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Batteries and Battery Management

A bank of linked batteries.

This bank of batteries is used to store power at Cap Hatien in Haiti. (Photo:Walt Ratterman)

Batteries are a critical component in nearly all energy systems involving an intermittent power source, including diesel generation, solar PV systems, wind, or intermittent grid; but have proven to be one of the most challenging components of an energy system to maintain.

Batteries provide a means to store energy which can be used to power a health facility when the intermittent power supply source is not operational (e.g. when the sun is not shining, the wind is not blowing, or the grid power is off). Storing power for periods of interrupted supply is only one of the important services battery systems provide to health facilities. They can also be designed to provide constant, clean power to sensitive loads such as laboratory equipment and computers, even while the primary power supply is operational.

Several factors can lead to battery failure including lack of routine maintenance, insufficient charging, and excessive depth of discharge. It should be noted that even under ideal conditions batteries can be expected to last between 3-7 years - which is significantly shorter than the expected lifetime of other system components (e.g. the solar panel). Batteries which are not used properly often fail in less than a year. Thus, if there is insufficient focus on proper battery use and maintenance, and if funds are not available to replace batteries when they fail, the sustainability of off-grid energy systems will be severely compromised.

The topics outlined on this page are focused on providing knowledge that will help to ensure the longevity of energy system battery banks. All stages of battery bank implementation, from selection and sizing to maintenance and monitoring, are covered.


 The Role of Batteries in an Energy System

power distribution schematic

A general schematic of how power is distributed to electrical loads in an inverter/battery system.

Inverter/battery systems (IBS) are a type of backup power supply designed to provide electricity to critical loads for several hours (usually between 4 and 24 hours) when primary power is unavailable. They are also used to provide constant high quality power to no-contact loads. Grid or diesel generator power is connected to a main distribution panel which connects power to non-critical loads and charges the battery banks via an inverter/charger. Batteries provide pure power to no-contact loads and, when primary power is unavailable, contact loads.

Batteries are also an essential part of any solar PV system, whether a stand-alone off-grid system, a diesel hybrid system or a grid connected system. In order to ensure that energy produced by solar panels is available for periods of low sunlight or nighttime use, a properly sized battery bank must be connected.

Use our HOMER Load Calculation and System Optimization tool to evaluate the viability of solar PV, diesel generator and hybrid energy systems for you facility's specific load profile and location. The tool will automatically size the battery bank required for each energy system type and calculate the least cost solution based on a net present value life cycle cost analysis.


 Considerations when Selecting a Battery

Since batteries are an essential component to a wide variety of products and services (e.g. consumer electronics, transportation, telecommunications), a multitude of battery types and designs exist. Furthermore, battery design is constantly evolving; driven by the ever-increasing demands of electric vehicles, handheld electronics and the need for grid stability. In order to understand battery design, it is necessary to be familiar with common battery performance metrics. While lead-acid batteries are the most ubiquitous battery type in use for backup power applications, the considerations listed here can be used to evaluate and compare the suitability of any type of battery for any given application. Determining which batteries are most suitable to the particular application in question, backup power for health facilities, requires a close examination of the demands such facilities place on their power supply and the role of an IBS in ensuring that power is available. The considerations outlined below are described within the context of health facility backup power and are rated in their level of importance to this application.


Capacity [Ah] or [Wh] High

The available capacity is the total amount of energy that a battery can deliver on a single charge. Capacity is normally expressed in ampere-hours [Ah], which is determined by measuring the number of hours a battery can supply a constant current before dropping below a useful voltage. To obtain capacity in terms of watt-hours [Wh], multiply the ampere-hour capacity by the voltage. Capacity is considered important for backup power systems because, ultimately, higher capacity systems allow for longer periods of power supply, or higher loads for a given battery size.

Rated capacity [Ah]
For lead-acid batteries the rated capacity is the number of ampere-hours available when the discharge current is supplied at a constant rate over a specified number of hours. Battery manufacturers often rate batteries for anywhere between 1 hour and 100 hours, with a 20-hour rating being the most commonly cited. Longer discharge times result in greater overall ampere-hour capacity because the battery experiences more losses at higher current draw. This is known as the Peukert Effect.

