Reference handbook

The large UPS battery handbook The large UPS battery handbook Understanding your UPS battery It’s well understood that the battery in a UPS is the most vulnerable part can extend its life, prevent of the system. In fact, battery failure is a leading cause of load loss. Knowing costly downtime, and save time how to maintain and manage your and money. UPS batteries will extend their life and save you time and potential trouble in the future. Improvements in battery technology have been evolutionary rather than revolutionary. Capabilities such as advanced charging regimens, software management for accurate remaining life information and firmware adding intelligence to batteries have reduced, but not eliminated, the risks inherent in depending on any battery. As a result, it’s prudent, if not essential, to take a close look at what may be increasing your risk of unexpected load loss from a failing UPS battery. After all, even large installations with many batteries are vulnerable to the failure of a single battery.

2 EATON The large UPS battery handbook Eaton.com/UPSbatteries Table of Contents

Table of contents

UPS battery overview ...... 3 VRLA ...... 3 Lithium- ...... 3 Other common causes of UPS failure ...... 3 VLA/flooded-cell ...... 4 Battery arrangement and power ...... 4 Battery facts...... 5 Four factors that affect battery life ...... 5 Battery disposal ...... 6 Battery maintenance for extended life ...... 6 Battery safety ...... 7 Battery FAQ ...... 8 Eaton battery products and services ...... 10 Eaton battery services overview ...... 10 Battery preventive maintenance ...... 10 Eaton batteries ...... 10 Why Eaton batteries? ...... 11 Eaton Cellwatch ...... 11 ...... 11 Extending battery service life ...... 12 Eaton PredictPulse ...... 12 Customer Support Center ...... 12 Customer success story ...... 13 Battery glossary ...... 14

3 EATON The large UPS battery handbook Eaton.com/UPSbatteries UPS battery 1. VRLA VRLA batteries are sealed, usually within polypropylene plastic. They were developed because they have the advantage of containing overview no sloshing acid that might leak or drip out when inverted or handled roughly. The term valve- There are primarily three regulated refers to the method of gas release. If the kinds of batteries used in gas pressure becomes too great inside the battery, UPSs—valve-regulated the valve will vent when it reaches a certain pressure. lead-acid (VRLA), also During the charging of a lead-acid battery, hydrogen is

Overview known as sealed or normally liberated. In a vented battery, the hydrogen maintenance-free lithium- escapes into the atmosphere. In a VRLA battery, the VRLA batteries are frequently hydrogen recombines with oxygen inside battery, used in UPS or other high-rate ion batteries, and vented applications lead acid (VLA) (also so water loss is minimized. Under normal float conditions, virtually all the hydrogen and oxygen is called flooded-cell). VRLA recombined. Re-sealable valves vent non-recombined batteries usually have gases only when pressure exceeds a safety lower up-front costs but threshold. have a shorter lifetime than VLA, usually around A VRLA battery is distinguished from a flooded-cell battery by the rate at which oxygen is evolved from five years. Flooded-cell the positive plate and diffused to the negative plate, batteries require more ultimately forming water. This rate is several orders of advanced maintenance magnitude faster than a flooded-cell battery. Because but have a longer lifetime, water can’t be added, its recombination is critical to up to 20 years. Lithium- the life and health of a the battery. Any factor that ion batteries are smaller increases the evaporation rate or water loss—such and lighter than the above as ambient temperature and heat from the charging current—reduces the battery life. types, and have changed the traditional status quo The shelf life of a VRLA battery is the length of time for UPS use. Costs are a battery can stand, open circuited, before it can no similar to VRLA, and longer be recovered to full capacity with a single new energy storage charge. Shelf life is determined by the length of time until the battery loses 40%–50% of its initial capacity applications with UPS due to self-discharge. systems, such as grid- sharing and peak shaving, Positive flag Extruded intercell are now viable. These Valve terminal welded connection, new capabilities provide low resistance more than just backup current path time, and can now

contribute to significant Cover/lid cost savings for the user in their day-to-day operations. Strap joining negative plates in parallel

Negative pasted plate lead alloy grid

Polypropylene container/jar Separator

Internal and external components of a valve-regulated lead-acid (VRLA) battery

4 EATON The large UPS battery handbook Eaton.com/UPSbatteries 2. Lithium-ion 3. VLA Lithium based batteries have multiple significant benefits VLA or flooded-cell batteries have thick lead-based plates over alternative DC storage techniques for UPS applications. that are flooded with an acid . This is a highly The technology has matured in heavy duty applications like reliable design—failures normally don’t occur until halfway electric vehicles, and is considered ideal for critical power through their 20-year pro-rated life, at which time the failure backup. Small size and light weight are the primary benefits, mode is most often a short circuit. This situation is not an but additional features like built-in battery management (not extreme emergency because any one shorted cell only affects just monitoring), make lithium-ion an attractive alternative to overall reserve time by a very small percentage. However, while Overview traditional batteries. they’re very reliable with a long life, there are downsides to flooded-cell batteries. They require more safety measures and a In addition, their high cycle-count (charge-discharge cycles), and space-consuming separate to use. faster recharge times compared with lead batteries allows their use in non-traditional UPS applications, like grid sharing, peak Regardless of the differences in UPS battery types, both shaving, and industrial or process control support. require monitoring and maintenance to ensure maximum life and system availability. The battery management system is deployed in each battery, as well as in a system level master controller. It manages charge current, voltage, and cell voltage balance, while making adjustments as necessary to eliminate any chance of overtemperature. If temperatures rise above safe levels, the management system will independently disconnect the battery or string via multiple different disconnection means, and notify the user via the battery cabinet monitor, and an alarm on the UPS.

Overall, a lithium-ion battery system provides lower TCO through comparable Capex costs, and Opex savings via a longer replacement interval, and Lithium-ion battery systems Flooded-cell batteries require more advanced maintenance but have a its ability to operate at higher provide a reliable and flexible longer battery service life ambinet temperatures. solution that ensures 24/7 system uptime

Other common causes of UPS failure Did you know? Batteries may be the number one contributor to UPS failure, but these are three other vulnerable components that shouldn’t be overlooked.

Capacitors: A capacitor is a fairly Filters: Because dust may block Fans: They may slow down or stall simple device that stores and releases air filters and cause a UPS to shut as they age, and a resulting over electrical energy. They can be as small down due to overheating, they must temperature condition will shut down as a thumbnail or as large as a soda be inspected every month. Replacing the UPS unexpectedly. Watch for fan can. A typical UPS contains a dozen or filters is an inexpensive component of fail alarms every week, and plan for more of different types and sizes. Like an effective UPS maintenance plan. replacement at the 8-10 year mark batteries, capacitors degrade over time. at the latest. There may not be visible effects upon immediate failure, but one failure will leave other capacitors to work harder and shorten lifespan.

