New batteries could make phones, drones, and electric cars last twice as long | Hacker News Reader

New batteries could make phones, drones, and electric cars last twice as long

news.mit.edu

171 pointsSergeAx107 comments

It seems like we're always hearing about the next big thing in battery technology, but they seem to stay in research forever, and never hit the consumer market.

The most exciting part of this, is that they say the'll be in consumer devices early 2017.

I'd love to have one in my quadcopter!

Progress in batteries has come a long way in the last 20 years. It's one of the reasons your quadcopter is even possible.

Do you know of anywhere that charts improvements in commercially available batteries? I have a similar impression to OP, but only based on anecdotes.

https://www.reddit.com/r/teslamotors/comments/29mxnz/the_pro...

"2010 (early) Max. capacity 2600mAh (This has existed before)

2011 (early) Max. capacity 2900mAh/3000mAh

2012 (early) Max. capacity 3100mAh

2012 (mid) Max. capacity 3400mAh

2013 (late) Max. capacity 3600mAh (Are not yet common)"

3600mAh is apparently still the max capacity available.

Battery capacity doubles every nine years.

I'm not narcissistic enough to give this "law" a name.

The opposite is also probably true. A battery technology that promises to double today's capacity is at least 9 years away from being commercially available.

Undoubtedly, but my impression is that it's been more of a gradual refinement of the same technology, rather than a sudden 2x improvement as claimed here.

Well, there have been clear technological jumps. I remember the time when the mainstream technology for electronic gadgets was NiCd. Then came NiMH -> Li-ion -> Li-Po. The differences are quite significant.

Li-Ion is nearly as old as NiMH. They coexisted for a long time, on very different price levels. When people think of battery progress, they usually just think of how LiIon got cheap enough for a use case that was on NiMH before. That certainly is also progress, but of a very differed kind than what they think it was.

I think it is clear progress if manufacturing becomes so much cheaper that the technology is actually available to more people.

It is progress, but because of the price-enabled technology switch, there are many misconceptions the kind of progress and its expected continuation. Outside of fixed installations, price only translates to capacity when there is a next level technology available at a higher price point. I don't see that now.

We might be left to forever squeeze out the last remaining bits of inefficiency from current technology (non-reacting mass fraction due to insufficient surface area per mass?)

Sure, of course. It's not like the amateurs used combustion engines in their flying models for decades.

Note that having a compressed energy ready for rapid release is exactly equal to handling an explosive in your laptop :)

There are a lot of experimental batteries that have like 5x capacity of the current Li-ion ones, but melt and explode when heated or crushed, which makes them effectively useless.

This is one of the hardest problems in high-capacity batteries - to avoid "rapid unscheduled heat dissipation" and the following "rapid unscheduled disassembly".

In that case, maybe what's actually needed is not battery capacity, but quicker and more convenient recharging systems?

Say solar, kinetic, or wireless charging stations spread throughout a city? Maybe incorporate some kind of "witricity" into the next WiFi proposal? If stuff can be recharged while it's being used, or within seconds, it shouldn't matter how much capacity the battery has.

..or an inherent groundstate failure mode?. I.e. the condition-based lowering of the activation energy of an endothermic crystalization. I don't know how feasible it would be though.

> but melt and explode when heated or crushed

But that’s exactly what Li-ion batteries already do. x)

What you really want to avoid is destroying non-rechargeable lithium manganese batteries, like a CR123. There are some true horror stories out there, like this one:

http://www.candlepowerforums.com/vb/showthread.php?120888-RO...

TL;DR: guy used stock flashlight with two stock CR123 batteries in series. One discharged faster than the other, so it got reverse charged from the one holding more charge, and promptly vented hydrogen gas that got ignited and blew up. Guy got glass and metal shrapnel damage to his foot, and hydrogen fluoride poisoning resulting in permanent lung damage and other bad symptoms. It's really horrible. Bad stuff starts at page 5.

https://www.youtube.com/watch?v=fG_UuPmLO1c

With nasty cough as a bonus

Wow, that was an incredibly unsafe thing to do. I guess I shouldn't be surprised that they weren't at least doing it outside, much less under a vent hood or at least wearing good masks.

Ok so that rules out phones, laptops and other devices that tend to get roughed up over time but I would still consider using it as energy storage for the solar panel on my house for instance.

