Tag Archives: Batteries

Tiny Batteries Drive Microbots

Microbots are mobile robots, with characteristic dimensions below one micrometer. They are a part of the bigger family of common larger robots and a growing number of smaller nanorobots. In fact, the nature of microbots is common to both their larger and smaller cousins. Being autonomous, microbots use their onboard computers to move in insect-like maneuvers. Often, they are a part of a group of identical units that perform as a swarm does, under the control of a central computer.

With their insect-like form being a common feature, microbots are typically cheap to develop and manufacture. Scientists employ microbots for swarm robotics, using many of them and coordinating their behavior to perform a specific task. Combining many microbots compensates for their lack of individual computational capability, producing a behavior resembling that of an anthill or a beehive where insects cooperate to achieve a specific purpose.

With the field of microbotics still growing, microbots have a long way to develop further. Researchers are working with these devices, and they are investing their money, time, and effort in improving their capabilities.

With each new iteration, scientists are empowering microbots with more processing power, newer modes of locomotion, a larger number of sensors, and expanding their storage methods while providing them with newer techniques of energy harvesting. Recently, there has been a big breakthrough in tiny batteries that can help microbots drive further than ever before.

Generating a 9 VDC output, these tiny batteries are capable of driving motors directly. They stack multiple layers while turning components into packaging.

Several universities and a battery corporation have joined hands in creating the tiny batteries, a novel design that not only produces a high voltage but also boosts its storage capacity.

To unlock the full potential of microscale devices such as microbots, batteries must not only be tiny, they must also be powerful. According to the team that developed the tiny battery, its innovative design uses an improved architecture for its electrodes.

However, this was an unprecedented challenge. As the battery size reduces, the packaging begins to take up more of the available space, leaving precious little for the electrodes and the active ingredients that give the battery its performance.

Therefore, in place of working on the battery chemistry, the team started to work on a new packaging technology. They turned the negative and positive terminals of the battery into actual packaging, thereby saving considerable amounts of space.

By growing fully-dense non-polymer electrodes and combining them with vertical stacking, the team was able to make micro batteries that do not require carbon additives for electrodes. This allowed the micro batteries to easily outperform competitive models in capacity and voltage.

According to the team, limitations of power-dense micro- and nano-scale battery design were primarily due to cell design and electrode architecture. They have successfully created a microscale source of energy that has both volumetric energy density and high power density.

The higher voltage helps to reduce the electronic payload of a microbot. The 9 VDC from the tiny battery can power motors directly, bypassing energy losses associated with voltage boosting, allowing the small robots to either travel further or send more information to their human operators.

Monitoring Battery Health

The prolific use of battery-powered instruments for regular use in the consumer and industrial fields requires monitoring battery health for proper functioning. Usually, a battery health monitoring system uses a microcontroller and a software user interface. This arrangement monitors all the batteries in a battery bank 24×7 and identifies weak batteries before they actually fail. This helps to improve the overall performance of the system. Stationary applications such as data centers commonly use such battery health monitoring systems.

In vehicles too, it is necessary to have precise and reliable information about the state of health and state of charge of the battery. Battery health is sensitive to temperature, and conventional trucks and buses with diesel engines also frequently fail during winter and autumn. Now, vehicle fleets use solutions for monitoring battery health and the fleet manager does this in a centralized manner.

Analog Devices Inc. presents a solution for monitoring the state of health of primary batteries. The LTC3337 from Analog Devices provides information such as battery cell impedance, voltage, discharge, and temperature. The data from LTC3337 is not only accurate, but the readings are in real-time.

For monitoring the state of health of the battery in real-time, the user must place the LTC3337 in series with the battery terminals. Analog Devices ensure that the series voltage drop is negligibly small when the IC is in series with the battery. Analog Devices has integrated an infinite coulomb counter with a dynamic range to tally all the accumulated battery discharges. LTC3337 stores this information in an internal register which the user can access through an I2C interface. The user can program a discharge alarm with a threshold based on this state of charge. As soon as the state of charge crosses this threshold, the IC generates an interrupt at its IRQ pin. The accuracy of the coulomb counter is constant down to a no-load condition on the battery.

Analog Devices has designed the LTC3337 to be compatible with a wide range of primary batteries with varying voltages. For this, the user can select the peak input current limit of the LTC3337 from 5 mA to 100 mA.

