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What is a Battery Management System (BMS)?

Himax - Battery-Bms

Battery-Bms

The power output depends on the battery, and the battery management system (BMS) is the core of it. It is a system for monitoring and managing the battery. It controls the charge and discharge of the battery by collecting and calculating parameters such as voltage, current, temperature, and SOC. The process, the management system that realizes the protection of the battery and improves the overall performance of the battery is an important link between the battery and the battery application equipment.

BMS mainly includes three parts: hardware, bottom layer software, and application layer software.

The hardware of the battery management system (BMS)

1. Architecture

The topology of Battery Management System(BMS) hardware is divided into two types: centralized and distributed.

(1) The centralized type

The centralized type is to concentrate all the electrical components into a large board, the sampling chip channel utilization is the highest and the daisy chain communication can be adopted between the sampling chip and the main chip, the circuit design is relatively simple, the product cost is greatly reduced, but All the collection wiring harnesses will be connected to the mainboard, which poses a greater challenge to the security of the BMS, and there may also be problems in the stability of the daisy chain communication. It is more suitable for occasions where the battery pack capacity is relatively small and the module and battery pack types are relatively fixed.

(2) The Distributed type

Distributed includes a mainboard and a slave board. It is possible that a battery module is equipped with a slave board. The disadvantage of this design is that if the number of battery modules is less than 12, the sampling channel will be wasted (generally there are 12 sampling chips. Channel), or 2-3 slave boards to collect all battery modules. This structure has multiple sampling chips in one slave board. The advantages are high channel utilization, cost-saving, flexibility in system configuration, and adaptation to different capacities. Modules and battery packs of different specifications and types.

2. Function

The hardware design and specific selection should be combined with the functional requirements of the vehicle and battery system. The general functions mainly include collection functions (such as voltage, current, and temperature collection), charging port detection (CC and CC2), and charging wake-up (CP and A+) ), relay control and status diagnosis, insulation detection, high voltage interlock, collision detection, CAN communication and data storage requirements.

(1) Main controller

Process the information reported from the controller and the high-voltage controller, and at the same time judge and control the battery operating status according to the reported information, realize the BMS-related control strategy, and make the corresponding fault diagnosis and processing.

(2) High voltage controller

Collect and report the total voltage and current information of the battery in real-time, and realize timely integration through its hardware circuit, and provide accurate data for the calculation of the state of charge (SOC) and the state of health (SOH) for the motherboard. Charge detection and insulation detection function.

(3) Slave controller

Real-time collection and reporting of battery cell voltage and temperature information, feedback of the SOH and SOC of each string of cells, and a passive equalization function, effectively ensuring the consistency of cells during power use.

(4) Sampling control harness

Provide hardware support for battery information collection and information interaction between controllers, and at the same time add redundant insurance function to each voltage sampling line, effectively avoid battery short circuit caused by wiring harness or management system.

3. Communication method

There are two ways to transfer information between the sampling chip and the main chip: CAN communication and daisy chain communication. CAN communication is the most stable. However, due to the high cost of power chips and isolation circuits, daisy chain communication is actually SPI communication. The cost is very low, and the stability is relatively poor. However, as the pressure on cost control is increasing, many manufacturers are shifting to the daisy chain mode. Generally, two or more daisy chains are used to enhance communication stability.

4. Structure

BMS(Battery Management System) hardware includes power supply IC, CPU, sampling IC, high-drive IC, other IC components, isolation transformer, RTC, EEPROM, CAN module, etc. The CPU is the core component, and the functions of different models are different, and the configuration of the AUTOSAR architecture is also different. Sampling IC manufacturers mainly include Linear Technology, Maxim, Texas Instruments, etc., including collecting cell voltage, module temperature, and peripheral configuration equalization circuits.

Bottom layer software

According to the AUTOSAR architecture, it is divided into many general functional modules, which reduces the dependence on hardware, and can realize the configuration of different hardware, while the application layer software changes little. The application layer and the bottom layer need to determine the RTE interface, and consider the flexibility of DEM (fault diagnosis event management), DCM (fault diagnosis communication management), FIM (function information management), and CAN communication reserved interfaces, which are configured by the application layer.

Application layer software of the BMS

The software architecture mainly includes high and low voltage management, charging management, state estimation, balance control, and fault management, etc.

1. High and low voltage management

Generally, when the power is on normally, the VCU will wake up the BMS through the hardwire or 12V of the CAN signal. After the BMS completes the self-check and enters the standby mode, the VCU sends the high-voltage command, and the BMS controls the closed relay to complete the high-voltage. When the power is off, the VCU sends a high-voltage command and then disconnects and wakes up 12V. It can be awakened by CP or A+ signal when the gun is plugged in in the power-off state.