As you have it isolated from the house in a specially built enclosure or garden shed it's less likely to get damaged and even if it is the damage can be manageable.

Then again in these cases it's more of a matter of how cheap it is vs the amount of energy it can hold and size doesn't matter a much.

Well, outside my house at a safe distance. But yes, better batteries as a utility company thing don't need to be as safe since they can be outdoors behind a fence like a propane tank.

For large stationary batteries the number of charge cycles you can get is a major factor.

Where weight and energy density is not a concern, you'd just use regular old-fashioned lead-acid. Lots of charge cycles, easily recycled, simple, no overheating, existing infrastructure.

When the Powerwall was announced, weren't people explaining one of the benefits over lead-acid based systems as you don't have to worry about accidentally generating noxious or explosive gases if the system isn't well vented? I just found something regarding that[1], but I'm unqualified to know how much of a problem this is in reality.

1: http://goodforgas.com/hazardous-gases-associated-lead-acid-b...

Also known as 'Engine rich exhaust'

Yeah, with the batteries becoming so powerful, I sometimes feel uneasy about having the equivalent of a hand grenade on my lap and the equivalent of a potent firework right by my ear as I make phone calls.

The videos of punctured lithium-ion batteries violently spewing smoke and flames is alarming.

Then there is Li-Po which can ignite if charged too much or if left to drain to low. I also suspect they'll burn if you give them a stern look or make a hurtful comment.

Yet you can take those on a plane but not a >100ml bottle of water.

> Note that having a compressed energy ready for rapid release is exactly equal to handling an explosive in your laptop :)

Animals can store a lot of energy, but they don't tend to explode with that energy when damaged. Are there techniques that could be learned from cells that could be used to make safer electrical batteries?

Fat does have much higher density of energy than Li-ion cell and it does not explode, but nobody seems to have figured out how to burn fat in closed space so that no exhausts are produced (there is always at least CO_2).

Yes, if we had all the "2x improvements" in batteries from press releases, batteries would be powering airliners by now.

"Yet just as safe and long-lasting as the lithium ion batteries used in consumer electronics" is not happy-making as energy density increases. The existing lithium-ion technology just barely keeps from overheating and blowing itself up, and it takes about six safety devices to prevent that. (Latest major hoverboard explosion story: [1] All those safety devices really are needed.) Lithium metal batteries (available now as non-rechargeable batteries) are even more dangerous, and are currently prohibited on US passenger-carrying aircraft. Lithium metal battery fires require a class D (flammable metal) fire extinguisher.

They're vague about the safety issue. "We're going to make the anode ultra-thin" is a concern. There are safer battery technologies, such as lithium iron phosphate. That won't run away thermally, and passes the "nail test", where a nail is driven through the battery. Less capacity than regular lithium ion, which is why it's not widely used, although you can buy such batteries commercially from A123. "Boosted" skateboards use them, because they don't blow up.

Solid Energy Systems, submit your cell for UL testing. Otherwise, lithium metal is, literally, not going fly.

Company website: [2]. Uses the common "all hype no info" template.

[1] http://wsvn.com/news/local/hoverboard-explosion-causes-house... [2] http://www.solidenergysystems.com/

Lithium-sulfur batteries look like the most possible candidate as the next incremental evolution of the lithium ion batteries. Lithium metal... not so much.

But I really hope for revolution in this space, rather than incremental changes. This will boost and give wings to so many other inventions.

Lithium-sulfur only works hot. It may be a great option for huge batteries connected to the power grid, but plugging a 200°C inflammable battery to your laptop might not increase its safety.

You must be talking about the flow version of lithium-sulfur. The ones with (presumably) graphite and cobalt oxide electrodes are going into e-scooters in China now [0]. However, they are yet far from the theoretical 2x in volumetric density of lithium-ion.

For a very good survey on the state of the art in lithium-sulfur look up this recent study [1].

[0] https://twitter.com/openbatt/status/766641735229464576

[1] http://doi.org/10.1039/C5CS00410A

> The existing lithium-ion technology just barely keeps from overheating and blowing itself up

This is somewhat due to the underlying technology, but more largely due to the prevalence of cheap counterfeits/knock offs scattered throughout the supply chain.

All sorts of problems with lithium-metal as we know it. A more benign version pitched by ZAF Energy is zinc-air. They inherit a few problems from pure metal electrodes (like dendrite growth) but not its thermal volatility. On the flipside, the performance increase will practically be not more than 2x that of lithium-ion.

