Samsung recall: Tech solutions to enhance lithium-ion battery safety | EDN

http://www.edn.com/design/power-management/4442706/Samsung-recall–Some-possible-tech-solutions-to-enhance-lithium-ion-battery-safety-

Exploding lithiun batteries are in headlines every now and then. How they can be made safer?

115 Comments

  1. Tomi Engdahl says:

    Making sense of complex global lithium-ion battery regulations
    http://www.edn.com/design/power-management/4458542/Making-sense-of-complex-global-lithium-ion-battery-regulations

    Unfortunately, lithium batteries have made major headlines in past two decades regarding safety. Many of these incidents have caused billions of dollars in brand and property damage. Some incidents have also caused deaths and severe injuries. Some of the most notable incidents include the following:

    UPS Cargo Airline Flight 6 crashed and killed both pilots in 2010; the root cause was traced to lithium-ion batteries in the cargo hold.
    Sony batteries used primarily in Dell laptops started catching fire in 2006; the root cause was traced to bad impurities within the cell causing a short (over 9 million batteries were recalled)
    Boeing Dreamliners were grounded due to battery fires in 2013; the root cause was an internal short in the cell (over $600 million of damage for Boeing)
    Samsung Note 7 batteries started catching fire in 2016; multiple root causes traced to cell manufacturing and multiple injuries reported. Samsung took a loss of over $5 billion due to the recall.

    These examples just highlight some of the incidents with lithium-ion batteries and the potential damage it could do. Due to its volatile nature, many organizations/countries have put regulations in place to ensure the batteries they are getting are safe. We will look into which battery regulations your battery may need and what they entail.

    Which regulations do you need?

    In order to determine which regulations your rechargeable lithium ion battery solution may need, you need to ask yourself some questions. Are you going be shipping batteries by themselves? 99% of the time, the answer will be yes. And if yes, then you will need to perform UN 38.3 testing (see transportation regulations section.) Next, are you going to be shipping battery products into Europe (EU)? If yes, then you will need to do IEC 62133 (see international regulations). Is your battery going to be used in a device that complies to a UL end device spec that calls for the battery to be UL certified? If yes, then you will need to do UL2054 (see US safety regulations). Is your battery going to be shipped to China, Russia, Thailand, India, Korea, or Japan? If yes, then additional testing is needed and is specific to the country (see other regulations).

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  2. Tomi Engdahl says:

    Samsung recall analysis: form factors and battery reliability
    http://www.edn.com/electronics-blogs/brians-brain/4458618/Samsung-recall-analysis–form-factors-and-battery-reliability

    Back in early January, EDN published my missive about the recent battery failure-induced recall of Samsung’s just-introduced Galaxy Note 7 “phablet.” At the time, the root cause(s) of the thermal runaway-categorized battery breakdowns had not yet been officially announced, but later that same month, Samsung revealed the results of its in-depth laboratory tests, which were eventually able to replicate field failures.

    As mentioned in my earlier writeup, Samsung initially used two different battery suppliers for the Galaxy Note 7, its own Samsung SDI subsidiary, along with an independent company called ATL.

    The two different batteries, according to Samsung, had two different associated failure mechanisms.

    For the first battery, Samsung says a design flaw in the upper right corner of the battery made the electrodes prone to bend and, in some cases, led to a breakdown in the separation between positive and negative tabs, causing a short circuit.

    Samsung believes there was nothing wrong with the design itself, but says a manufacturing issue led to a welding defect that prompted that battery to also short circuit and ignite.

    “We believe if not for that manufacturing issue on the ramp [of battery B], the Note 7 would still be on the market,” Samsung Electronics America head Tim Baxter told Recode.

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  3. Tomi Engdahl says:

    Samsung’s new eight-step battery safety check includes: durability testing, visual inspection, X-rays, charge and discharge tests, tests of total volatile organic compounds (TVOC), disassembling tests, accelerated usage tests, and open circuit voltage tests.