Reserve capacity [minutes]
The reserve capacity is the number of minutes a battery can sustain a 25 ampere current draw while maintaining a useful voltage. The reserve capacity is often specified for deep-cycle lead-acid batteries.

Charge/Discharge efficiency [%] High The efficiency at which a battery charges and discharges is considered highly important for health facility backup power. In many of the facilities where backup battery banks are deployed, electrical energy is at a premium. No matter what power source is charging the batteries, efficient use of that energy is important to the economic and technical performance of the system. High efficiency batteries equate to smaller solar arrays, lower fuel consumption at a generator or lower utility bills.
Charge/Discharge Rate (C-rate) Medium Charge and discharge rates are often given by a C-rate. The C-rate specifies the rate at which a battery's capacity can be charged or discharged. For example, a 1C charge rate means that the battery will reach full capacity after 1 hour. A C/5 charge rate means that the battery will reach capacity after 5 hours. In backup power systems batteries are typically discharged on a daily basis, and thus must recharge fast enough to provide full capacity at least once daily. Yet for some applications (e.g. electric vehicles) batteries are expected to charge within a matter of minutes. For this reason charge rate is considered to be of moderate importance in backup power applications.
Cost [$/Ah] or [$/kWh] Medium Costs should always be kept as low as possible, but not at the expense of battery quality or capability. For this reason cost is considered important, but should not take priority over quality metrics such as capacity, efficiency or life.
Life High

The lifespan of a battery is important, both from a technical standpoint and as an indicator of quality. The life of a battery is typically described in two ways: number of cycles and calendar life.

A cycle is one complete discharge and recharge. The number of cycles a battery can endure is highly dependent on the depth of discharge (DOD) that it commonly experiences. Therefore cycle life ratings must be accompanied by the % DOD that was used to attain them. For example, a flooded lead-acid battery subjected to an average DOD of 50% will last twice as long as the same battery with an average DOD of 80%. The battery system charge controller should be programmed never to discharge below 50%.

Calendar Life
The calendar life of a battery is the number of useful years it will operate. Regardless of the number of cycles a battery experiences, it will eventually wear out. Certain types of batteries will inherently have longer lives, but the calendar life is also a measure the battery's quality. A manufacturers' warranty should also reflect battery quality.

Maintenance/Durability Medium All backup battery systems require some regular preventative maintenance. Some battery technologies and designs are specifically intended for little-to-no maintenance while others require regular care and monitoring. While it is important to keep maintenance needs low, some degree of maintenance is acceptable and even desirable as it will keep health facility personnel engaged in the overall care of the backup power system. Durability is often a concern in transport and industrial applications, or in extreme climactic conditions. Backup power batteries may have to endure harsh weather, rough transportation or intermittent maintenance during implementation and use. Therefore, a rugged battery is necessary.
Self-discharge rate Medium All batteries will lose charge over time. The reasons for this vary depending on the type of battery but often include unwanted chemical reactions or impurities in the battery's materials. The self-discharge rate is the percentage of the battery's capacity that is dissipated over a period of time (e.g. %/day, %/month). Because backup power batteries will be constantly connected to chargers, low self-discharge is not critical. It should be noted, however, that higher self-discharge rates ultimately lead to higher overall consumption because more energy must be added to keep the batteries at full charge.
Size/Weight Low The size and weight of different battery technologies can be compared in several ways: specific energy [Wh/kg], energy density [Wh/liter], specific power [W/kg] or power density [W/liter]. While these metrics are very important for applications such as handheld electronics and electric vehicles they are less relevant when considering a stationary application like backup power. While the size and weight of the backup power batteries does not affect their performance, it will affect their cost of transportation and ease of installation.
Temperature Range Low Batteries are commonly designed for, and tested at, a specific temperature (25°C for lead-acid). The effect of temperature on battery performance is highly dependent on the technology and design of the battery. Some batteries are particularly well suited to temperature extremes, but most technologies will function within typical outdoor temperature ranges. Because the typical temperature range is site specific, and temperature sensitivity varies among battery technologies, the location and design of the battery bank should target the optimal operating temperature for the batteries.


