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Maintenance of Lead-acid Batteries Used in Telecommunications Systems

Authors:
  • National Institute of Telecommunications, Poland
  • The National Institute of Telecommunications

Abstract and Figures

The article presents numerous problems with standby batteries used in telecommunications systems, with a particular emphasis placed on the assessment of their real capacity. The methods used to evaluate the technical condition of batteries and to measure their real capacity are presented. Also, the a new test device which measures the actual battery capacity is presented. The said measurement is based on the discharge test method and is performed with the use of a new TBA-A automated test unit. The article is targeted for electronic designers, managers and telecommunications hardware maintenance personnel, as well as for other telecommunications systems experts.
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Paper Maintenance of Lead-acid Batteries
Used in Telecommunications Systems
Ryszard Kobus, Paweł Kliś, and Paweł Godlewski
National Institute of Telecommunications, Warsaw, Poland
Abstract—The article presents numerous problems with
standby batteries used in telecommunications systems, with
a particular emphasis placed on the assessment of their real
capacity. The methods used to evaluate the technical condition
of batteries and to measure their real capacity are presented.
Also, the a new test device which measures the actual battery
capacity is presented. The said measurement is based on the
discharge test method and is performed with the use of a new
TBA-A automated test unit. The article is targeted for elec-
tronic designers, managers and telecommunications hardware
maintenance personnel, as well as for other telecommunica-
tions systems experts.
Keywords—battery capacity measurements, maintenance, tele-
communications systems.
1. Introduction
Nowadays, a high degree of reliability is an aspect of key
significance in the delivery of telecommunications services.
This means that telecommunications systems should remain
powered even if a mains failure occurs. Lead-acid batteries
are the most popular back-up energy source and it is ex-
pected that such batteries will remain in use for a long time
to come, in spite of introduction, to the market, of new bat-
tery types and new reserve power source chemistries. The
above means that the problem of maintenance of good lead-
acid batteries still remains an issue of high importance.
2. Batteries Used in
Telecommunications Systems
Telecommunications systems should ensure continuous
availability of services. This applies both to commercial
services offered to the general public, and to emergency
services supplied over critical infrastructure networks. That
means that telecommunications systems should be powered
without any interruptions.
Telecommunications systems are powered by installations
relying on rectifier-based power systems (PS) and a num-
ber of batteries connected in parallel. The batteries should
be able to provide backup for a given telecommunications
system for a few hours or more. When the mains voltage is
present, PS supply energy to the telecommunications equip-
ment and to the batteries associated therewith. Under such
conditions, the rectifier provides float voltage (about 54 V)
to the batteries, preventing their self-discharge.
Figure 1 shows three basic configurations of power systems
dedicated to use on telecommunications sites. The simplest
structure, and thus the least reliable, is presented in Fig. 1a.
In the case of a mains failure, the powered equipment (PE)
is supplied from the battery until either the battery dis-
charges or the mains voltage is restored. Additionally, it
should be borne in mind that if rectifier or battery main-
tenance is performed, an additional, transportable backup
power source has to be connected. The configuration shown
in Fig. 1b is more reliable due to the added redundancy. It
allows to disconnect one rectifier unit or one battery with-
out any disturbances to the PE supply. The configuration
shown in Fig. 1c is the most reliable, but at the same time
the most expensive. It relies on two independent power
systems and two independent mains networks.
In order to increase the level of AC voltage supply reliabil-
ity even further a backup diesel generator may be connected
to the system via an automatic switch [1], [2]. Batteries are
the source of power during mains failures. Therefore, their
key features should include long battery life, low overall
costs of purchase and operation, as well as safety of use.
It should be noted that battery weight is not an important
factor in this particular case. Hence, lead-acid batteries ful-
fill all the requirements mentioned above. They are char-
acterized by high power density of up to 0.1 kWh/kg and
by low internal resistance. Despite of advanced technolo-
gies relying on other battery chemistries, i.e. NiCd, NiMH,
Li-Ion and Li-Po, lead-acid batteries remain the primary
standby source of energy in telecommunications power sup-
ply systems.