2. Charging management

(1) Slow charge

Slow charging uses an AC charging station (or 220V power supply) to convert AC to DC to charge the battery through an on-board charger. The charging station specifications are generally 16A, 32A, and 64A, and it can also be charged through a household power supply. The BMS can be awakened by CC or CP signal, but it should be ensured that it can sleep normally after charging. The AC charging process is relatively simple, and it can be developed in accordance with the detailed regulations of the national standard.

(2) Fast charge

Fast charging is to charge the battery with DC output from the DC charging pile, which can achieve 1C or even higher rate charging. Generally, 80% of the power can be charged in 45 minutes. Wake up by the auxiliary power A+ signal of the charging pile, the fast charging process in the national standard is more complicated, and there are two versions of 2011 and 2015 at the same time, and the different understanding of the technical details of the charging pile manufacturer’s unclear technical details of the national standard process also causes the vehicle charging adaptability A great challenge, so fast charging adaptability is a key indicator to measure the performance of BMS products.

3. Estimation function

(1) the State Of Power

SOP (State Of Power) mainly obtains the available charge and discharge power of the current battery through the temperature and SOC lookup table. The VCU determines how the current vehicle is used according to the transmitted power value. It is necessary to consider both the ability to release the battery and the protection of the battery performance, such as a partial power limit before reaching the cut-off voltage. Of course, this will have a certain impact on the driving experience of the whole vehicle.

(2) state of health

SOH (state of health) mainly characterizes the current state of health of the battery, which is a value between 0-100%. It is generally believed that the battery can no longer be used after it is lower than 80%. It can be expressed by the change of battery capacity or internal resistance. When using the capacity, the actual capacity of the current battery is estimated through the battery operating process data, and the ratio of the rated capacity to the rated capacity is the SOH. Accurate SOH will improve the estimation accuracy of other modules when the battery decays.

(3) the State Of Charge

SOC (State Of Charge) belongs to the BMS core control algorithm, which characterizes the current remaining capacity state, mainly through the ampere-hour integration method and EKF (Extended Kalman Filter) algorithm, combined with correction strategies (such as open-circuit voltage correction, full charge correction, charging End correction, capacity correction under different temperatures and SOH, etc.). The ampere-hour integration method is relatively reliable under the condition of ensuring the accuracy of current acquisition, but the robustness is not strong. Because of the error accumulation, it must be combined with a correction strategy. The EKF has strong robustness, but the algorithm is more complex and difficult to implement. Domestic mainstream manufacturers generally can achieve accuracy within 6% at room temperature, and it is difficult to estimate high and low temperatures and battery attenuation.

(4) the State Of Energy

SOE (State Of Energy) algorithm manufacturers do not develop much now or use a simpler algorithm, look up the table to get the ratio of the remaining energy to the maximum available energy in the current state. This function is mainly used to estimate the remaining cruising range.

4. Fault diagnosis

According to the different performance of the battery, it is divided into different fault levels, and in the case of different fault levels, the BMS and VCU will take different treatment measures, warning, limiting power, or directly cutting off the high voltage. Failures include data collection and rationality failures, electrical failures (sensors and actuators), communication failures, and battery status failures.

5. Balance control

The equalization function is to eliminate the inconsistency of the battery cells generated during battery use. According to the shortboard effect of the barrel, the cells with the worst performance during charging and discharging first reach the cut-off condition, and the other cells have some capabilities. It is not released, causing battery waste.

Equalization includes active equalization and passive equalization. Active equalization is the transfer of energy from more monomers to fewer monomers, which will not cause energy loss, but the structure is complex, the cost is high, and the requirements for electrical components are relatively high. Relatively passive The balance structure is simple and the cost is much lower, but the energy will be dissipated and wasted in the form of heat. Generally, the maximum balance current is about 100mA. Now many manufacturers can achieve better balance effects using passive balance.

The BMS(Battery Management System) control method, as the central control idea of ​​the battery, directly affects the service life of the battery, the safe operation of the electric vehicle, and the performance of the entire vehicle. It has a significant impact on battery life and determines the future of new energy vehicles. A good battery management system will greatly promote the development of new energy vehicles.

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What Causes Lithium Batteries To Swell?

Himax - Causes-of-Lithium-Battery-Swelling
Lithium-ion polymer batteries are widely used due to their long life and high capacity. However, there are some issues that can arise, such as swelling, unsatisfactory safety performance, and accelerated cycle attenuation.