5 EATON The large UPS battery handbook Eaton.com/UPSbatteries Battery arrangement and power In most UPSs, you don’t use just one cell at a time. They’re normally grouped together serially to form higher voltages, or in parallel to form higher currents. In a serial arrangement, the voltages add up. In a parallel arrangement, the currents add up.

However, batteries are not quite composition during charging and •  : The terminal where as linear as the two graphics to discharging, and the electrolyte the current flows in the right depict. For example, is dilute . In other all batteries have a maximum words, they contain components •  : The terminal current they can produce; a that react with each other to where the current flows out 500 milliamp-hour battery can’t create DC electrical current. • Valve (used in VRLA produce 30,000 milliamps for These components are: batteries): Used to vent the one second, because there’s no • Electrolyte: The medium build-up of gas that goes

Overview way for its chemical reactions beyond pre-determined levels to happen that quickly. It is that provides the ion transport mechanism also important to realize that at • Separator : A device used between the positive and higher current levels, batteries for the physical separation negative of a can produce a lot of heat, which and electrical isolation of cell, immobilized in VRLA wastes some of their power. electrodes of opposing batteries, and in liquid form polarities Like all batteries, UPS batteries in flooded-cell batteries are electrochemical devices. A • Jar : The container holding the • Grid : A perforated or UPS uses a lead-acid storage battery components battery in which the electrodes corrugated lead or lead alloy are grids of lead containing plate used as a conductor and lead oxides that change in support for the active material

Replacement lead acid batteries for data room battery cabinets

Connecting in series [double voltage, same capacity (ah)] + - + - +24V 12V 12V

Connecting in parallel [same voltage, double capacity (ah)] + + +12V 12V 12V - -

Series connection Parallel connection Connecting of the positive terminal Connecting all the positive or of a cell/battery to the negative negative poles of several batteries terminal of the next cell/battery increases the capacity of a battery increases the voltage of the battery network while maintaining a network while keeping the capacity constant voltage. constant.

6 EATON The large UPS battery handbook Eaton.com/UPSbatteries Battery facts Four factors that affect battery life Batteries have limited life, usually showing a slow degradation of 2. Battery chemistry capacity until they reach 80 percent of their initial rating, followed UPS batteries are electrochemical devices whose ability to store by a comparatively rapid failure. Regardless of how or where and deliver power slowly decreases over time. Even if you follow a UPS is deployed, and what size it is, there are four primary all the guidelines for proper storage, usage and maintenance, factors that affect battery life: ambient temperature, battery batteries still require replacement after a certain period of time. chemistry, cycling and service. 1. Ambient temperature 3. Cycling During a utility power failure, a UPS operates on battery power. The rated capacity of a battery is based on an ambient Once utility power is restored, or a switch to generator power is temperature of 25°C (77°F). It’s important to realize that any complete, the battery is recharged for future use. This is called variation from this operating temperature can alter the battery’s a discharge cycle. At installation, the battery is at 100 percent of performance and shorten its expected life. To help determine rated capacity. Each discharge and subsequent recharge reduces battery life in relation to temperature, remember that for every its relative capacity by a small percentage, albeit a much smaller 8.3°C (15°F) average annual temperature above 25°C (77°F), the percentage for lithium-ion chemistry. The length of the discharge life of the battery is reduced by 50 percent. cycle determines the reduction in battery capacity.

Lead-acid or lithium-ion batteries, can only undergo a maximum 2.4 number of discharge/recharge cycles before the chemistry is

depleted, but lithium-ion cycle count is typically 10X that of lead Facts Battery 1.2 acid. Once the chemistry is depleted, the cells fail and the battery must be replaced. 1.0 4. Maintenance 0.8 Battery service and maintenance are critical to UPS reliability. A gradual decrease in battery life can be monitored and evaluated 0.6 through voltage checks, load testing or monitoring. Periodic preventive maintenance extends battery string life by preventing Relative Life Relative 0.4 loose connections, removing and identifying bad batteries before they can affect the rest of the string. 0.2 Even though sealed batteries are sometimes referred to as 0.0 maintenance-free, they still require scheduled maintenance and 77 80 90 100 110 120 130 140 ºF service. Maintenance-free simply refers to the fact that they don’t 25 26.7 32.2 37.8 43.3 48.9 54.5 60 ºC require water to be added regularly. Average Annual Temperature Without regular maintenance, your UPS battery may experience Optimum operating temperature for a VRLA and lithium-ion heat-generating resistance at the terminals, or inside the jar battery is 25°C (77°F). High ambient temperature allows improper loading, reduced protection and premature failure. With unnecessary large quantities of charge current to flow which proper maintenance, the end of battery life can be accurately results in a shorter service life. estimated and replacements scheduled without unexpected downtime or loss of backup power. What can go wrong with batteries?

Condition Cause Battery life: design life vs. actual life Repeated cycling (charging and discharging), Plate separation damage during handling and shipping, and Determining battery life can be a tricky business. It’s often overcharging promoted based on design life, defined as how long the Normal aging, operating in an acidic environment battery can be expected to perform under ideal conditions. Grid corrosion and high temperatures Estimating actual battery life relies on taking into Heat (plates expand causing shorts), separator consideration the four factors discussed on this page Internal short circuit failure, handling and shipping, and grid corrosion that can affect it.

External short circuit Human error (shorting terminals) and leaks

Sitting discharged for an extended period, not on Sulfation of plates charge or being undercharged, such as battery shelf life being exceeded past manufacturer’s guidelines Often due to high temperatures or overcharging; Excessive gassing electrolyte volume is decreased Excessive gassing, high temperatures or Drying out overcharging, resulting in too little electrolyte for battery to function and provide full backup time