The user can calculate the coulombs from either the BAT IN or BAT OUT pin of the LTC3337—the AVCC pin connection decides this. Some applications require using supercapacitors at the output of the IC. Analog Devices has provided a BAL pin for connecting a stack for supercapacitors for the purpose.

Analog Devices offers LTC3337 as an LFCSP or Lead Frame Chip Scale Package with 12 leads. There is an exposed pad for improving its thermal performance.

The LTC3337 can withstand a voltage range of 5.5 VDC to 8.0 VDC at its input. Its quiescent current is as low as 100 nA. The user can preset the peak input current limits depending on the type of the primary battery. The presents are 5, 10, 15, 20, 25, 50, 75, and 100 mA levels.

LTC3337 is meant for monitoring the state of health of batteries in low-power systems powered by primary batteries. It is very helpful for batteries providing backup and supplies in keep-alive scenarios.

Batteries without Mass

Electric vehicles use various types of batteries to operate. But all of them have one thing in common—the weight of the batteries. Depending on the size of the vehicle, the battery weight is a significant part of the total weight of the vehicle. As a vehicle must carry its batteries along with it, it is unable to fully utilize its total capacity. Engineers and scientists are researching various ways of reducing the battery weight while enhancing its energy density.

Some scientists are thinking in more innovative ways. For instance, scientists in Sweden claim to have developed a structural battery. The advantage of such a battery is it is purportedly stored without mass, as its weight is actually a part of the load-bearing structure. With an energy density of 24 Wh/kg, the design of the battery allows solar-powered vehicles to integrate it easily.

At the Chalmers University of Technology in Sweden, scientists claim to have developed a structural battery. The construction primarily uses carbon fiber, and apart from the structure of the battery, the carbon fiber also acts as a load-bearing material, conductor, and electrode.

Structural batteries use materials with properties of electrochemical energy storage. The primary aim of such devices is to reduce the weight of an object, as the manufacturer can embed the battery to be a part of the structure of the object, such as a drone or an electric vehicle.

According to the scientists, they had started research and developing their massless batteries in 2007. Their main challenge had been to build devices that had good mechanical and electrical properties. They settled on carbon fibers for their battery, as it has the required strength and stiffness to allow integration into structures of electric vehicles. In addition, carbon fibers also exhibit good storage properties.

The scientists claim their batteries may also be applicable to the roof of light city vehicles such as rickshaws. The roof of these vehicles may have solar cells.

The batteries have a structural battery electrolyte matrix material, housing a negative electrode made of carbon fiber, and a positive electrode supported with aluminum film. A glass fiber separator keeps the two electrodes apart.

Apart from reinforcing the material, the carbon fiber also helps to conduct electrons while acting as a host for Lithium. In the same way, the positive electrode foil, apart from providing electrical functionality, also provides mechanical support.

The structural battery electrolyte favors the transport of Lithium ions while transferring mechanical load between the fibers of the device, its particles, and plies. The scientists demonstrated a battery with an elastic modulus of 25 Gpascals and a tensile strength that exceeded 300 Mpascals. While the elastic modulus demonstrates the resistance of the material to elastic deformation, the tensile strength demonstrates the maximum load that the material can support without damage.

With an energy density of 24 Wh/kg, the battery has about twenty percent capacity relative to presently available lithium batteries. However, as the battery reduces the weight of the vehicle significantly, the electric vehicle requires much less energy. Additionally, the lower energy density results in increased safety for the vehicle and its passengers.

Smart Batteries with Sensors

Quick-charging batteries are in vogue now. Consumers are demanding more compact, quick-charging, lightweight, and high-energy-density batteries for all types of electronic devices including high-efficiency vehicles. Whatever be the working conditions, even during a catastrophe, batteries must be safe. Of late, the Lithium-ion battery technology has gained traction among designers and engineers as it satisfies several demands of consumers, while at the same time being cost-efficient. However, with designers pushing the limits of Li-ion battery technology capabilities, several of these requirements are now conflicting with one another.

While charging and discharging a Li-ion battery, many changes take place in it, like in the mechanics of its internal components, in its electrochemistry, and its internal temperature. The dynamics of these changes also affect the pressure in its interface within the housing of the battery. Over time, these changes affect the performance of the battery, and in extreme cases, can lead to reactions that are potentially dangerous.