    Source: http://www.edn.com/electronics-blogs/brians-brain/4458618/Samsung-recall-analysis–form-factors-and-battery-reliability

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  4. Tomi Engdahl says:

    Chaim Gartenberg / The Verge:
    iFixit teardown confirms Note 7 Fan Edition is just a Note 7 with a new, smaller battery — Like a phoenix from the ashes, Samsung’s ill-fated Galaxy Note 7 has emerged from the fires of its battery woes reborn as the Samsung Galaxy Note 7 Fan Edition, a refurbished Note 7 that, hopefully, won’t explode.

    iFixit teardown confirms Note 7 Fan Edition is just a Note 7 with a new, smaller battery
    https://www.theverge.com/circuitbreaker/2017/7/13/15967474/samsung-galaxy-note-7-fan-edition-ifixit-teardown-smaller-battery

    Like a phoenix from the ashes, Samsung’s ill-fated Galaxy Note 7 has emerged from the fires of its battery woes reborn as the Samsung Galaxy Note 7 Fan Edition, a refurbished Note 7 that, hopefully, won’t explode. Samsung announced that it’d be using some original Galaxy Note 7 parts in the Fan Edition back when it was first announced, but it was unclear what that balance would be between old and new parts.

    Fortunately, iFixit has performed its traditional teardown of the resurrected phablet and confirmed that the answer to the question of “how much of Fan Edition is the same as an original Note 7?” is “Virtually all of it.” The biggest difference is perhaps the most crucial, though: the Fan Edition has a battery that’s roughly 9 percent smaller, offering 12.32 Wh of charge to the original Note 7’s 13.48 Wh battery.

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  5. Tomi Engdahl says:

    Freezing Plus Phase Change May Yield Safer, Flexible Lithium Batteries
    http://www.powerelectronics.com/batteries/freezing-plus-phase-change-may-yield-safer-flexible-lithium-batteries?NL=ED-003&Issue=ED-003_20170814_ED-003_790&sfvc4enews=42&cl=article_2_b&utm_rid=CPG05000002750211&utm_campaign=12477&utm_medium=email&elq2=b814c260429342f7b2d1c16c6db3afef

    The dangers associated with lithium-based batteries are well-known to designers. Any inconsistencies in the manufacturing process, mismanagement during charging/discharging cycles, or improperly managed thermal issues can cause fire and even explosion. It comes as no surprise, then, that the search for a safer way to build these high-density, lightweight, electrochemical energy-storage components has attracted significant attention.

    A four-person team at Columbia University’s Fu Foundation School of Engineering and Applied Science developed a technique that may offer a viable approach to a better electrolyte and, by extension, batteries.1,2 By controlling the structure of the solid lithium electrolyte, they developed a solid electrolyte that’s safer, non-flammable, and non-toxic, thus avoiding the concerns associated with liquid electrolytes.

    Creation of the electrolyte is based on lithium-aluminum-titanium-phosphate Li1+xAlxTi2-x(PO4)3 nanoparticles (LATP NPs), which are processed with other chemicals to form a ceramic precipitate.

    A new “ice templating” technique allows formation of a solid, ceramic-based, polymer lithium electrolyte for batteries with straight channels for improved conductivity, energy density, and flexibility.

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  6. Tomi Engdahl says:

    Samsung Galaxy Note 4 Batteries Are Being Recalled For Overheating Risk
    https://hardware.slashdot.org/story/17/08/16/2010201/samsung-galaxy-note-4-batteries-are-being-recalled-for-overheating-risk

    According to The Verge, over 10,000 batteries for the Galaxy Note 4 are being recalled for risk of overheating that could lead to burns or fires. Given last year’s Note 7 fiasco, this recall sure doesn’t sound good. It is, however, far more limited than the Note 7 recall and doesn’t appear to be Samsung’s fault.

    “FedEx Supply Chain is conducting this recall of non-genuine Samsung batteries as some of them are counterfeit,” the spokesperson said.

    Galaxy Note 4 batteries are being recalled for overheating risk
    https://www.theverge.com/2017/8/16/16156934/galaxy-note-4-battery-recall-att-fedex

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  7. Tomi Engdahl says:

    Keeping it safe: The lithium-ion battery
    http://www.edn.com/design/power-management/4458808/Keeping-it-safe–The-lithium-ion-battery

    As lithium ion batteries are becoming more and more prevalent in all of our electronics, there is a lot of circuitry that is keeping them from exploding. This article will pick-up from the introductory article, Making sense of complex global lithium-ion battery regulations, and go into detail of how the circuitry works inside a lithium-ion battery to keep it safe. We will discuss the numerous protection architectures out there and pros and cons of it.