7 EATON The large UPS battery handbook Eaton.com/UPSbatteries Battery disposal Battery maintenance Spot replacement of batteries Batteries in series are similar to a string Batteries that are replaced can still for extended life of holiday lights. When one unit fails, the contain a significant amount of hazardous entire string no longer works. When a waste, including the electrolyte and lead. Quantifying the combined effect of the four factors that affect battery life battery or group of batteries connected in Therefore, you must comply with EPA a series ceases to work, not only is the discussed in the previous page is difficult. guidelines for the disposal of all UPS battery string no longer functional, but it batteries. There are essentially two main You need a way to determine when a can be difficult to determine which battery categories of disposal, one for spent battery is near the end of its useful life has failed. so you can replace it while it still works, batteries and another for spills. The primary The most effective way to combat this ways to handle these two categories are: before the critical load is left unprotected. The only sure way to determine battery potential problem is to “spot” replace bad batteries that are less than three years Spent batteries capacity is to perform a battery run- down test. The module is taken off line, old. While the four factors affecting battery Send to secondary lead smelter for connected to a load bank and operated life play a large role in determining when a recycling. For lithium-ion, return to original at rated power until the specified runtime battery is vulnerable to failure, there’s no vendor or an authorized 3rd party recycler elapses or the unit shuts down due to low precise way to ensure that battery failure equipped to handle lithium batteries. battery voltage. If battery capacity is less can be predicted. The only way to identify than 80 percent of its rated capacity, the bad batteries early enough for spot Spilled batteries battery should be replaced. replacement is through continuous battery monitoring and scheduled maintenance. Place neutralized leaked material into Spot replace bad VRLA batteries that are sealed containers and dispose of as Thermal scanning of battery connections less than three years old and replace the hazardous waste, as applicable. Large during the battery run-down test identifies whole string between the fourth and fifth water-diluted spills, after neutralization loose connections. This test gives you year (10th year for lithium-ion). and testing, should be managed in the chance to see the battery during accordance with approved local, state and an extended, high-current discharge. Scanning should take place during Used batteries: good for the federal requirements. Consult your state environment? Battery Facts environmental agency and/or the EPA. discharge and recharge cycles. Which commonly used product has the An effective UPS battery maintenance Recycling highest rate of recyclability? Paper? Only program must include regular inspections, 73 percent of paper is recycled for reuse. One of the most successful recycling adjustments and testing, with thorough Aluminum at 54 percent and glass at efforts in the world is for lead-acid records kept of all readings. Trained 25 percent also fall short of the leader. batteries. According to Battery Council technicians should: More than 96 percent of all battery lead is International, more than 96 percent of recycled. Lead-acid batteries top the list of lead-acid batteries were recycled between • Inspect batteries and racks or cabinets most highly recycled consumer product. 1997 and 2001. Many states require lead- for signs of corrosion acid batteries be recycled, and several vertical return alignment leakage The processes for lead-acid support agriculture needs and options exist to dispose of used batteries, • Measure and record the float voltage enhance energy conservation. Beyond the including: and current of the successful reuse of nearly 100 percent of entire bank • If you’re engaged with Eaton on a the battery components, lead recycling battery upgrade or replacement, we’ll • Record the terminal voltage of selected facilities harness radiant heat from their take your old batteries and recycle them batteries furnaces to offset traditional heating costs. for you Residual sulfur trapped during recycling is • Check the electrolyte level in each cell, processed into fertilizer. Even the plastic • If you participate in Eaton’s UPSgrade if visible casings are crushed into pellets and are program, we take the old UPS and used to manufacture new battery covers recycle it. Visit Eaton.com/upsgrade for • Check voltage balance and internal and cases. details temperature of lithium-ion cells Recycling lead is also more energy • Log the ambient temperature • Check your local phone book for a local efficient than smelting or mining new recycler, or search for a recycler at • Compare data collected to previous lead. The recycled lead can be refined into www.earth911.com maintenance inspections to accurately new alloy repeatedly, giving it unmatched sustainability and cost stability—a trait • Some automotive stores accept batteries identify issues unlike most raw materials. for recycling Lithium-ion recycling Lithium batteries from a UPS are highly • Many municipalities have dump or Lithium-ion batteries contain no toxic likely to have a ‘second life’ in a solar recycling locations that will accept materials, but should be recycled or or electric vehicle application, before batteries for recycling. When disposing re-used, i.e. redeployed in solar, home ultimately being recycled. Contact the of batteries in this manner, be sure to backup, or refurb automotive use. battery vendor to see if this is get a dated receipt clearly detailing what batteries were dropped off, including quantities with the recycler’s full name, address and phone noted in the unlikely event you get audited.

8 EATON The large UPS battery handbook Eaton.com/UPSbatteries Appropriate personal protective equipment is essential when working on batteries or any UPS equipment

Battery safety Battery storage and recharge The materials in batteries make them volatile and therefore Batteries lose charge or self-discharge due to slight differences in Facts Battery potentially hazardous. Performing regular periodic maintenance local areas of the plates that discharge the battery. In effect there on your UPS batteries can go a long way in preventing unsafe are tiny, little batteries, inside that are not open circuited and will situations before they occur. discharge locally some of the active material. Self-discharge of the battery occurs continuously whether the battery is standing Sulfuric acid is very combustible and contact with organic open circuited or operating in the UPS. When the charger is on, a materials may cause fire and explosion. It also reacts violently portion of the float current (i.e. small current flowing through the with strong reducing agents, metals, sulfur trioxide gas, strong battery) goes to overcoming self-discharge and keeps the battery oxidizers and water. Contact with metals may produce toxic fully charged. sulfur dioxide fumes and may release flammable hydrogen gas. When your UPS battery has lost significant charge while not in For lead compounds, avoid contact with strong acids, bases, use, recharging (or restoring electric charge of your UPS through halides, halogenates, potassium nitrate, permanganate, another source) may be necessary. Proper recharging within the peroxides, nascent hydrogen and reducing agents. Lithium-ion stated shelf life will maintain the runtime to that of a new battery. batteries actually contain no toxic substances, and pose no If a battery has lost significant charge in storage, Eaton recharges hazard in normal handling. If a battery case is broken, consult the battery and adds a new label noting the next “recharge by” the vendor’s Material Safety Data Sheet (MSDS) for appropriate date. Locate the label on your battery to find the recharge date action. Different lithium-ion battery models use a variety of and appropriately manage your battery maintenance. different chemical components, and safety procedures will vary. If a battery system in the field is approaching the recharge date You should always refer to the material safety data sheet for and the UPS will not be installed before that date, then plans specific precautionary measures. Primary steps for safe handling should be made to recharge the batteries. UPS systems can and use are noted below. be connected to a temporary feed to recharge the batteries. In some cases, external battery charging systems can be brought Spills or leaks (for lead acid batteries) in to perform a refreshening charge. It is recommended that you Stop the flow of materials and contain/absorb small spills with use the Original Equipment Manufacturer (OEM) to recharge dry sand, earth or vermiculite. Don’t use combustible materials. batteries in the field to guarantee that the battery manufacturers’ If possible, carefully neutralize spilled electrolyte with soda guidelines are met and you warranty is maintained. ash, sodium bicarbonate or lime. Wear acid-resistant clothing, boots and gloves, and a face shield. Do not allow discharge of Failure to put the battery system in service or failure to recharge un-neutralized acid to get to the sewer. before the “recharge by” date will result in a permanent loss of battery capacity as well as cancellation of the battery warranty.

