Lead acid battery internal resistance measurement methods,how long car battery charge 2 amp qi,car battery types pdf,cheap car batteries kcmo yesterday - 2016 Feature

20.07.2014
One of the urgent requirements of a battery for digital applications is low internal resistance. Figure 1 demonstrates the voltage signature and corresponding runtime of a battery with low, medium and high internal resistance when connected to a digital load. As part of ongoing research to measure the runtime of batteries with various internal resistance levels, Cadex Electronics examined several cell phone batteries that had been in service for a while. If there is such a curve available: Is the open terminal voltage a reliable measure for the state of charge? Gentlemen, what was the method used to measure the internal resistance of cell phone batteries? This possibly seems a bit of an overkill but I am able to carefully see if any trends are occurring in any of my battery packs and I believe I have saved my helicopter exactly for this reason as one of my pack failed as I was spooling up the motor - as expected according to my recorded parameters. If this parameter is as important as I think it is, How much difference between the 3 cells is too much? By submitting this form, you are providing your express consent to receive electronic communications from Battery University. Furthermore, for the purpose of this document, it is important to understand the differences between the terms energy and power.  Energy is defined as power over time (how long) and power is defined as the rate at which energy is released (how much). A battery is a device that stores its energy for a later release.  It is an electrochemical device that converts chemical energy into electricity. Acid stratification occurs when a battery’s acid is concentrated heavily on the bottom of the battery vs.
It is important to charge at a proper rate since charging contributes to the same drawbacks a lead-acid (SLI) battery experiences during discharge cycles  (i.e. No rest results in a higher state of charge on the outer plates than the state of charge on the inner plates.  Resting helps the lead-acid (SLI) battery balance the charge between the plates.
Further adding to the drawbacks associated with lead-acid (SLI) batteries are banks of lead-acid batteries used for engine starting or high pulse-power applications.  Banks of batteries consist of two or more batteries grouped together. Similar to a battery, capacitors are an energy storage device that is capable of storing energy for a later release.  However, that is where the similarities end. Symmetrical EC’s, supercapacitors, or ultracapacitors, are powerful devices but have shortcomings when used for engine starting or high pulse-power applications. KAPower is unique and has none of the drawbacks associated with lead-acid (SLI) batteries or shortcomings associated with symmetrical ultracapacitors.
ESR (equivalent series resistance) is not closely dependent on temperature or state of charge.  The ability to supply high power in a wide range of operating temperatures and states of charge (voltage) is great. High leakage currents.  Must be isolated from batteries during periods of none use.
ESR is dependent on temperature and state of charge.  As temperature drops so does power. Ultimate performance and life expectancy is dependent on keeping individual cell voltages balanced with external (electronic) methods.
Cells are not hermetically sealed.  Will not create a catastrophic failure from over charging or exposure to extreme temperature. Electrolyte is a weak solution of KOH.  No extreme Hazardous Materials or related issues.
Cells must be hermetically sealed.  Potential for high-pressure rupture of vessel (cell). Shipping, storage and handling requirements may be stringent and must be adhered to. Failure of the components used for electronically balancing the voltage between cells (capacitor) is problematic.
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Dynamic Modelling of Advanced Battery Energy Storage System for Grid-Tied AC Microgrid ApplicationsAntonio Ernesto Sarasua1, Marcelo Gustavo Molina2 and Pedro Enrique Mercado2[1] Instituto de Energia Electrica, Universidad Nacional de San Juan, Argentina[2] CONICET, Instituto de Energia Electrica, Universidad Nacional de San Juan, Argentina1.
The internal resistance provides valuable information about a battery as high reading hints at end-of-life.
Before exploring the different methods of measuring the internal resistance of a battery, let’s examine what electrical resistance means and understand the difference between pure resistance (R) and impedance (Z). Most electrical loads are reactive and consist of capacitive reactance (capacitor) and inductive reactance (coil). A battery has resistance, capacitance and inductance, and the term impedance includes all three in one model.
