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Learn How to Arrange Batteries to Increase Voltage or Gain Higher Capacity

Batteries achieve the desired operating voltage by connecting several cells in series; each cell adds its voltage potential to derive at the total terminal voltage. Some packs may consist of a combination of series and parallel connections. Laptop batteries commonly have four 3.6V Li-ion cells in series to achieve a nominal voltage 14.4V and two in parallel to boost the capacity from 2,400mAh to 4,800mAh. Such a configuration is called 4s2p, meaning four cells in series and two in parallel.

 

It is important to use the same battery type with equal voltage and capacity (Ah) and never to mix different makes and sizes. A weaker cell would cause an imbalance, as a battery is only as strong as the weakest link in the chain.

 

Single Cell Applications

The single-cell configuration is the simplest battery pack; the cell does not need matching and the protection circuit on a small Li-ion cell can be kept simple. Typical examples are mobile phones and tablets with one 3.60V Li-ion cell. Other uses of a single cell are wall clocks, which typically use a 1.5V alkaline cell, wristwatches and memory backup, most of which are very low power applications.

 

Series Connection

Portable equipment needing higher voltages use battery packs with two or more cells connected in series.

Figure 2: Series connection of four cells (4s).
Adding cells in a string increases the voltage; the capacity remains the same.

 

High voltage batteries keep the conductor size small. Cordless power tools run on 12V and 18V batteries; high-end models use 24V and 36V. Most e-bikes come with 36V Li-ion, some are 48V. The car industry wanted to increase the starter battery from 12V (14V) to 36V, better known as 42V, by placing 18 lead acid cells in series.

Some mild hybrid cars run on 48V Li-ion and use DC-DC conversion to 12V for the electrical system.

 

 

Parallel Connection

If higher currents are needed and larger cells are not available or do not fit the design constraint, one or more cells can be connected in parallel. Most battery chemistries allow parallel configurations with little side effect.

Figure 4: Parallel connection of four cells (4p).

With parallel cells, capacity in Ah and runtime increases while the voltage stays the same.

 

Series/parallel Connection

The series/parallel configuration shown in Figure 6 enables design flexibility and achieves the desired voltage and current ratings with a standard cell size. The total power is the product of voltage-times-current; four 3.6V (nominal) cells multiplied by 3,400mAh produce 12.24Wh. Four 18650 Energy Cells of 3,400mAh each can be connected in series and parallel as shown to get 7.2V nominal and 12.24Wh. The slim cell allows flexible pack design but a protection circuit is needed.

Figure 6: Series/ parallel connection of four cells (2s2p).

This configuration provides maximum design flexibility. Paralleling the cells helps in voltage management.

 

Safety devices in Series and Parallel Connection

Positive Temperature Coefficient Switches (PTC) and Charge Interrupt Devices (CID) protect the battery from overcurrent and excessive pressure. While recommended for safety in a smaller 2- or 3-cell pack with serial and parallel configuration, these protection devices are often being omitted in larger multi-cell batteries, such as those for power tool.

 

 Simple Guidelines for Using Household Primary Batteries

  • Keep the battery contacts clean. A four-cell configuration has eight contacts and each contact adds resistance (cell to holder and holder to next cell).
  • Never mix batteries; replace all cells when weak. The overall performance is only as good as the weakest link in the chain.
  • Observe polarity. A reversed cell subtracts rather than adds to the cell voltage.
  • Remove batteries from the equipment when no longer in use to prevent leakage and corrosion. This is especially important with zinc-carbon primary cells.
  • Do not store loose cells in a metal box. Place individual cells in small plastic bags to prevent an electrical short. Do not carry loose cells in your pockets.
  • Keep batteries away from small children. In addition to being a choking hazard, the current-flow of the battery can ulcerate the stomach wall if swallowed. The battery can also rupture and cause poisoning.
  • Do not recharge non-rechargeable batteries; hydrogen buildup can lead to an explosion. ·Perform experimental charging only under supervision.

 

Simple Guidelines for Using Secondary Batteries

  • Observe polarity when charging a secondary cell. Reversed polarity can cause an electrical short, leading to a hazardous condition.
  • Remove fully charged batteries from the charger. A consumer charger may not apply the correct trickle charge when fully charged and the cell can overheat.
  • Charge only at room temperature.
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New Lithium-Based Battery Design Makes Use of Greenhouse Gas

TOPICS:Battery TechnologyCarbon DioxideGreen TechnologyMITSustainability
By DAVID L. CHANDLER, MIT NEWS OFFICE SEPTEMBER 22, 2018

This scanning electron microscope image shows the carbon cathode of a carbon-dioxide-based battery made by MIT researchers, after the battery was discharged. It shows the buildup of carbon compounds on the surface, composed of carbonate material that could be derived from power plant emissions, compared to the original pristine surface (inset). Courtesy of the researchers

New lithium-based battery could make use of greenhouse gas before it ever gets into the atmosphere.

A new type of battery developed by researchers at MIT could be made partly from carbon dioxide captured from power plants. Rather than attempting to convert carbon dioxide to specialized chemicals using metal catalysts, which is currently highly challenging, this battery could continuously convert carbon dioxide into a solid mineral carbonate as it discharges.

While still based on early-stage research and far from commercial deployment, the new battery formulation could open up new avenues for tailoring electrochemical carbon dioxide conversion reactions, which may ultimately help reduce the emission of the greenhouse gas to the atmosphere.

The battery is made from lithium metal, carbon, and an electrolyte that the researchers designed. The findings are described today in the journal Joule, in a paper by assistant professor of mechanical engineering Betar Gallant, doctoral student Aliza Khurram, and postdoc Mingfu He.