3. VLRA Batteries
Flooded lead-acid batteries have been used in the telecom-
munications sector for about 100 years now. Because of
their open design, they must be installed in separate, ven-
tilated and secured rooms. The first leak-proof, valve-
regulated lead-acid (VRLA) batteries first appeared in the
1960s in the USA, but they only began to be used on a wider
scale in Europe in the 1990s. It is difficult to say if VRLA
batteries are significantly superior to the flooded variety,
but they offer certain advantages which have contributed
to their widespread use. VRLA batteries have a shorter
lifetime, but their maintenance cost is lower. They do not
require separate, special rooms, but there is a need to pro-
vide float voltage thermal compensation. VRLA units can
be installed in rooms used by staff or other electronic equip-
ment, but in a designated area. Adequate room must be
106
Maintenance of Lead-acid Batteries Used in Telecommunications Systems
=
~
=
~
Rectifier 2
Rectifier 2
Rectifier 1
Rectifier 1
Battery B2 Battery B2
=
~
=
~
=
~
Battery B1 Battery B1 Battery B1
Rectifier
AC mains AC mains 1 AC mains 1
AC mains 2
(a) (c)(b)
Power supply Power supply Power supply 1 Power supply 2
Powered
equipment
Powered
equipment
Powered
equipment
Fig. 1. Examples of power system configurations.
provided around the battery system to allow maintenance,
including the exchange of blocks/cells. The area required
for installation of VRLA batteries can be smaller than in
the case of their flooded counterparts. The battery can be
placed vertically or horizontally and can be stacked with
the use of a dedicated rack enclosure.
All lead-acid batteries have a defined maximum storage
time of six months at the temperature of 18–30C. By the
end of that period, batteries should be either installed or
charged. Therefore, it is important to schedule the delivery
of batteries to the site and their date of production as close
as possible to the date of actual installation.
Two primary types of VRLA batteries exist, relying on gel
and AGM technologies. In the case of the gel technol-
ogy, silica dust is added to the electrolyte, forming a thick
putty-like gel. The Absorbed Glass Mat (AGM) technology
employs a fiberglass mesh between the individual battery
plates. The mesh absorbs and retains the electrolyte. Both
technologies offer similar advantages and disadvantages in
comparison to conventional battery types.
4. Battery Condition Monitoring
To improve operational functionality of batteries and to pro-
tect them against damage, the use dedicated equipment is
required. A relevant device can be integrated within the
power supply system, may constitute a part of the battery
itself, or may be installed as additional, stand-alone test
equipment [3], [4]. The following parameters can be mon-
itored with use of this equipment:
battery voltage,
charging/discharging current,
ambient temperature,
all cell/block voltages and temperatures,
AC ripple current and voltage.
Voltage and temperature measurements pertaining to all
cells/blocks enhance assessment of battery cell balancing
and help detect damaged cells. Comparisons of battery
string temperatures, in turn, allow for detection of thermal
runaways.
Specialized circuits are used in order to improve cell voltage
balancing. They reduce cell voltage if it is higher than
the prescribed limit value while the battery is charging.
Balancers are also used in which the cells with the lowest
voltage levels are charged with higher current in order to
manage cell voltage more effectively [3], [5], [6].
Generally speaking, monitoring systems are capable of in-
dicating the actual condition of the batteries, but do not
reflect their actual capacity.
5. Key Parameter Measurements
All battery manufacturers recommend periodic check of
batteries condition including:
leaks,
verification of cell interconnection resistance,
battery capacity measurements.