ZAF had a very in-depth visit at Microsoft Research in June 2015. It is interesting to see the tribulations of a startup in commercializing technology that might become feasible but isn't quite yet and maybe never will. The 1h+ pre-sale meeting was taped [0] and I have an article in the writing about it [1].

[0] https://www.youtube.com/watch?v=xWwvHPaimlU

[1] https://docs.google.com/document/d/1R5gkh_A2vb6mDI5-e-EBlvP8...

Relevant xkcd: https://xkcd.com/678/

Once production at scale comes into play most of these "breakthroughs" result in sub 10% gains annually. But 5%-10% yearly battery progress compounds over decades to be gargantuan improvements.

Think of Rule 72, a 7.5% annual battery improvement rate compounds to a doubling every 9.6 years, which is amazing.

This one seems more plausible because it's not about making rechargeable batteries denser, it's making lithium-metal batteries rechargeable. We already know they can achieve this density.

Of all the great leaps in battery tech that keep on coming, this seems like one of the most promising because they were forced to learn to manufacture on real industrial equipment.

Most of the time these great battery breakthroughs go nowhere because they only manage to demonstrate with a tiny hand-built cell (often as not only presenting the result of the one cell that did finally work out of dozens of attempts), but there's no path to commercialisation.

If they really do ship usable batteries by november this could be huge.

I remember SolidEnergy. We discussed it here on HN before. It was one of the, if not the most promising companies to have made "battery breakthroughs", a few years ago. And they also seem to be launching right on time (I believe they promised a 2016-2017 release date a few years ago).

What's strange though is that Tesla always brags about how it has a list with "hundreds" of such battery breakthroughs, and that they know everyone in the industry working on new tech, but none was anywhere close to coming to market, which is why they chose to go with normal Li-Ion batteries for Gigafactory.

And now we have this announcement? Was SolidEnergy that secretive with their battery tech evolution or why would Musk keep saying that then? I would imagine SolidEnergy would kill for a deal with Tesla. So I wonder what else is going on. Perhaps the battery is 2x as dense, but 4x as expensive, making it not useful for Tesla cars anytime soon?

This tech will take at least a few years to reach the point where they can start supplying enough batteries that Tesla would need for its cars.

...or Musk saying "Lets make those in our Gigafactory instead".

You realize that Tesla is not making the batteries in the gigafactory. That'd be Panasonic.

It may have something to do with patents? Or maybe Tesla realizes making the cars is enough, leave the batteries up to others? Or, they have the market momentum now, so lets go for it, the world will bend to our will.

SolidEnergy is going to make its own batteries, so I meant why isn't Tesla buying their batteries instead of Panasonic's batteries? But my best guess is it has something to do with price per Kwh being much higher or simply not being confident in SE's ability to scale up to 50GWh per year in the next 2-3 years, which is what Tesla is going to need for the Model 3.

There are many import properties of battery, which I don't see mentioned. They talk only about energy density and safety.

- What is the Power Density? If it can only charge and discharge slowly, then your Tesla becomes slow and not fun to drive, and you can't fill it up quickly at a supercharger, or maybe even overnight at home.

- What is the longevity of the cell? How fast does it degrade with usage?

- What are the temperature effects on the cell? Will the cell require a new thermal management system to get full capacity, power, and longevity?

- What is the cost?

Is it the case that the research was publicly-funded, but the profits are now being privatized?

American government funded research that turns into a business creating jobs in America sounds like a reasonable outcome to me. After China stole solar, we need some other industry with growth potential.

Edit: Do the down voters care to comment? Anti-nationalism, anti-capitalism, or what?

I don't know why you're being down voted. It is in the public interest for businesses like these to prosper.

My conspiracy theory is that the comment swung from -4 to +4 as China went to sleep and the US arrived at work.

The issue is publicly founded research aleviate the burden of the investment from the private sector, while selling the right to the new technology to a sole private entity. The whole thing could, unless the government blocked it, be sold to a private chinese company down the line.

This is how the system has worked, quite well, for decades if not centuries. The short term profit motive prevents the vast majority of companies from carrying out basic research like this and without IP protections most won't risk investing into manufacturing infrastructure that will quickly be copied in lower cost jurisdictions. There is a lot wrong with our patent system but it does its job for the most part.

