Posts Tagged‘battery’

Lithium-Air Batteries are the Future, Still Many Years Away.

There’s no question about it: batteries just haven’t kept pace with technological innovation. This isn’t for lack of trying however, it’s just that there’s no direct means to increasing energy densities like there is for increasing transistor count. So what we have are batteries that are mostly capable however have not seen rapid improvement as technology has rocketed away to new heights. There are however visions for the future of battery technology that, if they come to fruition, could see a revolution in battery capacity. The latest and greatest darling of the battery world is found in a technology called Lithium-Air, although it becoming a reality is likely decades away.

ambl012_fig_2Pretty much every battery in a smartphone is some variant of lithium-ion which provides a much higher energy density than most other rechargeable battery types. For the most part it works well however there are some downsides, like their tendency to explode and catch fire when damaged, which have prevented them from seeing widespread use in some industries. Compared to other energy dense mediums, like gasoline for example, lithium-ion is still some 20 times less dense. This is part of the reason why it has taken auto makers so long to start bringing out electric cars, they simply couldn’t store the required amount of energy to make them comparable to gasoline powered versions. Lithium-Air on the other hand could theoretically match gasoline’s energy density, the holy grail for battery technology.

Lithium-air relies on the oxidation (essentially rusting) of lithium in order to store and retrieve energy. This comes with a massive jump in density because, unlike other batteries, lithium-air doesn’t have to contain its oxidizing agent within the battery itself. Instead it simply draws it from the surrounding air, much like a traditional gasoline powered engine does. However such a design comes with numerous challenges which need to be addressed before a useable battery can be created. Most of the research is currently focused on developing a cathode (negative side) as that where the current limitations are.

That’s also where the latest round of lithium-air hype has come from.

The research out of Cambridge details a particularly novel chemical reaction which, theoretically, could be used in the creation of a lithium-air battery. The reaction was reversed and redone over 2000 times, showing that it has the potential to store and retrieve energy as you’d expect a battery to. However what they have not created, and this is something much of the coverage is getting wrong, is an actual lithium-air battery. What the scientists have found is a potential chemical reaction which could make up one of the cells of a lithium-air battery. The numerous other issues, like the fact their reaction only works in pure oxygen and not air, which limit the applicability of this reaction to real world use cases. I’m not saying they can’t be overcome but all these things need to be addressed before you can say you’ve created a useable battery.

Realistically that’s not any fault of the scientists though, just the reporting that’s surrounded it. To be sure their research furthers the field of lithium-air batteries and there’s a need for more of this kind of research if we ever want to actually start making these kinds of batteries. Breathless reporting of progressions in research as actual, consumer ready technology though doesn’t help and only serves to foster the sense that the next big thing is always “10 years away”. In this case we’re one step closer, but the light is at the end of a very long tunnel when it comes to a useable lithium-air battery.

Would You Pay $10,000 to Never Pay an Electricity Bill Again?

Make no mistake; renewables are the future of energy generation. Fossil fuels have helped spur centuries of human innovation that would have otherwise been impossible but they are a finite resource, one that’s taking an incredible toll on our planet. Connecting renewable sources to the current energy distribution grid only solves part of the problem as many renewables simply don’t generate power at all times of the day. However thanks to some recent product innovations this problem can be wholly alleviated and, most interestingly, at a cost that I’m sure many would be able to stomach should they never have to pay a power bill again.

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Thanks to the various solar incentive schemes that have run both here in Australia and other countries around the world the cost of solar photovoltaic panels has dropped considerably over the past decade. Where you used to be paying on the order of tens of dollars per kilowatt today you can easily source panels for under $1 per kilowatt with the installation cost not being much more than that. Thus what used to cost tens of thousands of dollars can now be had for a much more reasonable cost, something which I’m sure many would include in a new build without breaking a sweat.

The secret sauce to this however comes to us via Tesla.

Back in the early days of many renewable energy incentive programs (and for some lucky countries where this continues) the feed in tariffs were extremely generous, usually multiple times the price of a kilowatt consumed off a grid. This meant that most arrays would completely negate the energy usage of a house, even with only a short period of energy duration. However most of these programs have been phased out or reduced significantly and, for Australia at least, it is now preferable to use energy generated rather than to offset your grid consumption. However the majority of people with solar arrays aren’t using energy during peak times, significantly reducing their ROI. The Tesla Powerwall however shifts that dynamic drastically, allowing them to use their generated power when they most need it.

Your average Australian household uses around 16KW/h worth of electricity every day something which a 4KW photovoltaic system would be able to cover. To ensure that you had that amount of energy on tap at any given moment you’d probably want to invest in both a 10KW and 7KW Powerwall which could both be fully charged during an average day. The cost of such a system, after government rebates, would likely end up in the $10,000 region. Whilst such a system would likely still require a grid connection in order to smooth out the power requirements a little bit (and to sell off any additional energy generated during good days) the monthly power bill would all but disappear. Just going off my current usage the payback time for such a system is just on 6 years, much shorter than the lives of both the panels and the accompanying batteries.

