FAQs

VLA stands for Vented Lead Acid batteries, often referred to as flooded lead acid batteries, FLA batteries, flooded batteries, or wet cells.

VRLA stands for valve-regulated lead acid batteries. They may also be referred to as sealed lead acid or SLA batteries. The two primary types of VRLA batteries are absorbent glass mat or AGM batteries and gel cell batteries or gel batteries.

Batteries should be stored indoors, preferably at 77F (25C), or in a cool (60F to 85F), dry location and placed in service before the date stamped on the shipping carton. The indicated storage time is based on storage at 77F (25C); approximately 6 months for Lead Calcium alloy and approximately 3 months for Lead Antimony and Lead Selenium cells. See product manual for specific details.

Exercise caution when operating or storing batteries at low temperatures because of the possibility of electrolyte freezing. Although the specific gravity of a fully charged battery may present no freezing problem, the discharged specific gravity may. See product manual for more information.

C&D has a web based battery sizing application. Access the C&D Solution Portal. Click on Register for an Account and the program will take you through the application process. Once your request is approved, you will receive your user name and password. You user name is your email address. Please enter your email address carefully; it will be used to notify you.

The first 3 letters represent the intended use of the battery.

• TEL: Telecom Applications
• UPS: UPS Applications
• VRS: Renewable Energy Applications
• AES: Advanced Energy Storage
• DCS: Deep Cycle Applications

 
The next number represents the nominal voltage of the battery (6 or 12). The number following the dash is an approximation of the commonly used capacity for the application of the battery. These are typically represented in Ampere-Hours (TEL, VRS) or Watts (UPS). See battery label for additional information.

The remaining letters describe characteristics of the battery.

• F: Front Terminal
• N: Narrow Width
• S: Short Depth
• W: Wide Width
• G: Gas Collection
• MR: High Rate Max
• C: Cycling Version (TEL Only)

Freshening charge implies charging batteries during or after storage, when the voltage or specific gravity falls below a given level. Equalizing charge is given to restore batteries that have been discharged or to restore voltages to batteries whose voltage has fallen outside of the recommended range.

This is general information. For specific information, see the Installation & Operating Instructions manual for the product.

No. The sizing methodology remains the same.

 
What changes is the battery's operating profile. In systems without emergency generation, batteries no longer operate primarily under float service conditions and instead are subjected to a more cyclic operating profile.

 
This operating condition reduces the service life of batteries designed for float applications and should be considered when selecting the most appropriate battery technology for the application.

The number of battery cells is determined by the UPS electrical design and the DC voltage specified by the UPS manufacturer.

 
When the UPS manufacturer allows a voltage range, the system designer has greater flexibility to optimize the battery bank by selecting the combination of system voltage and battery capacity that best meets the application's runtime requirements, helping reduce costs while improving overall system efficiency.

IEEE standards do not specify a mandatory percentage of spare batteries.

 
However, for critical applications, it is considered a best practice to maintain spare batteries equivalent to approximately 0.5% to 1% of the total batteries installed.

 
These spare batteries should remain on float charge using an independent charger and can be used during preventive maintenance or scheduled battery replacements.

Battery sizing calculations should consider the battery bank's actual operating temperature. When the ambient temperature is below the battery's reference temperature, the required nominal battery capacity increases.

 
When the operating temperature is above the reference temperature, the required battery capacity decreases; however, battery aging accelerates.

 
Whenever possible, designers should use the temperature correction factors provided by the battery manufacturer. If manufacturer-specific data is unavailable, the correction factors presented in IEEE 485 may be used as a conservative design approach.

Design Life represents the theoretical life expectancy of a battery when operated under the ideal conditions specified by the manufacturer, including:

• Float operation
• Controlled ambient temperature
• Proper float voltage
• Minimal discharge events
• Proper maintenance

 
Service Life, on the other hand, represents the actual operating life achieved in the field and depends on real-world operating conditions, including ambient temperature, number of cycles, depth of discharge, recharge quality, equalization practices, and environmental conditions.

The primary factors include:

• Elevated operating temperatures
• Frequent deep discharges
• Incomplete recharging
• Improper equalization charging
• Excessive ripple current
• Overvoltage or undervoltage
• Contaminated environments
• Inadequate ventilation

  The more severe these operating conditions are, the shorter the battery's service life will be.

Temperature is the single most significant factor affecting the service life of VRLA batteries. As a general rule of thumb, an average increase of 18°F (10°C) above the battery's reference operating temperature can reduce battery service life by approximately 50%.