    Electronics

    Although lithium-ion chemistry has many advantages over other cell chemistries, the biggest drawback is its safety performance. A lithium-ion cell can create a thermal event if not used properly. Robust electronics and fusing needs to be incorporated in the battery design to ensure that it is being operated within safe operating conditions.

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  8. Tomi Engdahl says:

    The Science Behind Lithium Cell Characteristics and Safety
    https://hackaday.com/2017/09/18/the-science-behind-lithium-cell-characteristics-and-safety/

    To describe the constraints on developing consumer battery technology as ‘challenging’ is an enormous understatement. The ideal rechargeable battery has conflicting properties – it has to store large amounts of energy, safely release or absorb large amounts of it on demand, and must be unable to release that energy upon failure. It also has to be cheap, nontoxic, lightweight, and scalable.

    As a result, consumer battery technologies represent a compromise between competing goals. Modern rechargeable lithium batteries are no exception, although overall they are a marvel of engineering. Mobile technology would not be anywhere near as good as it is today without them. We’re not saying you cannot have cellphones based on lead-acid batteries (in fact the Motorola 2600 ‘Bag Phone’ was one), but you had better have large pockets. Also a stout belt or… some type of harness? It turns out lead is heavy.

    Rechargeable lithium cells have evolved tremendously over the years since their commercial release in 1991.

    two approaches, lithium-ion (Li-ion) and lithium-polymer (Li-Po) cells were developed

    Despite a large number of chemistries, lithium batters still have several parameters in common that are very relevant to using them safely and effectively in our projects.

    C-rate: This determines how quickly you can draw or store current. It is a simple multiplier – a cell with a C-rate of 2 can tolerate a discharge rate twice of that listed as the capacity. For example, in a 200 mAh cell, this means you could safely draw up to 400 mA.

    It’s worth noting that the C-rate to charge lithium cells is typically significantly lower than the discharging rate (although it depends on the exact chemistry used, some are much faster than others).

    Undervoltage: We’re told not to let the voltage of lithium cells drop below a given voltage (varies by cell type but often around 3 volts). This is unfortunate because we’re often ‘gifted’ dead lithium cells registering a low voltage that would be nice to use again, for example in a new flashlight. Even though they may charge again, it’s not a good idea to do so.

    It turns out that copper foil is generally used in the cells as a current collector. When the voltage drops below a certain threshold, some of the copper in the negative electrode starts to dissolve and migrate. When you then recharge the cell in question, it forms dendrites of elemental copper somewhere they shouldn’t be.

    Some (but not all) types of lithium cell have a built-in circuit that permanently disables the cell if the voltage drops too low, as a consumer safety feature. Cylindrical lithium cells such as the 18650 are more likely to contain this type of circuit than pouch cells.

    Overvoltage: Cells can also be damaged if charged to too high a voltage. The reactions that occur depend on the exact cell chemistry, but a common one is the plating of solid lithium metal on the negative electrode, resulting in a permanent loss of capacity. Lithium metal is extremely reactive and can react with the electrode and electrolyte to release heat and gas, potentially leading to a fire.

    Another common reaction is the decomposition of the electrolyte. The electrolyte is typically an organic solvent containing lithium salts, so can be electrolyzed

    The gas pressure can cause mechanical failure of the cell, and the solids can form block pores on the electrodes, reducing their capacity.

    Thermal runaway: Certain undesirable chemical reactions in a cell both generate heat, and occur faster at higher temperatures. Whether this leads to a fire or just a dead cell is an interaction of several factors, typically cell temperature, physical damage, and charge state

    Manufacturing defects: With the number of things that can go wrong with lithium cells, quality control is critical.

    Swelling of lithium cells: Abusing lithium cells as above can definitely cause swelling, especially in pouch cells. However, even if you use them correctly, a few cells will puff up for reasons that are poorly understood.

    Here, the main danger is that the pouch cell is punctured by something nearby. The pressure caused by a swelling lithium cell can also crack screens and warp keyboards.

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  9. Tomi Engdahl says:

    DIY LiPo Protectors
    https://hackaday.com/2017/09/25/diy-lipo-protectors/

    Spiderman’s Uncle Ben was known to say, “With great power comes great responsibility.” The same holds true for battery power. [Andreas] wanted to use protected 18650 cells, but didn’t want to buy them off the shelf. He found a forty cent solution. Not only can you see it in the video, below, but he also explains and demonstrates what the circuit is doing and why.