 Lead-Acid Batteries: Types and Performance

The lead-acid battery is a mature and proven technology that is employed all over the world in a variety of applications. Its most common uses are in automobiles, marine vehicles and backup power systems. Aside from its ability to meet a wide range of technical demands, the lead-acid battery has many advantages over other battery technologies:

  • Familiar technology
  • Distributed world-wide
  • Diverse design options
  • Competitive market
  • Large knowledge base in backup power applications

Lead-acid batteries are a solid choice for any backup power system, but much care must be taken when selecting the right type of lead acid battery. Because the lead-acid battery has been in production for so long, and is used for many purposes, an array of designs is available. The different design types are most easily defined by their intended purpose, their construction or their materials.


Engine-starting (application) These batteries are found in nearly every production automobile. Designed for engine ignition, they are able to discharge a very high current over a very short period. While these perform well for their intended use, they will do a very poor job under applications demanding high capacity and deep discharge.
Deep-cycle (application) This design is intended for deep discharge over long periods. Backup power systems and renewable energy storage are where these batteries shine. While they are also able to provide short bursts of high current, they are built to provide a long, sustained, constant current.
Marine (application) Boats and other marine vehicles often require both engine-starting and sustained power for onboard electronics. Marine batteries are a hybrid of engine-starting and deep-cycle designs. Flooded or Vented(construction) This is the most common and least expensive type of lead acid battery. Often referred to as 'wet-cells', 'flooded cells' or 'vented cells' they comprise lead plates and a liquid electrolyte solution of sulfuric acid and water. They require regular maintenance as the water concentration declines due to the out-gassing of hydrogen.
Gel (construction) These batteries are sealed, valve regulated lead-acid (VRLA) batteries, meaning that they cannot be (and do not need to be) opened for maintenance. Chemically, these are about the same as flooded lead-acid batteries except that the sulfuric acid solution is held in a silica gel, rather than the liquid form. This makes these batteries more robust, more efficient and lower maintenance. They are more expensive than flooded cell batteries without any increase in capacity or life.
Absorbed Glass Mat (AGM) (construction) AGM is another type of VRLA battery.Like gel lead-acid batteries, the sulfuric solution is not in liquid form, but rather absorbed into fiber glass mats. Again, these batteries are more durable, efficient and expensive than flooded cell batteries. They require virtually no maintenance and can be charged at the same rate as flooded cells. They are also less susceptible to damage arising from overcharging than gel VRLAs.
Calcium (material) Most VRLA batteries and engine-starting batteries have calcium added to the lead electrodes. The addition of calcium makes them more resistant to corrosion and overcharging which leads to lower self-discharge, less maintenance, longer life and higher max current output.
Antimony (material) Many industrial and deep-cycle batteries have antimony added to the lead electrodes. Antimony makes these batteries mechanically stronger, allowing for deeper discharges and greater durability. This strength results in a longer service life than calcium batteries. Self-discharge, however, is greatly increased.

The myriad designs and applications for lead-acid batteries inevitably leads to a wide range of performance characteristics for this class of battery. As seen in the following table, lead-acid batteries vary substantially in their technical capabilities.


MetricCapacityCharge/ Discharge RateSpecific energyCharge/ Discharge EfficiencySelf-discharge RateCycle LifeCalendar LifeCostTemperature Range
Lead-acid performance 35-780 Ah @ 20 hr C/3 - C/20 30 - 40 Wh/kg 89%-99% 1% -40% per month 500-3200 cycles @50% DOD 4-15 years $100-$250 per kWh -40 to 50°C

The above table should highlight the need to be exact when specifying the type and performance of lead-acid batteries for backup power systems. Luckily, the types of lead-acid batteries suitable for backup power can be narrowed down to those designed for deep-cycle applications. Within this broad category, two main types, in terms of construction and materials, are identified as having the optimal characteristics for this application: flooded antimony lead-acid and VRLA absorbed glass mat.

Battery TypeCostDeep Cycle PerformanceMaintenance
Flooded lead-acid
Lead-antimony Low Good High
Lead-calcium Low Poor Medium
Valve regulated lead-acid (VRLA)
Gel Medium Fair Low
AGM Medium Fair Low

The table to the right offers a qualitative comparison of the major battery types available for deep-cycle applications. Between flooded lead-acid batteries, lead-antimony stands out as having better deep cycle performance than lead-calcium, which is a critical characteristic for backup power batteries.

