House Powered by electric Car Battery

Jim Martin

Looks interesting but I doubt whether there'd be enough power for a house's typical requirements:[/URL]

http://www.theguardian.com/environment/shortcuts/2015/mar/22/hacking-car-batteries-home-power-tesla

85kWh (x3) not enough for a house's typical requirements??! :eek:
He's got two Model S's to charge too.
Here's the full story & here.

Assuming the $20, 000 figure is just for the battery because he also spent $20 000 on PV panels.

nokia69

Jim Martin wrote: »

Looks interesting but I doubt whether there'd be enough power for a house's typical requirements

its more than enough, it total over kill

but who knows maybe he has an aluminium smelter in his shed out the back

Tesla will be selling home battery backs soon, far smaller than this dude's set up of course

nokia69

nokia69 wrote: »

Tesla will be selling home battery backs soon, far smaller than this dude's set up of course

Present price to beat is €0.10 per kWh over lifespan charging at nightrate and discharging at day rate assuming they're 100% efficient or < €0.19 per kWh if you have renewables charging them and after they have paid for themselves.

Somehow I don't think they will with a 600 cycle battery.
At current prices those replacement car batteries are $0.235 per lifetime kWh.

nokia69

Sir Liamalot wrote: »

Present price to beat is €0.10 per kWh over lifespan charging at nightrate and discharging at day rate assuming they're 100% efficient or < €0.19 per kWh if you have renewables charging them and after they have paid for themselves.

Somehow I don't think they will with a 600 cycle battery.
At current prices those replacement car batteries are $0.235 per lifetime kWh.

their battery will last far longer than 600 cycles

Any data on that.
Or a graph. I based that figure on 100% discharge. 60% would be more realistic I think. It's just a lithium cell.

nokia69

Sir Liamalot wrote: »

Any data on that.
Or a graph. I based that figure on 100% discharge. 60% would be more realistic I think. It's just a lithium cell.

they will keep the cells between 20% and 80% of charge, the pack will then last for decades no problem

Hence the 60%. Decades aren't the issue I'm curious about the cycles.

nokia69

Sir Liamalot wrote: »

Hence the 60%. Decades aren't the issue I'm curious about the cycles.

one a day I assume depending on the set up, but once they stay inside the middle 60% then the cycles don't matter

Sorry rereading that it's a little unclear.
The $0.235 per kWh is based on a 100% discharge. So a 60% discharge is a lot more expensive per cycle.
So say it's 1000 cycles to 60% discharge...nothing gained.

Of course the cyclelife matters, it's chemistry. Every phone, drill and portable device has a finite and deteriorating battery lifespan. The only difference in the cells beside physical appearance is Tesla use nickel cobalt aluminium instead of nickel manganese cobalt which give slightly longer lifespan, expense and explode more easily.

nokia69

Sir Liamalot wrote: »

Sorry rereading that it's a little unclear.
The €0.235 per kWh is based on a 100% discharge. So a 60% discharge is a lot more expensive per cycle.
So say it's 1000 cycles to 60% discharge...nothing gained.

Of course the cyclelife matters, it's chemistry. Every phone, drill and portable device has a finite and deteriorating battery lifespan. The only difference in the cells beside physical appearance is Tesla use nickel cobalt aluminium instead of nickel manganese cobalt which give slightly longer lifespan, expense and explode more easily.

when you stay in the middle 60% the number of cycles no longer matters, the pack can be used every day and will last decades, how is that nothing gained ?

Wikipedia

Wikipedia wrote:

Manufacturers' information implies that the life of a battery that is not abused depends upon the number of charge cycles it undergoes, specifying typical battery capacity in terms of number of cycles (e.g., capacity dropping linearly to 80% over 500 cycles), with no mention of age of the battery. Research by Professor Jeff Dahn of Dalhousie University suggests this common industry practice of merely counting cycles, ignoring the effect of age, is a poor predictor of real-world battery life.[citation needed] On average, its lifetime consists of 1000 cycles. Battery performance is rarely specified over more than 500 cycles. This means that batteries of mobile phones, or other hand-held devices in daily use, are not expected to last longer than three years.

Link

Hardly the most authoritative source on the Tesla pack but consistent with findings of that chemistry.

If you can find any definitive data on the lifetime energy of a Tesla pack from the manufacturer to support any difference I'd love to see it.
That combined with the promise of reducing the cell cost by 50% would almost make it competitive.