This article will primarily focus on battery swelling and its causes, which can be divided into two categories: the first is a result of a change in thickness of the electrode, and the other is a result of the gas produced by the oxidation and decomposition of electrolytes.

The change in thickness of the electrode pole piece

When a lithium battery is used, the thickness of the electrode pole pieces, especially the graphite negative electrodes, will change to a certain extent.

Lithium batteries are prone to swelling after high-temperature storage and circulation, and the thickness growth rate is about 6% to 20%. Of this, the expansion rate of the positive electrode is only 4%, the negative electrodes is more than 20%.

The fundamental reason for the increase in the thickness of the lithium battery pole piece is due to the nature of graphite. The negative electrode graphite forms LiCx (LiC24, LiC12, LiC6, etc.) when lithium is inserted, and the lattice spacing changes, resulting in microscopic internal stress and an expansion of the negative electrode.

The figure is the schematic diagram of the structure change of the graphite anode plate in the process of placement, charge, and discharge.

The expansion of graphite negative electrodes is mainly caused by irreversible expansion after lithium insertion. This part of the expansion is mainly related to the particle size, the adhesive, and the structure of the pole piece. The expansion of the negative electrode causes the core to deform, which in turn causes the following: a cavity between the electrode and the diaphragm, micro-cracks in the negative electrode particles, breaking and reorganizing of the solid electrolyte interface (SEI) membrane, the consummation of electrolytes, and deterioration of the cycle performance.

There are many factors that affect the thickness of the negative pole piece although the properties of the adhesive and the structural parameters of the pole piece are the two most important reasons.

The commonly used bonding agent for graphite negative electrodes is SBR. Different bonding agents have different elastic modulus and mechanical strength and have different effects on the thickness of the pole piece. The rolling force after the pole piece is coated also affects the thickness of the negative pole piece in battery use.

When the amount of SBR added is inconsistent, the pressure on the pole piece during rolling will be different. Different pressures will cause a certain difference in the residual stress generated by the pole piece. The higher the pressure, the greater the residual stress, which leads to physical storage expansion, a full electric state, and an increase in the expansion rate of the empty electric state.

The expansion of the anode leads to the deformation of the coil core, which affects the lithium intercalation degree and Li + diffusion rate of the negative electrode, thus seriously affecting the cycle performance of the battery.

Himax - Causes-of-Lithium-Battery-Swelling

Bloating caused by lithium battery gas production

The gas produced in the battery is another important cause of battery swelling. Dependent on whether the battery is in a normal temperature cycle, high-temperature cycle, or high-temperature shelving, it will produce different degrees of swelling and gas production.

According to the current research results, cell bloating is essentially caused by the decomposition of electrolytes. There are two cases of electrolyte decomposition: one is that there are impurities in the electrolyte, such as moisture and metal impurities, which cause the electrolyte to decompose and produce gas. The other is that the electrochemical window of the electrolyte is too low, which causes decomposition during the charging process.

After a lithium battery is assembled, a small amount of gas is generated during the pre-formation process. These gases are inevitable and are also the source of irreversible capacity loss of the battery.

During the first charging and discharging process, the electrons from the external circuit to the negative electrode react with the electrolyte on the surface of the negative electrode to generate the gas. During this process, the SEI is formed on the surface of the graphite negative electrode. As the thickness of the SEI increases, electrons cannot penetrate and inhibit the continuous oxidation and decomposition of the electrolyte.

When a battery is used, the internal gas production gradually increases due to the presence of impurities in the electrolyte or excessive moisture in the battery. These impurities in the electrolytes need to be carefully removed. Inadequate moisture control may be caused by the electrolyte itself, improper battery packaging, moisture, or damage to the corners. Any overcharge and over-discharge, abuse, and internal short-circuiting will also accelerate the gas production rate of the battery and cause battery failure.

In different systems, the degree of battery swelling is different.

For instance, in the graphite anode system battery, the main causes of gas swelling are the SEI film formation, excessive moisture in the cell, abnormal chemical conversion process, poor packaging, etc.

In the lithium titanate anode system, battery swelling is more serious. In addition to the impurities and moisture in the electrolyte, lithium titanate cannot form an SEI film on its surface like a graphite-anode system battery to inhibit its reaction to the electrolyte.

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The Experience Using Lithium Vs. Lead-Acid

Lithium Vs. Lead-Acid

Lithium Vs. Lead-Acid

This week, we discuss the differences you experience when using lithium compared to lead-acid batteries. We compare everything from installation to weight and speed. Watch the full video to learn more about the benefits of switching to lithium.