Measuring the battery by resistance is almost as old as the battery itself and several methods have developed over time, all of which are still in use. DC load measurements work well to check large stationary batteries, and the ohmic readings of the device are very accurate and repeatable. The DC load method has limitations in that it blends R1 and R2 of the Randles model into one combined resistor and ignores the capacitor (see Figure 3). The two-tier DC load method offers an alternative method by applying two sequential discharge loads of different currents and time durations. Conductance measurement to evaluate starter batteries was first reported by Keith Champlin in 1975 by demonstrating a linear correlation between load test and conductance. Research laboratories have been using EIS for many years to evaluate battery characteristics. This article addresses the theory very well, but I was expecting to read something more practical, as applied to lead acid starting batteries.
Ok, so just how can I test the internal resistance of a lead acid battery?  I have a standard digital multimeter to use for this task. A) Divide the voltage across the resistor by the value of the resistor (0.1 ohms) to get the exact current flowing into the battery. If you use this note on your site or for any purpose please exclude my last name and e-mail address.
It will be highly appreciated if you can refer to me with some technical literature regarding this.
A good test of a battery’s condition, or internal resistance, is taking the difference between no-load and loaded terminal voltage, divided by the test current. I use a 555 timer running at 100 Hz drving a Power Fet with a current source in series as a load. 5) the headlight should be illuminated and you should be reading roughly 3 amps on DVM2, and roughly 12 volts on DVM1. 8) the internal resistance of the battery in ohms is equal to the difference in the two DVM1 voltage readings divided by the DVM2 current reading. Balancing a lithium battery pack for Electric Vehicle is difficult with large differences between battery cells resistance. Internal resistance values will change with respect to the battery SOC, age, operating tempature etc and hence both IR , impedance and conductance methods and not reliable test methods while comparing with load test.. It sure seems Li-Ion battery capacity goes down really fast with the number of cycles.  How do they overcome this in hybrid cars? Internal Resistance is a measurement, this measurement must be made by very specific battery Internal Resistance meters.
Any one who does pay the price so to get one, he does starting to collect personal experiences with it, regarding all type of battery cells. The individual components of the Randles model are molten together and cannot be distinguished.
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Also, I know that cold weather makes the life of Alkaline's and even Li batteries shorter, does the cold have a negative effect on Lead Acid batteries?
A genuine Yuasa NP7-12 battery datasheet here is designed to be operated in any orientation and is "perfectly sealed" according to Yuasa. There is an overpressure venting system which operates only when the battery generates excess pressure due to Hydrogen generation - which will not happen under normal operation due to designed recombination of gas.
The Genesis label on the battery pictured is due to rebranding of Yuasa (or Enersys) batteries in the US by Genesis. The NP Genesis batteries is used in general electronics and comes in many different sizes for various applications. In addition, the NP Genesis batteries offer a built-in design, which controls the gas generation and includes a recombination that is more than 99 percent during the float usage. Here is a superb Yuasa NP series sealed lead acid battery application manual which provides much detail on the care and feeding of your battery. Not the answer you're looking for?Browse other questions tagged batteries waterproof lead-acid or ask your own question. Measured in milliohms, the internal resistance is the gatekeeper that, to a large extent, determines the runtime.
Similar to a soft ball that easily deforms when squeezed, the voltage of a battery with high internal resistance modulates the supply voltage and leaves dips, reflecting the load pulses. This chart demonstrates the runtime of 3 batteries with same capacities but different internal resistance levels. All batteries were similar in size and generated good capacity readings when checked with a battery analyzer under a steady discharge load. The maximum pulse current of a GSM (Global System for Mobile Communications) cell phones is 2.5 amperes.
One can see a direct relationship between the battery's internal resistance and the talk time. Contrary to popular belief, the best battery performance is not achieved immediately after a full charge but following a rest period of a few hours. This change is caused by the decrease of the specific gravity, a depletion of the electrolyte as it becomes more watery. Battery University monitors the comments and understands the importance of expressing perspectives and opinions in a shared forum. While we make all efforts to answer your questions accurately, we cannot guarantee results. Post every flight I measure output voltage, IR of each cell, internal temperature and then I measure these same parameters pre and post charge. Knowing perilously little about battery electronics, I saw this as a sign of pending failure and I was, possibly by coincidence, correct. I’ve spent the whole class sitting on tinder trying to organise a slam pig for this evening. Internal resistance in charging or discharging state as a function of SOD for a Pb-acid battery at 25°C. Variation of internal resistance (a) and voltage (b) depending on the state of charge for Ni-MH battery at room temperature.