    Protection is important with LiPo technology. Sure, LiPo cells have changed the way we use portable electronics, but they can be dangerous. If you overcharge them or allow them to go completely dead and then charge them, they can catch fire. Because they have a low source resistance — something that is usually desirable — short-circuiting them can also create a fire hazard. We’ve covered the chemistry in depth, but to prevent all the badness you’ll want a charger circuit.

    The little circuit fits on top of a standard 18650 cell and uses two chips (one of which is just a dual MOSFET) and three discrete components. It does add about 3 mm to the cell. [Andreas] found that battery holders with a coiled spring would accommodate the extra length, but those with metal leaf springs would not.

    #160 40 Cent Do-It-Yourself Li-Ion Protectors for 18650 Cells (Tutorial) and how they work
    https://www.youtube.com/watch?v=1rg3ZWxBNUE

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  10. Tomi Engdahl says:

    iPhone 8 Plus Battery Bursts While Charging, Destroys Case and Screen
    The batteries are made by ATL, the Galaxy Note 7 supplier
    http://news.softpedia.com/news/iphone-8-plus-battery-bursts-while-charging-destroys-case-and-screen-517860.shtml

    An iPhone 8 Plus 64GB has reportedly burst in Taiwan while it was being charged, raising questions about Apple’s battery provider ATL, which also made the famous exploding Samsung Galaxy Note 7 batteries.

    Ever since the Samsung Galaxy Note 7 started catching fire, everyone is now looking for this problem with each new device release. In Samsung’s case, it was a production mistake that cost the company a lot and forced them to retire an entire line of devices.

    Apple hasn’t been spared, but the number of exploding iPhones was much lower if we take into account the total of units sold by the company. Now, their latest iPhone 8 and iPhone 8 Plus have started to ship to customers, and some problems have already begun to appear.

    “Battery destroys the shell and pushes out the screen”

    While it’s not as exciting as catching fire, the fact that a woman’s iPhone 8 Plus 64GB had the screen pushed out by an inflating battery is bad enough

    Furthermore, it’s been reported that she was using the official charger and that she wasn’t a heavy user

    “The battery maker is under scrutiny again”

    The company that makes the batteries for the latest iPhone 8 and iPhone 8 Plus is called ATL. It might sound familiar because it’s the same one that provided the batteries for Samsung Galaxy Note 7, and we all know how well that went.

    In fact, Samsung ditched the ATL battery supplier after they failed to confirm the new regulations imposed. Because they were unable to guarantee the safety of the cells in a way that satisfied Samsung, ATL was dropped as a supplier.

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  11. Tomi Engdahl says:

    Prevent Overcharging of Li-Ion Cells
    http://www.electronicdesign.com/test-measurement/prevent-overcharging-li-ion-cells?NL=ED-003&Issue=ED-003_20171018_ED-003_184&sfvc4enews=42&cl=article_1_b&utm_rid=CPG05000002750211&utm_campaign=13624&utm_medium=email&elq2=c97e193fb6c841159a02a74912e573aa

    Four-wire remote sensing is generally the best solution, which requires the use of multiple probes. Thus, your system should include probe-check functions to guard against failure.

    Over the years, serious concerns have emerged about lithium-ion cell safety. There have been factory fires, mobile phones and laptop computers bursting into flames, and even the grounding of a 787 aircraft. So, when forming or charging Li-ion cells in manufacturing or during characterization in R&D, special attention must be paid to prevent dangerous conditions that can lead to those cell fires.

    One key area of concern is applying overvoltage or overcharging during charging. If the charging voltage is increased beyond the recommended upper cell voltage or if the cell is overcharged, lithium ions can build up on the anode as metallic lithium, which is called lithium plating. The plating can occur as dendrites inside the cell, which could ultimately result in a short circuit between the electrodes. The short circuit can increase the internal cell temperature, which may lead to thermal runaway that results in damaged cells and possibly fire.

    To maintain the highest voltage-regulation accuracy and control when large current is flowing into/out of the cell, it’s best to use a four-wire system called remote sensing. By remote sensing, the cell-charging electronics can adjust output voltage to compensate for the voltage drop in the power leads, even as the current changes.

