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Tesla battery launch
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biffvernon



Joined: 24 Nov 2005
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Location: Lincolnshire

PostPosted: Fri May 01, 2015 9:06 am    Post subject: Tesla battery launch Reply with quote

Quote:
At $3,500 for a 10kWh model, excluding inverter and installation prices, the Powerwall can be used for backup power or to store solar energy.
Not rushing out to buy one just yet....


http://www.reuters.com/article/2015/05/01/us-tesla-motors-batteries-idUSKBN0NM34020150501
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Pepperman



Joined: 10 Oct 2010
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PostPosted: Fri May 01, 2015 12:06 pm    Post subject: Reply with quote

Assuming that price includes the power electronics, then it makes it cheaper than an equivalent setup using good quality lead acid batteries. That is pretty extraordinary.

I don't expect them to see much more than modest demand but the implications for EVs are much more significant.
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kenneal - lagger
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PostPosted: Fri May 01, 2015 2:52 pm    Post subject: Reply with quote

Typical journalists! Show a picture of the CEO instead of the product!!

It does sound very cheap at $350 per kWhr.
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Pepperman



Joined: 10 Oct 2010
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PostPosted: Fri May 01, 2015 3:07 pm    Post subject: Reply with quote

kenneal - lagger wrote:
Typical journalists! Show a picture of the CEO instead of the product!!

It does sound very cheap at $350 per kWhr.


It certainly does.

More info: http://www.teslamotors.com/powerwall
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Pepperman



Joined: 10 Oct 2010
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PostPosted: Fri May 01, 2015 3:44 pm    Post subject: Reply with quote

Looks like it doesn't include the power electronics according to Chris Goodall:

http://www.carboncommentary.com/blog/2015/5/1/teslas-home-battery-a-remarkable-achievement-that-doesnt-quite-make-financial-sense

Still, it bodes well for battery technology.

I wouldn't be surprised if they're selling these as a loss leader while the gigafactory is constructed. What will they be able to knock them out for when that's at full production?
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Potemkin Villager



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PostPosted: Fri May 01, 2015 8:55 pm    Post subject: Reply with quote

Pepperman wrote:
Assuming that price includes the power electronics, then it makes it cheaper than an equivalent setup using good quality lead acid batteries. That is pretty extraordinary.


Surprised It is incredibly amazing.
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Tarrel



Joined: 29 Nov 2011
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PostPosted: Fri May 01, 2015 11:43 pm    Post subject: Reply with quote

Well, an Ebay merchant is offering a 12V 100Ah deep cycle solar battery for 162. You'd need 8 for a 10kWh installation, making 1300 plus the electronics.

Is see the Tesla unit is Li-ion. I always thought the advantage of li-ion over lead-acid was weight, but this is hardly a problem with a domestic installation.

I wonder, is the Tesla battery new technology, or have they basically scaled up existing li-ion battery technology. (i.e. is it basically a giant iPad battery?)
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Pepperman



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PostPosted: Sat May 02, 2015 12:34 am    Post subject: Reply with quote

Tarrel wrote:
Well, an Ebay merchant is offering a 12V 100Ah deep cycle solar battery for 162. You'd need 8 for a 10kWh installation, making 1300 plus the electronics.

Is see the Tesla unit is Li-ion. I always thought the advantage of li-ion over lead-acid was weight, but this is hardly a problem with a domestic installation.

I wonder, is the Tesla battery new technology, or have they basically scaled up existing li-ion battery technology. (i.e. is it basically a giant iPad battery?)


No you would need at least 16. You really don't want to drop below 50% soc with lead acid if you want them to have a decent lifetime and even 50% depletion is pushing things.
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kenneal - lagger
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PostPosted: Sat May 02, 2015 3:27 am    Post subject: Reply with quote

Our lead acid batteries have lasted about 6 years using a 50 to 60% soc which is quite good. Having boasted about that they will probably now fail in the next couple of weeks. I have noticed that the charging voltage is edging upwards to about 14.5V but I'm not sure whether that is just a function of the brighter sunshine of the spring or their age.