IntroductionIn the last decade, power generation technology innovations and a changing economic, financial, and regulatory environment of the power markets have resulted in a renewed interest in on-site small-scale electricity generation, also called distributed, dispersed or decentralized generation (DG) (Abdollahi Sofla & Gharehpetian, 2011). Bito, 2005Overview of the Sodium-Sulfur (NAS) Battery for the IEEE Stationary Battery Committee.
The resistance of modern lead acid and lithium-ion batteries stays flat through most of the service life. The capacitive reactance decreases with higher frequency while the inductive reactance increases. Impedance can best be illustrated with the Randles model (Figure 2) that comprises resistors R1 and R2 as well as capacitor C.
When injecting a frequency of about 90 hertz, capacitive and inductive reactance converge with a 70–90Ah lead acid battery, resulting in a negligible voltage lag that minimizes the reactance. This has been the preferred method for taking impedance snapshots of batteries powering digital devices. High equipment cost, slow test times and the need for trained professionals to decipher the large volume of data have limited this technology to laboratory environments. For instance, how can I measure the internal DC resistance of a lead acid battery using only a resistor and a regular 5 amp battery charger? You cannot use charging current for calculating internal resistance as SoC influences the current the most. As you state “If you size the current source correctly” How do you determine this?
Wuld be more ealistic to compare the discharge chart of tested battery with experimental results at 1C .-1C is the nominal Ah capaity- taking care of time to measure Wh.
I'm not aware whether battery counterfeiting is an issue in the US but note that some low grade "sealed" batteries are not sealed.


The construction of the NP is the sealed technology, which means it is guaranteed to be leak proof regardless of the position in which the battery is installed. The lower the resistance, the less restriction the battery encounters in delivering the needed power spikes.
These pulses push the voltage towards the end-of-discharge line, resulting in a premature cut-off. The nickel-cadmium pack produced a capacity of 113%, nickel-metal-hydride checked in at 107% and the lithium-ion provided 94%.
This represents a large current from a relatively small battery of about 800 milliampere (mAh) hours. In Figure 5, we observe the internal resistance of nickel-metal-hydride when empty, during charge, at full charge and after a 4-hour rest period. However, all communication must be done with the use of appropriate language and the avoidance of spam and discrimination. Neither can we take responsibility for any damages or injuries that may result as a consequence of the information provided.
Other major factors that have contributed to this evolution are the constraints on the construction of new transmission lines, the increased customer demand for highly reliable electricity and concerns about climate change (Guerrero et al, 2010). Resistance measurement is not the only performance indicator as the value between batches of lead acid batteries can vary by 5–10 percent, especially with stationary units. Better electrolyte additives have reduced internal corrosion issues that affect the resistance. An analogy of inductive reactance is an oil damper that stiffens when applying a fast back-and-forth action. The inductive reactance is commonly omitted because it plays a negligible role in a battery, especially at a low frequency. The load current for a small battery is 1A or less; for a starter battery it might be 50A or more. Many garages use the carbon pile to measure starter batteries and an experienced mechanic gets a reasonably good assessment of the battery. In essence, the DC method sees the battery as a resistor and can only provide ohmic references.
Evaluating the voltage signature under the two load conditions offers additional information about the battery, but the values are strictly resistive and do not reveal SoC or capacity estimations. Note that the AC method shows different values to the DC method when measuring a reactive resistance, and both readings are correct. The pulse DC load method provides valuable readings for a DC application such as a heating element or an incandescent light, while the 1,000Hz method better reflects the performance requirements of a digital load, such as portable computing and mobile phones that rely to a large extent on the capacitive characteristics of a battery.
EIS reads R1, R2 and C values in the Randles model (Figure 7); however, correlating the data into CCA and capacity estimations requires complex modeling.
We recommend posting your question in the comment sections for the Battery University Group (BUG) to share. During charging the current significantly falls down at the same voltage supplied, so it would indicate that resistance grows up? In addition, the batteries offer the electrolyte suspension system, which includes high porosity and fiber materials that are designed to absorb the electrolyte. A current pulse of 2.4 amperes from an 800 mAh battery, for example, correspond to a C-rate of 3C.
A rest of a few hours will partially restore the battery as the sulphate ions can replenish themselves.