When distinguishing between AGM or silica gel VRLA batteries, it is important to note that AGMs are generally more robust in design and are less susceptible to damage during charging. Gel VRLAs can become damaged if charged improperly, due to the formation of permanent bubbles from gassing. Generally, AGM is preferred over gel VRLAs.

The pros and cons of both flooded antimony lead-acid and AGM VRLA are outlined below. In most cases the deciding factor when choosing between the two are cost constraints vs. maintenance needs.

Flooded Antimony Lead-Acid

Pros: These batteries are robust, inexpensive and provide excellent deep discharge capabilities, allowing for consistent 80% depth of discharge. Because these batteries can deliver the highest capacity and are among the least expensive, they are perhaps the most cost-effective choice.

Cons: Antimony batteries do require high maintenance as much water is lost from gassing, which also requires they be placed in a well-ventilated area. They also have the highest self-discharge rate of any lead-acid battery with rates of 2-10%/week.

VRLA Absorbed Glass Mat

Pros: AGM batteries are durable, and essentially maintenance-free. They have the highest charging efficiency of any lead-acid battery at 99% while their self-discharge rate is only about 1-3%/month. They have better charging capabilities than gel VRLAs. AGMs are also easier to transport and dispose of as there is no risk of leaking acid.

Cons: Recommended depth of discharge is usually around 50%, typical of deep-cycle batteries, but not as good as antimony lead-acid. They are also about 2-3 times more expensive than flooded cell designs.

These battery types will meet the demands of backup power systems. When choosing the specific manufacturer and model, other considerations should also be accounted for. The thickness of the lead electrode plates is one important design aspect that factors into the life of the battery. Manufacturing methods and material quality also play a significant role in performance. The quality of a lead-acid battery can be difficult to assess but generally a high quality battery can be characterized by higher cost, greater weight and the length of the manufacturers' warranties.


 Lead-Acid Batteries: Care and Use

Flooded (also referred to as wet-cell or vented) lead-acid and valve regulated lead-acid (VLRA) batteries have fundamental differences in their maintenance, charging and placement requirements. At the heart of these differences is a phenomenon that occurs in all lead-acid batteries, known as gassing.

The electrolyte in a lead-acid battery is a solution of sulfuric acid and water. When a battery is being charged, most of the energy being input is used to drive the chemical reactions taking place at the battery's electrodes, thereby restoring the energy that left the battery during discharge. A portion of the input energy, however, is diverted to the water in the electrolyte solution, resulting in a process called electrolysis which breaks the liquid water down into hydrogen and oxygen gas. The characteristic difference between flooded lead-acid batteries and valve-regulated lead-acid batteries is how this gassing is managed.

In flooded batteries, the hydrogen and oxygen gas produced during normal battery operation are simply released into the surrounding atmosphere. This has two major consequences: 1) a possibly explosive mixture of hydrogen and oxygen has been released, and 2) hydrogen and oxygen (in the form of distilled water) must now be replenished within the cell. Therefore, with flooded lead-acid batteries, ventilation and maintenance are key.

In VRLA batteries, the hydrogen and oxygen byproducts, which result from normal use, are typically recombined within the battery. A small portion of the gas, however, is not recombined, and must be vented, but this is negligible when compared to flooded batteries. Therefore, VRLA batteries do not have the ventilation or maintenance requirements of a wet-cell battery.

The way in which these two battery designs manage gassing results in major differences in where they can be located, how they must be charged and what kind of maintenance they require.



Battery Bank

This battery bank is housed on a rack allowing for easy access and proper ventilation. (Photo: Loby Gratia)

When designing and locating a battery bank the most important considerations are: ventilation, mounting and temperature. While temperature effects are a crucial factor in the performance of any battery, the ventilation and mounting requirements are quite different for flooded lead-acid and VRLA batteries.

When siting a bank of flooded lead-acid batteries, a well ventilated area must be chosen. Allowing hydrogen gas to accumulate in an enclosed space heightens the risk of an explosion. Also, easy access to the battery terminals and cell caps is essential for the necessary routine maintenance. Any battery rack or battery box designed for use with wet-cell batteries must accommodate these two constraints.

VRLA batteries do not vent gas to the extent that flooded lead-acid batteries do; therefore, ventilation is not of great concern, nor is easy maintenance access. This allows for VRLA batteries to be housed much closer together and without provision for access to the cell caps, which cannot be opened anyway.