Transcript:

Let’s start with installation. Lithium batteries are half the weight of the same capacity lead-acid batteries making them much easier to lift and install into your vehicle or equipment. A 100 Amp-hour lithium batteries weighs less than 30 lbs.!

The first thing people notice with lithium batteries when they operate their equipment, whether it’s a boat, golf cart or any other type of vehicle, is the feel. The reduced weight and higher power provided by lithium batteries, results in a noticeably faster and smoother ride.

The higher voltage of a lithium battery provides more power, which increases the ability to accelerate. You can reach top speed faster and more often. When maneuvering up a hill, or with a heavier load, or against the current, with lead-acid batteries, you just can’t reach full speed but with lithium batteries you can and do!

When lithium batteries are used for house power in an RV, people often use the benefit of less weight and more power, to add more of the items they really want in their RV.

You will experience full power throughout use. It is not uncommon to run accessories off your battery bank in a vehicle. With lead-acid batteries this can be problematic. For example, while powering a boat with lead-acid batteries, at some point the voltage will drop too low to allow the accessories to operate. With lithium you won’t lose power to those accessories as the voltage remains high until the batteries are fully depleted.

Another notable experience with lithium batteries is how long they last. You won’t be replacing your batteries every 1-5 years, depending on your particular application.

Equally important to what you experience is what you don’t experience. Let me explain.

You won’t experience a loss of valuable time. This point is two-fold in charging AND maintenance. First, lithium charges four to six times faster than lead acid. So there’s less time (and electricity) to recharge. Second, with lead-acid batteries you can’t avoid spending time cleaning acidic messes on the top of the batteries, in the battery compartment and on the floor. If you let it go too long, you may have to change battery cables due to corrosive build-up. With lithium there is no mess to clean up ever!

Finally, lead-acid batteries are easy to damage. Even with the best intentions, at some point, we will most likely not add water when needed, or not fully charge our batteries or leave them discharged for an extended period of time, resulting in permanent damage, shortening life. None of this impact’s lithium batteries. Lithium batteries truly provide peace of mind.

In fact, lithium batteries are so reliable and maintenance-free, you might even forget you have them!

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How to Extend the Life Of Standard Lithium-ion Battery?

In today’s mobile world, standard lithium-ion batteries are used in a myriad of situations, and battery life comes to be precious. It can be especially annoying when a mobile device has to be charged in a public place with only one available outlet.

There are many reports on how to save battery power, but what can we do to extend battery life? Here are a few ways that Himax has you covered.

Keep the battery at room temperature

Store the battery between 20 to 25℃. During the charging process, the temperature of the battery will increase due to the electric current. Therefore, do not leave your battery in the car or charge it if the temperature inside the car is too high. Heat is the biggest factor in shortening the life of a lithium battery.

Consider purchasing a high-capacity rectangle lithium battery

Standard rectangular rechargeable batteries will degrade over time regardless of whether they are used or not. As a result, spare batteries will not last longer than batteries in use. When purchasing a battery, be sure to ask about the latest manufacturing date of the product.

rectangular pouch batteries

Avoid completely discharging the lithium battery

If the discharge voltage of each cell of a standard lithium-ion battery falls below 2.5V, the safety circuit built into the battery will break, and the battery will appear to be depleted. For safety reasons, do not charge an over-discharged lithium-ion battery if it has been stored under these conditions.

Lithium-ion polymer batteries charging

If you are storing the lithium batteries for an extended period of time, store them at a storage charge in a cool place. Only by storing the battery properly can excessive power consumption be minimized and the life of the battery extended.

Stay tuned for more battery technology or visit Grepow’s Website now: https://www.grepow.com/

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Advantages of Lithium-ion Batteries

Recycle-Lithium-Batteries

Lithium-ion (Li-ion) batteries are inarguably the most popular type of rechargeable battery for consumer electronics. They can be used for a variety of products from mobile phones to cars, and their qualities are superior compared to other rechargeable batteries.

At NightSearcher we use high-quality lithium-ion (Li-ion) batteries for all but a few of our rechargeable flashlights, searchlights, head torches, and floodlights, as they allow us to provide the high-performance, durable products our customers are used to.

Below we’ve listed the biggest advantages of lithium-ion batteries from the customers’ point of view and delved into the science behind each characteristic.

 

Eco-friendly:

Lithium-ion batteries contain relatively low levels of toxic heavy metals found in other types of batteries, such as lead-acid and nickel-cadmium (NiCd) batteries. Cadmium, lead, and mercury have been battery stalwarts for years, but prolonged exposure to, and inadequate disposal of these metals is harmful to humans, animals, and plants. Although Li-ion batteries are safer than many other types of batteries they still require proper recycling, so never put your used batteries in with your regular rubbish.