I don’t know about you but that outlay seems like a no-brainer, especially for any newly built house. The cost of such a system is only going to go down with time as more consumers and companies increase their demand for panels and, hopefully, products like the Tesla Powerwall. Going off grid like this used to be in the realms of fantasy and conspiracy theorists but now the technology has been consumerised to the point where it will be soon available to anyone who wants it. If I was running a power company I’d be extremely worried as their industry is about to be heavily disrupted.

The Nikola Phone Case is Bunk.

I understand that a basic understanding of circuit fundamentals isn’t in the core curriculum for everyone but the lack of knowledge around some electrical phenomena really astounds me. Whilst most people understand the idea of radio waves, at least to the point of knowing that they power our wireless transmissions and that they can be blocked by stuff, many seem to overestimate the amount of power that these things carry. This misunderstanding is what has led several questionable Kickstarter campaigns to gain large amounts of funding, all on the back of faulty thinking that simply doesn’t line up with reality. The latest incarnation of this comes to us in the form of the Nikola Phone Case which purports to do things that are, simply, vastly overblown.

nikola phone caseThe Nikola Phone Case states that it’s able to harvest the energy that your phone “wastes” when it’s transmitting data using it’s wireless capabilities. They state that your phone uses a lot of power to transmit these signals and that only a fraction of these signals end up making their way to their destination. Their case taps into this wasted wireless signal and then captures it, stores it and then feeds it back into your phone to charge its battery. Whilst they’ve yet to provide any solid figures, those are forthcoming in the next couple weeks according to the comments section, they have a lovely little animated graph that shows one phone at 70% after 8 hours (with case) compared to the other at 30% (without case). Sounds pretty awesome right? Well like most things which harvest energy from the air it’s likely not going to be as effective as its creators are making out to be.

For starters the the idea hinges on tapping into the “wasted” energy  which implies that it doesn’t mess with the useful signal at all. Problem is there’s really no way to tell which is useful signal and which isn’t so, most likely, the case simply gets in the way of all signals. This would then lead to a reduction in signal strength across all radios which usually means that the handset would then attempt to boost the signal in order to improve reception, using more power in the process. The overall net effect of this would likely be either the same amount of battery life or worse, not the claimed significant increase.

There’s also the issue of battery drain for most smartphones devices not being primarily driven by the device’s radio. Today’s smartphones carry processors in them that are as powerful as some desktops were 10 years ago and thus draw an immense amount of power. Couple that with the large screens and the backlights that power them and you’ll often find that these things total up to much more battery usage than all of the radios do. Indeed if you’re on an Android device you can check this for yourself and you’ll likely find that the various apps running in the background are responsible for most of the battery usage, not your radio.

There’s nothing wrong with the Nikola Phone Case at a fundamental technological level, it will be able harvest RF energy and pump it back into your phone no problem, however the claims of massive increases in battery life will likely not pan out to be true. Like many similar devices that have come before it they’ve likely got far too excited about an effect that won’t be anywhere near as significant outside the lab. I’ll be more than happy to eat my words if they can give us an actual, factual demonstration of the technology under real world circumstances but until then I’ll sit on this side of the fence, waiting for evidence to change my mind.

Batteriser: It’ll Extend Battery Life, Just not as Much as Claimed.

Alkaline batteries are something that many of us have come to accept as a necessary evil. Either you pay up the premium price for the good batteries, and hope that their claims are as good as they say they are, or you risk it with a giant pack of cheap ones hoping that you don’t have to replace them every other week. They’re less of an issue now that decent rechargeables come as standard for many devices but I can count at least 4 devices in my living room still powered by these disposable power packs. I’ve heard all sorts of strange ways to extend the life of these things, from tapping them on something or warming them up in your hands, but none really provide a good solution. Batteriser purports to be able to squeeze up to 800% more life out of your alkaline cells, all by slipping on this thin metal sleeve.

batterizer_on_black-100588215-orig

All alkaline batteries start out their life providing a healthy 1.5v to the device they’re powering. As batteries become depleted however their output voltage begins to drop, slowly tapering down before dropping off a cliff depending on battery formulation. This is how all modern battery meters, including the one in your phone, work: by comparing the current output of the battery against its ideal voltage and then giving you an estimated amount of percentage left. Batteriser’s claim to fame is that, regardless of the current output of the battery, it will boost up the voltage to 1.5v making it appear “new” until all the chemical energy runs out. On the surface that might sound like some form of wizardry but it’s a well known circuit referred to as a Joule Thief.

