标签: battery

Recent teardowns I've written have highlighted the circuitry differences between hardware powered by batteries, therefore containing DC voltage regulation circuitry, and mains-powered equivalents containing more elaborate AC-DC converters. These discussions reminded me of a newly unveiled product, the Batteriser (here's the patent ), which was recently shown in AA-sized prototype form to a select set of journalists (yours truly not included, in the interest of full disclosure). The Batteriser is forecast to begin production-shipping in AA, AAA, C, and D cell-compatible form factors in late September, crowdfunded by an Indiegogo campaign . Founding company Batteroo's pitch is rich with intrigue and compelling claims: - Industrial espionage, - Up to 8x longer battery life - Products that "pay for themselves with the first set of revived batteries" And at minimum, the Batteriser, "crafted from stainless steel at 0.1 mm thin," represents an impressive Moore's Law case study of the now-possible extreme miniaturization of today's DC voltage boost and regulation capabilities. But what, if any, reality is there behind founder Bob Roohparvar's boasts? Plenty of detractors exist; see, for example, the commentary at Hackaday and Slashdot . Here are my thoughts. In his pitch to PC World's Jon Phillips , Roohparvar reportedly showed via a "power meter" that adding the Batteriser to an AA battery that had been drained to 1.3V restored the battery's like-new 1.5V output capabilities. I've no doubt that this is possible, but the "power meter" likely put a scant current demand on the setup. The Batteriser-boosted battery might not have fared nearly as well under more typical applications ("wireless keyboards, game console controllers, TV remotes, digital scales, blood pressure monitors, toys, and (of course) the ubiquitous flashlight"), especially when drained all the way down to 0.6V as Roohparvar suggests is feasible. Secondly, why couldn't the requisite boost and regulation circuitry alternatively be located within the powered device itself? In fact, as you likely already realize, it frequently is. Roohparvar happened to find a Bluetooth keyboard that wouldn't function reliably with 1.3V non-Batteriser'd AA power sources. But debunker Dave Jones , in spite of lots of searching, was unable to find an AA-based product that wouldn't work with batteries running at above 1.1V . And since battery discharge cycles are non-linear, that 1.1V level represents around 80% of a battery's full life. What about Batteroo's cost-savings claims? Each AA-sized Batteriser is forecast to cost $2.50; that's $10 for a four-pack, plus the prices of the batteries themselves. But I recently came across a 100-pack of alkaline AAs for $15 . Even if you buy into Roohparvar's pitch that a single Batteriser-enhanced AA can replace eight conventional counterparts, the comparative math just doesn't add up ... especially if, as Dave Jones claims, use of the Batteriser might lead to a short circuit-induced system fire . And what about Batteroo's advocacy about keeping an excessive drained-battery count out of landfills, which would normally resonate strongly with an avowed environmentalist such as me? Thankfully, batteries are no longer mercury-filled , although tossing them in the trash is still illegal in California. But why not instead invest in a set of NiMH rechargeables, which can be cycled thousands of times? Here, for example, is a g eneric twelve-pack of AAAs for $7.99 . And here's a brand-name twelve-pack of AAs for $14.99 . The charger's extra, of course, but the adder is scant; here's one for $12 that even comes with four AAs . At the end of the day, although I commend Batteroo on its miniaturization achievement, I struggle to find a strong commercialization market opportunity for it. And attempting to rationalize early-adopter's investments in your company by means of dubious-at-best claims is penny-wise, pound-foolish. But having said this, there may be some angle on the product that I've overlooked, which might lead me to a more positive opinion. If you see it, I'd like to hear about it. Please post your thoughts in the comments.     Brian Dipert is Editor-in-Chief of the Embedded Vision Alliance. He is also a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company's online newsletter. And he's an off-hours freelancer as the Principal at Sierra Media, where he contributes to (among other things) the Brian's Brain blog at EDN Magazine. Brian has a BSEE from Purdue University in West Lafayette, IN.