Battery date code chart for UPS productions:

Supplied Date code identifier Eaton YYMMDD CSB YYMMDD C&D Dynasty MMYY Enersys MMYYY Enersys High Rate DDMMMYY Northstar YYDDD (Julian) Panasonic MMDDYY Yuasa / B&B YYMMDD

9 EATON The large UPS battery handbook Eaton.com/UPSbatteries Battery FAQ

1. What is the “end of useful life”? 7. Our facility was damaged by a flood and our batteries were partially submerged in water. What should we do? The IEEE defines “end of useful life” for a UPS battery as being the point when it can no longer supply 80 percent of its rated The first concern in this situation is safety. Containing any capacity in ampere-hours. When your battery reaches 80 percent contamination is critical to preventing hazards to workers and the of its rated capacity, the aging process accelerates and the environment. battery should be replaced. 8. My UPS has been in storage for over a year. Are the 2. How can I ensure that my UPS batteries are maintained batteries still good? and serviced properly? As batteries sit unused, with no charging regimen, their battery With proper maintenance, battery life can be predicted and life will decrease. On average batteries loose 3% of capacity replacements scheduled without interrupting your operations. for every 30 days they sit uncharged due to the self-discharge These are IEEE and OEM recommendations for general characteristics of lead-acid batteries. It is imperative that they maintenance: are charged periodically during storage according to the battery manufacturer’s guidelines for temperature, charge duration and • Comprehensive maintenance programs with regular inspections resting period or permanent loss of capacity will occur. • Re-torque all connections, as required 9. What is thermal runaway? • Load testing • Cleaning the battery area, as required Thermal runaway occurs when the heat generated in a lead- acid cell exceeds its ability to dissipate it, which can lead to an 3. Do I have to replace my UPS batteries with the same brand explosion, especially in sealed cells. The heat generated in the of batteries? cell may occur without any warning signs and may be caused by overcharging, excessive charging, internal physical damage, Eaton recommends that if you use brand X and need to replace internal short circuit or a hot environment. Note that for lithium- one or two batteries in the string, you should use the same brand ion batteries the shelf life is typically two years at 25°C (75°F), because it will have the same characteristics. If you need to and one year at 60°C (140°F). replace the whole battery system, then you can change brands with fewer risks.

4. Are maintenance-free batteries maintenance free? Though sealed batteries are sometimes referred to as maintenance-free, they still require scheduled maintenance and service. The term maintenance-free refers to the fact that they don’t require fluid. Preventive maintenance is the key to maximizing your UPS battery service life. Thermal runaway 5. What about battery disposal? incident It’s imperative that your service technicians adhere to EPA Thermal runaway effects

Battery FAQ guidelines for the disposal of all UPS batteries. Remember, on adjacent battery it’s the owner’s responsibility to make sure these guidelines cabinet are followed.

6. Is there any difference between the batteries used by smaller UPSs, from 250 VA to 3 kVA, and the ones used by larger UPSs? While basic battery technology, and the risks to battery life, remain the same regardless of UPS size, there are some inherent differences between small and large applications. Smaller UPSs typically have only one VRLA battery that supports the load and 10. Is it safe to transport sealed batteries? needs maintenance. As systems get larger, increasing battery VRLA batteries marked as “non-spillable” are safe and capacity to support the load gets more complicated. Larger approved for all transportation methods as long as the container systems may require multiple strings of batteries, introducing is free of blemishes and local DOT regulations are followed. complexity to battery maintenance and support. Individual However lithium-ion battery shipments are governed under UN batteries must be monitored to prevent a single bad battery from Class 9 requirements and designated procedures. taking down an entire string and putting the load at risk. Also, as systems get larger, flooded-cell batteries become more common. 11. What is the difference between hot-swappable and The differences in battery maintenance between VRLA and flood- user-replaceable batteries? cell batteries discussed earlier apply. Hot-swappable batteries can be changed out while the UPS is running. User-replaceable batteries are usually found in smaller UPSs and require no special tools or training to replace. Batteries can be both hot-swappable and user-replaceable. Please check your user’s guide for details on your UPS batteries.

10 EATON The large UPS battery handbook Eaton.com/UPSbatteries 12. How is battery runtime affected if I reduce the load on All it takes is one bad battery to ruin an entire string and bring the UPS? your systems down during a or other interruption. There is no precise way to predict battery failure. Continuous The battery runtime will increase if the load is reduced. As a battery monitoring and scheduled maintenance are the most general rule, if you reduce the load by half, you triple the runtime. effective way to identify bad batteries early enough for spot 13. If I add more batteries to a UPS can I add more load? replacement. Adding more batteries to a UPS can increase the battery runtime 21. Why do batteries fail? to support the load, but it doesn’t increase the UPS capacity. Batteries can fail for a multitude of reasons, but common Be sure your UPS is adequately sized for your load, then add reasons are: batteries to fit your runtime needs. • High or uneven temperatures 14. What is the average lifespan of UPS batteries? • Inaccurate float charge voltage The standard service lifespan for VRLA batteries is three to five • Loose inter-cell links or connections years; lithium-ion, 10 years, and for flooded-cell batteries it’s up to 20 years. However, expected life can vary greatly due to • Loss of electrolyte due to drying out or damaged case environmental conditions, number and depth of discharge cycles, • Lack of maintenance, aging and adequate maintenance. Having a regular schedule of battery maintenance and monitoring will ensure you know when your 22. What is the importance of power density when talking batteries are reaching their end-of-life. about batteries?

15. Why are batteries disconnected on small, single-phase Batteries differ markedly in the number of watts per cell. A higher UPSs when they’re shipped? density battery provides more runtime for the footprint. You may even find you can reach your runtime requirements with fewer This is so that they’re in compliance with Department of battery cabinets, which reduces upfront and lifetime costs of Transportation regulations. battery preventive maintenance. 16. If I have the serial number from the Eaton UPS or battery 23. How is battery performance generally measured? cabinet, can I find out how old the batteries are? Batteries are generally rated for 100+ discharges and recharges, Every Eaton battery has a manufacturer date code that indicates but many show a marked decline in charging capacity after as when it was made. The battery or battery cabinet will also feature few as 10 discharges. The exception is lithium-ion batteries which a sticker for each time the batteries have been recharged while are typically rated for up to 2000 discharges over their service in storage. Stored batteries require charging periodically during life. The lower the charge the battery can accept, the less runtime

storage to avoid loss of capacity. Recharging stored batteries FAQ Battery it can deliver. Look for batteries with a high-rate design that doesn’t affect battery warranty as long as it does not exceed a sustains stable performance for a long service term. battery manufacturer’s guidelines for the number of recharges before a battery is put into service. 24. When are 10-year design life SVRLA batteries typically replaced in standard UPS applications? 17. Will Eaton replace batteries for other manufacturers’ UPSs? UPS battery life depends on a number of factors, including Yes. Eaton batteries works on nearly all other manufacturers’ operating temperature, number and duration of discharges, UPSs. In addition, we have extensive knowledge of Best Power, and if regular preventive maintenance is performed. While Deltec, IPM and Exide Electronics models because these product it’s theoretically possible for SVRLA batteries to last 10 years lines were purchased by Eaton. under optimum conditions, the industry typically recommends full replacement between years four and five for reliability 18. What are the risks associated with a lack of battery purposes in UPS applications. Note that lithium-ion battery typical maintenance? replacement interval is 10 years.