Currently, power plants equipped with carbon capture systems generally use up to 30 percent of the electricity they generate just to power the capture, release, and storage of carbon dioxide. Anything that can reduce the cost of that capture process, or that can result in an end product that has value, could significantly change the economics of such systems, the researchers say.

However, “carbon dioxide is not very reactive,” Gallant explains, so “trying to find new reaction pathways is important.” Generally, the only way to get carbon dioxide to exhibit significant activity under electrochemical conditions is with large energy inputs in the form of high voltages, which can be an expensive and inefficient process. Ideally, the gas would undergo reactions that produce something worthwhile, such as a useful chemical or a fuel. However, efforts at electrochemical conversion, usually conducted in water, remain hindered by high energy inputs and poor selectivity of the chemicals produced.

Gallant and her co-workers, whose expertise has to do with nonaqueous (not water-based) electrochemical reactions such as those that underlie lithium-based batteries, looked into whether carbon-dioxide-capture chemistry could be put to use to make carbon-dioxide-loaded electrolytes — one of the three essential parts of a battery — where the captured gas could then be used during the discharge of the battery to provide a power output.

This approach is different from releasing the carbon dioxide back to the gas phase for long-term storage, as is now used in carbon capture and sequestration, or CCS. That field generally looks at ways of capturing carbon dioxide from a power plant through a chemical absorption process and then either storing it in underground formations or chemically altering it into a fuel or a chemical feedstock.

Instead, this team developed a new approach that could potentially be used right in the power plant waste stream to make material for one of the main components of a battery.

While interest has grown recently in the development of lithium-carbon-dioxide batteries, which use the gas as a reactant during discharge, the low reactivity of carbon dioxide has typically required the use of metal catalysts. Not only are these expensive, but their function remains poorly understood, and reactions are difficult to control.

By incorporating the gas in a liquid state, however, Gallant and her co-workers found a way to achieve electrochemical carbon dioxide conversion using only a carbon electrode. The key is to preactivate the carbon dioxide by incorporating it into an amine solution.

“What we’ve shown for the first time is that this technique activates the carbon dioxide for more facile electrochemistry,” Gallant says. “These two chemistries — aqueous amines and nonaqueous battery electrolytes — are not normally used together, but we found that their combination imparts new and interesting behaviors that can increase the discharge voltage and allow for sustained conversion of carbon dioxide.”

They showed through a series of experiments that this approach does work, and can produce a lithium-carbon dioxide battery with voltage and capacity that are competitive with that of state-of-the-art lithium-gas batteries. Moreover, the amine acts as a molecular promoter that is not consumed in the reaction.

The key was developing the right electrolyte system, Khurram explains. In this initial proof-of-concept study, they decided to use a nonaqueous electrolyte because it would limit the available reaction pathways and therefore make it easier to characterize the reaction and determine its viability. The amine material they chose is currently used for CCS applications, but had not previously been applied to batteries.

This early system has not yet been optimized and will require further development, the researchers say. For one thing, the cycle life of the battery is limited to 10 charge-discharge cycles, so more research is needed to improve rechargeability and prevent degradation of the cell components. “Lithium-carbon dioxide batteries are years away” as a viable product, Gallant says, as this research covers just one of several needed advances to make them practical.

But the concept offers great potential, according to Gallant. Carbon capture is widely considered essential to meeting worldwide goals for reducing greenhouse gas emissions, but there are not yet proven, long-term ways of disposing of or using all the resulting carbon dioxide. Underground geological disposal is still the leading contender, but this approach remains somewhat unproven and may be limited in how much it can accommodate. It also requires extra energy for drilling and pumping.

The researchers are also investigating the possibility of developing a continuous-operation version of the process, which would use a steady stream of carbon dioxide under pressure with the amine material, rather than a preloaded supply the material, thus allowing it to deliver a steady power output as long as the battery is supplied with carbon dioxide. Ultimately, they hope to make this into an integrated system that will carry out both the capture of carbon dioxide from a power plant’s emissions stream, and its conversion into an electrochemical material that could then be used in batteries. “It’s one way to sequester it as a useful product,” Gallant says.

“It was interesting that Gallant and co-workers cleverly combined the prior knowledge from two different areas, metal-gas battery electrochemistry and carbon-dioxide capture chemistry, and succeeded in increasing both the energy density of the battery and the efficiency of the carbon-dioxide capture,” says Kisuk Kang, a professor at Seoul National University in South Korea, who was not associated with this research.

“Even though more precise understanding of the product formation from carbon dioxide may be needed in the future, this kind of interdisciplinary approach is very exciting and often offers unexpected results, as the authors elegantly demonstrated here,” Kang adds.

MIT’s Department of Mechanical Engineering provided support for the project.

Publication: Aliza Khurram, et al., “Tailoring the Discharge Reaction in Li-CO2 Batteries through Incorporation of CO2 Capture Chemistry,” Joule, 2018; doi:10.1016/j.joule.2018.09.002

 

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How To Properly Dispose Or Recycle Lithium Batteries

Recycle-Lithium-Batteries

According to the Environmental Protection Agency, billions of batteries find their way into landfills every year.

 

These batteries contain toxic substances which can then leech into the earth and water supplies. Fortunately, this negative impact on the environment can be avoided by battery recycling.

 

Did you know that you can recycle lithium batteries? You can, and it’s easier than you might think. Keep reading to learn more about the only safe way to get rid of old batteries.

 

Why Recycle Batteries

Before we go any further, let’s take a quick look at why it’s important to recycle batteries. When you understand why you’re doing something, you’re more likely to continue doing it.

