Category Archives: Batteries

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.

3-D Electrodes in Solid-State Batteries

Addionics is an Israeli startup in the rechargeable business. It is recently engaging in redesigning the battery architecture with respect to its electrode technology. The company wants to replace the regular 2-D electrode layer structure in traditional batteries. They want to integrate a 3-D electrode structure. They claim this will provide greater power and energy density, while also extending the life of the battery.

Addionics has five commercial projects lined up. They are presently targeting automotive applications with leading suppliers. The aim of each of these projects is to focus on different battery chemistries and integrate them with the smart 3-D electrode structure. The chemistries they are targeting are solid-state batteries, lithium polymer batteries, silicon anode batteries, lithium iron phosphate batteries, and lithium nickel manganese cobalt oxide batteries.

With the global economy striving towards electrification due to rising greenhouse gas emissions and climate change, the need for replacing renewable energy use, energy storage, and EV adoption is increasing. However, this can succeed only if there are batteries available that are more efficient, safe, and cost-effective.

Scientists all over are devoting huge efforts and expenditures to developing the next generation of batteries. They typically focus on battery chemistry, new chemicals, and unique chemical formulations. This includes lithium-metal and lithium-sulfur.

They are also trying to make current batteries either store more energy or charge/discharge at a faster rate. However, current batteries available in the marketplace today do not have the capacity to deliver both quick charging and extended range for EV applications.

There is also a challenging mismatch between the anode and cathode in current batteries. Addionics is striving to improve battery performance with their technology. They claim their 3-D electrode technology will improve battery performance irrespective of battery chemistry, and do so without increasing the battery price.

Although solid-state batteries hold plenty of promises, their major problem is the mismatch in the anode and cathode capacity. The new technology from Addionics has the advantage of not only solving the electrode mismatch but also providing a solid-state battery with higher energy and more stable performance.

Traditionally, battery electrodes are a 2-dimensional structure, made of dense metal foils with the active material as a layer on the top. However, this 30-year-old design is no longer able to meet the growing demands of performance.

The new 3-D electrode structure lowers the internal resistance of the battery, even at higher loads, as it has the active material integrated throughout the electrode. This increases the active surface area of the battery cell architecture and improves the properties of the electrodes, leading to lower heat generation, less material expansion, improved conductivity, and enhanced energy density in the battery.

The company claims that its new 3-D electrode technology offers significant advantages for any existing or emerging battery chemistry. They claim their new electrodes can reduce the charging time, extend its drive range, and improve the safety and lifetime of the battery. Moreover, the new electrodes do not change the battery size or its components. They also claim their new technology significantly lowers the manufacturing costs of any battery, irrespective of the battery chemistry.

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.

New Battery Technology for UPS

Most people know of the Lithium-ion battery technology in use mainly due to their overwhelming presence in mobile sets. Those who use uninterruptible power supplies for backing up their systems are familiar with the lead-acid cells and the newer lithium-ion cells. Another alternative technology is also coming up mainly for mission-critical facilities such as for data centers. This is the Nickel-Zinc technology, and it has better trade-offs to offer.

But the Nickel-Zinc battery technology is not new. In fact, Thomas Edison had patented it about 120 years ago. In its current avatar, the Nickel-Zinc battery offers superior performance when used in UPS backup systems. They offer better power density, are more reliable, safe, and are highly sustainable.

For instance, higher power density translates into smaller weight and size. This is the major difference between a battery providing energy and a battery providing power. In a data center, the UPS must discharge fast for a short period for maintaining operational continuity. This is what happens during brief outages, or until the backup generators spin up to take over the load. This is the most basic power battery operation, where the battery must deliver a high rate of discharge, and it does so with a small footprint.

On the other hand, Lead-acid and Lithium-ion technologies offer energy batteries. Their design allows them to discharge energy at a lower rate for longer periods. Electric vehicles utilize this feature, and the automotive industry is spending top dollars for increasing the energy density of such EV batteries so that the user can get more mileage or range from their vehicles. This is not very useful for data center backup, as the battery must have a higher energy storage footprint for supporting short duration high power output requirements.

This is where the Nickel-Zinc battery technology comes in. With an energy density nearly twice that of a Lead-acid battery, Nickel-Zinc batteries take up only half the space. Not only is the footprint reduced by half, but the weight also reduces by half for the same power output. As compared to Lithium-ion batteries, Nickel-Zinc batteries not only excel in footprint reduction, but they charge at a faster rate while retaining thermal stability. This feature makes them so useful for mission-critical facility uptime.

Nickel-Zinc batteries have proven their reliability as well. They have clocked over tens of millions of operating hours for providing uninterrupted backup power in mission-critical applications. Another feature very useful for data center operations is the battery string operations of the Nickel-Zinc technology.

When a Lithium-ion or a Lead-acid battery fails, the battery acts as an open circuit, preventing other batteries in the string from transferring power. On the other hand, a weal or a failed Nickel-Zinc cell remains conductive, allowing the rest of the string to continue operations, with a lower voltage. In emergency situations, this feature of the Nickel-Zinc battery is extremely helpful, as the faulty battery replacement can proceed with no operational impact and at a low cost.