Lightweight and compact:

Electrodes commonly used in lithium-ion batteries, lithium and carbon, are lightweight on their own, making for much smaller and lighter batteries than their older counterparts such as lead-acid batteries. For comparison’s sake, a typical 51Ah (= ampere-hour) lithium-ion battery weighs about the same as a 24Ah lead-acid battery (about 6-7kg), but provides over twice the capacity.
This particular characteristic of lithium-ion batteries is especially convenient in head torches, as we can increase the light output and runtime significantly without adding bulk and weight to the battery pack (and on your head!).

 

High energy density = A bigger punch:

Lithium is a highly reactive element with the ability to release and store large amounts of energy, allowing li-ion batteries to pack a high energy capacity in a small size. This translates to lithium-ion batteries lasting much longer between charges than other rechargeable batteries, while still maintaining their high level of performance.

A typical lithium-ion cell (= battery) has an average cell voltage of 3.6V, whereas a nickel-metal hydride (NiMH) cell averages at 1.2V, meaning three Ni-MH batteries are required to match the output of a single lithium-ion battery.

 

Low maintenance:

Older types of rechargeable batteries, such as nickel-cadmium or nickel-metal hydride batteries had a so-called “memory effect”, or “lazy battery effect”: If they were repeatedly partially discharged before being recharged, ultimately the battery would only deliver the amount of energy that was used during the partial discharges before its voltage would drop. To avoid this, NiCd and NiMH batteries would need to be regularly maintained by completely discharging and recharging them.

Lithium-ion batteries don’t suffer from the memory effect, which means they always give up their last bit of power, and you can recharge them whether you’ve used 100% or 25% of their capacity with no pesky maintenance needed!

 

More charge cycles:

Quality lithium-ion batteries last about a 1000 full charge cycles. A full charge cycle is when the battery is discharged to flat and then recharged to full, so using your battery until it’s at 75% capacity and then plugging it into recharge doesn’t constitute a full charge cycle. When your battery has recharged back to full, you can still use the 75% of the capacity that you were left with before you recharged your battery; only then has your battery gone through a full charge cycle.

 

Low self-discharge rate

Lithium-ion batteries also have a relatively low self-discharge rate. Self-discharge is a natural, irreversible phenomenon for batteries, where chemical reactions inside the batteries reduce their capacity even when the battery is not being used. The self-discharge rate of lithium-ion batteries peaks at about 5% within the first 24 hours after charging the battery, and then tapers off to 1-2% per month. In comparison, nickel-based rechargeable batteries lose about 10-15% of their capacity after charge and another 10-15% per month.

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The Difference Between Cylindrical, Prismatic And Pouch Cell Batteries

Cylindrical,-Prismatic-and-Pouch-Cell-Batteries

Cylindrical,-Prismatic-and-Pouch-Cell-Batteries

There are three main packaging forms of lithium batteries: they are cylindrical, prismatic and pouch cell packages. Each packaging has its own advantages and disadvantages, which we will review in today’s article.

Cylindrical Lithium Battery

There are many types of cylindrical cells, such as 14650, 17490, 18650, 21700, 26500 and so on. Many car models use this type of battery; Tesla, for instance, uses a 21700 cylindrical battery for its Model 3.

Advantage

The technology behind cylindrical lithium batteries have been around for quite some time, so the yield and consistency of the pack is high. The cost of these packs are also low, which allows them to be suitable for mass production. The cylindrical battery is particularly convenient for its variety of combinations and suitability for electric-vehicle designs.

Disadvantage

On the other hand, these batteries are usually packaged in steel or aluminum shells, making them heavy with a low specific energy.

Application

These batteries can be applied to power tools, toy models, digital electronic products, laptops, lamps, and other portable mobile energy systems.

Prismatic Lithium Battery

The packaging shell of a prismatic lithium battery is mostly made of aluminum alloy and stainless steel. The inner part of the battery adopts a winding or laminating process. The structure is relatively simple, and the production process is not complicated.

Advantage

Compared with cylindrical lithium batteries, these batteries are safer. Because they are not like cylindrical batteries that use higher strength stainless steel as the shell and accessories with explosion-proof safety valves, the overall weight is lighter, and the energy density is relatively higher.

Disadvantage

There is a low automation level due to the difficulty in having so many different types of lithium batteries. The monomers are also quite different, and there may be cases where groups of prismatic lithium battery packs are far below the life of a single lithium battery.

Application

These packs can be applied to electric vehicles, communication-based stations, energy storage, medical fields, etc.