Recycle-Lithium-Batteries

Here are some of the reasons why you should be recycling old batteries:

 

  • Conserves natural resources
  •  Reduces the amount of waste in landfills
  • Prevents pollution created by the collection of raw materials
  •  Creates new jobs in the recycling and manufacturing industries
  • Saves energy
  •  Avoids polluting the environment and groundwater supplies

Many of these benefits come from the fact that metals such as aluminum, nickel, and copper can all be harvested from old batteries. These can then be used in other ways and new metals don’t have to be taken from the earth.

 

What to Do Before Taking in Batteries

Before you take your batteries somewhere to recycle them, there are a few things you’ll want to do.

 

First and foremost, you need to keep your batteries out of your regular trash and recycling bin. Lithium batteries can cause sparks, even if they’re completely dead. This is why you want to avoid putting them with other recyclables.

 

To prevent them from sparking, cover the terminals or ends with electrical tape. It’s a good idea to get into the habit of doing this as soon as a battery is removed so it won’t cause any problems.

 

The other thing you want to do before you pack up your old batteries to recycle is to call ahead. You want to make sure the place you’re taking them accepts the type of battery you have so you don’t waste a trip out there.

 

You also need to ask about fees. Some places will charge a fee to recycle batteries for you whereas other places do it for free. Asking in advance will help you avoid an unpleasant surprise.

 

Where to Recycle Batteries

Recycling lithium batteries is as easy as finding a place that will take them. Here are a few resources you can use to recycle lithium batteries:

 

Recycling Center

One of the best places to take your batteries to where there’s a good chance they’ll take them is a local recycling center. Not every recycling center takes every type of battery, so this is one you’ll definitely want to call before going.

 

A quick search online should allow you to find several recycling centers near you so you can find one that will take your old batteries.

 

Household Hazardous Waste Center

If you’re unfortunate enough to not have a recycling center near you that will take your lithium batteries, you should be able to find a household hazardous waste center.

 

This will require another online query which should lead you to the right place that will definitely take your old batteries.

 

Scrap Yards

To make your trip worth it, you may consider taking your old batteries to a scrap yard. Many of these locations will purchase them from you because they can remove the metals from them and make a profit.

 

This is particularly great for hobbyists who have several large batteries lying around that are in need of recycling.

 

Scrap yards don’t often take alkaline batteries, so if you also have some smaller batteries saved up from various electronics, you’ll have to visit a couple of places to get rid of all of your batteries at once.

 

Local Library or Community Center

Sometimes, a city or local community will have a battery drive or else a specific location where you can drop off batteries to be recycled for you. Ask at your local library or community center for more information about this.

 

In most cases, they primarily take smaller household batteries and other used electronics rather than larger batteries. For this reason, you’ll want to double-check that your larger vehicle batteries will be accepted.

 

Because of how close these places generally are to you compared to recycling centers, this can be the most convenient option.

 

Electronic and Hardware Stores

Here are some stores that may accept batteries for recycling:

 

  • Staples
  •  Best Buy
  • Home Depot
  • Lowes

As you can imagine, hardware stores are more likely to accept larger batteries since they sell them for tools and smaller vehicles.

 

Electronic stores may only accept smaller batteries used in cell phones and other electronics, so you’ll definitely want to ask before taking them there.

 

It’s also important to keep in mind that not every store location offers this service. Call ahead and ask about the specific types of batteries you’re looking to recycle before showing up with them.

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Industrial Applications

Industrial applications have unique power needs and the choice of battery is important. While consumer products demand high energy density to obtain slim and elegant designs, industry focuses on durability and reliability. Industrial batteries are commonly bulkier than those used in consumer products but achieve a longer service life.

Batteries are electro-chemical devices that convert higher-level active materials into an alternate state during discharge. The speed of such transaction determines the load characteristics of a battery. Also referred to as concentration polarization, the nickel and lithium-based batteries are superior to lead-based batteries in reaction speed. This attribute reflects in good load characteristics.

Discharge loads range from a low and steady current flow of a flashlight to intermittent high current bursts in a power tool, to sharp current pulses on digital communications equipment, laptops and cameras. In this paper we evaluate how the various battery chemistries perform in a given application.

What’s the best battery for video cameras?

Nickel-cadmium batteries continue to power a large percentage of professional cameras. This battery provided reliable service and performs well at low temperature. nickel-cadmium is one of the most enduring batteries in terms of service life but has only moderate energy density and needs a periodic full discharge.

The need for longer runtimes is causing a switch to nickel-metal-hydride. This battery offers up to 50% more energy than nickel-cadmium. However, the high current spikes drawn by digital cameras have a negative affect and the nickel-metal-hydride battery suffers from short service life.

There is a trend towards lithium-ion. Among rechargeables, this chemistry has the highest energy density and is lightweight. A steep price tag and the inability to provide high currents are negatives.

The 18650 cylindrical lithium-ion cell offers the most economical power source. “18” defines the cell’s diameter in millimeters and “650” the length. No other lithium-ion cell, including prismatic or polymer types, offers a similar low cost-per-watt ratio.

Over the years, several cell versions of 18650 cells with different Ah ratings have emerged, ranging from 1.8Ah to well above 2Ah. The cells with moderate capacities offer better temperature performance, enable higher currents and provide a longer service life than the souped up versions.

The typical 18650 for industrial use is rated at 2Ah at 3.60 volts. Four cells are connected in series to obtain the roughly 15 volts needed for the cameras. Paralleling the cells increases the current handling by about 2A per cell. Three cells in parallel would provide about 6A of continuous power. Four cells in series and three in parallel is a practical limit for the 18650 system.