In parallel operation also, Nickel-Zinc batteries are more tolerant of string imbalances, thereby maintaining constant power output at significantly lower states of health and charge as compared to batteries of other technologies.

Battery Electrolyte from Wood

Although there exist several types of batteries, all of them function with a common concept—batteries are devices that store electrical energy as chemical energy and convert this chemical energy into electricity when necessary. Although it is not possible to capture and store electricity, it is possible to store electrical energy in the form of chemicals within a battery.

All batteries have three main components—two electrodes or terminals made of different metals, known as anode and cathode, and the electrolyte separating these terminals. The electrolyte is the chemical medium allowing the flow of electrical charges between the terminals inside the battery, When a load connects to a battery, such as an electrical circuit or a light bulb, a chemical reaction near the electrodes creates a flow of electrical energy through the load.

The most commonly used battery today, the lithium battery, typically uses a liquid electrolyte for carrying electrical charges or ions between its electrodes. Scientists are also looking at alternatives like solid electrolytes for future opportunities. A new study offers cellulose derived from wood as one type of solid electrolyte. The advantage of this solid electrolyte from wood is its paper-thin width, allowing the battery to bend and flex for absorbing stress while cycling.

The electrolyte presently in use today in lithium cells has the disadvantage of containing volatile liquids. There is thus a risk of fire in case the device short-circuits. Moreover, there is the possibility of the formation of dendrites—tentacle-like growths—and this can severely compromise the battery’s performance. On the other hand, solid electrolytes, made from non-flammable materials, allow the battery to be less prone to dendrite formation, thereby opening up totally modern possibilities with different battery architecture.

For instance, one of these possibilities involves the anode, one of the two electrodes in the battery. Today’s batteries usually have an anode made from a mix of copper and graphite. With solid electrolytes, scientists claim they can make the battery work with an anode made from pure lithium. They claim the use of pure lithium anode can help to break the bottleneck of energy density. Increased energy density will allow planes and electric cars to travel greater distances before recharging.

Most solid electrolytes that scientists have developed so far are from ceramic materials. Although these solid electrolytes are very good at conducting ions, they cannot withstand the stress of repeated charging and discharging, as they are brittle. Scientists from the University of Maryland and Brown University were seeking an alternative to these solid electrolytes, and they started with cellulose nanofibrils found in wood.

They combined the polymer tubes they derived from wood with copper. This formed a solid ion conductor with conductivity very similar to that in ceramics, and much better than that from any other polymer ion conductor. The scientists claim this happens as the presence of copper creates space within the cellulose polymer chains allows the formation of ion superhighways, enabling lithium ions to travel with substantially high efficiency.

With the material being paper-thin and thereby highly flexible, scientists claim it will be able to tolerate the stresses of battery cycling without damage.

A Bending and Stretching Battery

All electrical and electronic equipment we use in our daily lives requires power to operate. Movable equipment depends on batteries for their mobility. We are used to various types of batteries, like dry cells, lead-acid batteries, rechargeable Ni-Cd and Li-Ion batteries, and so on. However, all the batteries in common use are rigid, non-flexing structures. That may be changing now, as some researchers have claimed to have created a battery that is flexible and stretchable like a snake but unlike a snake, totally safe for humans.

Researchers in Korea claim to have developed a new type of battery that is flexible and stretchable with smooth movements imitating the movements of scales on a snake’s body. However, they have issued assurances that the battery is totally safe for use. This flexible and stretchable battery has a range of applications in contoured devices like wearables and soft robotics.

Although individual scales on the body of a snake are rigid, they can fold together to offer protection against enemies and external forces. The structural characteristics of the scales allow them to move alongside other scales, offering flexibility and stretching capabilities to the snake’s body. At the Korea Institute of Machinery and Materials, researchers from the Ministry of Science and ICT decided to replicate the reptilian characteristics in a mechanical meta structure.

Most conventional wearable devices have the battery in a tight formation with the frame. The new device has several small and rigid batteries in series and parallel connections within a scale-like structure. The researchers ensure the safety of the battery by optimizing its structure so that there is minimum deformation of each battery. They have even optimized the shape of each cell in the battery to offer the highest capacity per unit area.

The connective components and the shape of the battery cell hold the key to this unique device. Each cell is a small hexagonal, resembling the scale on a snake. The researchers have connected each cell with polymer and copper, and there is a hinge mechanism to allow folding and unfolding.

With an aim to mass production in the future, the researchers claim the batteries can be cut and folded with flexible electrodes, with Origami inspiring their manufacturing process.

Wearable devices for humans requiring soft and flexible energy storage can make the best use of these flexible batteries. Another application might be in rehabilitation medical devices for the sick and elderly requiring physical assistance. Soft robots can make use of these flexible batteries as power supply devices at disaster sites when conducting rescue missions. With their ability to freely change shape and move flexibly, these soft robots can move through blocked narrow spaces unhindered by flexible batteries.

Senior researcher, Dr. Bongkyun Jang co-led the research team has commented that mimicking the scales of a snake helped the researchers to develop a flexible battery, making it stretchable and safe to use. The researchers hope that in the future they can develop more soft energy storage devices while boosting their storage capacity. They also hope to develop multi-functional soft robots offering a combination of artificial muscle with actuation technology.

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.