Essentially the Batteriser device is a DC to DC converter, one that takes a wide range of input voltages and boosts them up to 1.5v. They’re coy on exactly how far down their converter can go but considering that most batteries become completely unusable past the 0.6v range my guess is that they don’t work past that. Their claim is that most devices will consider a battery dead below the 1.4v range which, if you take the rather gross assumption battery capacity decreases linearly as a function of voltage (which the graphs I liked to earlier clearly show is false), then they can provide almost 800% more life out of a single AA battery.

That claim, as you can probably guess, is well out of touch with reality.

This isn’t exactly a new and unknown phenomenon, it’s an inherent property of any kind of chemical battery that you’ll find on the market today. Developers of products that use alkaline batteries know this and will often include circuitry of this nature within them in order to make their devices last longer. Indeed it doesn’t take long to find numerous home made versions of such a device, albeit with far less slick packaging than what Batteriser is showing. So, if the claims in the patent match the final production device, it might be able to squeeze some more juice out of your batteries but I wouldn’t be surprised if the additional life you got wasn’t as great as they claim it is, especially for any modern portable device.

The real innovation here is the miniaturization of the whole package which, admittedly, is quite neat in its own right. However the claims they’re making are wildly out of alignment with reality, something which isn’t going to help their case when the eventual Indiegogo campaign hits. Still I’d be interested to see just how well it functions in the real world as even a simple doubling of battery life would likely be worth the asking price (currently $10 for 4 of them, reusable). At the very least it’s on the plausible side of these kinds of crowdfunded projects rather than being outright snake oil like we’ve seen so many times before.

Tesla’s Powerwall: Home Power Revolutionized.

The problem that most renewables face is that they don’t generate power constantly, requiring some kind of energy storage medium to provide power when its not generating. Batteries are the first thing that comes to everyone’s mind when looking for such a device however the ones used for most home power applications aren’t anymore advanced than your typical car battery. Other methods of storing power, like pumped hydro or compressed air, are woefully inefficient shedding much of the generated power away in waste heat or in the  process of converting it back to electricity when its needed. Many have tried to revolutionize this industry but few have made meaningful progress, that was until Tesla announced the Powerwall.

Tesla Powerwall

The Powerwall is an interesting device, essentially a 7KW (or 10KW, depending on your application) battery that mounts to your wall that can provide power to your house. Unlike traditional systems which were required to be constructed outside, due to the batteries producing hydrogen gas, the Powerwall can be mounted anywhere on your house. In a grid-connected scenario the Powerwall can store power during off-peak times and then release it during peak usage thereby reducing the cost of your energy consumption. The ideal scenario for it however is to be connected to a solar array on the roof, storing that energy for use later. All of this comes at the incredibly low price point of $3,000 for the 7KW model with the larger variant a mere $500 more. Suffice to say this product has the potential for some really revolutionary applications, not least of which is reducing our reliance on fossil fuel generated power.

The solar incentives that many countries have brought in over the last few years has seen an explosion in the number of houses with domestic solar arrays. This, in turn, has brought down the cost of getting solar installed to ridiculously low levels, even less than $1/watt installed in some cases. However with the end of the feed-in tariffs these panels are usually not economical with the feed-in rates usually below that of the retail rate. Using a Tesla Powerwall however would mean that this energy, which would otherwise be sold at a comparative loss, could be used when its needed. This would reduce the load on the grid whilst also improve the ROI of the panels and the Powerwall system, a win-win in anyone’s books.

It would be one thing if Tesla was just making another product however it seems that Elon Musk has a vision that extends far beyond just ripping the battery out of its cars and selling them as grid connected devices. The keynote speech he gave a few days ago is evidence of that and is worth the watch if you have the time:

In its current incarnation the Tesla Powerwall is a great device, one that will make energy storage feasible to a much wider consumer base. However I can’t help but feel that this is just Tesla’s beachhead into a much larger vision and that future revisions of the Powerwall product will likely bring even larger capacities for similar or lower prices. Indeed this is all coming to us before Tesla has completed their Gigafactory-1 which is predicted to reduce the cost of the batteries by some 30% with further iterations driving it down even more. Suffice to say I’m excited about this as it makes a fully renewable future not only inevitable, but tantalizingly close to reality.

The New Battery Tech Conundrum.