Lithium-ion requires a protection circuit to provide safe operations under all circumstances. Each cell in series is protected against voltage peaks and dips. In addition, the protection circuit limits each cell to a current about 2A. Even if paralleled, the current of a lithium-ion pack is not high enough to drive digital cameras requiring 10 to 15A peak current. Tests conducted at Cadex Electronics have shown that the 18650 allows short current peaks above the 2A/cell limit. This would allow the use of lithium-ion on digital cameras, provided the current bursts are limited to only a few seconds.

What’s the best battery for still cameras?

The power requirement of a professional digital camera is sporadic in nature. Much battery power is needed to take snapshots, some with a powerful flash. To view the photo, the backlit color display draws additional power. Transmitting a high-resolution image over the air depletes another portion of the energy reserve.

Most non-professional cameras use a primary lithium battery. This battery type provides the highest energy density but cannot be recharged. This is a major drawback for professional use. Rechargeable batteries are the answer and lithium-ion fits the bill but faces similar challenges to the video cameras.

battery for still cameras

What is the best battery for medical devices?

One of the most energy-hungry portable medical devices is the heart defibrillator. The battery draws in excess of 10 amperes during preparation stages. Several shocks may be needed to get the patient’s heart going again. The battery must not hamper the best possible patient care.
battery for medical devices
Most defibrillators are powered by nickel-cadmium. nickel-metal-hydride is also being used but there is concern of short service life. In a recent study, however, it was observed that a defibrillator battery cycles far less than expected. Instead of the anticipated 200 cycles after two years of seemingly heavy use, less than 60 cycles had been delivered on the battery examined. ‘Smart’ battery technology makes such information possible. With fewer cycles needed, the switch to higher energy-dense batteries becomes a practical alternative.

Sealed lead-acid batteries are often used to power defibrillators intended for standby mode. Although bulky and heavy, the Lead-acid has a low self-discharge and can be kept in prolonged ready mode without the need to recharge. Lead-acid performs well on high current spurts. During the rest periods the battery disperses the depleted acid concentrations back into the electrode plate. Lead-acid would not be suitable for a sustained high load.

The medical industry is moving towards lithium-ion. The robust and economical 18650 cells make this possible. The short but high current spurts needed for defibrillators are still a challenge. Paralleling the cells and adding current-limiting circuits that allow short spikes of high current will help overcome this hurdle.

What is the best battery for power tools?

Power tools require up to 50 amperes of current and operate in an unfriendly environment. The tool must perform at sub zero temperatures and endure in high heat. The batteries must also withstand shock and vibration.

Most power tools are equipped with nickel-cadmium batteries. nickel-metal-hydride has been tried with limited success. Longevity is a problem but new designs have improved. lithium-ion is too delicate and could not provide the high amperage. Lead-acid is too bulky and lacks persistent power delivery. The power tool has simply no suitable alternatives to the rugged and hard-working nickel-cadmium.

In an attempt to pack more energy into power tools, the battery voltage is increased. Because of heavy current and application at low temperatures, cell matching is important. Cell matching becomes more critical as the number of cell connected in series increases. A weak cell holds less capacity and is discharged more quickly than the strong ones. This imbalance causes cell reversal on the weak cell if the battery is discharged at high current below 1V/cell. An electrical short occurs in the weak cell if exposed to reverse current and the pack needs to be replaced. The higher the battery voltage, the more likely will a weak cell get damaged.

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New Technique Produces Longer-lasting Lithium Batteries

Date:APRIL 22, 2019

Source:Columbia University School of Engineering and Applied Science

An artificial boron nitride (BN) film is chemically and mechanically robust against lithium. It electronically isolates lithium aluminum titanium phosphate (LATP) from lithium, but still provides stable ionic pathways when infiltrated by polyethylene oxide (PEO), and thus enables stable cycling. Credit: Qian Cheng/Columbia Engineering

The grand challenge to improve energy storage and increase battery life, while ensuring safe operation, is becoming evermore critical as we become increasingly reliant on this energy source for everything from portable devices to electric vehicles. A Columbia Engineering team led by Yuan Yang, assistant professor of materials science and engineering, announced today that they have developed a new method for safely prolonging battery life by inserting a nano-coating of boron nitride (BN) to stabilize solid electrolytes in lithium metal batteries. Their findings are outlined in a new study published by Joule.

 

While conventional lithium ion (Li-ion) batteries are currently widely used in daily life, they have low energy density, resulting in shorter battery life, and, because of the highly flammable liquid electrolyte inside them, they can short out and even catch fire. Energy density could be improved by using lithium metalto replace the graphite anode used in Li-ion batteries: lithium metal’s theoretical capacity for the amount of charge it can deliver is almost 10 times higher than that of graphite. But during lithium plating, dendrites often form and if they penetrate the membrane separator in the middle of the battery, they can create short-circuits, raising concerns about battery safety.

“We decided to focus on solid, ceramic electrolytes. They show great promise in improving both safety and energy density, as compared with conventional, flammable electrolytes in Li-ion batteries,” says Yang. “We are particularly interested in rechargeable solid-state lithium batteries because they are promising candidates for next-generation energy storage.”

Most solid electrolytes are ceramic, and therefore non-flammable, eliminating safety concerns. In addition, solid ceramic electrolytes have a high mechanical strength that can actually suppress lithium dendrite growth, making lithium metal a coating option for battery anodes. However, most solid electrolytes are unstable against Li—they can be easily corroded by lithium metal and cannot be used in batteries.