 
Low temperatures also affect battery performance by reducing the available discharge capacity and may promote sulfation when automatic temperature compensation of the charging voltage is not provided.

Lifespan of VRLA batteries in UPS applications will vary greatly depending on the selected technology.

• Standard VRLA has a life expectancy of 3-5 years
• Pure Lead 5-8 years
• Advanced Pure Lead 8-10 years

Achieving a long service life depends on maintaining proper temperature, correct float voltage, regular maintenance, and avoiding deep discharges or overcharging. A proactive maintenance strategy is required, including periodic inspections, testing, and timely replacement of weak units to maintain overall system performance and reliability.

Cable and protection device sizing should consider:

• Maximum application current
• Required discharge time
• System voltage
• Interrupting capacity
• Voltage drop
• Applicable standards (IEEE 485, IEEE 1187, NBR 5410, and IEC 60364)

 
It is also recommended to:

• Use cables of equal length for parallel battery strings to ensure proper current sharing.
• Periodically verify connection torque.
• Perform thermographic inspections to identify potential hot spots before failures occur.

According to the C&D Technologies maintenance guidelines:

• Perform a capacity test every two years.
• Whenever possible, use the same discharge rate employed during the acceptance test.
• Once the measured capacity reaches 85% of its rated capacity, perform capacity testing annually.
• Before testing, perform a refresh charge (equalization charge) for 12 to 24 hours.

Yes. However, IEEE 1188 recommends performing a risk assessment before conducting the test.

 
In critical applications, when the battery already shows clear signs of degradation, it may be more appropriate to replace the battery bank proactively rather than subject it to a discharge test.

Capacity testing should continue until the battery reaches its End of Life (EOL).

 
As the battery approaches this stage, operators should evaluate the operational risks before deciding whether to perform another capacity test or proactively replace the battery bank.

The cell open circuit voltage (OCV) is approximately equal to the electrolyte specific gravity (SG) number plus the number 0.84. For example, with an electrolyte SG of 1.300 the OCV will be 2.14 (1.300 + 0.84), or with SG of 1.215 the OCV will be 2.06.

Potentially, some of the cells could “reverse.” The active material on the plated could be stressed and sloughed. This over-discharge can reduce the life expectancy of the cell. If over-discharged at a very low rate, the cell could become hydrated resulting in “through separator" shorts.

The primary ingredients in a flooded battery are lead and acid.

A properly designed and installed battery bank should include:

• An ambient temperature that complies with the battery manufacturer's specifications
• Adequate ventilation
• Connections tightened to the manufacturer's specified torque values
• Properly sized cables
• Balanced current sharing between parallel battery strings
• Correctly specified protective devices
• Complete installation documentation to support future inspections and maintenance activities

 
Following these best practices helps maximize battery reliability, safety, and service life while ensuring the UPS system performs as expected in critical applications.

The battery system installation may be subject to local, state and national building, fire and electrical codes. There are also guides as published by the IEEE. Relevant codes and guides may include, among others, the following:

• National Electric Code (NEC) Section 480 – Storage Batteries
• Uniform Building Code (UBC) Article 307
• Uniform Fire Code (UFC) Article 64
• IEEE – 1187 “Recommended Practice for Installation of Valve Regulated Lead Acid Batteries”
• IEEE – 484 “Recommended Practice for Installation Design and Installation of Vented Lead Acid Batteries for Stationary Applications”
• OSHA 1926.403

Key indicators include:

• Reduced battery capacity
• Increased internal resistance
• Reduced conductance
• Voltage deviations between battery blocks or cells
• Elevated operating temperature
• Reduced runtime
• Bulging, leaks, or physical deformation
• Terminal corrosion
• Increased float current

 
More important than any single measurement is tracking how these parameters change over time. Trend analysis provides the most reliable indication of battery health.

The following records should be maintained:

• Complete battery bank identification
• Electrical configuration
• Routine inspection records
• Capacity test results
• Failure history
• Battery replacements
• Calibration records for test instruments
• Historical trends for temperature, voltage, internal resistance, and capacity

 
Maintaining these records supports proactive maintenance planning and improves overall system reliability.

The battery system maintenance may be subject to local, state and national codes depending on the application. These codes and guides may include, among others, the following:

• IEEE – 1188 “Recommended Practice for Maintenance and Testing of Valve Regulated Lead Acid Batteries”
• IEEE – 450 “Recommended Practice for Maintenance and Testing of Vented Lead Acid Batteries for Stationary Applications”

The msEndur II (ATP) modules may be stacked up to 8 modules high.