    Remote Sensing Prevents Overvoltage, But…

    Remote sensing with a four-wire connection ensures the voltage on the cell will be maintained carefully, as the sense wires provide a voltage-regulation feedback system to the charger that permits the charger to regulate voltage accurately. Thus, no overvoltage can be applied and there’s no overcharging. Remote sensing also means four probes will be in contact with the cell. This raises the concern about probe failures, as more probes and associated wires mean more possible failures.

    Solution: Probe Check

    While a four-wire system has exceptional benefits, using more probes means that there’s greater potential for probe failure. As a result, a well-designed charger will include probe-check functions. The application of overvoltage is the most hazardous condition, since it can lead to fire, so the most basic level of probe check should detect sense probe failures.

    A simple method to implement a sense probe check is to detect if there’s a difference between the voltage measured on the sense lines and the voltage on the power lines. This difference will occur upon failure of a sense probe.

    Beyond this basic probe-check method, other more advanced and sophisticated methods can be deployed. One more advanced probe check involves sensing the resistance of the probes and even automatically detecting which of the four probes has failed. Of course, adding more sophistication to the charger increases the cost and complexity.

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  12. Tomi Engdahl says:

    Laptop Flipflop: Now U.S. Tries To Ban Laptops In Checked, Not Carry-On, Luggage
    https://www.forbes.com/sites/martinrivers/2017/10/21/laptop-flipflop-now-u-s-tries-to-ban-laptops-in-checked-not-carry-on-luggage/2/#1b63c2c5245f

    Seven months after America banned laptops from the passenger cabins of flights from the Arab World – forcing travelers to check them into cargo holds – the Federal Aviation Administration (FAA) wants global airlines to ban the very practice its government had previously imposed on them.

    The FAA’s advice is based on new safety tests showing that the rechargeable lithium-ion batteries found in laptops could bring down an aircraft if they overheat when packed next to flammable items in checked luggage.

    ts findings are published in a paper submitted to the International Civil Aviation Organization (ICAO), the UN agency that issues non-binding air safety guidance to the international community. The proposed ban has already won the backing of the European Aviation Safety Agency (EASA) and Airbus, the European aircraft manufacturer, establishing a consensus that ICAO is unlikely to overrule. Even after it weighs in, though, individual governments will retain the final say on ratifying any measures.

    The report cites ten experiments the FAA conducted with fully-charged laptops packed inside a suitcase.

    For the first four tests, the bag contained no other hazardous items and the resultant fires were extinguished by the Halon fire-suppression system that is widely used in cargo holds. In a fifth experiment without other hazardous items, the Halon system was not present and the suitcase was fully consumed by fire.

    But it was the subsequent tests that were most alarming, as they demonstrated how certain everyday items can exacerbate thermal runway to such a degree that the lifesaving Halon system becomes ineffective.

    Other experiments showed that nail polish remover, hand sanitizer and rubbing alcohol also accelerate battery fires, but it was the explosive effect of the aerosol can that had experts most concerned.

    While an exploding aerosol can is unlikely to cause structural damage to an aircraft, the impairment of the Halon system means that a fire could spread freely through the cargo hold and into other compartments such as the passenger cabin and electronics bay. This chain of events, the FAA warns, “could lead to the loss of the aircraft”.

    One reason that such an incident has not yet occurred, it suggests, is that passengers are “not typically placing their [laptops] in checked baggage”

    The FAA has repeatedly warned about the dangers of lithium-ion batteries and devices that use them, specifically banning spare batteries and e-cigarettes from checked luggage. Other battery-powered devices such as hover-boards and certain cell-phones have also been subject to FAA edicts.

    When did laptops become such a danger on planes?
    http://mashable.com/2017/05/12/laptop-ban-airline-europe-trump/#im3DkzrefOqu

    First shoes, then liquids, and now laptops.

    With reports suggesting the airplane cabin laptop ban may soon expand from flights originating in eight Middle Eastern and African countries to parts of Europe, it’s clear that our computers have now joined the list of things we have to worry about when flying.

    However, some big questions remain: Why now, and why are laptops considered OK in a plane’s cargo hold but not in its cabin?

    CNN reported in March that an unspecified al Qaeda affiliate was in fact working to disguise explosives as laptop components. As such, we know that the initial laptop ban wasn’t totally out of the blue.