Battery designers are now moving towards smart batteries with built-in sensors. They are using piezoresistive force and pressure sensors for analyzing the effects charging and discharging have on the batteries in the long run. They are also embedding these sensors within the battery housing to help alert users to potential battery failures. Designers are using thin, flexible, piezoresistive sensors for capturing relative changes in pressure and force.

Piezoresistive sensors are made of semi-conductive material sandwiched between two thin, flexible polyester films. These are passive elements acting as force-sensitive resistors within an electrical circuit. With no force or pressure applied, the sensors show a high resistance, which drops when the sensor has a load. With respect to conductance, the response to a force is a linear one as long as the force is within the range of the sensor’s capabilities. Designers arrange a network of sensors in the form of a matrix.

When two surfaces press on the matrix sensor, it sends analog signals to the electronics, which converts it into a digital signal. The software displays this signal in real-time to offer the activity occurring across the sensing area. The user can thereby track the force, locate the region undergoing peak pressure, and identify the exact moment of pressure changes.

The matrix sensors offer several advantages. These include about 2000-16000 sensing nodes, element spacing as low as 0.64 mm, capable of measuring pressure up to 25,000 psi, temperature up to 200 °C, and scanning speeds up to 20 kHz.

Designers also use single-point piezoresistive force sensors for measuring force within a single sensing area. They integrate such sensors with the battery as they are thin and flexible, and they can also function as a feedback system for an operational amplifier circuit in the form of a voltage divider. Depending on the circuit design, the user can adjust the force range of the sensor by changing its drive voltage and the resistance of the feedback. This allows the user complete control over measuring parameters like maximum force range, and the measurement resolution within the range. As piezoresistive force sensors are passive devices with linear response, they do not require complicated electronics and work with minimum filtering.

Wireless Charging and Electric Vehicles

In our daily lives, we are increasingly using wireless products. At the same time, researchers are also working on newer trends in charging electric vehicles wirelessly. With more countries now implementing regulations for fuel economy and pushing initiatives for replacing fossil-fuel based vehicles with those driven by electricity, automotive manufacturers have focused their targets on development of electric vehicles. On one hand there are technological advancements on lithium-ion batteries and ultra-capacitors, while on the other, researchers are working on infrastructure and the availability of suitably fast charging systems that will lead to a smoother overall transition to the adoption of electric vehicles.

Charging the batteries of a vehicle requires charging systems using high power conversion equipment. They convert the AC or DC power available from the power supply sources into suitable DC power for charging. As of now, the peak power demand from chargers is of the order of 10-20 KW, but this is likely to climb up depending on the time available for charging, and the advancements made in capabilities for battery charging. Therefore, both governments and OEMs are gearing up for developing high-power charging systems to cater to the power needs of future electric vehicles.

Wireless charging systems transfer power from the source to the load without the need for a physical connection between the two. Commonly available schemes use an air-cored transformer—with power transfer taking place without any contact between the source and the load. Wireless power transfer technology is available in various ranges, starting from mobile power charger systems rated for 10s of watts, to high power fast chargers for electric vehicles rated for 10s of kilowatts.

Earlier, the major issues with wireless charging systems were their low efficiency and safety. The technology has now progressed to the stage where achieving efficiencies of over 80% is commonplace. Although this is on par with wired power charger systems, increasing the spacing between the primary and secondary coils allows the efficiency to drop exponentially, which means the efficiency improves as the spacing between the coils decreases. Researchers are also looking at adopting various other methods of constructing the coils to address the issue.

Likewise, smart power controls are taking care of safety, by detecting power transfers taking place spuriously and suspending power transmission directly. Manufacturers are ensuring safety at all stages by implementing regulatory guidelines such as SAE J2954.

Although several methods exist for wireless power transfer, most popular are the resonance and inductive transfer methods. The inductive method of power transfer uses the principles of the transformer, with the AC voltage applied to the primary side inducing a secondary side voltage through magnetic coupling, and thereby transferring power.

The inductive method of power transfer is highly sensitive to the coupling between the primary and secondary windings. Therefore, as the distance increases, the power loss also increases, reducing the efficiency. That restricts this method to low power applications alone.

Based on impedance matching between the primary and the secondary side, the design of a resonant method allows forming a tunnel effect for transferring magnetic flux. While minimizing the loss of power, this method allows operations at higher efficiency even when placing the coils far apart, making it suitable for transferring higher levels of power.

What is an Instantly Rechargeable Battery?