Please accept our advice as a free public support rather than an engineering or professional service. Along with DG, local storage directly coupled to the grid (aka distributed energy storage or DES) is also assuming a major role for balancing supply and demand, as was done in the early days of the power industry.
Rincon-Mora, 2006Accurate Electrical Battery Model Capable of Predicting Runtime and I-V Performance. Because of this wide tolerance, the resistance method works best when comparing the readings of a given battery from birth to retirement. Figure 1 shows capacity fade with cycling in relation to the internal resistance of Li-ion cells. In addition, the DC load method gets similar readings from a good battery that is partially charged and a marginal battery that is fully charged. The single-frequency method (Figure 5) sees the components of the Randles model as one complex impedance called the modulus of Z. I, fortunatly have some background in lead-acid battery service and maintenance but this is over thirty years old and, needless to say, I’ve needed upgrading. This method may not conform to the standard methods, but I have confirmed it is an accurate measure of internal impedance.
Gharehpetian, 2011Dynamic performance enhancement of microgrids by advanced sliding mode controller.
Service crews are asked to take a snapshot of each cell or monoblock at time of installation and then measure the subtle changes as the cells age. DG and DES, are presently increasing their penetration in developed countries as a means to produce in-situ highly reliable and good quality electrical power (Kroposki et al, 2008).Incorporating advanced technologies, sophisticated control strategies and integrated digital communications into the existing electricity grid results in Smart Grids (SGs), which are presently seen as the energy infrastructure of the future intelligent cities (Wissner, 2011). Smart grids allow delivering electricity to consumers using two-way (full-duplex) digital technology that enable the efficient management of consumers and the efficient use of the grid to identify and correct supply-demand imbalances.
Smartness in integrated energy systems (IESs) which are called microgrids (MG) refers to the ability to control and manage energy consumption and production in the distribution level. In such IES systems, the grid-interactive AC microgrid is a novel network structure that allows obtaining the better use of DERs by operating a cluster of loads, DG and DES as a single controllable system with predictable generation and demand that provides both power and heat to its local area by using advanced equipments and control methods (Hatziargyriou et al, 2007).
This grid, which usually operates connected to the main power network but can be autonomously isolated (island operation) during an unacceptable power quality condition, is a new concept developed to cope with the integration of renewable energy sources (RESs) (Katiraei et al, 2008).Grid connection of RESs, such as wind and solar (photovoltaic and thermal), is becoming today an important form of DG (Mathiesen et al, 2011).
The penetration of these DG units into microgrids is growing rapidly, enabling reaching high percentage of the installed generating capacity. However, the fluctuating and intermittent nature of this renewable generation causes variations of power flow that can significantly affect the operation of the electrical grid (Tiwaria et al, 2011; Kanekoa, 2011). With proper controllers, these advanced DESs are capable of supplying the microgrid with both active and reactive power simultaneously and very fast, and thus are able to provide the required security level. However, much less has been done particularly on advanced distributed energy storage and its utilization in emerging electrical microgrid, although major benefits apply (Molina, 2011; Vazquez et al, 2010).
Moreover, no studies have been conducted regarding a comparative analysis of the modeling and controlling of these modern DES technologies and its dynamic response in promising grid-interactive AC microgrids applications.In this chapter, a unique assessment of the dynamic performance of novel BESS technologies for the stabilization of the power flow of emerging grid-interactive AC microgrids with RESs is presented.
Generally, electrochemical batteries include the classic and well-known lead-acid type as well as the modern advanced battery energy storage systems.
In this work, of the various advanced BESSs nowadays existing, the foremost ones are evaluated.
In this sense, the design and implementation of the proposed ABESSs systems are described, including the power conditioning system (PCS) used as interface with the grid. Moreover, the document provides a comprehensive analysis of both the dynamic modeling and the control design of the leading ABESSs aiming at enhancing the operation security of the AC microgrid in both grid-independent (autonomous island) and grid-interactive (connected) modes.Section 2 details the general considerations for selecting batteries.