The increased interest in long-life embedded applications such as remote data logging or utility meters brings up the eternal engineering question: how are we going to power these devices? These devices should operate on a small battery for 10, 20, or more years without any attention, often under difficult environmental conditions.   For shorter-life installations on the order of a few years, the battery decision analysis begins with some basic analysis of the current drain on the battery under various duty cycles and operational modes compared to the energy capacity of the battery (mA-hour). This can get fairly involved for applications with complicated operational cycles, but it's not too hard to at least put an upper-bound, worst-case number on requirements. However, when you need to run for a decade or more, the basic electrical analysis of load current and power versus capacity is only a small factor. Issues such as self-discharge, chemical deterioration and enclosure corrosion become major concerns.   Which is why I was intrigued when I read “Designing and Fabricating a Multiple-Decade Battery in Aerospace Defense Technology. The article detailed a thermoelectric generator (TEG) based on radioactive decay that could run for 150 years, in theory. The architecture used a two-step process which I had not read about before, where the decay generates light, and then that light generates power via photovoltaic cells. The authors allude to the low efficiency, but unfortunately give no numbers, although I suspect it is in the 5% range.   Behind this deceptively simple symbol is a complex world of electrochemical and even radioactive activity.   TEGs powered by radioactive decay have been used successfully for decades, especially for deep-space vehicles where solar radiation is minimal. These TEGs use a single-stage conversion process based on heat of radioactive decay rather than the photons of the two-step process, with Seebeck-junction thermocouples to generate the electrical power from the decay's heat.   This approach powers the Voyager 1 and 2 craft launched in 1977, which are still traveling and sending back data even as they have crossed the vague border of our solar system into exospace. (For a fascinating book on these spacecraft, see "Voyager: seeking newer worlds in the third great age of discovery" by Stephen J. Pyne; and note that their extraordinary journey was made conceivable by the space-mechanics insight of a graduate student working on his own.) There's some also work being done to use thermocouples to capture waste heat from engines, but how practical they will be (cost, reliability, size, efficiency) is still unclear.   Of course, you can theoretically make a decay-based battery last as long as needed by using more of the core material. The question is how long the rest of the assembly and electronics will last under the application's operating conditions before it deteriorates and falls apart, unrelated to the radioactive-decay mechanism itself. But, hey, if the battery doesn’t meet last 100+ years, no one from today will around from today to criticize the work?   I also saw two other articles on long-life batteries, albeit on "only" a few decades. “Choosing the Right Batteries for High-Tech Batteries" from NASA Tech Briefs looked at the attributes of various chemistries, and especially the many interesting sub-varieties of the lithium-battery family. In a word: it’s complicated. When you need a few decades of use, even at very low current levels or low-rate pulsed duty cycles, there are many factors which come into the analysis such as self-discharge and temperature ratings. The mA-Hr capacity becomes only one of many parameters to consider.   While the author of this article is from a leading vendor of such batteries (Tadiran) and perhaps has some bias, I'd rather hear from someone who has real units out in the field and a track record, and who has dealt with subtle manufacturing and production issues, rather than just an academic expert. The same vendor also had a piece "Power Your Wireless Sensors for 40 Years" which had some overlap with the previous piece, but added new information as well.   Are you involved in decisions for long-life battery selection? How do you assess basic capacity needed with complex operational cycles? How do you decide on the long-life chemistry and form factor that will work?

Over time, I have developed a horror of replaceable, single-use batteries. I'm not particularly a greenie, but it just seems to be an incredible waste when rechargeable batteries are available. The LED torches you get these days are much more efficient battery users, but when I saw these LED torches in a local store for only $5 and bought a few, I still wanted to make them rechargeable, off a 12 V supply.   They use the square 6 V lantern batteries with the springs on the top. You do see rechargeable ones, but they're hellishly expensive. I'd picked up a box of these boards that someone was chucking out. Each board had five rectangular 400 mAH NiCd cells, a PCB, and some components. I'd removed and used some of the batteries in other projects. Those batteries were made by Sanyo and if there's one thing Sanyo do well, it is make rechargeable batteries. But could I use them for this project?   I took apart an old lantern battery to see what I could do with it. It had four compartments with one large zinc-carbon cell in each, each of which I removed. But if I removed two of the dividers, my Sanyo NiCds just fitted lengthways into the larger compartment. By forming them into 6 V packs consisting of three cells on top of each other and two vertically, I found I could fit 10 of my packs into a modified empty lantern cell case. That's 4 AH of battery, albeit in small chunks. The remaining space in the top of the battery pack was minimal. But I love challenges like this...   I decided I wanted the sharing components and a charging circuit inside the battery. Sharing is easy. Each battery pack had the negative terminals tied together, and a Schottky diode (to minimise voltage drop) from its positive terminal onto the common positive terminal. For charging, I worked on the principle that when it is charged, a NiCd will approach 1.5 V per cell. I used a 7809 regulator to give a 9 V supply, with a standard diode (0.6 V drop) and a 33-Ω resistor in series to each battery pack. If the cell is at 1.5 V, the charge current will be (9 – 0.6 – (5 x 1.5)) / 33 = 0.9 V / 33 Ω = 27 mA, well below the 1/10 C – 40 mA in this case—that is safe for trickle-charging a NiCd. If the battery is discharged, say at 6 V, the current would be larger, around 72 mA. The result was a fast initial charge tapering off to a low rate, which is safe if you leave it on for days. Since the battery packs had the Schottky diodes going to the main positive terminal, I thought I could use the positive terminal for charging as well. This was my circuit:   The small space left inside the top of the battery meant I'd have to use surface-mount components, something I'd never done before. More challenge. I got some SMD diodes, resistors, and regulators really cheap off Element 14's bargain pages and designed a PCB around them. The battery springs were mounted to the case with rivets. I drilled these out and used small bolts and nuts to connect them to—and securely mount—my PCB. I had a fair bit of PCB real estate available due to the small size of my SMD components, so I used some for a heat sink for my regulator.   