The batteries required to power them have so far impeded advancement of electric cars. A primary difference between vehicles powered by fossil fuels and those powered by batteries is that batteries tend to discharge with use and require a finite time to recharge, immobilizing the vehicle for that period. On the other hand, simply filling up the gas-tank with fossil fuel is enough to keep the car rolling on the road. However, that may be changing now.

Research at the Purdue University has led to the development of a new type of battery that can be recharged instantly. The new battery is also affordable, safe, and environmentally friendly. Presently, the viability of electric vehicles hinges on the availability of charging ports in convenient locations. However, the new battery technology allows drivers of hybrid and electric vehicles to charge up very quickly and easily similar to what the drivers of conventional cars do at a gas station.

This breakthrough will definitely boost the switching to electric cars. Not only does the new technology make it more convenient to drive electric cars, but it also reduces substantially the total infrastructure necessary for charging electric cars. Researchers, both professors and doctoral students, from the Purdue University have co-founded IF-Battery LLC for developing and commercializing the technology.

The new battery is a flow type and does not require to be charged at an electric charging station—it is enough to replace the fluid electrolyte of the battery. This is very similar to filling up the gas tank. The fluids from the spent battery can be collected and recharged at any hydroelectric, wind, or solar plant. Therefore, when an electric car using this new battery arrives at the refueling station, the driver can simply deposit the spent fluids for recharging, while filling up his or her battery with new fluids just as he or she might fill gas in a traditional car.

The difference between this flow battery and those developed earlier so far is this new battery does not have any membrane. The membranes other flow batteries use are expensive and vulnerable to fouling. Not only does membrane-fouling limit the number of recharge cycles of the battery, but can also contribute to a fire. Components used in the IF-Battery are safe to store in a family home, and are stable enough so major production and distribution centers can use them, and are cost effective.

In place of building several charging stations, it would be far simpler to transition the existing gas-station infrastructure for accommodating cars using the new battery system. As the battery chemicals are very safe, existing pumps could even be used to dispense these chemicals.

Although sale of electric and hybrid vehicles are growing worldwide, industry and consumers alike are facing the challenge of extending the life and charge of the battery and the infrastructure necessary to charge the vehicle.

At this time, the researchers need more time to complete their research before they can bring the technology to regular use. The researchers are trying to draw interest from investors and working towards publicizing their innovation.

Battery Monitoring with Comparators

So many portable consumer electronics gadgets in use today use small, button- or coin-cell batteries. Sometimes it is necessary to monitor their state-of-charge (SOC) and health efficiently without affecting their SOC significantly, but this can be a challenge. However, simple low-power monitoring circuits for small batteries using comparators can overcome this challenge.

Managing Batteries in Portable Systems

Usually, the system engineer budgets the system power requirements carefully during the system design. A micro-controller or microprocessor within the gadget is the actual brains that manages the system reliably and performs the required functions. Since it is typical for the controller to be power-hungry, as it is the workhorse of the system, there is not much sense in making the controller do all the work. To prevent unnecessary power dissipation, the controller is designed to remain asleep for extended periods, only waking up when flags are presented on the GPI pins.

Therefore, engineers resort to using low-power circuits for continually monitoring the vital functions of the system. When these circuits detect an event, they flag the micro, usually in the form of interrupts. The micro then wakes up to perform its required duty. One of the vital functions of such circuits is to monitor the state of the battery. When the battery voltage dips below the pre-defined threshold, it means it has discharged and requires charging. Likewise, as soon as the battery voltage crosses another pre-defined threshold, it means it is completely charged with no further requirement of further charging. Similarly, it is important to monitor the case temperature of the battery and the ambient temperature, as this provides much information about the loading conditions on the battery, and the presence of a fault.

Using Comparators for Monitoring

Although there are sophisticated battery monitors with fuel gauges, and monitoring battery voltage and temperature with an analog-to-digital converter is possible, these essentially require careful tradeoffs with portable gadgets. A designer must consider form factor, cost, accuracy, speed, and power consumption when creating the design, as different systems may have different priorities.

It is possible to have a simple comparator monitoring the voltage at the battery terminals. For a fully charged battery, the output voltage of the comparator transitions from high to low and from low to high for indicating a fully discharged battery. When implemented with external hysteresis, thresholds can be pre-defined to yield the proper output states.