I priced up new gell lead acid batteries last year and was quoted about 1350 for a 920Ahr 12V installation which is 11kWhrs or effectively 5.5kWhrs usable power at 50% soc. So those L-ion batteries look very good value assuming that I would get 6 years use out of them.

I have talked to some owners of EVs locally and they are saying that they get a much better battery life by limiting the maximum charge to 80% and not fully discharging them. On that basis the Tesla batteries are not half the cost but they are well worth looking at.
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kenneal - lagger
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PostPosted: Sat May 02, 2015 4:19 am    Post subject: Reply with quote

Having just read the Tesla spec, the voltage is 350 to 450 volts so my current set up would not work very well as it is 12V and with 10 panels at say 14V I could only get 145V input.

They are also saying that they do a 10kWh system for "backup" applications and a 7kWh system for "daily cycle" applications.

Perhaps Adam2 could help with an explanation? I presume an MPPT controller would be required and my current 12V DC to 240V AC inverter would not work.
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Pepperman



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PostPosted: Sat May 02, 2015 6:32 am    Post subject: Reply with quote

Take a look at the Trojan T105. It's 225Ah at 6V and costs 105 from battery megastore who do free delivery. You'd need 8 to get 900Ah so it works out a fair bit cheaper. You'll need to facto in making up some extra cables but if you know someone with a hydraulic crimp it's easy enough. They're good batteries.
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Catweazle



Joined: 17 Feb 2008
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PostPosted: Sat May 02, 2015 7:48 am    Post subject: Reply with quote

I wonder how insurance companies would react to someone having a li-ion battery of that size in the house.
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Tarrel



Joined: 29 Nov 2011
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PostPosted: Sat May 02, 2015 9:14 am    Post subject: Reply with quote

Catweazle wrote:
I wonder how insurance companies would react to someone having a li-ion battery of that size in the house.


Yes, I was thinking that you wouldn't want one of those going up in flames!
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Tarrel



Joined: 29 Nov 2011
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Location: Ross-shire, Scotland

PostPosted: Sat May 02, 2015 9:14 am    Post subject: Reply with quote

Pepperman wrote:
Tarrel wrote:
Well, an Ebay merchant is offering a 12V 100Ah deep cycle solar battery for 162. You'd need 8 for a 10kWh installation, making 1300 plus the electronics.

Is see the Tesla unit is Li-ion. I always thought the advantage of li-ion over lead-acid was weight, but this is hardly a problem with a domestic installation.

I wonder, is the Tesla battery new technology, or have they basically scaled up existing li-ion battery technology. (i.e. is it basically a giant iPad battery?)


No you would need at least 16. You really don't want to drop below 50% soc with lead acid if you want them to have a decent lifetime and even 50% depletion is pushing things.


Good point. Thanks for the clarification.
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Pepperman



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PostPosted: Sat May 02, 2015 11:13 am    Post subject: Reply with quote

kenneal - lagger wrote:
Having just read the Tesla spec, the voltage is 350 to 450 volts so my current set up would not work very well as it is 12V and with 10 panels at say 14V I could only get 145V input.

They are also saying that they do a 10kWh system for "backup" applications and a 7kWh system for "daily cycle" applications.

Perhaps Adam2 could help with an explanation? I presume an MPPT controller would be required and my current 12V DC to 240V AC inverter would not work.


I believe larger domestic arrays are usually connected to deliver hundreds of volts using panels with a Voc of 37V - much bigger than the nominally 12V panels you have.

This is really designed for big US homes with big roofs and consequently a big PV installation - an array of 10 standard domestic PV panels wired in series will take you up to 370V and in the states you could easily fit at least a couple of strings of 10 panels on a suburban roof giving you 5kW and upwards.

In the UK you could get away with a smaller battery and lower voltages (but it would still be hundreds of volts).
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