Everything just fit inside the battery case. I used a couple of layers of plastic to separate the batteries from the PCB. The components were on the other side from the batteries but the bolt heads protruded through. I did not want any shorts. The torches worked well. I get a good few hours of light out of them on a fully charged battery. I did find a couple of minor problems: * The battery is not short-circuit proof. I did inadvertently short one once. It blew a PCB track under a diode, but no components. I have since modified the PCB to have a constriction in the main track away from any diodes, so if it does blow it will blow there, where it's at least accessible. * The batteries showed a far higher than expected self-discharge rate. Although there are diodes that stop the individual batteries discharging into the regulator, I failed to notice that the main common positive line goes, through a diode, to the regulator input. The 7809 regulator will not work with 6 V going into it, but it will draw a quiescent current. I kind of like it when this happens. It shows me that I'm not as smart as I think I am... * Fortunately I included a link on the board (LK1 In the schematic) so that the 12 V charging source can be connected separately. I opened the link and took a wire outside the battery. I could take this to a socket, but will probably put a couple of contacts on the body of the torches and build a charging bay for them. * When the batteries are very flat, the regulator tends not to give the full 9 V out. I found this was due to my regulators being the M type, which limit at 500 ma, though this wasn't stated when I bought them. It's not a problem, since it only limits the charge current delivered to a flat battery pack and as it charges the regulator very soon starts regulating correctly again. These batteries were not rated for fast charging, so this limit is probably a good thing! All in all... Cost: Less than $10 per torch. Running cost: almost nothing. Satisfaction: Priceless! Don Tavidash s ubmitted this article as part of Frankenstein's Fix, a design contest hosted by EE Times (US).  

We are aware that battery capability, which is primarily defined using energy density by volume and by weight, is a criucial factor in determining what we can expect of the units they power. Pundits at all levels of technical knowledge from near-zero to quite advanced keep reminding us of this obvious fact, and then opine on what they think will or should happen next. In many cases, these writers have an agenda (of course, a common one is "send us more grant money and funding so we can finish the job"), so it's hard to separate facts from hopes and wishful thinking.   That's why I was impressed by a recent article in The Wall Street Journal, " Tech World Vexed by Slow Progress on Batteries ," which I thought was one of the best and clearest assessments of the present status of battery technology and advances I have seen. The article made two points:   There have been significant advances in the last few years that have made many products practical, including smart phones and battery-powered tools. (The author cites specific examples.) Although each advance may have been modest in itself, they do add up to a genuine and substantial increase in performance metrics. The much-vaunted "breakthrough" that everyone wants, hopes for, or claims they are "this close" to, just isn't in sight. When you step back and look at the bigger picture, there's certainly been progress, but it has been in incremental layers, not major leaps. The breakthrough to allow practical batteries that are much, much lighter in weight, denser in capacity, and lower in cost (hopefully, all at the same time) is not just around the corner. It seems that we are bombarded with researchers claiming that they on the path for the breakthrough, but that hasn't materialized when you peel back the hype.   The supposed imminent "quantum leaps" (a very misused phrase) are really just modest advances of varying degrees, not game changers or "paradigm shifts," to use another cliché. Further, translating even a modest prototype battery improvement into actual volume manufacturing and OEM adoption is a long-term undertaking -- on the order of ten years or more. Regardless of the technology or chemistry you have, battery manufacturing is a very capital- , materials-, and production-intensive process.   There's another problem with supposed breakthroughs: You can only recognize them in retrospect, so you need the perspective of hindsight. It's like peak detection, in that you can only determine that you have had a peak after it has passed. Breakthroughs are very hard, if not impossible, to see as they approach or even as they happen, and it is even harder to see how they will really unfold. Consider these major breakthroughs in our industry: The transistor (1947) was demonstrated as an analog amplifier. Its role as a digital-switching building block was not really foreseen. The integrated circuit (1958) was an analog audio oscillator. The impact of large-scale integration for digital functions was not apparent. The laser (1960) was called "a solution in search of problems to solve" by observers. We know how that situation turned out!   While there may be a genuine order-of-magnitude battery breakthrough at some point, perhaps it will have an underlying principle that is fundamentally different from the electrochemical devices we now know as batteries. Maybe there will be a mini-fusion device (no, not the discredited cold fusion), something using an electrochemical basis quite different from what we know of, or even a device with a non-chemical basis for an entirely new type of battery.   After all, it's naive to think that we already are aware of all the basic processes that can happen at the molecular level and just have to work harder and smarter with them. The history of advances in science and engineering has many examples of cases where everything was presumed to be known, except that it wasn't. (See the insightful but very densely written classic The Structure of Scientific Revolutions by T.S. Kuhn, or at least get a readable summary of it.) There have been times where disparate advances come together in ways no one anticipated. (See the series Connections by James Burke.)   What's your assessment of the true state of battery technology advances and hype-versus-hope reality?