The primary risks of improperly maintained batteries are: load 25. How can I determine the age of a battery? loss, fire, property damage and personal injury. Batteries shipped on or after January 1, 2000 have a four-digit 19. Who are the major battery manufacturers? shipping code with the first two digits as the year and the following two as the month in which the battery was shipped There are many battery manufacturers, but the major ones are: from the factory. For example, a code of 1710 would be C&D, Enersys, CSB, Samsung, Yuasa, Panasonic and GS – to interpreted as 2017, October. name a few.

20. If I have one bad battery, should I only replace that faulty battery, or replace the entire battery string?

Having one faulty battery doesn’t mean you have to replace the entire battery string, which can be very costly. You can replace the bad battery with a fully charged unit but you also need to test the health of the entire string to the cell level to identify if additional strain from the faulty battery damaged other units.

11 EATON The large UPS battery handbook Eaton.com/UPSbatteries Eaton battery products and services

Eaton’s line of premium batteries for Eaton three-phase UPS models is backed by a service network of trained and qualified battery service technicians Eaton battery services overview Battery preventive maintenance Eaton provides a comprehensive set of services for batteries. Preventive maintenance ensures uptime and extends battery life by eliminating problems before they happen. Whether a battery • Battery preventive maintenance/onsite inspection: fails from defect or deterioration, the best time to find out is technicians test, inspect, clean and analyze battery during preventive maintenance service, not when the battery is performance and provide a detailed report that includes any called on to support the critical load. Eaton will custom design a recommendations for corrective action preventive maintenance package that’s best for you, including the • Eaton battery: includes options to replace individual batteries following features: or the entire string • Comprehensive maintenance schedule for your VRLA or flooded-cell batteries per IEEE guidelines • Eaton CellWatch: battery monitoring • Measure cell voltage levels • 10 percent partial replacement coverage: coverage for parts and labor for a bad battery up to 10 percent of the total count • Visual inspection for leaks or bad cells of batteries installed • Spot check for connection torques • Customer Support Center: complete 24x7 command center • Load testing for all Eaton services • Inspection of battery environment • Detailed hard copy of battery test and inspection results • Written inspection report and recommendation For more information on Eaton batteries, please visit This also includes spot replacement of batteries. When we Eaton.com/UPSbatteries identify one or two bad batteries, we replace them immediately onsite if the Eaton technician has replacements available at the time of the preventive maintenance regimen, or schedule prompt replacement if batteries need to be ordered. Eaton VRLA battery models available Model Warranty Labor adder Eaton 12V 34W battery 2-year parts/1-year labor 2-year parts/2-year labor Eaton 12V 120W battery 2-year parts/1-year labor 2-year parts/2-year labor Products & Services Eaton 12V 200W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 280W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 330W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 390W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 502W battery 3-year parts/1-year labor 5-year parts/5-year labor Eaton 12V 540W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 620W battery 3-year parts/1-year labor 3-year parts/3-year labor Eaton 12V 651W battery 3-year parts/1-year labor 5-year parts/5-year labor

12 EATON The large UPS battery handbook Eaton.com/UPSbatteries Eaton batteries Why Eaton batteries? Eaton Cellwatch As a part of our commitment to delivering Proven performance. Eaton batteries Eaton Cellwatch is an advanced battery the highest reliability in power availability, have been thoroughly tested by our monitoring system for three-phase Eaton offers a line of premium batteries engineering team and shown to adhere UPSs. All information collected by for our three-phase UPS models. to our stringent performance and quality Eaton Cellwatch is gathered at a central Eaton batteries combine field-proven specifications. monitoring unit, where it’s analyzed on performance and quality at competitive ® High power density. An optimized design Windows -compatible software. The pricing and are backed by our network delivers more watts per cell, more power system uses fiber-optic technology, which of trained battery customer service for the volume than other batteries on is non-conducting and introduces no engineers. the market. As a result, Eaton batteries electrical noise, so all readings are precise and accurate. Prior to using a battery in an Eaton provide more runtime for the footprint, more runtime per dollar. product, a thorough review of the Eaton Cellwatch provides continuous performance, manufacturing and design High-rate design. Charge after charge, monitoring of your batteries to allow you data is conducted. The presence of the batteries approved for the Eaton to proactively identify and address battery specific attributes of the design and brand sustained high runtime levels, while issues. This includes: manufacturing process, important for UPS performance of non-qualified batteries battery use, is confirmed. dropped off markedly after only 10 • Monitoring of voltage, internal discharges. resistance and temperature Following the review and assuming the outcome is successful, a statistically Extended warranty coverage. Eaton • Immediate warning and specific battery significant sample of the batteries is offers a full three years (excluding 34W identification of deterioration and obtained from the manufacturer. This and 120W battery models which are two imminent failure years) of parts coverage with full (not pro- sample is required to have been built • Reduction of the possibility of damage rated) replacement of any failed battery. from the manufacturer’s existing process to entire battery string for that battery. A series of tests and In the unlikely event a replacement physical examinations are conducted on battery fails within the first year, Eaton • Replacement based on actual battery this sample; including a set of discharges will send a technician on-site to install the condition, preventing costly premature using various loads to characterize the replacement battery at no charge. With replacement performance of the battery, charge tests regional stocking locations, we can get and tests for float current stability at replacement batteries to you quickly. • Minimum of 120 days of activity history, normal to high-float voltages. Failures enabling you to trend individual battery Expert technical support. Eaton batteries or inconsistencies in performance are and string performance are backed by our service network of investigated further and reviewed by trained and qualified battery service • Continuous monitoring of string and the manufacturer. In some cases, a tear- engineers who are available to install battery discharge currents ranging from down analysis is performed to identify and maintain your batteries. Beyond the 25A to 1000A the cause of the problem. If the battery is warranty period, you can choose battery found acceptable and all open issues are • Programmable alarm functions monitoring services and maintenance resolved, a limited series of discharges, plans that take the guesswork and • Remote monitoring capabilities (optional) with recharge, are performed. administrative tasks out of battery management. • May be used to detect thermal runaway This intense and thorough quality testing in advance ensures that Eaton batteries are ready for Easy installation. No special harnesses peak performance at their stated capacity are needed when these batteries are as soon as they’re deployed. installed with new UPSs. Harnesses are Thermal runaway & Services Products readily available for legacy UPSs. Thermal runaway is the most dangerous and potentially catastrophic situation involving lead-acid batteries. It occurs when the heat generated in a lead-acid cell exceeds its ability to dissipate it, which can lead to an explosion, especially in sealed cells. The heat generated in the cell may occur without any warning signs and may be caused by overcharging, excessive charging, internal physical damage, internal short circuit or a hot environment.