The left visual shows that a Lithium aluminum titanium phosphate (LATP) pellet that touches lithium metal will be immediately reduced. The severe side reaction between lithium and solid electrolyte will fail the battery in several cycles. The right shows that an artificial BN film is chemically and mechanically robust against lithium. It electronically isolates LATP from lithium, but still provides stable ionic pathways when infiltrated by polyethylene oxide (PEO), and thus enables stable cycling. Credit: Qian Cheng/Columbia Engineering

 

“Lithium metal is indispensable for enhancing energy density and so it’s critical that we be able to use it as the anode for solid electrolytes,” says Qian Cheng, the paper’s lead author and a postdoctoral research scientist in the department of applied physics and applied mathematics who works in Yang’s group. “To adapt these unstable solid electrolytes for real-life applications, we needed to develop a chemically and mechanically stable interface to protect these solid electrolytes against the lithium anode. It is essential that the interface not only be highly electronically insulating, but also ionically conducting in order to transport lithium ions. Plus, this interface has to be super-thin to avoid lowering the energy density of batteries.”

 

To address these challenges, the team worked with colleagues at Brookhaven National Lab and the City University of New York. They deposited 5~10 nm boron nitride (BN) nano-film as a protective layer to isolate the electrical contact between lithium metal and the ionic conductor (the solid electrolyte), along with a trace quantity of polymer or liquid electrolyte to infiltrate the electrode/electrolyte interface. They selected BN as a protective layer because it is chemically and mechanically stable with lithium metal, providing a high degree of electronic insulation. They designed the BN layer to have intrinsic defects, through which lithium ions can pass through, allowing it to serve as an excellent separator. In addition, BN can be readily prepared by chemical vapor deposition to form large-scale (~dm level), atomically thin scale (~nm level), and continuous films.

“While earlier studies used polymeric protection layers as thick as 200 μm, our BN protective film, at only 5~10 nm thick, is record-thin—at the limit of such protection layers—without lowering the energy density of batteries,” Cheng says. “It’s the perfect material to function as a barrier that prevents the invasion of lithium metal to solid electrolyte. Like a bullet-proof vest, we’ve developed a lithium-metal-proof ‘vest’ for unstable solid electrolytes and, with that innovation, achieved long cycling lifetime lithium metal batteries.”

The researchers are now extending their method to a broad range of unstable solid electrolytes and further optimize the interface. They expect to fabricate solid-state batteries with high performance and long-cycle lifetimes.

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Transport of Lithium Batteries According to UN 38.3

UN38.3 Battery

Anyone who has ever dealt with lithium batteries knows the demanding process for transportation. Lithium cells and batteries are classified as dangerous goods class 9 and thus are on a par with liquid nitrogen. The requirements for safe transport are correspondingly high.

Whether by rail, road or air, the eligibility of lithium cell or battery shipments is regulated by the transport test 38.3 of the United Nations. A shipment is only permitted if the following eight individual tests are passed.

UN38.3 Battery

1) Altitude Simulation

This test simulates the environmental conditions prevailing in the cargo hold of an aircraft at an altitude of up to 15,000 meters. The battery is exposed to an extremely low air pressure of 11.6 kilopascal for a total of six hours. The test is passed if:

 

the battery shows no loss of mass

the overpressure valve of the battery remains closed

the battery housing is free of cracks or leaks,

the voltage level of the battery differs from the initial value by a maximum of 10% after completion of the test.

2) Thermal Test

If the altitude simulation has been successfully completed, the next step is to check the behavior of the lithium battery in case of strong temperature fluctuations. This stresses the battery seals and internal electrical connections. The batteries are initially stored for at least six hours at a surrounding temperature of 72 degrees Celsius. The temperature is then lowered to -40 degrees Celsius for a further six hours. This test procedure, for which Jauch uses a specially designed thermal shock chamber, must be carried out over 10 complete cycles. Finally, the batteries are stored at room temperature for at least another twelve hours. The test is passed when all the criteria mentioned under 1) have been met.

 

3) Vibration Test

The third part of the UN 38.3 transport test puts the battery in a vibration generator, where the battery is subjected to frequencies between 7 and 200 Hertz. The test is designed for a total of three hours and simulates the typical jerking in the hold of a truck while driving. The criteria mentioned under 1) also apply in this case.

 

4) Impact Test

Just like the vibration test, the impact test also serves to prevent possible damage to the battery by rough transport. Depending on the size of the lithium battery, impacts of 150G/6mS or 50G/11mS affect the housing. Just as in the vibration test, the criteria listed under 1) apply here as well.

 

5) External Short Circuit Test

For this test, the battery is first heated from the outside to a temperature of 57 degrees Celsius before an external short-circuit is caused. As a result, the battery temperature rises, but must not exceed 170 degrees Celsius. Once the battery has cooled down to 57 degrees again, the short-circuit condition must remain for another 60 minutes. The test is only passed if neither flames, cracks nor other damage to the battery housing are detected for up to six hours afterwards.

 

6) Impact and Crush Test

This test is carried out at cell level and simulates external damage to the cells that can occur because of a strong impact, such as a traffic accident. For this purpose, depending on the cell type and shape, a stamp with a precisely defined size and press depth is pressed into the cells. Damaged in this way, an internal short-circuit can occur in the cell. The test is passed if, as with the external short-circuit test, the housing temperature does not exceed 170 degrees Celsius at any time and no signs of cracks or similar appear on the housing up to six hours after the test.

 

7) Overcharging Test

The UN 38.3 transport test prescribes an overcharge test for all rechargeable lithium batteries. For 24 hours, twice the maximum permissible charging current is applied to the battery. The battery must then be stored in a secure area for seven days. No damage may occur during this period for the battery to pass.