The comparators can be tiny-footprint devices with internal references, consuming very low quiescent currents. When large-value resistors are used in the circuit, the overall operating current will be comparable to the typical self-discharge rate of the battery. By designing the circuit to operate from a low supply voltage of about 1.7 V and consuming less than 2 µA of current, the circuit will be able to produce the proper output state even when the battery has only a minimum charge remaining.

The component values necessary to realize the application for battery state monitoring must be selected with care. The determined threshold value should provide a narrow band of hysteresis to allow for more cushion for component variation and tolerances. Using resistors with 0.5% makes the circuit work with ±1% accuracy.

Boosting Battery Life in IoT Devices

Earlier, the assumption was unused energy from the environment, machines, people, and so on could be used to power valuable devices and this would be done for free. The assumption was based on the convergence of four key technologies to enable mass adoption of energy harvesting—efficient voltage converters, efficient harvesting devices, low-power sensors, and low-power microcontrollers. However, it was soon realized that although energy harvesting does operate for free, the system needs investment, which is not free. That has led to the thinking that perhaps energy harvesting may not be the right technology for powering smart energy applications.

Now, with the growth of IoT devices, more sophisticated sensors, more pervasive connectivity, and secure, low-power microcontrollers, there are more devices to be powered than ever before. With most devices being small and battery powered, design engineers are facing challenges such as energy efficiency and long battery life.

In reality, it is no longer worthwhile using sensors for measuring and analyzing the energy consumption of individual light bulbs, since the cost of such a system would be more compared to the energy cost to run the lamp. In addition, there are numerous low-energy-consuming light sources available.

Development of engineering systems now place more emphasis on maximizing performance and saving energy. This is because most IoT devices spend a significant part of their life sleeping or hibernating, where the part is neither operating nor completely shut down. In this state, the device is actually drawing quiescent current, and this places the maximum impact on battery life, as it contributes to the standby power consumption of the system.

The development of nanoPower technology has led to great advancements in maximizing performance and saving energy. Newer products, with advanced analog CMOS process technology, now operate in their quiescent state with nanoampere currents that are almost immeasurable. The trick in maximizing energy-saving benefits from these products is first by duty-cycling them, and secondly by decentralizing the power-consuming architecture.

Benefits of nanoPower technology also extend to their ability to turn off circuits within the system. For instance, the nanoPower architecture may allow powering critical components such as real-time clocks and battery monitoring, while cutting off power to major consumers such as the RF circuits and the microcontroller, which can either turn off or enter their lowest power-consumption mode.

System monitoring ICs play a huge role here with their small packages and nanoamp quiescent current levels. Comparators, op amps, current sense amplifiers, and more help ensure important issues such as the voltage levels on microcontrollers are at proper levels. For instance, a nanoPower window comparator monitors the battery voltage and provides an alert if the battery voltage goes beyond allowable levels. Apart from being a valuable safety function, this also helps to extend the battery life, as the microcontroller need not operate until it has received an alarm from the comparator.

Another power-saving scheme is OR-ing the battery supply with voltage from a wall wart or an additional battery, using OR-ing diodes. These are Schottky diodes in series with the battery supply for limiting the voltage drop. For instance, MAX402000 diodes can save tens to hundreds of milliWatts of battery power when used in a smart way.

A Cheaper Alternative for Batteries—Sodium Ion

A vast majority of electronic equipment running on batteries rely on the Lithium-ion technology for their electrode material. Since Lithium is relatively rare, its mining and refining make it an expensive material to use. This has led scientists to search for a cheaper alternative, and they have turned to the cheapest substance available, the common salt. A team from Stanford has developed a battery based on Sodium-ion whose cost per storage capacity is far lower than that of the existing batteries based on Lithium-ion.

Salt, being nearly omni-present in our oceans, together with its ability to carry charge, is a near-perfect candidate for low-cost energy storage. Many forms of Sodium-based batteries are now available, some with a unique design of anode made from a carbonized oak leaf to a more standard format for use in laptops. According to the lead researcher of the Stanford study, Zhenan Bao, although Lithium offers a superior performance, its rarity and high cost is leading people to search for materials such as Sodium to build low-cost but high performance batteries.

The research team uses a battery with Sodium salt cathode and a Phosphorous anode—materials that are abundant in nature. Near the cathode, Sodium ions combine with oppositely charged myo-inositol ions. To improve the charge-recharge cycle, the researchers had to study the forces at work at atomic-level, when Sodium ions detach and attach from the cathode.