Pouch Cell Lithium Battery

There is little differentiation between the positive electrode, negative electrode material and separator that are used in pouch cell lithium batteries, cylindrical and prismatic lithium batteries. The biggest difference between them is the packaging material, aluminum-plastic film.

The packaging materials are usually divided into three layers: the outer barrier (usually an outer protective layer composed of nylon BOPA or PET), the middle barrier (a middle layer consisting of aluminum foil) and the inner layer (a multifunctional layer).

Advantage

The aluminum-plastic film packaging has a certain degree of flexibility. When a safety problem occurs, the pouch cell battery will bulge up and crack but will not explode or cause a fire because the gas cannot be released.

Disadvantage

However, most pouch cells need to be customized. Currently, the manufacturers that can customize pouch cell batteries are Gateway Power, Himax and so on.

Application

The applications are in smartphones, drones, wearable devices, automotive industry, military fields, etc.

In general, the cylindrical, prismatic and pouch cell batteries have their own advantages and disadvantages. Each battery has its own leading field and has been well applied.

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What’s The Difference Between A BMS And PCM?

BMS-AND-PCM

Before we go straight into comparing these protection boards, let me help define these first.

Define the PCM, PCB and BMS

Generally speaking, battery protection boards can be divided into two types. We usually refer to them as the PCM (Protection circuit module) or otherwise known as the PCB (Protection circuit board), and the BMS (Battery management system).

A battery management system (BMS) or Protection Circuit Module (PCM) is one of the most important parts of a lithium battery. Without either one of these two components, a lithium battery could be very dangerous.

BMS-AND-PCM

The features of PCM

The PCM is mainly composed of hardware electronic components, and it protects the charging and discharging of the lithium battery pack. When the pack is fully charged, the PCM can ensure that the voltage difference between the single cells is less than the set value in order to achieve balanced voltages between the different cells. At the same time, the PCM will detect the over-voltage, under-voltage, over-current, short-circuit, and over-temperature status of every single cell in the battery pack to ultimately protect and extend the battery’s life.

BMS modules

The BMS, also called the battery manager, maintains the same features as a PCM and PCB but also has the ability to offer additional protection and features. It provides real-time monitoring of the battery and transmits data through software. The status information is given to the electrical equipment. The BMS itself includes a management system, a control module, a display module, a wireless communication module, and a collection module for collecting battery information of the battery pack, and others.

lectric shavers and power tool batteries are protected with PCM and PCB. Drones batteries, on the other hand, utilize a BMS. The drone operator will have the ability to check the battery level in real-time and calculate the remaining run time of the battery. This requires the battery to support these data transmissions, which can only be offered by a BMS.

Which solution is better for your project?

The PCM and PCB can only offer the basic levels of protection and are cheaper whereas the BMS includes all the functionalities of a PCM and PCB AND more (although the price tag increases as well). So, if you’re trying to decide between these boards, it’ll really depend on exactly what market your product will be geared towards. If you still can’t make a decision, feel free to reach out to us, and we’ll help you.

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The Difference Between Lipo And NiMH Battery

LiPO-US-NI-MH

LiPO-US-NI-MH

The biggest difference between NiMH and LiPo batteries is the chemical properties that enable the charging of the batteries. NiMH (Nickel-metal hybrid) uses nickel-based technology and LiPo (Lithium Polymer) batteries use a lithium-ion technology.

What the battery types have in common is that they both store a certain amount of energy depending on their capacity. Batteries can be manufactured with different voltages and capacities by installing battery cells in series or parallel inside the battery pack. One should be careful not to drop the batteries or damage the cases of the battery cells because it can cause a short circuit. Both battery types must be disposed of properly as hazardous waste.

The Batteries Differ in Their Properties and Uses.

NiMH batteries are easier to use. They must be fully discharged before charging and must be charged full before storing (Unless Manufacturer tells otherwise. Exampl. Traxxas). NiMH battery chargers are also very simple.

LiPo batteries don’t have to be fully discharged and they must be stored with a 50-70 % charge level. The charging must be done with a charger with balance charging. It is good to charge and store LiPo batteries in a LiPo safe bag.