1000 cycles to 60% = 600 cycles to 100%..same difference, nothing gained.

nokia69

Sir Liamalot wrote: »

Link

Hardly the most authoritative source on the Tesla pack but consistent with findings of that chemistry.

actually outside of Tesla Professor Jeff Dahn is one of the best public sources of information on lithium ion cells, and he claims that the Tesla batteries will last decades if they are kept in the middle 60% of the cell, watch the video below and you will understand what I'm talking about

we still don't have details on the Tesla home batteries but my guess is they will use the same or better chemistry as the model S and will have a similar BMS system

a battery pack that lasts decades is clearly better than a pack that lasts 3 years

plugincars.com

I'm not watching a repost of a 1hr13 movie on batteries. Much as I love a good battery documentary. No thanks. I do know how to keep different chemistries healthy.

Time doesn't matter, any battery can last decades if you don't use it.
Are you not suspicious that nobody's published lab tests?

plugincars.com wrote:

Obviously, nobody knows exactly how long Tesla packs will last. The math is somewhat simple, though. The full capacity of a lithium-ion battery cell should be good for 300 to 500 cycles. So if you drive a Roadster through 300 194-mile standard-mode cycles, it translates to 58,200 miles. If it’s 500 cycles, how does 97,000 miles on one set of batteries sound?

Link

So comparing apples and cooking apples you can get 87kWh (@ C100) of lead acid here with a lifetime energy cost of €0.12 per kWh (3000 cycles to 50% DOD).
150 year old technology that and I didn't particularly shop around.

nokia69

Sir Liamalot wrote: »

I'm not watching a repost of a 1hr13 movie on batteries. Much as I love a good battery documentary. No thanks. I do know how to keep different chemistries healthy.

Time doesn't matter, any battery can last decades if you don't use it.
Are you not suspicious that nobody's published lab tests?

of course time matters, if you buy a battery and you want to use it everyday, then you need to know how long it will last with everyday use

BTW the roadster cells are not the same as the model S

Sir Liamalot

Sir Liamalot wrote: »

At current prices those replacement car batteries are $0.235 per lifetime kWh.

Oops my bad I took the wrong figure ($12,000):o :

pluginmotors wrote:

The company recently said it would replace Model S 85-kilowatt-hour packs for $12,000, but only after eight years of ownership if they sign up upon purchase. The company is betting that battery costs will have come down considerably by then. Right now, such a battery pack is probably a $34,000 item.

Make that $0.67 per kWh

nokia69

you don't understand the point I'm making

nokia69

nokia69 wrote: »

of course time matters, if you buy a battery and you want to use it everyday, then you need to know how long it will last with everyday use

To do this you measure energy used over time & energy returned over time. Hence why the battery is rated in watt hours.
The net energy seen by the battery gives it it's age.

Saying it will last years is just smoke & mirrors it means nothing. I guarantee you if you put a dead short across the terminals it will last minutes and if you never use it, it will last decades.

nokia69

nokia69 wrote: »

you don't understand the point I'm making

I do I just disagree, and there's no evidence to support your belief that it will last indefinitely, it won't.
It's well engineered certainly.

nokia69

Sir Liamalot wrote: »

I do I just disagree, and there's no evidence to support your belief that it will last indefinitely, it won't.
It's well engineered certainly.

I never said indefinitely

I said that a Tesla model S battery pack will last for decades, if it is only cycled in the middle 60% of the battery, I posted you a video that backs up my claim, the man in the video is the same person you quoted above my post (its a long video fair enough if you don't want to watch it)

you seem to be claiming that all model S battery packs will need to be replaced after eight years, this is just not true

Teslamotors want to start selling/leasing home battery systems, if these systems only last 3 years then they won't sell many but if they last decades then Tesla will have no problem selling millions of home battery systems

The lithium ion cell will give it's maximum potential lifespan if it remains in the mid 60% that's a given and I agree. If you take one battery and cycle it every day from 80% to 20% then it will last 3 - 4 years, now take an identical battery and cycle it 80% to 60% every week it will last over20 years.

To make life a whole lot easier you can calculate it in kilo Watt hours to which the battery will only give you a limited amount before the cathode breaks down as described in your link.