The newly developed Sodium-ion battery has a reversible capacity of 484 mAh/gm, which translates to an energy density of 726 Wh/Kg. The research team claims the energy efficiency of the new batteries to be greater than 87%. Regarding the cost comparison between similar storage capacity batteries, the team says the new Sodium-ion battery will cost less than 80% of the cost of a Lithium-ion battery of similar storage capacity.

To obtain more performance from the Sodium-ion battery, the research team is planning to work more on its phosphorous anode. In addition, to be able to dictate the size of the Sodium-ion battery necessary to store a certain amount of energy, the team also plans to examine the volumetric energy density in comparison to that of Lithium-ion batteries.

Faradion Limited, of Sheffield, UK, has developed Sodium-ion technology that offers energy densities in batteries far exceeding those of other known Sodium-ion technologies. In addition, their new technology produces energy densities that exceed those from popular Lithium-ion materials such as Lithium iron phosphate. Faradion makes current collectors in their Sodium-ion batteries from Aluminum rather than from the more expensive copper that Lithium cells use.

According to electrochemical tests Faradion has conducted, they list the advantages of the Sodium-ion materials over conventional Lithium-ion materials as follows—better rate capability, better thermal stability (safer), improved transport safety, improved cycle life, and similar shelf life. Further, Sodium-ion material processing is similar to that followed for Lithium-ion materials at every step, beginning from synthesis of the active materials to the processing of electrodes.

Innovate UK co-funds a project for Williams Advanced Engineering, where the novel Sodium-ion technology from Faradion is currently being employed to build 3 Ah prismatic cells. Williams is further incorporating these cells into batteries for commercial use.

Super Efficient Diamond Batteries from Nuclear Waste

So far, we have been dumping our dangerous nuclear waste into oceans or deep inside the earth, hoping they will stay there. Now, there is a better way out. Scientists are now confident they can use nuclear waste as a source of energy to convert radioactive gas into diamonds of the artificial type, not as jewelry, but to be used as batteries.

Scientists claim the diamonds can generate their own electrical current. As they are made of radioactive material with long half-life, the batteries could potentially provide power for thousands of years. According to Tom Scott, a geochemist from the University of Bristol in the UK, the batteries will simply produce direct current, without emissions, and without requiring any moving parts or maintenance.

The radioactive material, encapsulated within a diamond, will turn the long-term problem of handling nuclear waste into a nuclear powered battery producing a long-term supply of clean energy. As a demonstration of their claims, Scott’s team has developed a prototype diamond battery using an unstable isotope of Nickel-63 as its source of radiation.

The half-life of Nickel-63 is approximately 100 years. That means after 100 years, the prototype battery would still be retaining about 50 percent of its original charge. However, the scientists claim they have an even better source for making these batteries. They want to use the huge quantities of nuclear waste generated and stockpiled by UK.

From the 1950s through the 1970s, the first generation of Magnox nuclear reactors in the UK used graphics blocks to sustain nuclear reactions. However, the graphite blocks turned radioactive and generated an unstable carbon isotope, the Carbon-14.

Although UK had retired the last of these Magnox reactors by 2015, the decades of power generation has left a huge amount of nuclear byproduct as waste—nearly 95,000 tons of radioactive graphics blocks need to be safely stored and monitored.

Additionally, as Carbon-14 has a half-life of 5,730 years, UK may have to take care of this dangerous waste for a long, long time. However, it also means this material could be used to make batteries that last an amazingly long time—provided scientists could repurpose them into the diamond structure, just as they did with Nickel-63.

Carbon-14 emits only short-range radiation, one quickly absorbed by any nearby solid material. According to Neil Fox, one of the researchers, although touching or ingesting Carbon-14 would be dangerous, encasing it within diamond would prevent any short-range radiation from escaping. Moreover, diamond would offer the ultimate protection, as it is the hardest substance known to man.

The team presented their ideas at a lecture at the University of Bristol, but has yet to publish their research. The researchers claim that although Carbon-14 batteries would be good for low-power applications, their endurance would be on an entirely different scale.

For instance, an alkaline battery weighing 20 grams has an energy density of 700 Joules/gram, giving a life of 24 hours of continuous usage.

On the other hand, a diamond battery with 1 gram of C-14 will deliver only 15 Joules per day. However, it will continue to produce this level of output for more than 5,730 years—giving a total energy density of 2.7 TeraJoules/gram.