Battery maintenance always requires that periodic site vis-
its be paid (even on unmanned sites), but attempts are made
to minimize the maintenance time. It is recommended that
only a few measurements be made to evaluate the condition
of a battery, with a particular focus on its capacity and the
remaining lifetime. With the accuracy of all crucial pa-
rameter measurements, the time and cost of tests, as well
as the need to mitigate test-related risks taken into consid-
eration, one may conclude that no single method meeting
all the requirements exists [4], [7], [8]. Therefore, internal
resistance measurements and discharge tests are among the
most commonly used procedures. The properties of such
methods are described in detail below.
107
Ryszard Kobus, Paweł Kliś, and Paweł Godlewski
6. Internal Resistance Measurement
The common internal resistance measurement procedure is
cheap, fast and safe, and usually does not require that the
battery undergoing the test be disconnected from the power
system. It relies either on the analysis of DC pulses or
on resistance measurements performed with the use of AC
signals [5], [9]. The resistance reflects not only the battery
capacity, but also:
grid corrosion,
loss of active material from electrodes,
possible sulfation,
temperature increase,
internal short circuit,
other cell failures.
Measurement equipment manufacturers recommend that
a principle be adopted in line with which a 20% loss of
battery capacity is related to a 25% increase in the resis-
tance of each cell. It is also estimated that the loss of
battery capacity is related to only 40% of the total inter-
nal resistance (for the entire battery). Additionally, internal
battery resistance may vary by approximately ±10% for
the same type. Therefore, it is recommended to measure
each cell and the entire block separately, and directly at
battery terminals. If the measurements are performed pe-
riodically under the same conditions, i.e. temperature and
charge level, it is possible to identify deterioration of the
cells based on historical data analysis. Unfortunately, re-
search fails to prove that the internal resistance test may
be considered an equivalent of the battery capacity mea-
surement that relies on the discharge test. Hence, it is not
commonly used to actual battery capacity assessment.
7. Discharge Test
The discharge test is the only reliable method used to eval-
uate actual battery capacity with a high degree of accuracy.
It takes a long time to perform – even up to 20 hours. While
the measurements are performed, the battery needs to be
disconnected, which results in a considerable depletion of
the amount of reserve energy available on site. A few test
procedures and equipment setups may be employed, which
can provide results characterized by a varying degree of ac-
curacy. The cost of the measurements performed may vary
as well. Examples of the test procedures are presented
below.
7.1. Discharge Test Built into the Power System
Modern DC power systems offer an advanced functionality
enabling the efficient use of energy from VRLA batteries,
referred to as the “battery test”. This function is capa-
ble of controlling the powered equipment based on prior-
ity levels assigned (e.g. critical equipment and non-critical
equipment). The test may be run periodically, e.g. after
a prolonged mains failure, or on-demand. Charging volt-
age may be boosted or reduced.
The test is based on a simultaneous, partial discharge of all
batteries (up to 50% of the batteries’ design capacity). Dur-
ing the test, the output voltage of the power system’s rec-
tifier is temporarily reduced to the pre-programmed value,
e.g. 44 V. If the batteries manage to keep the telecom-
munications equipment powered up, over a pre-defined pe-
riod of time, with the voltage remaining higher than the
rectifier-provided value, the test result is deemed positive.
If the battery voltage drops below the rectifier-fed value,
over a period of time that is shorter than specified, the test
result is considered negative.
Power consumption of modern telecommunications systems
remains constant. Therefore, the amount of energy drained
from batteries can be measured quite easily. Interpretation
of test results is much easier when cell voltage of all bat-
teries is monitored. This solution is simple and cheap to
implement, but the capacity of batteries available at the fi-
nal stages of the test is unpredictable. Therefore, the real
battery capacity is unknown.
7.2. Discharge Test Using Battery Discharger
In order to determine the real capacity of a battery,
a discharge with the current of 0.1 C is usually performed
[10]–[12]. There are many types of battery dischargers,
but in general, all of them are passive and rely on the
transformation of power into heat. The majority of modern
battery dischargers are equipped with monitoring circuits
that measure the following parameters: battery voltage, in-
dividual cell voltage, discharging current and battery tem-
perature. Hence, they are capable of working out the bat-
tery capacity. It is possible to set threshold values for the
parameters referred to above, and to program the discharger
to discontinue the test if one of them is reached. This sim-
plifies the entire test procedure and allows to protect the
battery from damage caused by excessive discharge. An
example of the discharger unit that can sink up to 120 A
Fig. 2. Battery discharger with nominal current of 120 A.