By monitoring every jar or cell in the battery system for signs of failure, Eaton Cellwatch is uniquely suited to find the Eaton Cellwatch battery monitoring system monitors key causes and symptoms of thermal runaway performance indicators for each individual battery to provide adequate time to detect and replace a bad battery, mitigating before damage occurs. the risk of downtime

13 EATON The large UPS battery handbook Eaton.com/UPSbatteries Extending battery service life Eaton PredictPulse Insight Eaton’s ABM® technology uses a unique three-stage charging Remote monitoring and management is like a second set technique that significantly extends battery service life of eyes that is keeping tabs on your equipment 24 hours a day, and optimizes recharge time compared to traditional trickle 7 days a week and will notify you of any issues. PredictPulse™ charging. An integrated battery management system tests and Insight is a monitoring and management service that collects monitors battery health and remaining lifetime and provides and analyzes data from connected power infrastructure devices, advance notification to guide preventive maintenance. Optional providing us with the insight needed to make recommendations temperature-compensated charging monitors temperature and take action on your behalf. Once activated, managed changes and adjusts the charge rate accordingly to properly devices send parametric data to Eaton’s monitoring center every charge the battery and greatly extend battery life. A variable 15 minutes. We compare current and historical performance battery bus accommodates 384V to 480V configurations, so data against specified parameters to determine if anything is the battery capacity can be matched to your exact runtime out of the ordinary. At the same time, the data appears on requirements—either a specific runtime, an extension to existing your PredictPulse dashboard and alarms in the mobile app. If battery runtime or legacy battery installations. With remote something is amiss, we’ll notify you of the alarm and how we monitoring of the UPS and battery system, Eaton is able to recommend addressing it. respond to alarms and real-time battery data to avert potential battery problems. Note: ABM is not applicable for flooded-cell or This means less time spent managing IT equipment, reduced lithium-ion systems. risk, access to real-time status information and expedited repairs. You’ll also receive a report each month summarizing 100% the past 30 days of status, performance, alarms and upcoming UPS with ABM service needs. UPS with Float Charge UPS with Lithium-Ion ime

90% Battery Backup T (in minutes and seconds)

80% I I I I I I I I I I I I I 0 10 20 30 40 50 60 70 80 90 100 110 120 Battery Age (in months)

Although batteries are sold with a variety of published life spans, the fact is, some demonstrate a useful life of as little as three to five years. Eaton’s exclusive ABM technology significantly increases the life of VRLA UPS batteries. The Eaton Customer Monitoring Center stands ready to assist 24x7

Customer Monitoring Center Eaton’s global 24x7 service operations command center is a hardened, secure facility for all UPS product service scheduling, technical support and remote monitoring support.

Customer support staff are The benefits of the Customer • Eases customer hassle of managing trained to qualify and prioritize all Monitoring Center include: battery health

Products & Services incoming calls using defined • Increased reliability via remote • Saves time for busy facility or IT processes, complemented by a diagnostic and remote repair tools managers knowledge database, with tech delivered by Eaton product experts • Enhanced internal self-monitoring support and domain experts at • Expedited service response to resources and capabilities their disposal 24x7. critical UPS and battery alarms • Monthly reports designed for both (reduces risk and cost of downtime) technical and non-technical use • 24x7 notification of critical alarms • Development of trending database or trends on both UPS and battery

14 EATON The large UPS battery handbook Eaton.com/UPSbatteries Maintaining uptime, even in the world’s worst weather

The Mt. Washington The Mt. Washington Years ago, MWO deployed a 15 The field technicians trekked to Observatory (MWO) is a kVA Eaton 9355 uninterruptible the top of Mt. Washington with Observatory can’t have private, non-profit scientific power system (UPS) with more four new strings of batteries for any interruptions in and educational institution than 170 minutes of runtime the observatory. They safely dedicated to advancing the to help ensure that even when removed 32 trays of batteries power, which is why understanding of the natural the most extreme weather hits, and two cabinets—about systems that create the Earth’s the organization can continue 3,840 pounds of materials. we have the Eaton weather and climate. The gathering and storing vital data. This helped MWO significantly UPS. We’re collecting summit of Mt. Washington is When an outage happens, consolidate its UPS solution, data continuously, and home to some of the most the 9355 immediately kicks saving valuable space at the dangerous and unpredictable on to keep MWO’s systems summit. those types of weather in the world, so MWO operating until its generator can Eaton’s reliable service was instruments do not like maintains a mountaintop power up. Although this usually invaluable to the staff at station to conduct research, takes just a matter of seconds, MWO. “We’re in an extreme interruptions in power. oversee educational programs without a highly reliable UPS environment here…we have to It’s also holding and collect real-time data that to bridge the gap, those fix things on site and there’s no feeds into the National Weather seconds could result in holes hardware store just down the together our entire Service’s forecast models. in the organization’s 80-year street,” said an IT specialist IT infrastructure. At an elevation of 6,288 feet, continuous weather history. at MWO. “Even in the best the observatory is prone to While the 9355 performed of conditions, we’re a difficult Cyrena-Marie Briedé, director of direct lightning strikes; during place to get to. Eaton still summit operations flawlessly through the years, winter, conditions become even by 2014, its batteries needed to manages to provide service on & Services Products more treacherous with ice, be replaced. The MWO IT team a regular basis and when we snow and blistering hurricane- reached out to Eaton to arrange need it.” force wind gusts—all of which a battery replacement and get With a more compact UPS can knock out electricity. the UPS on a service plan. solution, real-time system Discovering that MWO updates and the addition of had reduced its equipment an environmental monitoring since the UPS was first probe, MWO is in an excellent installed, Eaton’s service team position to preserve its 80-year determined that 90 minutes weather history and capture as of runtime—rather than the much data as possible during originally slotted 170 minutes— extreme weather. Watch this would be more than sufficient video for the full story: for the organization. Eaton.com/MWO

In winter, the Mt. Washington Observatory is an ice and snow palace, battered by hurricane-force wind gusts