The batteries in our portable devices never seem to be big enough, in fact in some cases they seem to be getting worse. Gone are the days when forgetting to charge your phone for days at a time wasn’t an issue and you’ll be lucky to get a full day’s worth of use out of your laptop before it starts screaming to be plugged back into the wall. The cold hard fact of the matter is that storing electrical energy in a portable fashion is hard as energy density is often a function of surface area, meaning those lovely slim smartphones you love are at odds with increasing their battery life. Of course there are always improvements to be made however many breakthroughs in one aspect or another usually come at the cost of something else.

saupload_775px_supercapacitors_chart.svgTake for instance the latest announcement to come out of Stanford University which shows a battery that can be fully charged in under a minute and, if its creators are to be believed, replace the current battery tech that powers all our modern devices. Their battery is based on a technology called aluminium ion which works in a very similar way to the current lithium ion technology that’s behind most rechargeable devices. It’s hard to deny the list of advantages that their battery tech has: cheaper components, safer operation and, of course the fast charging times, however those advantages start to look a lot less appealing when you see the two disadvantages that they currently have to work past.

The voltage and energy density.

As the battery tech stands now the usable voltage the battery is able to put out is around 2 volts which is about half the voltage that most devices currently use. Sure you could get around this by using various tricks (DC step up converter, batteries in series, etc.) however these all reduce the efficiency of your battery and add complexity to the device you put them in. Thus if these kinds of batteries are going to be used as drop in replacements for the current lithium ion tech they’re going to have to work out how to up the voltage significantly without impacting heavily on the other aspects that make it desirable.

The latter problem is the more difficult one and is something that all new battery technology struggles with. With any battery tech you’re usually balancing quite a few factors in order to make the best tradeoffs for your particular use case however one of the most typical is between charge times and the amount of power you can store. In general the quicker your battery can charge the less dense it is energywise, meaning that fast charge time comes at the cost of usable life once it’s off the charger. Indeed this is exactly the issue that the new aluminium ion battery is struggling with as its current power density does not match that of lithium ion.

Now this isn’t to say that the idea is worthless, more that when you hear about these amazing kinds of batteries or supercapacitors (different kind of technology, but they’re an energy storage medium all the same) that have some kind of revolutionary property your first reaction should be to ask what the trade offs were. There’s a reason why sealed lead acid, nickel metal hydride and other seemingly ancient battery technologies are still used the world over; they’re perfect at doing the job they’ve found themselves in. Whilst charging your phone in a minute might be a great thing on paper if that came with a battery life that was a mere 20% of its long charging competitors I’m sure most people would choose the latter. Hopefully the researchers can overcome their current drawbacks to make something truly revolutionary but I’ll stay skeptical until proven otherwise.

 

The Intriguing Science Behind Bouncing Dead Batteries.

Everyone can relate to the frustration of having a drawer full of batteries that are in an unknown state of charge. For most people the only method they have to deduce whether they’re good or not is to try them out in a device, something that inevitably leads to frustration when your spares show up dead as well. The inclusion of battery testers on the batteries themselves (or in the packaging) seemed like a great idea however it never seemed to catch on presumably due to cost factors. Whilst geeks like myself might have a voltmeter handy to get accurate readings in an instant they’re not a ubiquitous device and an effective way of testing batteries still eludes most.

That is until they see this video:

Honestly when I saw this video I was pretty sceptical as the video, whilst highly informative, is anything but scientific. Instead of having 2 batteries from the same brand (and preferably from the same batch) for comparison the effect could be explained by differences in manufacturing between the two. I didn’t take the opportunity to test it myself however, even though I do have a drawer full of batteries that are all in unknown states, but after seeing this video parroted around various life hacking sites I figured that if it was total bunk someone would’ve called shenanigans. It seems that the video is accurate and the science behind why empty batteries bounce is very interesting.

It’s not, as many have speculated, related to a reduction in weight between a full battery and a discharged one. Batteries like this are a closed system, chemically speaking, so save for a few milligrams here and there due to handling or (more catastrophically) a breach in them batteries don’t change their weight. Instead it’s a quirk of the manufacturing process and the change in densities of the various materials inside the battery, all of which result in it becoming bouncy.

In a typical alkaline battery the chemical reaction that takes place to produce charge also results in the materials shrinking. The reason for this is that as the battery discharges oxygen molecules from the cathode (negative ) manganese oxide terminal migrate to the anode (positive) zinc anode, producing zinc oxide. When this occurs the total volume decreases as the oxygen atoms are able to pack themselves much tighter on the zinc oxide terminal than they can on the manganese oxide. This results in the internals shrinking somewhat and, as a consequence, tugs on the side of the pressure seal on the bottom of the battery. This causes it to bow outwards providing a spring like structure which results in the bounce when dropped.

Now I haven’t looked at a lot of batteries recently but I can image that some other designs might make this trick fail due to the design of the cathode terminal. This also means that the trick is probably unique to the cylinder style batteries (A, C, D, etc.) as whilst other types of batteries have similar chemical reactions their construction is vastly different. So I wouldn’t recommend dropping your car or latern batteries to try and test them out, lest you want to spend some time in the chemical burn ward and paying for a large chemical spill.