-CCB VRLA Battery System General Description
-Circuit Breaker
-Figure 1 - Series Connected String of Batteries
-Figure 2-Parallel Strings of Batteries
-VRLA Battery Safety Concerns
-Electrical Hazards
-Disposal
-Chemical Hazards
-Fire, Explosion and Heat Hazards
-Caution
-Handling Hazards
-Preparation for VRLA Battery
-Periodic Maintenance
-Quarterly Maintenance
-Semi-Annual Maintenance
-Annual Maintenance
-Bi-Annual Maintenance
CCB VRLA BATTERY SYSTEM
PERIODIC MAINTENANCE AND TROUBLESHOOTING GUIDE
CCB VRLA Battery System General Description
In general the battery system is a group of 2 volt cells or 6, 10 or 12 volt batteries connected in a series string to provide a total system of higher voltage. For example, as shown in Figure 1, four of the nominal 12 volt batteries may be connected in series to provide a 24 cell system with a nominal voltage of 48 volts.
Circuit Breaker
Multiple strings of the series connected batteries may be connected in parallel to provide a total system with a capacity of the sum of the capacities of the individual strings. For example, as shown in Figure 2, two each 48 volt 90 ampere hour capacity strings can be connected in parallel to provide a nominal 48 volts at 180 ampere hours.
The CCB VRLA battery is a lead acid battery which facilitates an oxygen recombination cycle. The net result is that under normal conditions there is minimal gas emission and loss of water from the electrolyte. The electrolyte is immobilized in either a gel form or is absorbed within an absorbent separator between the plates. Consequently, the battery is maintenance free in terms of electrolyte maintenance¨Cthat is, there is no requirement nor capacity to add water to the cells or to measure the electrolyte specific gravity.
VRLA Battery Safety Concerns
Maintenance and servicing of the CCB VRLA battery should only be performed and supervised by personnel knowledgeable of lead acid batteries and required personal safety and equipment safety precautions. Keep unauthorized personnel away from the batteries and maintenance activities.
Electrical Hazards
Battery systems present a risk of electrical shock and high short circuit currents. The following precautions should be observed when maintaining VRLA batteries:
1. Remove all personal metal objects (watches, rings, etc.).
2. Use insulated tools.
3. Wear full eye protection and rubber gloves.
4. Observe circuit polarities.
5. Do not make or break live circuits.
6. Prior to handling batteries on a metal rack, assure the battery is not inadvertently grounded by observing the ground fault detector indicator. In its absence, measure the voltage between the battery and the rack. It should be zero. If not, determine the cause and correct prior to proceeding.
7. Do Not lay metal tools and hardware on top of the batteries.
8. As appropriate, use an insulating blanket to cover exposed portions of the battery system when performing extended maintenance that could result in personal or equipment contact with the energized conductors.
Certain types of rectifier circuits used in charging the VRLA battery may not include a line isolating transformer. In these cases extreme caution should be exercised when maintaining and collecting data on the battery system.
The VRLA battery is sometimes enclosed in cabinets with very limited access. Again, extreme caution must be exercised when maintaining and collecting data on the battery system.
Disposal
Lead acid batteries are to be recycled. Batteries contain lead and dilute sulfuric acid. Dispose of in accordance with Federal, State and local regulations. Do not dispose of in a landfill, lake or other unauthorized location.
Chemical Hazards
Any gelled or liquid emissions from a VRLA battery is electrolyte which contains dilute sulfuric acid which is harmful to the skin and eyes; is electrically conductive; and is corrosive.
If electrolyte contacts the skin, wash immediately and thoroughly with water. If electrolyte enters the eyes, wash thoroughly for 10 minutes with clean water or a special neutralizing eye wash solution and seek immediate medical attention.
Neutralize any spilled electrolyte with the special solutions contained in a "spill kit" or with a solution of 1 Ib. bicarbonate of soda to 1 gallon of water.
Fire, Explosion and Heat Hazards
Lead acid batteries can contain an explosive mixture of hydrogen gas which can vent under overcharging conditions.
Do not smoke or introduce sparks in the vicinity of the battery.
Prior to handling the batteries, touch a grounded metal object, such as the rack, to dissipate any static charge that may have developed on your body.