Aside from less stringent ventilation and maintenance requirements, VRLA batteries also have an advantage in that they contain no liquid. This allows for the batteries to be placed on their side as well as on their bottom. Flexibility in battery orientation is helpful not only when storing the batteries, but also during transportation.

Regardless of the type of battery in use, temperature will affect performance. Ideally, lead-acid batteries should be kept at a temperature of 25°C (77°F). Higher temperatures will result in an increase in capacity (AH) and a decrease in life (cycles). Lower temperatures have an opposite effect, leading to decreased capacity and longer life. Inevitably, battery temperature will deviate from the ideal, due not only to ambient conditions but also to heat generated within the battery itself during charging and discharging. When siting a battery bank a couple of simple precautions can be taken to minimize the temperature fluctuations experienced by the battery. Firstly, a battery bank should be kept out of direct sunlight and away from any other source of heat (e.g. generator exhaust). Secondly, batteries should not be stored directly on the ground as this will lower their temperature. Keeping the battery bank shielded from heat and insulated from cold will help to ensure top performance.



Power Inverters

These inverters at Hôpital Saint Antoine de Jérémie, Haiti, act as charge controllers for the energy system's battery bank. (Photo: Loby Gratia)


Charging is a central part of any backup power system. The manner in which a battery is charged plays a significant role in its performance and life. Proper charging will ensure that a battery realizes its full potential in terms of number of cycles and total lifetime output. Different types of batteries require different charging methods in order to maximize efficiency and minimize damage. This is true even among different types of lead-acid batteries. There are four different modes of charging, each characterized by three inter-related parameters: voltage, amperage and time. Each of these modes plays a different role in the charge cycle.

Typically, lead-acid batteries undergo a three stage charging regimen. First, the bulk stage applies a constant current to the battery which gradually increases the voltage. This stage normally accounts for 80% of the total recharge. The second stage is called the absorption stage and is characterized by a constant voltage and decreasing amperage. This stage brings the battery to full charge, which is said to occur when the current drops to a rate of C/50. Maintaining the correct constant voltage throughout the absorption stage is important to battery life and performance and will vary depending on the type of battery (e.g. AGM deep cycle, flooded lead-antimony). The final stage in the three stage charging process is the float charge which is designed to counteract the battery's natural self-discharge and keep the battery at full capacity. A float charge is accomplished by lowering the constant voltage applied during the absorption stage, resulting in a very small current meant only to maintain full capacity.

A fourth mode of battery charging is the equalization stage. Equalization charging is not a part of the typical charging cycle and is only performed periodically, on an as-needed basis, or not at all, depending on the type of battery. An equalization charge is essentially an absorption charge set at a higher (10%-15%) voltage and is meant to equalize the voltage of each cell. As batteries are regularly charged and discharged, the chemical composition of each cell can become disturbed. Electrolyte stratification, when acid concentrates at the bottom of the cell, and sulfation, the build-up of sulfate crystals on the surface of the lead electrodes, are two problems that naturally occur in lead-acid batteries. An equalization charge will help to reverse these problems and keep the battery operating at optimum performance.

While these four modes of charging are generally applicable to any lead-acid battery, each type of lead-acid battery and even different manufacturers will have specific voltage and amperage requirements for each mode. In order to ensure optimum battery performance and life, all batteries should be charged in accordance with manufacturer specifications. Since these charging parameters are a function battery design and construction they will vary depending on a number of factors; it is, however, possible to make some over-arching observations.

The charging of flooded lead-acid batteries is commonly performed at a higher constant voltage in the absorption stage than VRLA (gel and AMG) lead-acid batteries. This is because the gassing that occurs in all lead-acid batteries occurs primarily during absorption charging. In a flooded lead-acid battery this process is necessary and helps to keep the electrolyte solution well-mixed. Any hydrogen lost from the cell will be replaced in the form of distilled water during maintenance. In sealed VRLA batteries, however, hydrogen cannot be replaced, so any venting of gasses will affect battery life. Gel VRLAs are especially sensitive to gassing as small bubbles will form in the silica gel, resulting in permanent damage.