Section 4 defines the parameters to be considered in each type of battery and reviews some of the existing models for batteries. Selection criteria of BESS technologiesUnlike other commodities, there are not significant stocks or inventories of electricity to mitigate differences in supply and demand. Electricity must be produced at the level of demand at any given moment, and demand changes continually. Without stored electricity to call on, electric power system operators must increase or decrease generation to meet the changing demand in order to maintain acceptable levels of power quality (PQ) and reliability. Presently, generating capacity is set aside as reserve capacity every hour of every day to provide a buffer against fluctuations in demand. In this way, if the reserve capacity is needed, it can be dispatched or sent to the grid without delay. There are costs, at times considerable, for requiring the availability of generating capacity to provide reserves and regulation of power quality.
However, economic storage of electricity could decrease or even eliminate the need for generating capacity to fill that role.
For the selection of a specific energy storage technology in order to participate in the power reserve of a grid-tied AC microgrid, storage capacity must be defined in terms of the time that the nominal energy capacity is intended to cover the load at rated power. All storage technologies are designed to respond to changes in the demand for electricity, but on varying timescales. Responding to these short-timescale fluctuations keeps the voltage and frequency characteristics of the grid electricity consistent within narrow bounds, providing an expected level of power quality.
PQ is an important attribute of microgrid electricity, as poor quality electricity—momentary spikes, surges, sags (dips), or severe contingencies like outages—can harm electronic devices.Energy management (long timescales). Higher-capacity technologies capable of outputting electricity for extended periods of time (up to some hours) moderate the extremes of demand over these longer timescales. These technologies aid in energy management, reducing the need for generating capacity as well as the ongoing expenses of operating that capacity. This is the case of serious failures of generation or disconnection of the MG from bulk power system. In the first case the level of storage system performance is lower than in the second, but the power requirements and dynamic response are significantly higher. It is required that the technology has been proven by industry to ensure a real solution.High reliability.
Storage devices should hold costs competitive with the benefit incorporated into the operation of the MGs.Long lifetime, exceeding 2000 cycles.
This action will significantly improve regulation and reduce the impact of any disturbances in the main power system. High re-charge rate, to quickly restore the lost reserve from the BESS units and to allow quickly absorb large excesses of energy. Overview of BESS technologiesThe term Battery contains the classic and well-known lead-acid (Pb-acid) type as well as the redox flow types batteries, and also include the so called advanced battery energy storage systems (ABESSs). Lead acid batteriesEach cell of a lead-acid battery comprises a positive electrode of lead dioxide and a negative electrode of sponge lead, separated by a micro-porous material and immersed in an aqueous sulphuric acid electrolyte. In flooded type batteries (with an aqueous sulphuric acid solution) during discharge, the lead dioxide on the positive electrode is reduced to lead oxide, which reacts with sulphuric acid to form lead sulphate; and the sponge lead on the negative electrode is oxidized to lead ions, that reacts with sulphuric acid to form lead sulphate. Valve regulated (VRLA) type uses the same basic electrochemical technology as flooded lead-acid batteries, except that these batteries are closed with a pressure regulating valve, so that they are sealed. For this reason, Pb-acid batteries require more space and have greater weight than any other type of batteries. However, they have significant advantages that positions best suited for applications requiring high power and speed. The units are robust and secure, and allow extremely fast downloads, in periods of about 5 ms.
The cost of these batteries is in the order of $ 300 to $ 600 per kWh and performance can reach 90% (Chen 2009).Another problem with these batteries is their relatively short lifetime measured in charge-discharge cycles, which reaches 500 cycles for the batteries most basic to 1000 cycles for the latest models (Chen 2009). Another major problem they have is the charging time of around three hours to the total load of batteries.Despite these disadvantages, Pb-acid batteries have been used in many storage systems. The earliest transportable battery system of lead-acid is located at the Phoenix distribution system is a multi-mode battery. Nickel cadmium and nickel metal hydride batteriesBatteries of Ni-Cd type have a cadmium electrode (positive) and a nickel hydroxide (negative). With sealed cells and half the weight of conventional lead acid batteries, these batteries have been used in a wide range of portable devices.
Today, due to environmental problems and memory effect, Ni-Cd batteries are being replaced by Ni-MH or Li-Ion. Memory effect, also known as battery effect or battery memory, is an effect that describes a specific situation in which Ni-Cd batteries gradually lose their maximum energy capacity if they are repeatedly recharged after being only partially discharged. The source of the effect is changes in the characteristics of the underused active materials of the cell.Ni-Cd batteries have the advantage of a long life (up to 2000 charge-discharge cycles) and if they are charged and discharged properly maintain their properties to the end of its life.