> The whole thing could, unless the government blocked it, be sold to a private chinese company down the line.

It wouldn't be the first battery company out of MIT to go that route. https://en.wikipedia.org/wiki/A123_Systems

If our trade policies assume a free market then we open the door to these situations. There's no free trade treaty to blame when China out maneuvers more developed countries like this. Perhaps the solution is to become more mercantilist instead of worshiping free markets.

The public funds things that result in private profits all the time. I.e. education, roads, etc. It's not really outrageous. It's the state's duty to provide a platform for its people to excel.

I was aware that public funds are sometimes spent on useful things. But is it right that the taxpayer absorbs the cost and risks of research, with the profits going into strictly private hands?

In theory, we would tax those profits to pull some of that value back to society, but anti-tax sentiment is so high in the USA that we don't really do that.

This has always been the case. Researchers are free to take the results of their publicly-funded research and run. The govt. sees it as a win-win.

It's money well spent because of the jobs created. Taxes from those jobs and profits from the corporations is the ROI.

Or the government could own the patent and licence it to american business and prevent rent seeking from the inventors.

It is the same income, but the outcome for the society is better I think. There will still be jobs created and corporate profits.

So we're taxed in order to generate more money in taxes... How is that a "return on investment"? When is the return, exactly?

And if you follow the logic about jobs, why doesn't the government (i.e. the taxpayer) fund every potentially profitable venture (without asking for any share of the rewards)?

I'm not saying that it's the best arrangement, but that's how it works now. Most university research are publicly funded via the National Science Foundation (NSF) and the National Institutes of Health (NIH).

So without such funding, most research will be grounded. Companies like Yahoo!, Google, Sun Microsystems (RIP), Akamai, etc, were/are the result of publicly-funded research.

Federal Acquisition Regulations govern the allocation of IP arising from many gov. funded activities. For the DOE, I believe the default is that the rights are assigned to the government, with a right to practice being retained by the recipient of funds. https://www.govregs.com/uscode/42/2182. That said, agencies will waive these rights in some cases.

The reason things are set up this way is that the government is great at funding long-term research, whereas industry is pretty terrible at it, for the most part. But then when it comes to making an invention actually useful to people and producing it at a reasonable price, the government is awful and industry is amazing.

Care to provide a single fact in support of those two amazing assertions?

On the research side, see things like the internet. Corporations, with rare exceptions like Bell Labs, don't fund research that has no clear commercial potential or that might but it would take decades to pay off.

On the production side, we have countless products like automobiles and smart phones that corporations have produced, but none from the government. The only semi-exception I can think of is the USSR turned out a lot of great military technology, but that was part of an arms race, not providing commercial products.

But you are familiar with these sorts of examples, yet you think my claim is all wrong. Is it because you have lots of specific examples, for research and also for production?

The answer here isn't batteries with more capacity. The answer is:

* more areas to lock your bike/scooter/moped (electric or otherwise)

* coin-/card-operated charging stations (as in, "plug in while you shop")

* charging stations where you work (to charge your EV during the day)

I don't think swappable battery stations would be useful, since batteries are damaged by deep-discharging them, and swap-stations would end up with too many damaged batteries that way.

As more people start using EVs, it will be a no-brainer for companies (or even local electric utility companies) to start placing EV charging stations all over town.

What's your market? If it's the US, there's certainly a need for longer travel distances between charging cycles. Most EV's don't have enough charge to allow for commuting to and from work yet. Especially when you factor in grabbing groceries, taking errands, or other things. I'm not sure what the right amount of range should be, but it feels like it needs to be around 150 miles or so to allow for a comfortable buffer.

Here's the census data from 2009 where they did a study on commuting in the US: https://www.census.gov/prod/2011pubs/acs-15.pdf It's pretty thorough.

Yes, the US.

My point is, you can either increase range by having better batteries, or you can do so by charging up while at your destination (ex., in your parking lot at work).

It gets even better if you're running errands and you've got a charging station at the grocery store, library, city hall, etc.

Having to rely on others to ensure you can get around causes a lot of anxiety. Also, it's probably a lot easier to get consumers to add chargers to their homes and automakers to extend the range of cars than to convince uninvested third parties to build out infrastructure.

> Having to rely on others to ensure you can get around causes a lot of anxiety.

