# Aluminum-air car battery demo



## Cynnergy (Jun 4, 2014)

Thought this might be of interest.  I can't claim I understand the details, but then I don't think the reporter did either .  It's great to see some real money going into new battery technology.

http://www.cbc.ca/news/technology/e...ive-range-in-demo-by-phinergy-alcoa-1.2664653


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## begreen (Jun 4, 2014)

Thanks for posting. That's an interesting idea for a range extender. Not sure how they would prevent battery freeze in cold winter climates, but I imagine they have something in mind.


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## Jags (Jun 4, 2014)

Hmmm...not understanding how alumina is generating electric.  Must learn more...


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## Cynnergy (Jun 4, 2014)

_"The batteries are "charged" not from the electrical grid, but from hydroelectric power generated at Alcoa's smelter in Baie-Comeau, Que., Tzidon said._"

I'm also not sure how the aluminum smelter is generating hydropower.  Our newest form of inexhaustible energy?  .


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## Grisu (Jun 4, 2014)

Cynnergy said:


> _"The batteries are "charged" not from the electrical grid, but from hydroelectric power generated at Alcoa's smelter in Baie-Comeau, Que., Tzidon said._"
> 
> I'm also not sure how the aluminum smelter is generating hydropower.  Our newest form of inexhaustible energy?  .



I have read somewhere that Alcoa runs some hydroelectric dams that power several of their aluminum smelters. Since aluminum is produced through electrolysis the smelters consume A LOT of electric power (Wanna be green? Ditch soda cans etc.). Reading through the article I think what happens is that they produce elemental aluminum probably under some kind of inert gas conditions or similar to prevent it from spontaneously oxidizing. Then they put that in water with some elctrolyte and feed it air which will lead to oxidation of the aluminum to alumina. That reaction energy is captured as electricity powering the EV. "Recharging" here means pulling out the whole "battery" and replacing it with a new one. The spent one goes back to the smelter where the alumina is reduced again to aluminum. Essentially at any fueling stop you have to pull out a 210 lb battery and replace it with a new one. Not only does that sound mightily inconvenient, I am also wondering how the energy balance looks like compared with hydrogen generated by electrolysis and used in a fuel-cell car. Somehow I have my doubts this technology will catch on.


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## woodgeek (Jun 4, 2014)

The catch is that the battery is non-rechargeable.  The energy to turn the weeks is put in when the battery is manufactured, by Al electrolysis at Alcoa.


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## webbie (Jun 4, 2014)

How about this one?
http://phys.org/news/2014-06-lithium-sulfur-battery-revolution-cheap.html


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## Cynnergy (Jun 5, 2014)

Ooh that looks interesting Webbie.  I hope they can make them so they don't spontaneously combust!

I am particularly interested in whether these types of batteries could be used in off-grid electricity system.  How much electricity do you get out of a 210 lb aluminum-air battery?  If I had to exchange it every month, I'm not interested.  Once or twice a year, that's do-able.

I think there is still an aluminum smelter in Kitimat, BC.  They use hydropower too.  I'd sure prefer to see an aluminum battery recharging facility there than the Northern Gateway tarsands pipeline terminus!  Kitimat has a deep-sea port so it could easily accommodate battery recharging via marine shipping for the west coast of North America.  Probably not cost-effective though.  But it would be better for the marine ecosystem in case of a spill.


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## woodgeek (Jun 5, 2014)

Cynnergy said:


> I am particularly interested in whether these types of batteries could be used in off-grid electricity system.  How much electricity do you get out of a 210 lb aluminum-air battery?  If I had to exchange it every month, I'm not interested.  Once or twice a year, that's do-able.



If a 210 lb battery gives ~1000 mi of EV range, figure 3 mi/kWh.....330 kWh.  Swapped 2x per year, 660 kWh, same as a <1 kW PV system.


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## Grisu (Jun 5, 2014)

webbie said:


> How about this one?
> http://phys.org/news/2014-06-lithium-sulfur-battery-revolution-cheap.html



500 cycles and you are down to 50% capacity? Let's say you drive your EV during the day and recharge at night. That gives you roughly 1.5 years and your range has been cut in half. And that is apparently after several attempts to make the lithium-sulfur battery a viable option through better design; not an initial finding that sulfur could be used as cathode. What does it matter that it is cheaper to produce than other such designs when it is inferior to current batteries?


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## jharkin (Jun 5, 2014)

Grisu said:


> 500 cycles and you are down to 50% capacity? Let's say you drive your EV during the day and recharge at night. That gives you roughly 1.5 years and your range has been cut in half. And that is apparently after several attempts to make the lithium-sulfur battery a viable option through better design; not an initial finding that sulfur could be used as cathode. What does it matter that it is cheaper to produce than other such designs when it is inferior to current batteries?