15 EATON The large UPS battery handbook Eaton.com/UPSbatteries Battery glossary

Absorbed electrolyte – Actual capacity – The total Average voltage – The Battery nominal voltage – Electrolyte that’s been number of ampere-hours that average of the individual The nominal voltage of one cell immobilized in an absorbent could be withdrawn from a cell voltages of all the cells multiplied by the number of separator. cell based on a specific set of in a battery. This term may cells in the battery. operating conditions (including be applied to a variety of Absorbed electrolyte cell – A initial state-of-charge, discharge conditions, including average Battery rack – A structure cell, usually a valve-regulated rate, initial cell temperature float voltage and average used to support a group of sealed lead-acid type, which and end voltage) and the age discharge voltage. cells. The most common utilizes absorbed electrolyte. of the cell. rack material is steel with a Battery – Two or more cells corrosion-resistant coating. Absorged glass mat (AGM) Ambient temperature – The connected together electrically. battery – Designed with average temperature of the Cells may be connected in Boost charge – An overcharge held in thin glass surrounding air that comes into series or parallel, or both, to of any length. fibers woven into a mat to contact with the battery. provide the required operating voltage and current levels. increase surface area enough Cathode – The to hold sufficient electrolyte on Anode – The electrode in an in an the cells for their lifetime. AGM electrochemical cell where – An where reduction takes place. batteries are also known as oxidation takes place. During apparatus that restores the During discharge, the positive “starved electrolyte” or “dry” discharge, the negative charge of a secondary battery. electrode of the cell is the because the fiberglass mat has electrode of the cell is the Also known as a rectifier. cathode. During charge, this no excess fluid. anode. During charge, this reverses and the negative reverses and the positive Battery duty cycle – The load electrode of the cell is the Accessories – The components electrode of the cell is the a battery is expected to supply cathode. required to complete the anode. for a specified time period. battery installation, including Carbonization – A condition connectors, flame-arrestor As found (condition) – A term Battery management system where the electrolyte becomes vents, cell numbers and used to inform the person – Required for lithium-ion contaminated with potassium hardware. performing a capacity test that systems, this monitors and carbonate to a point where it the battery should be tested controls cell balance and can influences cell performance. Activation charge – The without performing certain take action to disconnect checks, so the test results will process of making a dry- a failing battery string Capacity – The ampere-hour reflect the effect (good or bad) charged cell functional by automatically. capacity assigned to a cell by of the maintenance practice introducing electrolyte and the manufacturer for a given followed for the installation. charging. Battery monitor – A piece of discharge time, at a specified equipment used to monitor electrolyte temperature and Active material – The material Average temperature – The various parameters of a specific gravity to a given end- in the electrodes (plates) of average of the individual cell battery, such as individual cell of-discharge voltage. the cell that reacts chemically temperatures of all the cells in voltage, battery voltage and a battery. to produce electric energy temperature. Cell – The basic electrochemical when the cell discharges, unit, characterized by an anode which is restored to its original and cathode, used to receive, composition during the charge store and deliver electrical process. energy. Glossary

16 EATON The large UPS battery handbook Eaton.com/UPSbatteries Cell temperature – The Efficiency – The Flooded-cell – A cell design Grid – A framework for a temperature at which a cell electrochemical efficiency, that’s characterized by an plate in a cell that supports or is operating. In the U.S., the expressed as a percent, of excess of free electrolyte, retains the active material and reference for cell temperature the ratio of the ampere-hour and in which the products of conducts the . is 25°C (77°F). output of the battery, to the electrolytes, such as gasses, ampere-hour input required and evaporation, can freely exit High level line – A line on the Charge – The conversion of to restore the initial state of the cell through a vent. (Also side of a jar that shows the electrical energy into chemical charge. see wet-cell.) maximum level of electrolyte energy within a secondary cell. that should be present in a Electrode – The site at which Freshening charge – A charge cell. Closed-circuit voltage – The the electrochemical reaction given to a battery following voltage of a cell when it’s takes place. non-use or storage. High performance cell – A discharging. cell designed to supply a duty Electrolyte – A conducting Full-float operation – cycle requiring a high current Constant current charge – medium in which the flow of Operation of a DC system with for a short period of time. A charge in which the electric current takes place. the battery, battery charger and current output of the charge load connected in parallel, with Hit – Indicates that a standby is maintained at a constant Element – The positive and the battery charger supplying battery has been discharged. value. Sometimes this may be negative plate groups with the normal DC load plus any self-discharge or charging accomplished using two-rate separators assembled for one Hit counter – A device used current, or both, required by charging. cell. to record the number of the battery. discharges experienced by a Constant voltage charge – A End cell – A cell that can be battery. charge in which the potential added to or removed from a Fully-charged – The condition that exists following a long- voltage at the output terminals battery circuit to adjust battery Hydration (lead-acid cell) – term constant current charge. of the battery charger is voltage. A condition caused by maintained at a constant value. discharging a cell, and failing to End voltage – The cell voltage Gassing – Evolution of gas by recharge it in a timely manner. Cycle – A discharge and at which the discharge is one or more of the plates in a cell, resulting from subsequent charge of a cell. terminated. Immobilized electrolyte – of water into hydrogen and Electrolyte that’s retained by a oxygen within a cell during Density – The weight of a Energy density – The ratio of gel or absorbent mat. charging, overcharging or local given volume of electrolyte at the available energy from a cell action. Lithium-ion batteries, if a specified temperature. to its volume or weight. overcharged, may emit small Initial charge – The charge amounts of gasses (CO2, CO, given to a new battery before Depth of discharge – The Flame-arrestor vent – A cell- Phosphorus Oxide). See the placing it in service. ampere-hours removed venting device that prevents vendor’s MSDS for safety from a fully charged battery, the propagation of an external measures. Initial voltage – The closed- expressed as a percentage flame into the cell. circuit voltage at the beginning of its rated capacity at the Gelled electrolyte – of a discharge. applicable discharge rate. Flame-retardant material – A Electrolyte that’s been material capable of limiting the immobilized by the addition of Integrity test – A test used Discharge – The conversion of propagation of a fire beyond a gelling agent. to detect conduction path chemical energy into electrical the area of influence of the problems. energy within a cell. energy source that initiated it. Gelled electrolyte cell – A cell, usually lead-acid or VRLA, Inter-cell connection Discharge rate – The rate in Float current – The current that uses gelled electrolyte. resistance – The total electrical amperes at which current is drawn by a cell that’s being resistance of the connection delivered by the battery. float charged. General purpose cell – A between the terminals of cell designed to supply a duty two cells that are electrically Dry-charged cell – A cell Float voltage – The voltage cycle requiring a high current connected to each other. that’s been assembled with applied during full-float for a short period of time its plates dry, and in a charged operation. followed by a low current for state, ready to be activated by a long period of time. This

the addition of electrolyte... term is used in the U.S. for Glossary allowing easier shipping and cells designed for switchgear storage. tripping, generating stations and control applications.