The system is capable of delivering up to 40 MW during 15 minutes and is designed to act as a dumping reserve before activation of turbo-gas plants. So far, this battery system is the largest in the world.Ni-HM batteries share several characteristics with Ni-Cd batteries. They improve Ni-Cd batteries by changing the nickel hydroxide electrode and the other by a metal hydride alloy.
Lithium ion, lithium polymer and lithium sulphur batteriesThese batteries are built with alternating layers of electrodes, among which cyclically circulate lithium ions. The Li-Ion batteries have no memory effect and support recharge before being fully discharged.


Subsequently, thanks to improvements developed by Sony with the Li-Ion batteries in 1990 were popularized in electronic equipment such as laptops or mobile phones. In addition, the flat design of the containers, the high energy density and the topping charge characteristic make them ideal for automotive applications.This type of battery has a ratio of energy density three times greater than Pb-acid batteries.
This difference is due to the characteristics of low atomic weight of lithium, about 30 times lighter than lead. In addition to having a higher voltage than lead-acid cells, this means fewer cells in series to achieve the desired voltage and lower manufacturing costs.In addition to the strict selection of batteries with same voltage and internal resistance for connection in parallel or in series, it is also necessary that each battery cell should be charged to the same value as the other cells permanently. After a year unused, the capacity can be significantly reduced as well as the voltage level.The big drawback with Lithium-ion type batteries is that they are not adaptable to permanent deep discharge duty cycles even in cases in which its nominal capacity is respected. Even more, this type of battery does not accept overloads.The lithium polymer batteries are a variation of the Li-Ion. Their characteristics are very similar, but allow a higher energy density and a significantly higher discharge rate.
It is expected that once the mass production of Li-po is reached it will be priced lower than those of Li-Ion due to its simpler manufacturing.Lithium sulphur batteries operate quite differently from Li-Ion batteries. This installation in the Kasai Green Energy Park, a massive testing site for large-scale, renewable power storage systems is located near Osaka (Japan). In the power storage building, economical late-night power is mainly used to charge batteries, which is then consumed during the day, while in the administration building, unconverted DC electricity from photovoltaic modules is the main source of power for charging batteries and direct consumption.
Sodium sulphur batteries Sodium sulphur batteries are one of the most favourable energy storage candidates for applications in electric power systems. They consist of an anode and a cathode of sodium and sulphur, respectively and a beta alumina ceramic material (beta-Al203) that is used as electrolyte and separator simultaneously.
The tubular configuration of these batteries allows the change of state of the electrodes during charge and discharge cycles and minimizes the sealing area favouring the overall design of the cell (Wen 2008).
Figure 1 shows the tubular design of each cell of sodium sulphur batteries.The greatest advance in this type of battery has achieved very rapidly during the past two decades as a result of the collaboration between the Tokyo Power Company (TEPCO) and the NGK Insulators Company. TEPCO and NGK developed these batteries aiming at displacing the use of pumping stations.Sodium sulphur batteries, usually work at temperatures between 300 and 350°C. At these temperatures, both sodium and sulphur and the reaction products are in liquid form, which facilitates the high reactivity of the electrodes. In this characteristic lies the high power density and energy of these batteries, nearly three times the density of lead acid batteries. They are environmentally safe because of the seal system with which they are constructed, thus not allowing any emissions during operation. They have a high efficiency in charge and discharge and a lifespan of approximately 15 years. The cells also have high efficiency (around 89%) and minimal degradation, which contributes to the life cycle, much larger than other cells (Baxter 2005).
This type of battery has no self-discharge problems if they are kept at nominal operating temperature, which leads to having a high efficiency.
For this purpose, the built containers have embedded heaters capable of maintaining the temperature with low energy consumption.
One of the most important characteristics of the sodium batteries is their ability to deliver power pulses of up to five times of its rated capacity over a period of time up to 30 seconds continuously. This is the fundamental reason because these batteries are considered economically viable for both power quality and energy managements applications. At 90% depth of discharge, the cell has a lifespan of 4500 cycles, while 65% have a life of 6500 cycles and 20% a lifespan of 40 000 cycles. In practice, sodium battery discharge is limited to less than 100% of its theoretical capacity due to the corrosive properties of sodium polysulfide (Na2S3).