Properties and remarks on NiMH batteries:

NI-MH-Battery

 

  • Easy and worry-free charging and storing “Safe choice for beginners”
  • Cheaper to manufacture
  • A common battery type in home appliances and devices
  • Rated voltage of cells 1.2V
  • Must be fully discharged before charging
  • Storing fully charged (Unless Manufacturer tells otherwise. Exampl. Traxxas)
  • Batteries are built with standard sized cells with metal cases
  • “Memory effect”: Batteries must always be fully discharged in order to keep full capacity available

Properties and remarks on LiPo batteries:

LiPO-Battery

  • Easy to use with the right devices
  • Manufacturing process is more complicated
  • Becoming a common battery type in home appliances and devices
  • Rated voltage of cells 3.0 V when discharging
  • A charger with balance charging must always be used for charging
  • Storing with 50-70 % charge level (Voltage per cell 3.85V-3.9V)
  • A LiPo safe bag must be used when charging and storing
  • Lighter than NiMH
  • Can be built in different sizes
  • “Memory effect”: almost non-existent, batteries don’t have to be fully discharged before recharging

The advantages of lithium batteries compared to NiMH batteries are undeniable.

The weight/power ratio in LiPo batteries is significantly better. LiPo batteries are noticeably lighter and they can store the same amount or more energy relative to their capacity than NiMH batteries. The power output of LiPo batteries is greater in quality and quantity. The power output of LiPo batteries is steady throughout the discharge, whereas the power output of NiMH batteries starts to decrease soon after charging because of higher discharge rate of the battery type.

Therefore with a LiPo battery with the same capacity as a NiMH battery a longer drive time and better performance can be achieved.

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Multifunctional Lithium Battery Testing

Battery Pack

With the increasing applications of lithium-ion batteries in drones, electric vehicles (EV), and solar energy storage, battery manufacturers are using modern technology and chemical composition to push the limits of battery testing and manufacturing capabilities.

Nowadays, every battery, regardless of its size, performance, and life, is determined in the manufacturing process, and the testing equipment is designed around specific batteries. However, since the lithium-ion battery market covers all shapes and capacities, it is difficult to create a single, integrated testing machine that can handle different capacities, currents, and physical shapes with required accuracy and precision.

As the demand for lithium-ion batteries becomes more diversified, we urgently need high-performing and flexible testing solutions to maximize the pros and cons and achieve cost-effectiveness.

The complexity of a lithium-ion battery

Today, lithium-ion batteries come in a variety of sizes, voltages, and applications that were originally not available when the technology was first put on the market. Lithium-ion batteries were originally designed for relatively small devices, such as notebook computers, cell phones, and other portable electronic devices.

Now, they’re a lot bigger in size for such devices as electric cars and solar battery storage. This means that a larger series, the parallel battery pack has a higher voltage, larger capacity, and larger physical volume. Some electric vehicles can have up to 100 pieces of cells in series and more than 50 in parallel.

A typical rechargeable lithium battery pack in an ordinary notebook computer consists of multiple batteries in series. However, due to the larger size of the battery pack, the testing becomes more complicated, which may affect the overall performance.

In order to achieve the best performance of the entire battery pack, each battery must be almost the same as its adjacent cells. Batteries will affect each other: if one of the batteries in a series has a low capacity, the other batteries in the battery pack will be below the optimal state. Their capacity will be degraded by the battery monitoring and rebalancing system to match the battery with the lowest performance.

The charge-discharge cycle further illustrates how a single battery can degrade the performance of the entire battery pack. The battery with the lowest capacity in the battery pack will reduce its charging state at the fastest speed, resulting in an unsafe voltage level and causing the entire battery pack to be unable to discharge again.

Battery Pack

When a battery pack is charged, the battery with the lowest capacity will be fully charged first, and the remaining batteries will not be charged further. In electric vehicles, this will result in a reduction in the effective overall available capacity, thereby reducing the vehicle’s range. In addition, the degradation of a low-capacity battery is accelerated because it reaches an excessively high voltage at the end of its charge and discharge before the safety measures take effect.

No matter the device, the more batteries in a battery pack that is stacked in series and in parallel, the more serious the problem.

The obvious solution is to ensure that each battery is manufactured exactly the same and to keep the same batteries in the same battery pack. However, due to the inherent manufacturing process of battery impedance and capacity, testing has become critical–not only to exclude defective parts but also to distinguish which batteries are the same and which battery packs to put in.

In addition, the charging and discharging curve of the battery in the manufacturing process has a great impact on its characteristics and is constantly changing.

Modern lithium-ion batteries bring new testing challenges

Battery testing is not a new thing, but, since its advent, lithium-ion batteries have brought new pressure to the accuracy of testing equipment, production capacity, and circuit board density.

Lithium-ion batteries are unique because of their extremely dense energy storage capacity, which may cause fires and explosions if they are improperly charged and discharged. In the manufacturing and testing process, this kind of energy storage technology requires very high accuracy, which is further aggravated by many new applications. The wide range of lithium-ion batteries that are available affects the testing equipment as they need to ensure that the correct charge and discharge curve is followed accurately in order to achieve the maximum storage capacity and reliability and quality.