In order to achieve the correct charging sequences, carried out at the correct voltages and charge rates, a charge controller is necessary. Many different types of chargers exist, from manually controlled constant voltage chargers to sophisticated microprocessor-controlled chargers. In the case of an inverter/battery backup system, the inverter (the piece of equipment responsible for converting between AC and DC current) also acts as the battery charger. Such inverter/charger systems are capable of properly re-charging, float charging and discharging a battery bank based on battery specifications and connected loads. While inverter/chargers are preprogrammed to perform the complete charging regimen, it is important that the voltage and amperage set points be programmed based on battery manufacturer specifications.

Temperature will affect optimal charging parameters and some manufacturers will provide temperature-corrected voltage specifications. In fact, many advanced charge controllers, such as inverter/chargers, will allow for the use of a temperature sensor and will automatically apply a temperature-corrected voltage.



Maintenance Technician

Maintenance technicians wearing proper protective gear during battery maintenance. (Photo: Loby Gratia)

As previously discussed, flooded lead-acid batteries need regular maintenance and monitoring while sealed VRLA batteries are far less maintenance intensive. In either case, there are some simple maintenance activities that should be periodically undertaken.

Battery systems should be kept clean. Dirt and even acid will inevitably accumulate on the batteries, inverters and cables that make up the IBS; these should all be cleaned as needed. With flooded lead-acid batteries especially, acid will mist out of the vented caps and settle on the battery casings. A basic solution (i.e. baking soda and water) can be used to neutralize the acid. A clean battery will ensure that there is no parasitic electrical current running between the battery terminals, increasing the self discharge rate. The frequency of such maintenance will depend on where the batteries are located; housing them away from dirt and activity will help to minimize the need for cleaning.

Safety precautions are necessary when properly maintaining a flooded lead-acid battery. Because this maintenance entails the handling of acid, eye protection (and preferably a full face shield) and thick rubber gloves must be worn. If battery acid gets on clothing is will disintegrate away the fibers, so old or protective clothing should be worn.

Testing the specific gravity of the battery cells is the only way to be sure that the batteries are chemically sound. The specific gravity of a solution is the ratio the solution's density to that of pure water. With the batteries cell caps open, a specific gravity electrolyte tester is used to draw the electrolyte solution out of the battery cell, at which point a reading can be taken. At 25°C and 100% charge, a battery should have a specific gravity of 1.260. Each cell should be checked to ensure that the specific gravity is equal among all cells. While the battery is open, it is also important to check the fluid levels within each cell. There should be no exposed metal surfaces. If a cell requires a recharge of water, it must be distilled water. The cell should be filled only to the point that the tip of the cell cap dips into the solution.

VRLA batteries do not need to be checked for specific gravity or fluid levels within the cell. For any battery, the best recommendation is to follow all of the manufacturers' maintenance and charging specifications.



Lead-acid batteries enjoy a very high rate of recycling. This is due primarily to the high value of lead, much of which is used in the production of new lead-acid batteries. In fact, 97% of all battery lead is recycled and new batteries contain 60% - 80% recycled lead and plastic. Used lead-acid batteries are collected and then processed in a recycling facility. The batteries are first smashed to pieces, and then put into a separating vat where the lead, plastic and electrolyte are separated into different recycling streams for processing. Recycled lead and plastic from batteries is often used in the production of new batteries. The electrolyte solution can be used in the production of glass, textiles and ceramics, or neutralized and treated as waste water.

Lead-acid battery recycling is one of the most successful examples of a closed-loop recycling process. In order for that process to succeed, however, regulations must be in place and strictly enforced. For many countries in the developing world, this is not the case. Since lead is still highly valuable around the world, lead-acid battery recyclers are prevalent. In many cases, those recyclers are not equipped, trained or incentivized to properly process batteries. Improper processing and handling of those batteries has a negative effect on human and environmental health. Any project employing lead-acid batteries, especially in an effort to increase human and environmental health, should ensure that proper facilities and oversight are available for the recycling process.


 Standards Relevant to Lead-Acid Batteries

A number of standards have been developed for the design, testing and installation of lead-acid batteries. The internationally recognized standards listed in this section have been created by the International Electrotechnical Commission (IEC) and the Institution of Electrical and Electronics Engineers (IEEE). These standards have been selected because they pertain to lead-acid battery use in stationary applications, including UPS, rural electrification, and solar PV systems. These standards should be referenced when procuring and evaluating equipment and professional services.