I am not claiming the Model S needs to be replaced after 8 years I am saying it will need to be replaced after discharging 51 000kWh give or take.
Which is a lot more expensive than you'd buy from the national grid or store in lead acid.

nokia69

Sir Liamalot wrote: »

I am not claiming the Model S needs to be replaced after 8 years I am saying it will need to be replaced after discharging 51 000kWh give or take.
Which is a lot more expensive than you'd buy from the national grid or store in lead acid.

this is just wrong, the amount of kWh that gets charged and latter discharged from a lithium ion battery is not what sets its working life

nokia69

Sir Liamalot wrote: »

The lithium ion cell will give it's maximum potential lifespan if it remains in the mid 60% that's a given and I agree. If you take one battery and cycle it every day from 80% to 20% then it will last 3 - 4 years, now take an identical battery and cycle it 80% to 60% every week it will last over20 years.

well in this case it what really matters is the battery chemistry

if you have the right cell chemistry then in both cases the batteries could last just as long, doing cycles once a day or once a week won't make a difference, and your change of 20% to 60% makes no difference, the higher voltages do more damage than the lower ones

nokia69

nokia69 wrote: »

this is just wrong, the amount of kWh that gets charged and latter discharged from a lithium ion battery is not what sets its working life

True but it's the best litmus test you will get unless you autopsy the cells.

Battery University wrote:

The lithium-ion battery works on ion movement between the positive and negative electrodes. In theory such a mechanism should work forever, but cycling, elevated temperature and aging decrease the performance over time. Since batteries are used in demanding environmental conditions, manufacturers take a conservative approach and specify the life of most Li-ion between 300 and 500 discharge/charge cycles.

Link

nokia69 wrote: »

well in this case it what really matters is the battery chemistry

I agree and with correct management you can get more that the manufacturer suggests, or less vice versa

nokia69 wrote: »

if you have the right cell chemistry then in both cases the batteries could last just as long, doing cycles once a day or once a week won't make a difference, and your change of 20% to 60% makes no difference,

Of course it does, the electron flow is caused by the chemistry inside the battery changing.

nokia69 wrote: »

the higher voltages do more damage than the lower ones

True and this would be reflected by only getting 300 cycles from your battery.

All that said it's too expensive per kWh produced per beer token invested to compete with it's rivals and a big pain to recycle.

nokia69

SL you should watch the video I posted

its clear that you don't know what you are talking about

I'll give it 10 minutes if you can tell me "skip to whatever minutes in!"

nokia69

Sir Liamalot wrote: »

I'll give it 10 minutes if you can tell me "skip to whatever minutes in!"

OK watch it from 34 minutes in for a while

then go to 62 minutes in and watch for a while

but you should watch the whole video its very interesting IMO

I'm a lead acid man myself. Anytime I look at lithium I take away weight and see no advantage.

nokia69

better cycle life, do any lead acid batteries last for eight years with 20K cycles and still keep running

lead acid has worked well for a long time but it looks to be that Lithium ion is about to replace it for almost all applications

I got sucked in there a bit longer than 10mins...
All that says to me is we're still learning how to make these. It's nice to see that dedication but it's not ground breaking.

The graph @ 34mins shows 500-1000 cycles: to 80% rated capacity, as is industry standard on a cycle count and fair enough that's to full discharge.
If it gets 20000 cycles over it's lifetime that's very very impressive.

@ 1hr02 he sings the praises of lithium titanate but that's a different battery to what they're developing. Tesla packs are nickel cobalt aluminium.

He says it himself if the Coulombic efficiency is 1 then the battery will last forever. However it is not and the parasitic reactions are going to happen every time you cycle it moreso at greater depth of discharge and rate of recharge, same with all batteries.
Thermal management is great but it's only there for fast charging, it's passive most of the time.

I'll hang about til them graphene-carbon nanotube super caps are mainstream.

Anyways it has to be cheaper than €0.09c per kWh/lifetime at today's prices to be viable to the market major. If it is, power to it.
As far as I'm concerned I wouldn't buy a new battery without a datasheet.

nokia69

nokia69 wrote: »

better cycle life, do any lead acid batteries last for eight years with 20K cycles and still keep running

lead acid has worked well for a long time but it looks to be that Lithium ion is about to replace it for almost all applications

OPzS last longer than 20 years, dunno about cycle life it's all relative, the datasheet says 8K to 20% DOD.

Lithium is better at large loads, it'd be interesting trying to tie a wind turbine to it though.
Coulombic efficiency with lead acid is based on discharge level.


51 000kWh with an average household demand of 10kWh will last 14 years cycling daily.

3000 cycles on the outside for those Panasonic cells.

nokia69

‏@elonmusk
Major new Tesla product line -- not a car -- will be unveiled at our Hawthorne Design Studio on Thurs 8pm, April 30

will most lightly be a home battery system using Lithium ion cells

nokia69

http://www.teslamotors.com/presskit/teslaenergy

The Tesla Powerwall is a rechargeable lithium-ion battery designed to store energy at a residential level for load shifting, backup power and self-consumption of solar power generation. The Powerwall consists of Tesla’s lithium-ion battery pack, liquid thermal control system and software that receives dispatch commands from a solar inverter. The unit mounts seamlessly on a wall and is integrated with the local grid to harness excess power and give customers the flexibility to draw energy from their own reserve.