I suppose. But as it stands I'm already relying on gas stations.

> Also, it's probably a lot easier to get consumers to add chargers to their homes {snip}

Sorry if I was unclear. I was assuming that as a given. If I've got an EV, it's going to be plugged into the charger at home every night.

> I don't think swappable battery stations would be useful, since batteries are damaged by deep-discharging them, and swap-stations would end up with too many damaged batteries that way.

That depends - just design a tamper evident battery that contains enough electronics so that when you swap it you pay for not just the power to recharge it, but also the damage you did by using it. So long as the fees are upfront and the devices using it will give me plenty of notice before expensive damage happens I'll be find paying for it.

If your swapable battery is just a bunch of batteries you have the risks you state. However it isn't that expensive to ensure that doesn't happen.

Could work, though I think it would add operational complexity ("hey, I paid to swap in good batteries, but these barely held a charge!").

I wonder if it's possible to have a battery go into a low-current mode when it gets down to $n percent charge ("Warning: time to recharge or swap! You have $x Amp-hours left! Going into econ mode."), then disconnect itself completely when down to $m (where $m < $n, and going lower than $m would significantly affect the life of the battery).

> Could work, though I think it would add operational complexity ("hey, I paid to swap in good batteries, but these barely held a charge!").

That is part of the business model: the batteries know how much charge they can take, so when one no longer has full capacity you sell it for less. Someone needs to work out what the price levels are so that people don't feel cheated, that is tricky math, but I think we know enough about battery life cycle (over different usage) to come up with something. It will probably be a multi-level thing, a "new battery" will be slightly more than a "slightly used" one, and have a longer safe range before they charge you abuse fees. A "new battery" that is never abused will after so many uses without abuse degrade to "slightly used", the users of it as "new" will pay for the normal wear and tear. If you are not trading in every time the battery needs charging you just pay a small monthly rental fee - if you never abuse your battery when it wears out you can trade in a "no longer usable battery" for a "new one" for just the normal trade in fee. If you abuse the battery you just pay for the actual costs that your abuse did to the battery.

It could work, the real trick isn't the technology (that is a simple computer watching the recharge and discharge rates). Even the business model isn't that complex (though the math is tricky). the hard part is convincing everyone to use your standard form factor for batteries. If every different car has a different battery in some way this will not work. It is only when you have one (or a few) models of battery that everyone has that this can work. There are only 3 grades of gasoline at the gas pump - if your engine would be fine on 60 octane gasoline (like my antique tractor) you just have pay for the more expensive 87 octane anyway. If your engine needs 100 octane (some race cars) - too bad you have to buy your own drum. The same way you need to ensure there is a one size fits all battery. (if you want more having two is an option)

If we can double battery life, hardware makers will double power usage. Phones are designed to last about a day on a full charge, and incremental battery improvement won't change that.

Good thing we have VR phones and 4k displays right around the corner to "take advantage" of this increase in battery capacity! Oh, and all the Pokemon Go-like games.

If battery life is really what people care about, even over features, then everbody would be using dumbphones instead of smartphones. So as much as people cynically complain about companies, battery life isn't what people value after all.

I don't see many people claiming they want battery life over features, generalized like that.

There are plenty of people claiming to want battery life over thickness. And I don't even think a 1 cm thick phone will sell - there's a limit in that.

Right. If you look at the sales of battery cases, you have an absolute minimum number of people who are willing to pay more and accept much more thickness for more battery life.

I'd be happy to buy a 50% thicker iPhone if it could handle a whole day of hard usage.

I don't think this is true. I've never been given a true option about batteries.

It's not like I get to choose two different versions of the same model of phone, where $a has a bigger battery, and $b has $feature. It's usually a funky mismatch between two different models, with different specs, some of which make it faster, and some of which have a bigger battery.

But I've never seen phones with a 1-to-1 comparison for batteries.

You mean like the Moto Z and the Z force? Z has a 2600mAh battery and is thinner. Z force has a 3500mAh battery for a 1.8mm addition of thickness. Motorola has done this before with the Droid Maxx.

Yeah, I'd love to have something like that for every phone. They aren't completely the same, but they are close enough for me. I don't think I've seen any other phone with a choice like that, though.

