feed inverter and the ~400 V PV array that would normally have been connected to it directly.

If so, I'm wrong about needing a PV charge controller with it, but not the other stuff.

But if so, how hard would it have been to just say that -- somewhere? And if so, how can it do anything for you in a blackout, or operate off-grid, as nolE skuM said it would?
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Post by offgridQLD » Tue, 05 May 2015, 15:22

Apparently the 100kwh commercial size unit is $25,000 US.

If you put aside all the hype and misleading presentations and just think of the things as batterys (with a few small potentially useful extra's thrown in ) That's not bad value.

Just compare the raw stored energy potential at $2,500 pr 10kwh to other offerings.You could strip the thing down and build five 20kwh electric car banks for $25,000.

I find the commercial box more appealing.

Kurt





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Post by Johny » Tue, 05 May 2015, 15:33

offgridQLD wrote:You could strip the thing down and build five 20kw electric car banks for $25,000.
I thought the same thing Kurt - but the low peak power rating kind of shoots that down.

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Post by weber » Tue, 05 May 2015, 15:44

It would be good if you used the correct units, Kurt. The commercial unit is 100 kWh but presumably only 20 kW.
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Post by offgridQLD » Tue, 05 May 2015, 15:44

It would be good if you used the correct units, Kurt. The commercial unit is 100 kWh but presumably only 20 kW."

Sorry fixed.

If they are using the same Panasonic 18650 cells as they are in the cars (I don't see why they wouldn't) Then the cells are good for way more output then they limit them to in the stationary banks.

Kurt

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Post by offgridQLD » Tue, 05 May 2015, 16:01

Going off this picture it looks like they perhaps use 15 x 7kwh units for just over 100kwh? Or potentially 150kwh if they are using the 10kwh packs. It doesn't look like it would be to hard to strip the unit down into 3 x 35kwh packs (assuming they are the 7kwh packs). You can see the liquid cooling tank in the door.

http://cdn.arstechnica.net/wp-content/u ... C_4904.jpg

I notice that the model S pack also has 15 modules (Edit: it could be 16 as the front one might be double layer?) that look like they would fit into the little black case in the commercial unit. Could it be that they just use the same bank? though the model S is only 85kwh. Though I assume some of the newer 18650 cells are slightly higher AH capacity for the same size.

Image

It will be interesting when people start to get there hands on them and start ripping them apart Image

Kurt
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Post by Adverse Effects » Tue, 05 May 2015, 20:31

offgridQLD wrote:It will be interesting when people start to get there hands on them and start ripping them apart Image

Kurt


as i posted a while ago

Lithium Ion 18650 EV Module - 57 Volt, 3kWh

Image


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Post by weber » Tue, 05 May 2015, 23:10

Imagine if Musk had told the truth:

Musk: "We put a battery in a box."

Crowd: (goes wild with applause which quickly dies off to be replaced by sounds of puzzlement) "Huh?"

Musk: (apologetically) "It comes in 5 colors"
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Post by T1 Terry » Wed, 06 May 2015, 04:22

offgridQLD wrote: Apparently the 100kwh commercial size unit is $25,000 US.

If you put aside all the hype and misleading presentations and just think of the things as batterys (with a few small potentially useful extra's thrown in ) That's not bad value.

Just compare the raw stored energy potential at $2,500 pr 10kwh to other offerings.You could strip the thing down and build five 20kwh electric car banks for $25,000.

I find the commercial box more appealing.

Kurt

So, what are the chances of any of us getting our hands on these units? No doubt they would require sea freight as they wouldn't allow one of those things on a plane. Previous experience with shipping into Sydney turned into a rather expensive exercise but multiple units would at least split the costs a bit.

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Post by Richo » Wed, 06 May 2015, 20:57

weber wrote: It turns out the "Powerwall" is just a battery.
10 kWh (400 V) for US$3500, and it's only good for 3 kW peak (0.33C).
How pathetic is that?


Well the way I see it is if I had a gigafactory pumping out squillions of batteries some are bound to be second rate and not go into a Telsa.
What to do with 2nd's that have crap specs?
I know put it in a powerwall Image

Brilliant Image


We get rid of the crap and still make a bit of money Image
So the short answer is NO but the long answer is YES.
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Post by weber » Thu, 07 May 2015, 01:06

I guess I've been a little unfair. Musk could have honestly said "We've put a lithium battery in a box with a BMS and we're selling it 25% cheaper per kilowatt hour than other lithium batteries in a box with a BMS (which, by the way, we didn't invent). There is a catch however. It's more than double the cost per peak kilowatt."

Note that's only 25% cheaper per kWh, not 1/2 the cost or 1/3 or 1/4 of the cost! as I've read from some rabid drooling commentators who presumably took Musk at his word when he said (my bolding):
Elon Musk wrote:You can actually go, if you want, completely off grid. You can take your solar panels, charge the battery packs, and that's all you use. So it gives you safety security, and it gives you a complete and affordable solution. And the cost of this is 3500 dollars."
But hey, they have won with their dirty marketing tricks, since we're still talking about it.

Their strategy of giving no information about what its interfaces are, how to use it in a larger system, what other devices it can and must connect to to be useful, worked. Tesla knows that the less people know about something the more they will write about it and the more they will project their fantasies onto it.

Does this June 2012 offering from Panasonic look familiar?
http://www.panasonic.com/business/pesna ... System.pdf
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Post by reecho » Thu, 07 May 2015, 18:06

So.........


38,000 reservations taken and all sold out until mid 2016.



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Post by Johny » Thu, 07 May 2015, 18:14

He's almost got an Apple like following.
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Post by lesmando » Thu, 07 May 2015, 19:24

Pricing has been released via solar city for the battery and needed electrical bits.

http://insideevs.com/solarcity-reveals- ... powerwall/

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Post by reecho » Thu, 07 May 2015, 19:58

Still waiting to see "whats in the guts" of the Powerwall so I can make up my own mind.

It appears they are targeting Europe and Australian markets for this, according to reports...

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Post by Gabz » Fri, 08 May 2015, 14:58

because we have high peak tariffs and if your on HV or industry connection you also have demand chargers which is the largest current draw detected by you meter times $.70c (something like that changes with distributor) charged for 12 month window then it goes to the 2nd largest or higher.

we have a SCADA screen saying if you make 2 pumps run at once it will add $20k in demand charges, check with supervisor before operating.

so spending $25kUSD on a battery with the demand charges the way they are looks like a pretty good option.

so i can see why they are target Aus but not with a 43degree max operating temp :-S
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Post by offgridQLD » Fri, 08 May 2015, 15:07

"so i can see why they are target Aus but not with a 43degree max operating temp :-S"


If your running a commercial operation and spending big money on power electronics and batterys. Throwing them in a small insulated room with a Air conditioner is the likely plan.

I have now refrigerated my power room with a small spit system. Never gets over 24C.

Kurt

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