108
Maintenance of Lead-acid Batteries Used in Telecommunications Systems
(a) (b)
Fig. 3. Stand-alone battery ATE: (a) up to 160 A and (b) up to 50 A.
Powered
equipment
Battery B1 Battery B2
DC
power
system
Powered
equipment
Battery B2
AC mains power
Battery B1
TBA 160-IŁtest device
To power
system
MCU
=
=
TBA-ST
-48 V
0 V
Maintenance
center
MCU DC
power
system
AC mains power
Test device
(a) (b)
Fig. 4. Power system with ATE (a) stand-alone TBA160-IŁ and (b) built-in test functionality (TBA-ST).
from 48 V batteries is presented in Fig. 2 [13]. However,
tests performed with the use of such devices are time con-
suming, as the full test procedure requires that several steps
be completed:
disconnecting the battery to be tested from the power
system,
charging the battery to its full capacity,
discharging the battery,
re-charging the battery to restore its operational pa-
rameters,
reconnecting the battery to the power system.
Unfortunately, the return charging process is not monitored
and battery energy efficiency cannot be assessed. Each
stage of the process requires that battery connections be
altered, and that the measurements be activated manually.
One full battery test cycle takes approximately one day
to complete, which means that in the case of sites with
two batteries, the power system operates with a reduced
energy capacity for two days. Therefore, often only partial
discharges are performed.
It needs to be added that large amounts of heat are dis-
sipated in the course of the test, which increases ambient
temperature in the room and, of course, the battery temper-
ature. The above means that not only all discharge energy
is lost, but that air conditioning systems in use on the site
consume more power as well.
7.3. Battery Test Automation
The entire battery test cycle can be automated, thanks to
the use of sophisticated testers, either of the stand-alone
variety, or ones that are built-in to the power supply sys-
tem. TBA-IL is an example of a stand-alone portable device
designed to measure real capacity of batteries at telecom-
munications sites (Fig. 3). The device can be connected to
the battery and the power system via universal flexible ca-
bles, or with the use of a dedicated terminal box. As men-
tioned above, the battery undergoing the test needs to be
disconnected from the power system. TBA160-IŁ was de-
veloped within the framework of a project titled “The new
generation of VRLA battery control devices for telecom-
munications power systems”, and was subsidized by the
European Union under the Innovative Economy Operating
Program [14].
109
Ryszard Kobus, Paweł Kliś, and Paweł Godlewski
The test unit can operate in a full automatic mode (Auto-
mated Test Equipment) – Fig. 4a. All input parameters
and measurement results are stored in its memory and may
be transferred to a local or remote PC by means of the
LAN-WAN interface. The unit presented in Fig. 3 is very
efficient – energy discharged from the battery is returned
to the power system and less than 5% energy is dissipated
in the form of heat. The enclosure of the device is also
smaller than that of a typical resistive discharger.
The ATE test device may be integrated with the power sys-
tem, as shown in Fig. 4b. In this case, it is supervised
by a power system controller and managed by the main-
tenance center. In such a case, the ATE comprises only
a bidirectional power converter and relevant sensors. There-
fore, the built-in test device can be a few times cheaper
than the stand-alone version. Automated battery switch-off
functionality is another of the advantages of this particular
configuration. No manual operation is required, and the
switching-off process is initiated by the power system con-
troller. However, there are certain restrictions inherent in
this solution. The only drawback is the fact that the built-in
unit is capable of controlling batteries with the maximum
capacity of 1000 Ah.