Show me a current generation battery technology that has a better cycle life.... Old fashioned lead acid deep cycle gets that kind of lifetime IF you limit cycles to 40% DoD or less. Lithium Ion used in high power applications is lucky to give you more than a couple hundred cycles before measurable capacity loss exists. A123 cells do better... maybe up to 500 cycles or more if used at reasonable currents and they are less effected by DoD. But I'm not ware of any battery tech that current can manage 1000s of cycles with no performance loss.

  I would  most current hybrid cars only get reasonable lifetimes because they treat the batteries very gently - i.e. only charging to 80% and not discharging below 20%.


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## Grisu (Jun 5, 2014)

The authors are quite skimpy on the details so it is unclear what DoD they used. The loss of capacity seems to be relatively linear meaning at 1000 cycles you are looking at maybe 10% to 20% capacity. A123 batteries, however, retain 65% capacity after 20,000 cycles at least in the lab. http://www.a123systems.com/Cycle-Life-Testing-The-Lithium-Ion-Battery-Ultramarathon.htm

Nevertheless, there are already better Li-S designs out there. Look at this one here:
"By charging the Li-S battery within the lower plateau capacity, high capacity and long cyclability with an ultra-low capacity degradation rate of 0.0011% per cycle (~0.53% for 500 cycles here)..."
http://www.nature.com/ncomms/2013/131218/ncomms3985/full/ncomms3985.html
The capacity is certainly also much better than standard lithium batteries. What they seem not to have tested is the self-discharge rate of their batteries.


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## begreen (Jun 5, 2014)

I note that zinc-air batteries are being used by some telcos and other commercial applications. Fluidic Energy and Eos are two manufacturers that have developed this type of battery with a high cycle-life.


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## jharkin (Jun 5, 2014)

Grisu said:


> The authors are quite skimpy on the details so it is unclear what DoD they used. The loss of capacity seems to be relatively linear meaning at 1000 cycles you are looking at maybe 10% to 20% capacity. A123 batteries, however, retain 65% capacity after 20,000 cycles at least in the lab. http://www.a123systems.com/Cycle-Life-Testing-The-Lithium-Ion-Battery-Ultramarathon.htm
> 
> Nevertheless, there are already better Li-S designs out there. Look at this one here:
> "By charging the Li-S battery within the lower plateau capacity, high capacity and long cyclability with an ultra-low capacity degradation rate of 0.0011% per cycle (~0.53% for 500 cycles here)..."
> ...




Interesting, my experience with a lot of this stuff is in hobby applications where we typically subject the batteries to 10-20C+ discharge rates. In those conditions even the A123s wont make a 1000 cycles and Ive seen cheap liPo's die in under 100 charges.  

I tend to forget that an electric car, even a very high performance electric car like the Tesla is positively babying the batteries compared to how with treat them in RC toys!


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## begreen (Jun 5, 2014)

Yes, Tesla, the Prius, Volt, etc. are quite conservative in the discharge limits for their batteries. This helps extend their lifespan considerably.


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## jharkin (Jun 5, 2014)

begreen said:


> Yes, Tesla, the Prius, Volt, etc. are quite conservative in the discharge limits for their batteries. This helps extend their lifespan considerably.



I was thinking not just DoD, but the rate.   Consider a Volt has a range of what, about 30-40 miles on battery?  Driving country roads thats about an hour of drive time or a 1C discharge.  The teslas big battery bank that can take you a couple hundred miles runs for a few hours so its only a fraction of a C.


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## begreen (Jun 5, 2014)

Not following. What is a 1C discharge?


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## BrotherBart (Jun 5, 2014)

begreen said:


> Not following. What is a 1C discharge?



http://batteryuniversity.com/learn/article/what_is_the_c_rate


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## jharkin (Jun 5, 2014)

begreen said:


> Not following. What is a 1C discharge?



In battery terminology C refers to the one hour discharge rate capacity of a battery.  So 1C is discharging in an hour, 2C is discharging at a rate that will drain the battery in 30 minutes, C/2 is the rate that will drain the battery in 2 hours,  and so forth.

For example a battery that's nominally 10amp-hours:

1C = 10amps
2C= 20 amps
10C = 100amps
C/10 = 1 amp
The reality is not always that simple though as published battery specs are not based on a 1 hour rate, and for most battery chemistries the usable capacity varies based on the discharge rate (more capacity the slower you discharge).  Deep cycle lead acid batteries specs are based on a C/20 rate.  NiCD and NiMH small rechargable batteries have the capacity typically rated at C/5. Lithium Ion varieties are usually rated at 1C.

Our hobby batteries for R/C helicopters planes and cars are run hard at rates up to 10, 20C  (5-6 minutes run time)  with bursts even higher. they tend to get very hot used this way, which is what kills the lifespan.


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## begreen (Jun 5, 2014)

So the C depends on the battery pack capacity? What about the discharge rate? Would the RC discharge rate be comparable to the maximum acceleration for a car? I would think an RC plane would put a much more rapid drain on the battery pack than say average driving.  If so, the numbers for the Volt or Tesla would not be much less than what one gets on average.