For systems requiring NEBS qualification, there may be other height restrictions, depending on battery model.

RE02446 rail cover replaced RE02069 (used on 1-5/8 x 1 rail RD00422). RE02447 rail cover replaced RE02070 (used on 1-5/8 x 1-5/8 rail RD00200).

Do not use oil or grease as a lubricant for cell installation. Lubrication is usually not required due to the low friction interface of the insulation covers. If necessary, a small amount of water, unscented talcum powder or Dow-Corning III can be applied to the rail covers to reduce friction.

RD00422-L is the C&D part number for 1-5/8 in. x 1 in. unistrut rail and RD00200-L is the C&D part number for 1-5/8 in. x 1-5/8 in. unistrut rail. L is the length in feet.

Rack grounding provisions are integrated into the base of each RDB series frame. Two holes are located at the center of the frames bottom cross members and may be used to secure a standard NEMA lug. These holes are 0.44 inch in diameter and 1 inch between centers.

Yes, C&D has a variety of product designed to meet the demands of on or off grid renewable energy sites. The Advanced Energy Storage (AES) Series is a VRLA solution ranging from 168-224AH. The Liberty AES Series is a 2V VRLA solution designed for higher demand applications.

The primary references are:

• IEEE Std 485 — Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications.
• IEEE Std 1188 — Recommended Practice for Maintenance, Testing, and Replacement of Valve-Regulated Lead-Acid (VRLA) Batteries for Stationary Applications.
• IEEE Std 1187 — Recommended Practice for Installation Design and Installation of Valve-Regulated Lead-Acid (VRLA) Batteries for Stationary Applications.

 
These standards provide industry-recognized guidance for the design, installation, inspection, testing, and maintenance of battery banks used in mission-critical applications.

The standard MCTII is installed with plates parallel to the rack rails. The MCTII is also available with plates perpendicular to the rac

CAUTION – Do not add water or electrolyte to cells, particularly before initial charging. Adjust electrolyte levels only when cells are fully charged and stabilized at float voltage.

Before adding water or acid to a battery, you must consider its condition and state of charge. For example, a new battery that has recently experienced vibration during shipment will appear to have a low electrolyte level. Do not add water or acid to cells unless the plates are covered. If electrolytes cover the plates, the battery should be placed on charge. (See product manuals for charging instructions). The gases produced by charging will displace the electrolyte and raise it to an acceptable level between the container's high- and low-level marks. Had the level been adjusted to the High mark before charging, charging could have caused the electrolyte to rise to a point where it could overflow through the vent or be forced up into the flame arrestor, requiring needless maintenance.

Note: Adding water to a battery to increase the initial electrolyte level will reduce the specific gravity.

If, after charging, the electrolyte levels have not risen between the high- and low-level lines, electrolytes (sulfuric acid and water solution) of the same specific gravity may be added to bring levels to the high mark. Adding electrolytes is a procedure that should be done only after consultation with C&D or performed by a C&D agent.

Batteries shipped on or after January 1, 2000 have a four digit shipping code with the first two digits being the month and the following two being the year in which the battery was shipped from the factory. For example, a code of 1000 would be interpreted as October, 2000.

C&D Technologies' technical support team is available to assist you Monday through Friday, 8AM to 5PM Eastern Time (excluding some holidays). For emergencies, 24-hour support is also available.

• Contact Technical Support online
• Call +1 (562)-236-3045 or (800) 423-6569 toll-free

Battery sizing calculations should consider the battery bank's actual operating temperature. When the ambient temperature is below the battery's reference temperature, the required nominal battery capacity increases.

 
When the operating temperature is above the reference temperature, the required battery capacity decreases; however, battery aging accelerates.

 
Whenever possible, designers should use the temperature correction factors provided by the battery manufacturer. If manufacturer-specific data is unavailable, the correction factors presented in IEEE 485 may be used as a conservative design approach.

Temperature is the single most significant factor affecting the service life of VRLA batteries. As a general rule of thumb, an average increase of 18°F (10°C) above the battery's reference operating temperature can reduce battery service life by approximately 50%.

 
Low temperatures also affect battery performance by reducing the available discharge capacity and may promote sulfation when automatic temperature compensation of the charging voltage is not provided.