8. Universal Module for
Charging/Discharging Batteries
The National Institute of Telecommunications (ITL) boasts
extensive experience in designing devices for testing bat-
teries used at telecommunications sites. ITL cooperates
with the Electronic Power and Market (EP&M) company.
A consortium led by ITL won a contract from the Na-
Fig. 5. Universal battery charging/discharging module.
tional Centre for Research and Development for designing
a “Control systems for telecommunications site energy re-
serve solution - SKOT”. TBA-A with the module shown in
Fig. 5 was developed within the framework of this project,
which can serve as a TBA-ST device integrated with the
power system. There are similar solutions available on the
market, i.e. [15], but ITL TBA-ST ATE offers optimized
functionality. The TBA-ST is dedicated for medium size
telco sites and it is capable of driving/sinking current of
up to 50 A. When combined with the TBA-W control unit,
the TBA-A module forms another ATE unit. Its firmware
was also developed under the project in question.
The core of the TBA-A has the form of a bidirectional addi-
tive/subtractive power converter based on T1–T4 switching
transistors, L1 inductor and C1–C2 capacitors. The switch-
ing process is controlled by the PWM circuit at the fixed
frequency of 35 kHz, enabling output voltage to be regu-
lated, and the energy from the tested battery (either Bat-
tery 1 or Battery 2) to be transferred to the power system or
in the reverse direction. The charging and discharging cur-
rent is stabilized by using a high accuracy LEM current sen-
sor. The input and output voltage is monitored for exceed-
ing threshold values. The power conversion is controlled
by the STM32F103VE 32 bit microcontroller. It gener-
ates PWM waveforms, reads battery voltage, power system
voltage, each cell/block voltage and charging/discharging
current from the LEM transducer. It also offers an external
communications interface. All parameters and operational
modes can be transferred remotely via the RS232/485 in-
terface. The serial port is used also for downloading the
measurement results. The TBA-A is also equipped with an
additional RS232 port used for servicing. More details are
presented in Fig. 6 and in [16].
The firmware of the device presented above constitutes is
core component, as it controls the bidirectional converter.
It was developed based on the authors’ extensive experi-
ence. The first power converter dedicated to charging/dis-
charging batteries was developed by ITL 15 years ago and
weighed approximately 10 times more than the current so-
lution [6], [17]–[19]. The use of fast MOSFET transistors
with internal diodes, the 32-bit ARM-based microcontroller
and sophisticated firmware has enabled to develop a very
small, light and powerful unit.
Voltages of the batteries (B1 and B2 in Fig. 6) and cells
(a1...a4, b1...b4) are measured with the accuracy better
than 1%. The real capacity calculated in relation to the
capacity at 20C is saved with the accuracy 2%. In ad-
dition, the device calculates works out the energy of the
discharged battery. The test device offers high energy ef-
ficiency. About 95% of the discharged energy is returned
to the power system to supply telecommunications equip-
ment. As no heat is generated, the measurement condi-
tions remain very stable. The room itself and especially
the battery are not exposed to any additional heat, which
means that the air conditioner operates under stable ambi-
ent conditions. The TBA-ST ATE device was developed
under the “Monitoring system for telecommunications site
110
Maintenance of Lead-acid Batteries Used in Telecommunications Systems
S
STM32F 103VE
MCU
I/O
MCU ready
Maintenance
centre
(opt.)
Powered equipment
Fig. 6. TBA-A block diagram and its connection to the power system.
MCU
Rectifiers
SCS
Win controller
TBA-ST
Batteries
Fig. 7. Power system with a built-in universal battery testing module.
energy reserve solutions – SKOT” project. The project was
implemented by the National Institute of Telecommunica-
tions and the EP&M company, and was co-financed by the
European Regional Development Fund under the Innovative
Economy Operational Program.
9. Deep or Partly Battery Discharge
The primary objective of the study is to evaluate the energy
reserves stored in the battery. It is usually assumed, in the
case of telecommunications power systems, that the battery
remains operational if its capacity (Q) is not lower than 80%
of rated value at the discharge current of 0.1 C. That is why
the designed battery capacity is 20% greater. It enables to
achieve the required capacity within the power system at the
end of the battery’s lifetime declared by its manufacturer.