Do not charge batteries in a sealed container. The individual batteries should have 0.5 inches of space between the batteries to allow for convection cooling. If contained, assure the container or cabinet and room have adequate ventilation to prevent an accumulation of potentially vented gas.
Caution
Do not attempt to remove the vents (valves) from the CCB VRLA battery or add water. This presents a safety hazard and voids the warranty.
Handling Hazards
The individual batteries may weigh from 25 to 100 pounds depending on part number. Exercise care when handling and moving batteries. Assure the use of appropriate handling equipment.
Preparation for VRLA Battery
Periodic Maintenance
There is little difference between the periodic maintenance associated with a VRLA battery and a vented (wet) cell battery with the exception of that related to the liquid electrolyte. Naturally, it is not required to measure electrolyte specific gravity or add water to the VRLA cells.
For optimum reliability, it is recommended that the battery system be monitored quarterly. If the battery system incorporates an automatic monitoring system to gather the electrical and environmental data, the quarterly checks are limited to the evaluation of the recorded data and a visual check of the battery.
In general the types of checks to be made during the periodic maintenance include:
1. System charging voltage.
2. Ambient temperature.
3. Battery pilot unit temperatures.
4. Interunit connection hardware resistance or tightness.
5. Individual battery float voltage.
6. Momentary high rate load test.
7. Battery system capacity test.
A test of the individual unit resistance, impedance or conductance, while optional, is also recommended on a periodic basis. This data and its trend can be a valuable aid in troubleshooting the system and predicting the need for a system capacity test.
Prior to starting the periodic maintenance activity assure that all required maintenance tools and equipment and safety equipment is available and functional. Notify anyone who will be affected by the intended maintenance or troubleshooting activity.
Also, all units in the battery should be numbered so as to facilitate the recording and analysis of data unique to each unit.
Required Maintenance Tools and Equipment
At a minimum, the following tools and equipment are required to maintain and troubleshoot the CCB VRLA battery.
1. digital voltmeter
2. socket wrenches, insulated
3. box end wrenches, insulated
4. torque wrench calibrated in in.-Ibs.
5. rubber gloves
6. full face shield
7. plastic apron
8. portable eyewash
9. spill kit
10. fire extinguisher (class C)
The following equipment is optional depending on the type of maintenance to be performed.
1. micro-ohm meter
2. battery resistance, impedance or conductance test set
3. 100 amp momentary load test set
4. system load bank (DC if to be performed at the battery and AC if to be performed by loading UPS output)
Quarterly Maintenance
The following checks should be completed quarterly.
1. Assure the battery room is clean, free of debris and well lighted.
2. Assure that all facility safety equipment is available and functional.
3. Measure and record the air temperature within the battery room.
4. Visually inspect the battery for:
a. cleanliness.
b. terminal damage or evidence of heating.
c. container or cover damage.
d. evidence of overheating.
5. Measure and record the battery system DC float charging voltage at the battery. Optionally measure and record the AC ripple voltage at this time also.
6. Measure the DC voltage from each polarity of the battery to ground to detect any ground faults.
7. If possible, measure and record the battery system DC and AC float charging current.
8. Measure and record the temperature of the battery pilot unit. Sense the temperature on the side of the unit in the center or at the negative terminal of the unit.
9. Measure and record the individual unit DC float charging voltage.
10. Measure and record the System Equalization Voltage.
Semi-Annual Maintenance
1. Repeat the quarterly checks.
2. Optionally perform the 10 sec. high rate (e.g. 100 amp) load test to assure the individual batteries are functional.
3. Optionally measure and record the resistance/impedance/conductance of the individual units to trend the condition of the individual units over time and to detect dramatic differences between individual units and the norm.
Annual Maintenance
1. Repeat the semi-annual checks.
2. Retorque all the interunit connecting hardware to the values noted in Table 2. This can be omitted if the connection resistance is measured and found to have not increased more than 20% from the value at installation.
Bi-Annual Maintenance
The battery should be capacity tested every two years at the service load or at the battery rating related to the service requirements. Ideally, this will be the same rate at which it was acceptance tested when originally installed. Once the battery is found to be at 85% of rating, it should be capacity tested annually.