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## jharkin (Jun 6, 2014)

begreen said:


> So the C depends on the battery pack capacity? What about the discharge rate? Would the RC discharge rate be comparable to the maximum acceleration for a car? I would think an RC plane would put a much more rapid drain on the battery pack than say average driving.  If so, the numbers for the Volt or Tesla would not be much less than what one gets on average.



Yes exactly - the "C" rate is simply whatever load the battery can sustain for one hour from full charge to discharge (expressed in either watts or in amps @ the batteries nominal voltage).  All  batteries have more available total capacity at lower discharge rates than high rates because as you up the amperage the internal resistance of the battery causes more energy to be lost as heat.

This effect is very pronounced in lead acid and they have formulas to calculate the load at diffrerent rates with a constant called "pukerts constant" that gives you the ratio of amp rate to time.  If you take a typical deep cycle like for example a T6 golf cart battery, its "20 hour" capacity might be 200Ah (at 6v, so is ~ 1,200Wh).  So you can pull 10amps for 20 hours - stated as "C/20=10A".  But its 1 hour rate drops to less than 60% of that due to these losses so 1C capacity would be 120Ah, stated as "1C=120A"

Deep cycle discharge graphs usually look kinda like this (example is a nominal 100Ah 12v sealed AGM lead acid)




ref: http://www.solar-electric.com/lib/wind-sun/45978.pdf



Lithium Ion on the other hand doesn't loose as much capacity under heavy load, and the A123 cells (Lithium Iron Phoshate) are particularly strong.  My reference to a 500 cycle lifetime was from a test done by one of the hobby electronics companies that tested them at 2C-20C  rates



ref http://www.revolectrix.com/support_docs/item_1229.pdf

This test is a 2.3Ah nominal A123 cell (the "M1" 26650 cell developed for the first gen DeWalt LiIon cordless tools) discharged at rates from 4Amps ( 1.8C or 30 min) to 47Amps (20C or 3 minutes) Notice that the A123 discharged at a 20C still supplies 90% of its 1 hours rated capacity.  The cells that Grisu pointed out can go 20,000 cycles at 1C would start to degrade at around 500 cylces when used for high power at 12C, and as short as 230 cycles at 16C and only 40 cycles at 20C.   Note that in this tesing "end of life" is measured when the cell capacity falls to 80% of new - which is an industry standard -  so in this test even the life would be a bit longer if using the 60% spec from that A123 press release.

What they found in testing is that heat is the enemy of lifetime for the lithiums, the fast discharge rates would heat up the cells at the 10-12C rate point was an inflection point where cell temp goes over 140F during discharge and the life falls off steeply.


Going back to Lead Acid, lifetime is killed both by heat from fast discharges AND by deep discharges which cause irreversible sulfation of the lead plates. Again here is a typical lead acid life vs. DoD chart for a cheap deep cycle battery.  Higher end brands like those used in solar power systems can deliver greater lifespans.


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## woodgeek (Jun 6, 2014)

Cool Jeremy.

The Leaf, unlike other EVs does not have a thermal management system (i.e. active cooling) for the battery.  The possibility exists for overheating damage, if you go to high discharge rates at high ambient temps.....e.g. park it in the sun in Arizona for a few hours, and then drive it on the highway flat out at 75 mph, and then charge it at a 3C rate at a quickcharging station.  No bueno.

My 36k mile 3 year lease corresponds to about 1000 cycles to a 50% depth of discharge.

The on-board charger can be set to limit charging to 80% SOC, I will prob set mine that way for July and August, try to keep it parked in the shade, and skip the quick chargers.  My home charger is about C/4 in a 50-70°F garage.  

When are you going to get a BIG RC car you can ride in?


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## jharkin (Jun 6, 2014)

woodgeek said:


> When are you going to get a BIG RC car you can ride in?



hahaha geek.. not anytime soon it seems. I did a ton of reading and research and reading on all this stuff but it turns out, at least for RC toys, the amount of gear and equipment you need to run big ones electic (batteries, chargers, power supplies to run the chargers) is actually MORE expensive than just running the toys on gas directly. At RC meets you see guys with thousands of dollars into Honda generators, 1000+watt battery chargers and lithium packs the size of motorcycle batteries to power these things.. probably burning more gas then if they just bought a gas model to start with.  Plus inspite of my environmentalist streak I have to admit i'm still a closet  knuckledragger and like playing with old fashined gas engines - so I mostly stick to gas power.

I have been using A123 for all the onboard electronics and was researching deep cylces thinking about building a field power station, maybe with solar, to recharge the support gear at weekend events.

And on the cars.. after all our research and even looking at the accord hybrids we finally decided we needed utility more than anything (i odnt commute much anymore) and I ended up buying a gas guzzlin truck  I figure 5 years down the road or so we will probably pick up a hybrid something for DD and demote the truck to weekend warrior duty.


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