 

8) Fast Discharge Test

The final test is also carried out at cell level. The cell is subjected to a discharge current exceeding the permitted maximum. This procedure is repeated several times. As with overcharging, rapid discharge must not damage the battery in any way in order to successfully pass this test.

 

According to UN 38.3, a battery may not be shipped by rail, road or air until it has passed each of these eight test procedures.

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LITHIUM BATTERIES: CYLINDRICAL VERSUS PRISMATIC

By and large, lithium batteries bring a wide range of different benefits to the table that are difficult – if not impossible – to replicate in any other way. Also commonly referred to as lithium-metal batteries (due to the fact that they use lithium as an anode), they’re typically capable of offering a very high-charge density (read: longer lifespan) than other alternatives that are on the market today.

For that reason alone, lithium batteries have a wide range of applications in our daily lives, especially for those critical in nature that we tend not to spend too much time thinking about. Specialized types of lithium batteries are used in pacemakers and other implanted medical devices, for example, because they can often last 15 years (or longer) under the right circumstances. They’ve even started to replace traditional alkaline batteries in many everyday devices like clocks, digital cameras, watches, portable data assistants, and more, all thanks to that longer lifespan that minimizes the need to replace the battery over time.

LITHIUM BATTERIES: CYLINDRICAL VERSUS PRISMATIC

Example of cylindrical lithium batteries.

Issues like mechanical vibrations, thermal cycling from charging and discharging, and the mechanical expansion of current conductors are all things that can affect a battery’s lifespan. Therefore, the design of these cylindrical units is intended to help mitigate risk from these and other factors as much as possible.

 

On the inside of a cylindrical battery, a series of cells are combined and operate in parallel to one another. This is done to help increase both the voltage and the overall capacity of the battery pack.

 

For these reasons, cylindrical batteries are usually the kind that are found in the aforementioned medical device systems. Smaller, more specially designed cylindrical cells are also commonly found in portable devices like laptop computers. Notably, Tesla also made headlines recently by selecting cylindrical lithium batteries to power its fleet of popular electric cars.

 

What Are Prismatic Lithium Batteries?

A prismatic lithium battery, on the other hand, features a cell that has been encased in either aluminum or steel, mainly for the purposes of increased stability. This, in turn, creates several key advantages right out of the gate. Because of this unique construction and makeup, prismatic lithium batteries tend to be very thin, very light and offer an effective use of space.

Example of prismatic lithium batteries.

 

Because the rectangular shape of your average prismatic Li battery offers far better layering than other options, they typically give engineers a higher level of flexibility when designing products that will one day feature prismatic batteries as power sources. Because of that, it should come as no surprise that prismatic batteries are typically found in smartphones, tablets, and similar types of electronic devices where mobility is a major priority.

 

Due to these properties, modern day prismatic batteries are also commonly used in larger critical applications like energy storage systems and in electric powertrains.

 

Cylindrical Versus Prismatic Batteries: Breaking Things Down

There’s a reason why cylindrical lithium batteries are the most commonly available (and used) type today. When compared to their prismatic counterparts, they can typically be produced much faster and with a lower cost-per-KWh (kilowatt hour) at the same time. The design itself better supports the types of automation processes that are commonplace in factories and in other manufacturing environments across the country, for example, which only aid in creating a better sense of product consistency and keeping those ultimate costs as low as possible.

 

One of the major reasons why prismatic cells have increased in popularity over the last few years, however, has to do with their large capacity. That, coupled with their naturally prismatic shape, make it very easy to connect four different cells together to help create something like a 12-volt battery pack.

 

The prismatic design does come with its own challenges, however, particularly as they relate to what happens if something goes wrong. If one cell in a prismatic battery goes bad for any reason, for example, the entire battery pack that it is a part of is essentially compromised. Because the cells in a cylindrical battery are combined in a series and in parallel, these are the types of problems that designers and other engineers don’t really have to worry about.

 

Because of the design of cylindrical Li batteries, they also tend to radiate heat (and thus control their own temperature) more easily than their prismatic counterparts. Because of the way that prismatic cells are all placed together, this certainly works to increase the capacity, but it also leaves room for a higher probability of design inconsistency and short circuiting. The larger size of the prismatic cell may also be attractive in certain situations, but it also minimizes the chances that such a battery could be used in a heavily automated environment. That larger cell size also creates perhaps the biggest disadvantage for prismatic batteries: the increased capacity makes it far more difficult for the battery management system to properly regulate heat and prevent the battery itself from overcharging.

 

As previously stated, the thin form factor of a prismatic battery leads to increased flexibility for product designers – this does, however, create a few disadvantages of its own. It is that very same design that ultimately makes prismatic batteries somewhat difficult and expensive to properly design and manufacturer, which are costs that are almost certainly passed along to consumers. That flexibility has also created a limited number of “standardized” cell sizes, which only adds to difficulty in that regard. This also contributes to a higher than average KWh price as well.

 

It’s important to note, however, that the topic of costs is also one that comes with a few important caveats. Experts agree that because prismatic cells can often be larger than their cylindrical counterparts and will thus cost more initially, they offer more opportunity for cost reduction in the long-term. Based on that, you may want to think about the cost factor in the following way: is it more important to save money now by going cylindrical, or can you depend on your ability to innovate and potentially save a larger amount of money over time? The answer to that question, of course, is one that only you can answer based on whatever it is you’re trying to do.

 

Maybe the biggest advantage of cylindrical batteries in most situations is that they are very safe. If the internal pressure of a cylindrical lithium battery grows too high, most of the cells are designed to rupture – thus mitigating safety risks from situations like a fire or an explosion.