At 90% capacity of sodium polysulfide composition corresponds approximately to 1.82 V per cell. At this point, the main obstacles to large-scale applications of the sodium battery are its high cost of production which depends largely on the quantity of batteries produced.
The approximate cost of these batteries, including the power electronic converters is $ 2500 to 3000 per kW (Iba at al 2006). Moreover, the protection of intellectual property the company holds over the electrolyte difficult to study and implement appropriate models to simulate their dynamic behaviour (Hussien 2007). The greatest sodium BESS installed is about 34 MW in Aomori, Japan, forming a hybrid system with a 51 MW wind farm. POSCO succeeded in developing a sodium sulfur battery for the first time in Korea, with the goal of commercializing by 2015 with RIST (a research institute wholly owned by POSCO). General Electric commercializes its Durathon battery which uses sodium metal halide chemistry and Fiamm Sonick battery is made up of salt (NaCl) and nickel (Ni). In China, research works began in the 70's and since 1980 the Chinese Institute SICCA has become the only institution outside of Japan with research in the area of sodium sulphur batteries.
Dynamic model of advanced BESSThe most important characteristics of a battery are determined by the voltage of their cells, the current capable of supplying over a given time (measured in Ah), the time constants and its internal resistance (Sorensen 2003). The two electrodes that supply or receive power are called positive electrodes (ep) and negative (en), respectively.
Inside the battery, the ions are transported between the negative and positive electrodes through an electrolyte.
The polarization factor synthesizes or summarizes the contribution of complex chemical processes that can take part inside the cell between the electrodes through the electrolyte and are dependent of the battery type.
Figure 3 shows an schematic with the potential difference across the cell with and without load. Both the voltage V0 and the resistance R0 generally have a variable behaviour depending on the state of charge, the depth of discharge and also according to whether is charging or discharging the battery. The voltage Vi in open circuit decreases linearly with the discharge Qd in Ah, and the internal resistance Ri increases linearly with Qd. That is, the open circuit voltage is lower and the internal resistance is higher in a state of partial discharge compared to the initial values V0 and R0 for fully charged battery. Figure 4 shows this battery model in schematic form.In studies where it is necessary to study the dynamic behaviour of the battery system, possible variations of values of Kv and KR should be taken into account. In these cases, the voltage and internal resistance of the battery does not have a linear behaviour as the one proposed in equation (4). The following sub-section briefly describes some characteristics of different types of batteries required for proposing a general model of the advanced BESSs. Analysis of performance characteristicsThis sub-section discusses major performance characteristics curves of advanced BESS devices, obtained from the literature and by own experimental set-ups.
This figure shows not only a nonlinear variation but also a hysteresis loop that clearly differentiates the broad difference that has the internal resistance in charging or discharging state.In the case of Ni-MH batteries, Figure 6 shows the variation of open circuit voltage (Voc) and the internal resistance (Rseries) for different states of charge. As shown, the open circuit voltage varies with the SOC, but is almost independent of the depth of discharge.
This figure shows the variation of open circuit voltage (Voc) and the internal resistance (Rseries) for different charge states. As shown, the open circuit voltage varies with SOC but is almost independent of the depth of discharge. On the other hand, in such batteries it can be seen that the internal resistance is not only independent of the state of charge, but also of the depth of discharge. Due to their internal reactions, the electromotive force of the sodium battery is relatively constant, but decreases linearly after 60 to 75% depth of discharge (Van der Bosche 2006). Figure 9 also shows that depending on the state of charge, charge direction and the temperature at which the battery is operated, the internal resistance can vary up to four times its base value (Hussien 2007).
Proposed general model of BESSFigures 5 through 9 shows a large nonlinearity in the behaviour of the most important batteries parameters. These features should be included in a model that wants to accurately represent the behaviour of batteries in power quality or energy management events.
Based on the analysis in the previous section, it can be seen that both, the battery voltage and the current capable of being delivered at any given time, generally depends on several factors. In this way, for both cases (power quality or energy management events) the value of the parameters depends on the operating temperature of the battery. It has been considered for the realization of the model that the battery is in a state of charge such that the characteristics curves are for the unit fully charged or discharged.
