House Powered by electric Car Battery

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 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.

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.

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

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.

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.

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.

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 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 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.

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

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

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.