 

In The End

None of this is to say that cylindrical lithium batteries are inherently “better” than their prismatic counterparts, or vice versa. As is often the case with these types of situations, there is no “one-size-fits-all” approach to battery selection. Much of your decision will ultimately come down to the eventual application and the amount of risks and potential disadvantages that you’re willing to accept as a result. There will be some situations where a prismatic battery absolutely makes the most sense. There will be situations where cylindrical batteries seem like the logical choice.

 

More often than not, choosing the right type of lithium battery to meet your needs will come down to three factors:

 

The amount of money you’re willing to pay, the effectiveness of the battery you’re trying to unlock, and the safety considerations given the application.

If space isn’t necessarily at a premium and you need to find a cost-effective way to guarantee both performance and longevity, cylindrical batteries offer what you need.

If cost isn’t a factor and you need as much power as possible in an already small space, prismatic is likely the direction you’ll want to head in.

Only by trying to learn as much about these options as possible will you be able to make the best decision given your needs in the moment. Ultimately, your ability to do that successfully is all that matters.

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BATTERY END OF LIFE VS. STATE OF CHARGE

Written by Anton Beck
Posted on August 16, 2019 at 9:03 AM

 Within the context of a discussion about batteries, defining the term “state of charge” is simple. It’s a term that essentially refers to how “full” your battery is, at least in terms of its remaining energy. Compared to how much energy a battery can store at 100%, your current state of charge shows you how much is remaining, thus allowing you to predict when a recharge may be in order.

The larger implications of that term, however, are far less straightforward.

If you truly want to get the most out of your battery and make sure that it lasts as long as possible, there are a few key things about concepts like charge/discharge cycles, End of Life and more that you’ll definitely want to know more about.

Learn How To Expedite Your Battery Pack Design & Development

Charge And Discharge Cycles: Breaking Things Down

At its core, a “charge/discharge cycle” is exactly what it sounds like – a situation where the energy in a battery is discharged before subsequently being charged back up again.

It’s important to note that rarely does this ever mean taking a battery from 100% capacity to 0% and back again. Instead, most manufacturers use an 80% DoD (depth of discharge) formula for a battery’s overall rating. This means that roughly 80% of the available energy in a battery is delivered, while about 20% remains in reserve. Using this technique is an efficient way to increase a battery’s overall service life, prolonging its lifespan significantly in many applications.

 

The expected charge and discharge cycles for a battery depend less on the battery chemistry and more on the overall capacity of the battery itself. The only real difference has to do with when a full charge must be applied. For lead acid batteries, for example, a full charge should be applied every few weeks (or at least every few months) because a constant low charge will ultimately cause sulfation and damage the unit. With nickel-based batteries, a partial charge is totally acceptable. With lithium-ion batteries, a partial charge is actually better than a full charge because of the implications it brings with it for the long-term health of the battery.

End Of Life

The end of life for a battery is exactly that – the moment where the battery reaches the end of its usefulness and/or lifespan and can no longer operate at anywhere close to the peak capacity that you once enjoyed.

Generally speaking, end of life for a battery will be determined in one of three different ways depending on the product’s manufacturer.

Cycle life. This refers to the total number of times that a battery can be charged and discharged, as outlined above. Manufacturers will typically include the recommended cycle life on the product’s packaging or in other documentation available at the time of purchase.

Warrantied life. This will usually be outlined in a specific number of years, like any other product that you may have. A battery with a 10-year life under warranty is typically expected to reach true end of life by roughly that time.

Total energy throughput. This is the total amount of energy that will pass through the battery over the course of its lifespan and this will usually be measured in megawatt-hours.

Occasionally, manufacturers will reference end of life using a measurement called expected operational life. If this is present, it will usually be somewhat longer than the “warrantied life” measurement. At that point, your battery will no longer be covered under any type of manufacturer’s warranty, but it will still continue to function until about the time that the listed number of years have passed.

It’s important to note, however, that end of life does not mean that your battery will suddenly become useless after a certain amount of time has passed. Far from it. It simply describes the total amount of time that you can expect your battery to operate at peak performance.

For the sake of example, consider the battery in your smartphone, tablet, or other type of mobile device. When you charge your phone for the first time after buying it, 100% may get you approximately 10 hours of use before you must charge the battery back up again. Over time, that number will slowly decrease. You may notice that you only get nine hours out of 100% capacity, or eight-and-a-half, even though your general use and operational conditions haven’t changed.

Once that battery reaches true end of life, that number is going to start to rapidly drop. This is because 100% no longer represents the same amount of stored energy that it once did. You’ll still be able to use your battery, but there will come a day where it won’t be able to hold a charge at all, at which point it will likely have to be totally replaced.

Best Practices For Prolonging The Life Of Your Battery

Consumers can absolutely manage their batteries differently to obtain more life cycles from a battery. They just need to remember to follow a few key best practices over time.

For starters, you should always keep your battery at a moderate temperature whenever possible. Instances of extreme heat or extreme cold can cause the battery to expand or contract, both of which will cause long-term issues and could ultimately lead to problems like corrosion.

Along the same lines, always store your batteries in a cool place whenever you’re not using them. If you’re going to be storing a battery for an indefinite period, don’t allow its charge to deplete to zero. Instead, store your battery with a charge of about 50% for the best long-term results.

For certain types of batteries like lithium-ion, you should also avoid deep cycling; don’t let your battery drain down to 0% before you charge it back up again. Experts at Battery University agree that lithium-ion batteries tend to last the longest when they are operating between 30% and 80% charge as often as possible.

Finally, you should also do whatever you can to avoid abusing your battery over time. Batteries will always experience additional stress via harsh discharges and rapid charges. If you’re going to be using a battery with a particular application, make sure that the battery is optimized for the power and energy requirements you’re working with. If necessary, increase the size of your battery to combat this type of unnecessary stress.