I have developed a horror of replaceable, single-use batteries over the years. I'm not particularly a greenie, but it just seems to be an incredible waste when rechargeable batteries are available. The LED torches you get these days are much more efficient battery users, but when I saw these LED torches in a local store for only $5 and bought a few, I still wanted to make them rechargeable, off a 12 V supply.   They use the square 6 V lantern batteries with the springs on the top. You do see rechargeable ones, but they're hellishly expensive. I'd picked up a box of these boards that someone was chucking out. Each board had five rectangular 400 mAH NiCd cells, a PCB, and some components. I'd removed and used some of the batteries in other projects. Those batteries were made by Sanyo and if there's one thing Sanyo do well, it is make rechargeable batteries. But could I use them for this project?   I took apart an old lantern battery to see what I could do with it. It had four compartments with one large zinc-carbon cell in each, each of which I removed. But if I removed two of the dividers, my Sanyo NiCds just fitted lengthways into the larger compartment. By forming them into 6 V packs consisting of three cells on top of each other and two vertically, I found I could fit 10 of my packs into a modified empty lantern cell case. That's 4 AH of battery, albeit in small chunks. The remaining space in the top of the battery pack was minimal. But I love challenges like this...   I decided I wanted the sharing components and a charging circuit inside the battery. Sharing is easy. Each battery pack had the negative terminals tied together, and a Schottky diode (to minimise voltage drop) from its positive terminal onto the common positive terminal. For charging, I worked on the principle that when it is charged, a NiCd will approach 1.5 V per cell. I used a 7809 regulator to give a 9 V supply, with a standard diode (0.6 V drop) and a 33-Ω resistor in series to each battery pack. If the cell is at 1.5 V, the charge current will be (9 – 0.6 – (5 x 1.5)) / 33 = 0.9 V / 33 Ω = 27 mA, well below the 1/10 C – 40 mA in this case—that is safe for trickle-charging a NiCd. If the battery is discharged, say at 6 V, the current would be larger, around 72 mA. The result was a fast initial charge tapering off to a low rate, which is safe if you leave it on for days. Since the battery packs had the Schottky diodes going to the main positive terminal, I thought I could use the positive terminal for charging as well. This was my circuit:   The small space left inside the top of the battery meant I'd have to use surface-mount components, something I'd never done before. More challenge. I got some SMD diodes, resistors, and regulators really cheap off Element 14's bargain pages and designed a PCB around them. The battery springs were mounted to the case with rivets. I drilled these out and used small bolts and nuts to connect them to—and securely mount—my PCB. I had a fair bit of PCB real estate available due to the small size of my SMD components, so I used some for a heat sink for my regulator.   Everything just fit inside the battery case. I used a couple of layers of plastic to separate the batteries from the PCB. The components were on the other side from the batteries but the bolt heads protruded through. I did not want any shorts. The torches worked well. I get a good few hours of light out of them on a fully charged battery. I did find a couple of minor problems: * The battery is not short-circuit proof. I did inadvertently short one once. It blew a PCB track under a diode, but no components. I have since modified the PCB to have a constriction in the main track away from any diodes, so if it does blow it will blow there, where it's at least accessible. * The batteries showed a far higher than expected self-discharge rate. Although there are diodes that stop the individual batteries discharging into the regulator, I failed to notice that the main common positive line goes, through a diode, to the regulator input. The 7809 regulator will not work with 6 V going into it, but it will draw a quiescent current. I kind of like it when this happens. It shows me that I'm not as smart as I think I am... * Fortunately I included a link on the board (LK1 In the schematic) so that the 12 V charging source can be connected separately. I opened the link and took a wire outside the battery. I could take this to a socket, but will probably put a couple of contacts on the body of the torches and build a charging bay for them. * When the batteries are very flat, the regulator tends not to give the full 9 V out. I found this was due to my regulators being the M type, which limit at 500 ma, though this wasn't stated when I bought them. It's not a problem, since it only limits the charge current delivered to a flat battery pack and as it charges the regulator very soon starts regulating correctly again. These batteries were not rated for fast charging, so this limit is probably a good thing! All in all... Cost: Less than $10 per torch. Running cost: almost nothing. Satisfaction: Priceless! Don Tavidash s ubmitted this article as part of Frankenstein's Fix, a design contest hosted by EE Times (US).