In this sense, the depth of discharge must be taken into account in the maximum simulation time and the limitations recommended by the manufacturer.The state of charge of the battery is the most important factor of all the above and should be taken into account directly in the model. From the graphs shown above (Figures 5 through 9) it can be inferred a general model to simulate the battery considered. A model that includes all the batteries tested should consider that the open circuit voltage and internal resistance varies with the state and direction of the charge.
The most convenient solution is to use directly the curves described in Figures 5 through 9 with the value of SOC.Given the battery type, operating temperature and the depth of discharge, a model that takes into account these factors is show in Figure 10. This figure shows the outline of a general battery model, depicted as an example for a NaS-type battery. Test of proposed BESS modelThe developed model of the BESS was tested using a single cell in order to validate the model. Figures 11 and 12 show the variation of internal resistance to changes of SOD for discharging and charging, respectively, in a NaS T5 type cell at 320?C. This module is a 50 kW pack consisting of 320 cells connected in series for obtaining a higher capacity storage device with higher voltage. Because of methodology of modelling used, the model can be easily modified to simulate the temperature variation.
ConclusionWith the exception of conventional lead-acid batteries, advanced batteries analyzed in this chapter represent the cutting edge technology in high power density BESS applications.
In addition to small size and low weight of the Li-Ion, they offer higher energy density and high storage efficiency, making them ideal for portable devices and flexible grid-connected distributed generation applications in microgrids. However, some of the biggest drawbacks of Li-Ion technology are its high costs (due to the complexity arising from the manufacture of special circuits to protect the battery) and the detrimental effect of deep discharge in its lifespan (Divya & Ostergaard 2009). Although the Ni-Cd and Pb-acid batteries can provide large peak power, they contain toxic heavy metals and suffer from high self-discharge.Sodium sulfur-type BESS devices are best suited to the requirements set by modern microgrid applications. These batteries can act in contingencies where rapid action is required to maintain the adequate levels of the grid frequency, but also in the case of high penetration of renewable generation, such as wind or solar photovoltaic, since the NaS battery can operate as the perfect complement in valley hours. They are environmentally safe and have low maintenance while operate at high temperatures; it does not represent a major drawback. The biggest drawbacks are the cost and the limited information about these type of batteries which difficult the development of experimental prototypes and computer models.
Fundamentally, redox reactions are a family of reactions that are concerned with the transfer of electrons between species.
Thus, in order to produce a redox reaction in the system, an element to yield electrons and one that will accept them must exist.
Oxidation involves an increase in oxidation number, while reduction involves a decrease in oxidation number.
Electropositive elemental metals, such as lithium, sodium, magnesium, iron, zinc, and aluminum, are good reducing agents. These metals donate or give away electrons readily.In redox processes, the reductant transfers electrons to the oxidant.
Thus, in the reaction, the reductant or reducing agent loses electrons and is oxidized, and the oxidant or oxidizing agent gains electrons and is reduced. The pair of an oxidizing and reducing agent that are involved in a particular reaction is called a redox pair or couple.When a net reaction proceeds in an electrochemical cell, oxidation occurs at one electrode, the anode, and reduction takes place at the other electrode, the cathode.
The cell consists of two half-cells joined together by an external circuit through which electrons flow and an internal pathway that allows ions to migrate between them. Since the oxidation potential of a half-reaction is the negative of the reduction potential in a redox reaction, it is sufficient to calculate either one of the potentials. Therefore, standard electrode potential is commonly written as standard reduction potential.The sign of the potential depends on the direction in which the electrode reaction has elapsed. The potential is then positive, when the reaction occurs in the electrode (facing the reference) is the reduction, and is negative when oxidation. The most common electrode as a reference electrode is called the reference or normal hydrogen, which has zero volts.Finally, the voltage of a cell is determined by the reduction potential of redox couple used and is usually between 1 V and 4 V per cell.
For this work, are of interest only secondary batteries (rechargeable) which are based on some kind of reversible process and can be repetitively charged and discharged. In this way, only this type of batteries are considered here when batteries are referred.AcknowledgementThe authors wish to thank the CONICET (Argentinean National Council for Science and Technology Research), the UNSJ (National University of San Juan), and the ANPCyT (National Agency for Scientific and Technological Promotion) under grant FONCYT PICTO UNSJ 2009 – Cod.



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