International Electrotechnical Commission (IEC)
Flooded or vented lead-acid IEC 60896-11 ed1.0: Stationary lead-acid batteries - Part 11: Vented types - General requirements and methods of tests
Valve regulated lead-acid IEC 60896-21 ed1.0: Stationary lead-acid batteries - Part 21: Valve regulated types - Methods of test
  IEC 60896-22 ed1.0: Stationary lead-acid batteries - Part 22: Valve regulated types - Requirements
Safety IEC 62485-2 ed1.0: Safety requirements for secondary batteries and battery installations - Part 2: Stationary batteries
Rural electrification IEC/TS 62257-8-1 ed1.0: Recommendations for small renewable energy and hybrid systems for rural electrification - Part 8-1: Selection of batteries and battery management systems for stand-alone electrification systems - Specific case of automotive flooded lead-acid batteries available in developing countries


Institute of Electrical and Electronics Engineers (IEEE)
Flooded or vented lead-acid 450-2010: Recommended Practice for Maintenance, Testing, and Replacement of Vented Lead-Acid Batteries for Stationary Applications
  484-2002: Recommended Practice for Installation Design and Installation of Vented Lead-Acid Batteries for Stationary Applications
Valve regulated lead-acid 1187-2002: Recommended Practice for Installation Design and Installation of Valve-Regulated Lead-Acid Batteries for Stationary Applications
  1188-2005: Recommended Practice for Maintenance, Testing, and Replacement of Valve-Regulated Lead-Acid (VRLA) Batteries for Stationary Applications
  1189-2007: Guide for Selection of Valve-Regulated Lead-Acid (VRLA) Batteries for Stationary Applications
System design 485-2010: Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications
  1184-2006: Guide for Batteries for Uninterruptible Power Supply Systems
Solar system 937-2007: Recommended Practice for Installation and Maintenance of Lead-Acid Batteries for Photovoltaic (PV) Systems
  1013-2007: Recommended Practice for Sizing Lead-Acid Batteries for Stand-Alone Photovoltaic (PV) Systems
  1361-2003: Guide for Selection, Charging, Test and Evaluation of Lead-Acid Batteries Used in Stand-Alone Photovoltaic (PV) Systems
  1562-2007: Guide for Array and Battery Sizing in Stand-Alone Photovoltaic (PV) Systems
  1661-2007: Guide for Test and Evaluation of Lead-Acid Batteries Used in Photovoltaic (PV) Hybrid Power Systems
Other 1375-1998: Guide for the Protection of Stationary Battery Systems
  1491-2005: Guide for Selection and Use of Battery Monitoring Equipment in Stationary Applications
  1561-2007: Guide for Optimizing the Performance and Life of Lead-Acid Batteries in Remote Hybrid Power Systems
  1657-2009: Recommended Practice for Personnel Qualifications for Installation and Maintenance of Stationary Batteries


 Battery Monitoring

Critical loads require constant battery backup power in order to ensure a consistent, uninterrupted power supply. Battery banks are complex systems with many variables contributing to their reliability; by monitoring those variables, problems can be identified before they result in system failure. A battery monitoring system acts as an interface for the operator, communicating critical information on the status of the battery bank. Monitoring systems may also interact automatically with other elements of the energy system, like inverters and generators, to help protect the batteries and other equipment.

Battery monitors track a variety of parameters to provide information on the health and status of the battery bank. A battery monitor connects directly with a system's battery bank and inverter/charge controller to obtain data on voltage, current and resistance within the system. Monitoring systems may also be equipped to track specific gravity, electrolyte levels and temperatures within individual cells. Typically, the monitor will display key information such as the state of charge of the battery bank, consumed amp-hours, voltage and remaining battery life. Monitors can also be programmed to issue audible alarms or control other devices automatically when problems occur.

Battery monitoring systems can play an important role in ensuring a robust and sustainable energy system. Battery banks represent a large portion of the investment necessary for solar photovoltaic and battery backup power systems, protecting that investment requires maintenance and monitoring. Institutional support and technician training are two vital aspects of system sustainability, battery monitoring can bolster both. Battery monitors help technicians by providing them critical, real-time information on battery performance. Facility managers benefit from battery monitoring by being able to track energy use more effectively.

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