When a lithium-ion battery in particular reaches its natural end of life, you should also make sure that you dispose of it properly. You can’t just throw them in the garbage. They are technically considered to be hazardous waste in this state. Instead, contact your local landfill to find a battery recycling drop-off location in your area.

 

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Five tips for extending lithium-ion battery life

There’s lots of press about how to conserve battery power, but not much about how to take care of your batteries. Here are a few things you can do to increase battery longevity.

In today’s mobile world, battery life is precious. If you don’t believe me, go to an airport and watch the road warriors. It can get downright nasty when two spot the only available outlet at the same time.

It doesn’t take long to learn what helps preserve the current charge on the battery. What’s not well known is how to care for the battery itself. That’s just as important. Doing so allows the battery to operate efficiently. Here are a few ways to keep your lithium-ion batteries healthy.

1: Keep your batteries at room temperature
That means between 20 and 25 degrees C. The worst thing that can happen to a lithium-ion battery is to have a full charge and be subjected to elevated temperatures. So don’t leave or charge your mobile device’s battery in your car if it’s hot out. Heat is by far the largest factor when it comes to reducing lithium-ion battery life.

2: Think about getting a high-capacity lithium-ion battery, rather than carrying a spare
Batteries deteriorate over time, whether they’re being used or not. So a spare battery won’t last much longer than the one in use. It’s important to remember the aging characteristic when purchasing batteries. Make sure to ask for ones with the most recent manufacturing date.

3: Allow partial discharges and avoid full ones (usually).
Unlike NiCad batteries, lithium-ion batteries do not have a charge memory. That means deep-discharge cycles are not required. In fact, it’s better for the battery to use partial-discharge cycles.

There is one exception. Battery experts suggest that after 30 charges, you should allow lithium-ion batteries to almost completely discharge. Continuous partial discharges create a condition called digital memory, decreasing the accuracy of the device’s power gauge. So let the battery discharge to the cut-off point and then recharge. The power gauge will be recalibrated.

4: Avoid completely discharging lithium-ion batteries
If a lithium-ion battery is discharged below 2.5 volts per cell, a safety circuit built into the battery opens and the battery appears to be dead. The original charger will be of no use. Only battery analyzers with the boost function have a chance of recharging the battery.

Also, for safety reasons, do not recharge deeply discharged lithium-ion batteries if they have been stored in that condition for several months.

5: For extended storage, discharge a lithium-ion battery to about 40 percent and store it in a cool place
I’ve always had an extra battery for my notebook, but it would never last as long as the original battery. I know now that it’s because I was storing the battery fully charged. That means oxidation of lithium-ion is at its highest rate. Storing lithium-ion batteries at 40 percent discharge and in the refrigerator (not freezer) is recommended

Final thoughts
Lithium-ion batteries are a huge improvement over previous types of batteries. Getting 500 charge/discharge cycles from a lithium-ion battery is not unheard of. Just follow the above guidelines.

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Which battery is better polymer or lithium?

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Lithium Ion vs. Lithium Polymer Batteries – Which Is Better?

Lithium-ion or lithium-polymer? The (what seems like) endless debate on batteries in modern consumer electronics. Today, we’re going to talk about the differences between these battery types. While we may not be able to settle the score once and for all on which is better. we hope to give you the information you need to make the best possible choice!

What’s the Difference?
A lithium-ion battery is a rechargeable battery format that first grew in popularity thanks to their adoption by major electronics companies in the early 1990s. They are essentially a group of very rigid electricity generating compartments, which consists of three pieces: a positive electrode; a negative electrode; and an electrolyte, or liquid chemical compound between them. Most lithium-ion batteries, unlike more traditional ones, also include an electronic controller, which regulates power and discharge flows so your battery doesn’t overheat or explode.

The most significant difference between lithium-ion and lithium-polymer batteries is the chemical electrolyte between their positive and negative electrodes. In Li-Po batteries it isn’t a liquid. Instead, Li-Po technology uses one of three forms: a dry solid, which was largely phased out during the prototype years of lithium polymer batteries; a porous chemical compound; or, a gel-like electrolyte. The most popular among these is the last one, which is the type of battery you’ll find in newer laptop computers and electric cars. The catch is that plenty of companies are not actually selling you a true Li-Po battery, instead it’s a lithium-ion polymer battery, or a Li-ion in a more flexible casing.

Is One Better than the Other?
Both lithium-ion and lithium-polymer batteries have their pros and cons. Typically, the advantages of a lithium-ion is their high power density, lack of what’s called the memory effect (when batteries become harder to charge over time), and their significantly lower cost than lithium-polymer. In the words of Wired, “Lithium-ion batteries are incredibly efficient. They stuff freakish amounts of energy in a tiny package.” But, as anyone might have seen with the recent saga of a certain cellphone brand being banned from flights, lithium-ion batteries are inherently unstable, suffer from aging, and are potentially dangerous. If the barrier that separates the positive and negative electrode is ever breached, the chemical reaction can cause combustion (fire). As Li-ion batteries have become more popular in consumer electronics, businesses have tried to lower costs by cutting corners. While quality batteries are perfectly safe, you should always be careful when buying no-name brands.

Lithium-polymer batteries, on the other hand, are generally robust and flexible, especially when it comes to the size and shape of their build. They are also lightweight, have an extremely low profile, and have a lower chance of suffering from leaking electrolyte. But lithium-polymer batteries aren’t perfect either: they are significantly more costly to manufacture, and they do not they have the same energy density (amount of power that can be stored) nor lifespan as a lithium-ion.