Due to the adverse operating conditions, some batteries
fail to achieve the average declared life expectancy, but
a significant portion of them remain operational until the
end of the specified period. It should be noted that the
efficiency of each battery is determined by the condition of
its weakest cell.
Figure 8 shows the results of checks performed on various
batteries rated at 48 V/1000 Ah after operation lead times.
The drawings present cell voltages during the discharge and
charge test under the same conditions. The cell discharge
cut-off voltage was set at 1.80 V. If the voltage of any of
the tested cells drops below that value, the battery discharge
stops.
The initial charging current was set at 0.1 C (100 A), the
final charging battery voltage was 56.00 V, and the highest
cell voltage was set at 2.38 V. If either the voltage of the
battery reaches 56.00 V or any the voltage of any of the
cells is equal to 2.38 V, the charging current is decreased
and the charging process is stopped.
The discrepancies between cell voltage characteristics
shown in Fig. 8 tend to increase with time of use, and
with the reduced battery capacity. It can also be noted that
111
Ryszard Kobus, Paweł Kliś, and Paweł Godlewski
V/cell V/cell V/cell V/cell
2.3 2.3 2.3 2.3
2.2 2.2 2.2 2.2
2.1 2.1 2.1 2.1
2.0 2.0 2.0 2.0
1.9 1.9 1.9 1.9
1.8 1.8 1.8 1.8
Q = 36% Q = 70% Q = 85% Q = 100%
Time
Fig. 8. The results of inspection of various 48 V/1000 Ah batteries.
in the first stage of the discharging process, cell voltages
are usually similar and do not suggest a failure of any of
the cells. Moreover, the voltage of smaller capacity cells
recorded during the first stage of discharge process may be
higher than that of higher capacity cells. Such a case is
presented in Fig. 9. The cell with the lowest voltage in the
2.3
2.25
2.2
2.15
2.1
2.05
2.0
1.95
1.9
1.85
1.8
Cell voltage [V]
13530 75 120 180 240 300 360 420 476
Time [min]
Fig. 9. Detailed discharge characteristics of a 700 Ah battery.
final stage of the discharge phase (after 360 minutes) has
the smallest capacity. But in the first stage of the discharg-
ing process, the voltage of this particular cell was good, and
no evidence enabling to predict its reduced capacity existed.
This means that is not easy, or even impossible, to evaluate
battery parameters, especially its capacity, based on the cell
voltage chart during the first stage of the discharge process.
The National Institute of Telecommunications [20] has
performed research focusing on this particular issue, but
no effective algorithm to predict the battery capacity based
on short discharge results only has been developed yet.
10. Conclusions
Currently, the discharge test method remains the only re-
liable way to evaluate the real capacity of batteries. Such
a measurement method renders results with the accuracy
of ±2%, a level that is unattainable in the case of re-
maining methods. Unfortunately, measurements made with
dischargers or stand-alone testers are expensive and time
consuming. The use of a measurement module that is in-
tegrated with the power supply system can significantly re-
duce the cost of testing batteries to the level that is com-
petitive with alternative solutions.
The method presented and the ATE testers do not reduce
the measurement lead time, but offer the opportunity to
stop the test at any given moment, e.g. if the continuity of
power supply is jeopardized. Once the test is completed, the
battery is reconnected to the power system and the reserve
power is increased.
The measurement module enables also to disconnect the
battery remotely, should a need arise.
These benefits make the application of the ATE system
very profitable in the case of remote telecommunications
facilities.
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ołowiowych”, Wiadomości Elektrotechniczne, vol. 6, no. 10–11,
2014 (in Polish).
[21] W. Fechalos, “Battery System and Management Method”, U.S.