The battery can provide a number of different benefits to the customer including:

Load shifting – The battery can provide financial savings to its owner by charging during low rate periods when demand for electricity is lower and discharging during more expensive rate periods when electricity demand is higher
Increasing self-consumption of solar power generation – The battery can store surplus solar energy not used at the time it is generated and use that energy later when the sun is not shining
Back-up power – Assures power in the event of an outage
The Powerwall Home Battery increases the capacity for a household’s solar consumption, while also offering backup functionality during grid outages.


The Powerwall is available in 10kWh, optimized for backup applications or 7kWh optimized for daily use applications. Both can be connected with solar or grid and both can provide backup power. The 10kWh Powerwall is optimized to provide backup when the grid goes down, providing power for your home when you need it most. When paired with solar power, the 7kWh Powerwall can be used in daily cycling to extend the environmental and cost benefits of solar into the night when sunlight is unavailable.

Tesla’s selling price to installers is $3500 for 10kWh and $3000 for 7kWh. (Price excludes inverter and installation.) Deliveries begin in late Summer.

Powerwall specs:

Mounting: Wall Mounted Indoor/Outdoor
Inverter: Pairs with growing list of inverters
Energy: 7kWh or 10kWh
Continuous Power: 2kW
Peak Power: 3kW
Round Trip Efficiency: >92%
Operating Temperature Range: -20C (-4F) to 43C (110F)
Warranty: 10 years
Dimensions: H: 1300mm W: 860mm D:180mm

$0.55 per kW hour lifetime at installer costs for 7kW.
Smaller than the average house consumption.
Proprietary system.

envaction

That is actually a pretty interesting thing to think about. Being able to use a car battery to power your home. I think that it would be something cool to think about, but I don't know who actually has the time for that. I mean if you could hire someone, then it might be worth it. But in the end is it worth? Would anyone here do it?

Jim Martin

Anyone know if the Tesla deliveries began as expected at the end of the summer?

Sh1tbag OToole

I don't think it makes a whole lot of sense to bring in a massive battery pack designed for average household consumption. Shouldnt the aim be to reduce the power consumption as much as possible, then come up with a few ways of generating power at different times (solar, wind, TEG modules) then get the smallest battery pack you can get away with?

Sh1tbag OToole

Sh1tbag OToole wrote: »

Shouldnt the aim be to reduce the power consumption as much as possible,

Couldn't agree more.

Sh1tbag OToole wrote: »

then come up with a few ways of generating power at different times (solar, wind, TEG modules)

Hahaha TEG modules, I spent 3 weeks giving myself a crash course in thermoelectrics to try to get them gizmo-tronics working. Stupid money for miniscule return. There's a technology still in it's infancy.

Sh1tbag OToole wrote: »

then get the smallest battery pack you can get away with?

Largest you can afford is usually more prudent, they're not really expandable after commissioning.

Sh1tbag OToole

Sir Liamalot wrote: »

Couldn't agree more.




Hahaha TEG modules, I spent 3 weeks giving myself a crash course in thermoelectrics to try to get them gizmo-tronics working. Stupid money for miniscule return. There's a technology still in it's infancy.




Largest you can afford is usually more prudent, they're not really expandable after commissioning.

Did you try any of the power harvesting IC's designed for TEG's? There are some commercial TEG generators out there that you attach to your stove but they're still a bit expensive although the price of the modules has come down.

Expanding ones battery capacity is only a problem these days because most charge controllers and inverters only do 1 channel.

Nah spent weeks researching TEGs and thermodynamics, I spec'd a system for myself that worked out about €35 per watt iirc.

PV is €1 p/w
Wind is about €3 p/w

Not at all a battery is just a bunch of cells you don't have two batteries you have one larger battery.

Lithium cells need to be completely discharged, rebalanced and recharged to add additional cells to a bank.
LA depending on usage may never come right as the newer stronger cells are discharged by the older weaker ones.

Sh1tbag OToole

Sir Liamalot wrote: »

Nah spent weeks researching TEGs and thermodynamics, I spec'd a system for myself that worked out about €35 per watt iirc.

PV is €1 p/w
Wind is about €3 p/w

Not at all a battery is just a bunch of cells you don't have two batteries you have one larger battery.

Lithium cells need to be completely discharged, rebalanced and recharged to add addition cells to a bank.
LA depending on usage may never come right as the newer stronger cells are discharged by the older weaker ones.