17 EATON The large UPS battery handbook Eaton.com/UPSbatteries Inter-cell connector – An Level line – A line or set of Multi-cell unit – A multi-cell Oxygen recombination electrical conductor used to lines on the sides of the jar container in which cells are efficiency – A ratio of the connect adjacent cells on the used to indicate the cell’s installed. quantity of oxygen recombined same rack. minimum or maximum of to the total amount of oxygen electrolyte level. Negative plate – The generated. Inter-cell connector safety electrode to which current cover – An insulated cover Lithium-ion cell – Lithium- flows from the external circuit Parallel – The interconnection placed over the inter-cell ion cells, made of lithium and when the cell is discharging. of cells in which all the like connector and post, used to other metals and chemicals, terminals are connected. prevent accidental contact by are lighter and more energy Negative terminal – The personnel or accidental short dense than comparable lead terminal toward which positive Parallel strings – The circuiting of the cell. acid cells. They are typically charge flows in the external interconnection of two or packaged in a ‘module’ that circuit, such as from the more strings in which the like Inter-rack connector – An contains enough cells to positive terminal, when the cell terminals of each string are electrical conductor used to attain the desired voltage discharges. connected. connect cells on two separate and current capability. Each cell is comprised of metal racks, most often insulated NiCad battery – A sealed Pasted plate – A grid filled electrodes, separators, internal copper wire. storage battery having a nickel with active material applied as fusing and vents, along with anode, a cadmium cathode, a paste. a management circuit that Internal impedance – The and an alkaline electrolyte. controls its balance of current resistance of a cell to an and voltage, ensuring over- Performance test – A alternating current of a specific temperature conditions do not Nominal gravity – The specific constant-current capacity test frequency. occur. gravity of the electrolyte made on a battery after being selected for the determination placed in service to detect Internal resistance – The of the rated capacity of the cell any change in the capacity Local action – The internal resistance of a cell to an when it’s fully charged. determined by the acceptance losses of a battery standing on electric current within a cell. test. open-circuit or on float charge, without considering any losses Open-circuit voltage – The Internal voltage drop – The incidental to any discharge. voltage of a cell with no Pilot cell – A selected cell product of the current passing current flow in either direction whose condition is assumed through the cell. after the cell has had time to to indicate the condition of the Long duration cell – A cell stabilize. entire battery. designed to supply a duty Jar – The container that cycle requiring a low current holds a cell or group of cells. for a long period of time. Overcharge – The forcing of Plante plate – A pure lead Common jar materials include current through a battery after plate for a lead-acid cell in thermoplastics, but hard it’s been fully recharged. which the active material is Low level line – A line rubber is sometimes used as formed directly from a lead on the side of a jar that well and nickel-cadmium cells substrate. represents the minimum level Oxygen index – The minimum may be in steel containers. of electrolyte that should be concentration of oxygen, Jars for flooded lead-acid cells present in a cell. expressed as volume percent, Plate – An assembly of active are normally transparent to in a mixture of oxygen materials on a supporting allow inspection of the plate and nitrogen that will just framework grid, frame or Modified-plante plate – A and sediment. support flaming combustion support strip. (Also called an lead-alloy grid containing holes of a material initially at room electrode.) into which pure lead corrugate Jar-to-cover seal – The seal temperature. strips are placed. at the interface of the jar and Pocket plate – A plate in which cover. Oxygen recombination – the active material is held in Multi-cell container – A multi- A process whereby oxygen perforated metal pockets on a compartment container in Lead-acid cell – A secondary generated at the positive support strip. Usually used for which each compartment may cell in which the electrolyte electrode recombines with nickel-cadmium cells. contain an individual cell. is a solution of sulfuric acid in hydrogen at the negative water. Lead-acid cells include electrode to convert to water. Point (of specific gravity) – pure lead cells and lead alloy One-thousandth of specific cells such as lead-antimony, gravity (SG). lead- and lead- selenium. Glossary

18 EATON The large UPS battery handbook Eaton.com/UPSbatteries Polarization – The change in Secondary cell – An State-of-charge – The actual Thermal runaway – A voltage at the terminals of a electrochemical cell that’s capacity of a cell, expressed as condition in which a cell cell when a specified current is capable of being discharged a percent of its rated capacity, on charge or discharge will flowing into it. and then recharged. that would be available if a destroy itself through internal discharge were to occur. heat generation caused by high Positive plate – The electrode Secondary battery – Two overcharge or over-discharge from which the current flows or more secondary cells Stationary battery – A current or other abusive to the external circuit when connected electrically. secondary battery designed conditions. the battery is discharging. for service in a permanent Sediment – The active material location. Tier rack – A rack in which Positive terminal – The that separates from the battery cells are placed directly above terminal from which the plates and falls to the bottom Step rack – A rack in each other at different levels. positive electric charge flows of the jar. which cells are placed at through the external circuit to different levels in a stepped Trickle charge – A charge the negative terminal when the Self-discharge rate – The arrangement. given to a battery with no cell discharges. amount of capacity reduction external load connected to it occurring per unit of time in Strap – The component in a to maintain it in a fully charged Power density – The ratio of a battery as a result of self- cell where all the plates of like condition. the available power from a cell discharge. polarity are joined. to its volume or weight. Valve – A normally sealed Separator – An ionic String – A common way to mechanism that allows for the Rated capacity – The ampere- permeable, non-conductive refer to a number of cells controlled escape of gasses hour capacity assigned to a cell spacer used to prevent connected in series to form a from within a cell. by its manufacturer for a given metallic contact between battery system. discharge time, at a specified plates of opposite polarity Valve-regulated sealed electrolyte temperature to a within a cell. Storage life – Also known as lead-acid cell – A cell that’s given end-of-discharge voltage. shelf life is the period of time sealed and fitted with a valve Series – The interconnection of when a battery is in storage. opens to vent it whenever Recombination vent – A vent cells in such a manner that the During a battery’s storage or the internal pressure exceeds in which most of the gasses positive terminal of the first shelf life, no current is flowing the external pressure by a set escaping from the cell are is connected to the negative into the battery, which means amount. catalytically recombined and terminal of the second and so there can be no corrosion of returned to the cell as water. on. the positive grid inside the Vent – A device that allows battery. Assuming standard the escape of gasses from Reference electrode – A Service life – The period of operating procedures are within a cell. special electrode that has time during which a fully followed, a battery’s shelf life a reproducible potential charged battery is capable of does not impact service life Voltage efficiency – A ratio against which other electrode delivering at least a specified performance or warranty. of the average voltage during potentials can be referred. percentage of its rated discharge to the average capacity. For most lead-acid Sulphation (lead-acid cell) – voltage during recharge, under Retainer – Any material that battery designs this is 80%. A state where the battery specified conditions. is used to prevent the loss has developed an abnormal of active material from the Shipping vent – The vent amount of sulphate and its Voltage spread – A term used positive plate. placed in the cell for the capacity is impaired which is to describe the difference purpose of shipping it. different from normal sulphate between the highest and that occurs during discharge. Reversal – A changing of the lowest individual cell voltage normal polarity of a cell. Specific gravity – The ratio of readings in a battery. the weight of a given volume Taper charge – A charge in which both current and voltage Rundown test – A partial of electrolyte to the weight of Wet-cell – A cell design decrease over the recharge discharge test to a voltage an equal volume of water at a that’s characterized by an period. other than the system specified temperature. excess of free electrolyte, designed and voltage. and in which the products of Standby battery – A battery Terminal – The part of a cell electrolytes, such as gasses, to which the external circuit is and evaporation can freely exit Sealed, lead-acid (SLA) designed to function only when the normal source of connected. the cell through a vent. (Also battery – non-spillable, Glossary see flooded-cell.) maintenenace-free valve power fails. regulated batteries designed with vents that cannot usually be removed.

19 EATON The large UPS battery handbook Eaton.com/UPSbatteries For more information, visit Eaton.com/UPSbatteries or call 1.800.356.5794

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