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  13. Tomi Engdahl says:

    Lithium Ion Versus LiPoly In An Aeronautical Context
    https://hackaday.com/2017/10/23/lithium-ion-versus-lipoly-in-an-aeronautical-context/

    When it comes to lithium batteries, you basically have two types. LiPoly batteries usually come in pouches wrapped in heat shrink, whereas lithium ion cells are best represented by the ubiquitous cylindrical 18650 cells. Are there exceptions? Yes. Is that nomenclature technically correct? No, LiPoly cells are technically, ‘lithium ion polymer cells’, but we’ll just ignore the ‘ion’ in that name for now.

    Lithium ion cells are found in millions of ground-based modes of transportation, and LiPoly cells are the standard for drones and RC aircraft. [Tom Stanton] wondered why that was, so he decided to test the energy density per mass of these battery chemistries, and what he found was very interesting.

    Lithium ion plane battery
    https://www.youtube.com/watch?v=UB8fas6zBSE&t=601s

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  14. Tomi Engdahl says:

    These Explosions Show Why the FAA Doesn’t Want Laptops in Luggage
    https://www.wired.com/story/these-explosions-show-why-the-faa-doesnt-want-laptops-in-luggage/

    Stop me if you’ve heard this one before. The US government wants a “laptop ban” on planes.

    But this time, it’s to prevent fliers from putting large electronics, like laptops, into their checked luggage. This seems like an about-face. Earlier this year, a chaotically implemented ban did the exact opposite, demanding passengers on flights from certain Middle Eastern and African countries pack tablets, DVD players, and laptops into their suitcases, to travel in the belly of the plane. Department of Homeland Security officials worried terrorists would disguise bombs as batteries inside these larger electronic gizmos.

    The department lifted that laptop ban in June, announcing more rigorous security screening instead. But the temporary increase in large electronics in the hold left the Federal Aviation Administration, which oversees America’s flying industry, with some questions: Is it safe to stow electronics—especially those with lithium-ion batteries—in cargo holds?

    It was time for the FAA to blow some stuff up. You know—science. The agency ran a series of experiments, placing laptops inside typical suitcases next to your standard flammable toiletries: nail polish remover, hand sanitizer, and most explosively, an aerosol can of dry shampoo.

    n separate tests, the FAA also experimented with a galley cart, which airlines might use to store large numbers of in-flight-entertainment tablets together. If a device there catches fire and spreads, the resulting bang is dramatic, and potentially deadly.

    The FAA’s recommended ban is being debated by a Dangerous Goods Panel at an International Civil Aviation Organization meeting in Montreal, Canada, this week. If there’s agreement, ICAO, which is part of the UN, could adopt the ban, which will likely be announced in January 2018 and implemented a year later.

    In summation: A ban may have lead to an opposite ban. But safety comes first.

    Reply
  15. Tomi Engdahl says:

    Current Sensing in Lithium-ion Energy Storage Systems
    For the highest accuracy, opt for a simple architectur
    http://www.powerelectronics.com/power-management/current-sensing-lithium-ion-energy-storage-systems?NL=ED-003&Issue=ED-003_20171120_ED-003_847&sfvc4enews=42&cl=article_1_b&utm_rid=CPG05000002750211&utm_campaign=14166&utm_medium=email&elq2=00148c1342614baaaebccec5b924cab5

    Current sensing has long been an important function implemented by battery management systems (BMS), modules which monitor and protect high-capacity batteries. In both lithium-ion and sealed lead-acid battery types, current measurements are used to protect the battery against abuse and ensure its safe use by providing for emergency shut-down in over-current conditions. For protection and safety functions alone, the accuracy of the current measurements can be at a fairly low level. The system designer may specify the over-current conditions conservatively, so that even if the current sensor severely underestimates the current, the safe shut-down threshold is not crossed.

    Now, however, the requirements for current sensing are becoming much more stringent in certain applications. Car manufacturers in particular are working furiously to improve the performance and consumer appeal of electric vehicles (EVs). Range anxiety is one of the biggest impediments to consumer adoption of EVs, and so the accuracy of an EV’s “fuel gauge”—that is the State of Charge (SOC) reading showing how much energy is available for use—is of critical importance to the driver. Accurate SOC measurements also enable the BMS to optimize operation for long cycle life, in EVs and in industrial equipment, by maintaining the SOC at between 0% and 80%.

    The accuracy of the fuel gauge depends absolutely on the accuracy of the BMS’s current measurements. And as this article will show, precision analogue circuitry and an appropriate architecture can provide much higher levels of accuracy than are commonly achieved in today’s BMS.

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