Probably still better to keep the old and the new separate so

The ones I saw were about $500 for 50wt, this was a few years ago now. They were a bit sparse on the details but I can only assume it was TEG-module based. It would provide power when it's being used at a time of the year when solar and wind might not generate much. It will be interesting to see if they'll get cheaper again.

Two medium batteries aren't as good as one larger one. It's an internal resistance thing.

TEG's will get cheaper. Few car companies looking at building thermopiles on the exhaust system to save a couple of horse power by not running alternators.

You can get peltier modules salvaged from cooler boxes and run them backwards if you want to tinker with some. They're even worse than TEGs ~3% efficient but you could make a stove fan or something from them.

Wind, hydro, CHP are all much better value.

It's easy be a net exporter of energy with PV alone. Generation in the Winter is only really an issue for the off gridders.

Sh1tbag OToole

Sir Liamalot wrote: »

Two medium batteries aren't as good as one larger one. It's an internal resistance thing.

TEG's will get cheaper. Few car companies looking at building thermopiles on the exhaust system to save a couple of horse power by not running alternators.

You can get peltier modules salvaged from cooler boxes and run them backwards if you want to tinker with some. They're even worse than TEGs ~3% efficient but you could make a stove fan or something from them.

Wind, hydro, CHP are all much better value.

It's easy be a net exporter of energy with PV alone. Generation in the Winter is only really an issue for the off gridders.

Ah sure feck it if someone is running their house off a battery when they have a perfectly good grid connection they're living a life of perpetual sin. There is no way that would make sense even if the rate of wear on the battery is 1% of what it is now. You definitely wouldn't appreciate the few watts from a TEG module unless you're off the grid

Perfectly good grid connection? :rolleyes: They lose half the energy they convert. A substantial amount of it is redeemed from hydrocarbons. They don't support micro-generators. Three phase costs an arm and a leg....

The point of a battery I find is to develop a tangible sense of the energy we use and how to increase efficiency. Once an appreciation of how difficult it is to cultivate electrons is achieved then, I find at least, the easiest way to make systems work is not to waste so much.
Load shifting could be a great benefit to the national generators whereby instead of having to build more to cater for peak demand we can distribute the load evenly on the existing ones and reduce the need for peaker plants operating at near idle.
Personally I'd much rather see micro grids sprouting up rather than pylons.
For me it's not about a financial return just a reliable system.

nokia69

Sir Liamalot wrote: »

3000 cycles on the outside for those Panasonic cells.

http://blog.evandmore.com/lets-talk-about-the-panasonic-ncr18650b/

To estimate the number of cycles that the cell can undergo in its lifetime, we charge it at a maximal current of 0,5C and discharge at a current of 1C at 25 degrees Celsius and then we count the number of charge/discharge cycles until the cell degrades down to 70% of its initial capacity (2250mAh). In the case of these cells, the number is about 500 cycles.
500 cycles? But that’s (relatively) low! Yes. But what is not shown on the spec sheet is that when you partially charge and discharge, degradation of the battery capacity is reduced. Thus, you can do over 40 000 charge/discharge cycles when going from 30% to 70% only. Or over 35 000 charge/discharge cycles from 20% to 80%; 28 000 cycles from 10% to 90%; 15 000 cycles from 8% to 92%, 7500 cylces from 6% to 94%, and the capacity reduction goes faster and faster, finally reaching 500 cycles when recharging from 0% to 100%.

nokia69

nokia69 wrote: »

... but once they stay inside the middle 60% then the cycles don't matter....
...if you have the right cell chemistry then in both cases the batteries could last just as long, doing cycles once a day or once a week won't make a difference, change of 20% to 60% makes no difference

Same goes for for LA except they can take more than double the abuse of full discharges and it's 50% to 100% they rather live, now calculate the price per Wh end user cost compensating for the reduced discharge and see who's on top..

Have a look at that OPzS datasheet again Nokia, that's the cycle life to 80% rated capacity based on lab tests from a manufacturer.

Capt'n Midnight

Peak demand here is when people arrive home from work. So I'd reckon a lot of them would be expecting to be putting their cars on charge.

From a user point of view the difference between day rate and night rate is about 10c a unit. BUT if you drive to work in the morning and you want to charge it before 11pm then you may not be able to use that stored energy.

From an economics point of view one of the main selling points of lots of charging car batteries is that you could potentially shed a lot of demand very quickly. But again that's only if they are charging at peak demand instead of night rate.

nokia69

Capt'n Midnight wrote: »

Peak demand here is when people arrive home from work. So I'd reckon a lot of them would be expecting to be putting their cars on charge.

I think most people start charging after 12 to get the night rate