Since there is no one size suitable for all batteries, choosing suitable test equipment and different manufacturers for different lithium-ion batteries will increase the test cost.

In addition, continuous industrial innovations mean that the constantly changing charge-discharge curve is further optimized, making the battery tester an important development tool for new battery technology. Regardless of the chemical and mechanical properties of lithium-ion batteries, there are countless charging and discharging methods in their manufacturing process, which pushes battery manufacturers to expect more unique test functions out of battery testers.

Accuracy is obviously a necessary capability. It not only refers to the ability to keep high current control accuracy at a very low level but also includes the ability to switch very quickly between charging and discharging modes and between different current levels. These requirements are not only driven by the need to mass-produce lithium-ion batteries with consistent characteristics and quality but also by the hope to use testing procedures and equipment as innovative tools to create a competitive advantage in the market.

12v-Battery-Pack

Although a variety of tests are required for different types of batteries, today’s testers are optimized for specific battery sizes. For example, if you are testing a large battery, a larger current is required, which translates to larger inductance, thicker wires, etc. So many aspects are involved when creating a tester that can handle high currents.

However, many factories do not only produce one type of battery. They may produce a complete set of large batteries for a customer while meeting all the test requirements for these batteries, or they may produce a set of smaller batteries with a smaller current for a smartphone customer.

This is the reason for the rising cost of testing–the battery tester is optimized for the current. Testers that can handle higher currents are generally larger and more expensive because they not only require larger silicon wafers but also magnetic components and wiring to meet electromigration rules and minimize voltage drops in the system. The factory needs to prepare a variety of testing equipment at any time to meet the production and inspection of various types of batteries. Due to the different types of batteries produced by the factory at different times, some testers may be incompatible with specific batteries and may be left unused.

Whether it is for today’s emerging factories for mass production of ordinary lithium-ion batteries or for battery manufacturers who want to use the testing process to create novel battery products, flexible test equipment must be used to adapt to a wider range of batteries’ capacity and physical size, thereby reducing capital investment and improving the return on investment.

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Energy Storage: Global Capacity Predicted To Surge By A Third Every Year In 2020s

Battery-Storage-Projects

Battery-Storage-Projects

EDF’S West Burton B battery storage project in Nottinghamshire, one of Europe’s largest battery storage projects | Credit: EDF

The consultancy predicts that US and China will drive global growth in cumulative energy storage capacity, which should top 740GWh by the end of the decade

Energy storage is poised for a decade-defining boom, with capacity set to grow by almost a third worldwide every year in the 2020s to reach around 741GWh by 2030, according to analyst Wood Mackenzie.

The firm’s latest forecasts for the burgeoning sector released on Wednesday point to a 31 per cent compound annual growth rate in energy storage capacity in the 2020s.

Growth will be concentrated in the US, which will make up just under half of global cumulative capacity by 2030, at 365GWh, the analysis predicts, while front-of-the-meter (FTM) energy storage will continue to dominate annual deployments, accounting for around 70 per cent of global capacity additions to the end of the decade.

The US FTM market is set to surge through 2021 due to significant short-term resources planned before slowing slightly through 2025. Beyond 2025, growth will become steadier as wholesale market revenue streams grow and utility investment is normalised, the report adds.

In particular, utility resource planning in the US is set to take a front seat for deployments over the coming decade, it says, in line with major recent shifts in utility approaches to renewables and storage, with the majority of utilities dramatically shifting planned resources towards renewables and storage due to cost and state-driven clean-energy goals.

“We note a 17 per cent decrease in deployments in 2020, 2GWh less than our pre-coronavirus outlook,” said the consultancy’s principal analyst Rory McCarthy. “We expect wavering growth in the early 2020s, but growth will likely accelerate in the late 2020s, to enable increased variable renewable penetration and the power market transition.”

Just behind the US in energy storage deployment, China is expected to see exponential growth in storage capacity, accounting for just over a fifth of global cumulative capacity at 153GW by 2030, according to Wood Mackenzie.

Europe’s growth story, on the other hand, is expected to be slower than its global counterparts, with the UK and Germany continuing to dominate the continent’s FTM market out to 2025, with the markets in France and Italy also opening up.

Wood Mackenzie senior analyst Le Xu emphasized that “storage holds the key to strong renewables growth.”

“The question is whether storage can capture stable long-term revenue streams,” she added. “Low-cost and longer duration storage can increasingly out-compete coal, gas and pumped hydro, enabling higher levels of solar and wind penetration. However, most lithium-ion energy storage systems economically max out at 4 to 6 hours, leaving a gap in the market.”