You can get extended battery packs for most phones with a removable battery. I had a Galaxy S2 a few years back that would last 4-5 days of moderate use on a charge with one of them, though it made the phone about 1.5cm thicker.

You are correct, but

A) I don't want to buy something to upgrade my phone. I'd rather it come like that in the first place.

B) Everyone says "nobody wants a bigger battery", but if everyone just buys them after the fact, how do the manufacturers know? Sounds like they are just passing the buck

C) Many phones don't have a removable battery, or it voids warranties to do so.

This looks great and with such an early release date it does seem the tech is not far away. Interesting that they are making the batteries and not licensing the tech considering it works with existing manufacturing technologies. I wonder how much extra cost if any for this increased energy density

I'm not in any way trying to undermine the research here, but I feel like it's a bit disingenuous to use the term "could" in your description.

Batteries are a difficult thing to engineer, and all this does is provide fodder for the 24-hour-news-cycle to give false hope.

Great, phones will be 2 times thinner /s

USB type C is identical from both sides, if we remove one side, it could be half thinner /s

And then one of the biggest selling points of USB type C is moot - namely its longitudinal symmetry, which allows to plug it in without caring about orientation.

Well, that was a practical joke for over 5 years with USB 2, and I do not find it so funny when plugging in my phone to the charger half sleep at 3 o'clock in the morning.

Actually, USB 2 is nice in one way, it makes it easier to explain half-spin particles in quantum mechanics. "Just like plugging in USB, you have to rotate more than 360° to get back to where you started."

After the umpteenth time of hearing that joke, it's still not funny, and it still makes half-integer spin seem more mysterious.

A much better analogy https://www.youtube.com/watch?v=QJRtxTyROOU

No, the next gen phones will need twice the power anyway, so no change in size.

They will probably have real-time rendered 3D graphics in the user interface, and more expensive signal processing of their sensors, because of higher resolution of the sensors (especially regarding the camera resolution). And more sensors in total.

> They will probably have real-time rendered 3D graphics in the user interface

They already do.

True anecdote from the early smartphone days: we were always having problems with rendering performance, but the next platform promised to have 4x faster CPU.

Later, it sunk in that the new screen had 5x as many pixels...

More about SolidEnergy, who is manufacturing these batteries: http://www.solidenergysystems.com/

What I find exciting about this is:

1. They were "forced to prototype on existing lithium ion manufacturing equipment". This brings them much closer to actual, scalable manufacturing.

2. Hu's ability to develop solutions when challenges arise. He figured out how to get the battery working at room temperature. He was able to adapt his approach to work on existing manufacturing equipment.

Hu sounds like a world class talent, and I admire his ability to overcome challenges. Here's hoping SolidEngergy succeeds!

I can already see Apple putting a battery 50% smaller and keep the same bad (according to my opinion) battery life of their iPhones in order to claim they have the thinner handset on the market.

Seriously, device thickness is for 2016 like camera megapixels was for 2006, it's totally unnecessary to keep pushing it and it hurts usability, yet, it looks good in the numbers you show the consumer, so companies keep doing it.

Yeah..."A novel electrolyte also keeps the battery from heating up and catching fire." We'll see how novel it is. I'll need a few cells, about 20min and a hammer as a literal smoke test at least

Quote: "That shrunk the battery size by half."

Nit-pick. To "shrink by half" would have the effect of doubling the size. Maybe he meant "to half the original", but surely not "by half."

This reminds me of the commonly heard "torn in half" when either "torn into halves" or "torn in two" is what's meant.

I'm glad that isn't the actual title, as that is truely bad.

Call me cynical, but I doubt the benefits of any such dramatic breakthrough would last long. As soon as the battery ability expands, the hardware and software will begin to expand their battery demands as well.

Maybe in software, but I doubt that the efficiency of motors in drones or cars would change. It's not like there are abstractions to chase in hardware, are there?

It will decrease. Making 99% efficient engine is order of magnitude more expensive than 90%. Double the battery density and suddenly the case for lighter and expensive parts disappears.

That wouldn't be decreasing, just increasing at a slower rate.

I can't wait until I can start downvoting stories on HN. Haven't we had this conversation here, over and over?

"Amazing New Battery will..."

Well actually...

Do this mean we can start making standalone smartwatches (that have GPS/LTE/Wifi) and go back to making 4" phones again?

iPhone 4s FTW.

http://www.johnsonbatterytech.com/

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