Patent Application Publication, US 2011/0298626A1
Ryszard Kobus received his
B.Sc. and M.Sc. degrees from
the Faculty of Electronics of the
Warsaw University of Technol-
ogy in 1975. Kobus has been
working at the National In-
stitute of Telecommunications
since 1975. He is a member of
the Expert Technical Commit-
tee CEN/TC 331 specializing in
postal services, and the deputy
chairman of the Postal Service Committee PKN/TC 259.
He is a co-author of many patented telecommunications
solutions. Research interests: telecommunications, mea-
surements and evaluation of quality of telecommunications
services, quality surveys, evaluation the quality of postal
services, standardization.
E-mail: R.Kobus@itl.waw.pl
National Institute of Telecommunications
Szachowa st 1
04-894 Warsaw, Poland
Paweł Kliś received his B.Sc.
degree from the Faculty of
Electrical Engineering of the
Opole School of Engineering in
1976. He has been working at
the National Institute of Tele-
communications since 1976,
formerly in the Power Systems
Department, currently in the
Central Chamber for Telecom-
munications Metrology. He is
a co-designer of numerous telecommunications power sys-
tems and devices. He is a co-author of several scien-
tific publications and co-author of several patents. His
research interests include: telecommunications power sys-
tems, metrology of basic electrical parameters.
E-mail: P.Klis@itl.waw.pl
National Institute of Telecommunications
Szachowa st 1
04-894 Warsaw, Poland
Paweł Godlewski received his
B.Sc. degree from the Fac-
ulty of Electronics of the War-
saw University of Technology
in 1973. He has been work-
ing at the National Institute
of Telecommunications since
1973. He is the designer of
many devices, and co-author of
a system for the assessment of
quality of telecommunications
services, a well as AWP-IL and TBA-IL ATE equipment.
He is the author of numerous scientific publications and
co-author of patented solutions. His research interests in-
clude: visualization systems used in the telecommuni-
cations sector, programmable measurement devices for
telecommunications.
E-mail: P.Godlewski@itl.waw.pl
National Institute of Telecommunications
Szachowa st 1
04-894 Warsaw, Poland
113
... In such a power system, the measurement of available capacity of any battery can be performed by portable instruments, e.g. RRR shown in Fig. 1a, or electronic loads as well as TBA-IŁ [1]. The measurements require disconnection of the battery from the system bus by service operator. ...
Article
Full-text available
The article describes the results of testing a Ben-ning AC/DC power supply, with integrated NIT TBA-ST meter. Such integration enables accurate and energy-efficient measurements of available capacity of individual 48-voltage VRLA/AGM batteries with remote management possibilities. The full compliance with the requirements for telecommuni-cation power systems, the great functionality, upgrade ability, immunity to user errors and the high accuracy of capacity and voltage measurement of battery monoblocks of proposed solution are presented. Keywords-battery capacity tester, battery discharge tester, VRLA real capacity.
... Therefore, to clearly determine the actual capacity, it is best to discharge the battery with 10hour current, i.e. 0.1CA. After discharging, to maintain the best condition, the battery should be immediately fully charged -preferably with a current close to 0.1CA (maximum -2 times more or 2 times less) [17]. The result of the test is the real capacity Q expressed in amperehours (Ah) and the percentage of nominal capacity (Q =% C), but you can also measure the number of watt-hours (Wh) received (it is also useful). ...
... In such a power sys- tem, the measurement of available capacity of any battery can be performed by portable instruments, e.g. RRR shown in Fig. 1a, or electronic loads as well as TBA-IŁ [1]. The measurements require disconnection of the battery from the system bus by service operator. ...
Article
Full-text available
The article describes the results of testing a Benning AC/DC power supply, with integrated NIT TBA-ST meter. Such integration enables accurate and energy-efficient measurements of available capacity of individual 48-voltage VRLA/AGM batteries with remote management possibilities. The full compliance with the requirements for telecommunication power systems, the great functionality, upgrade ability, immunity to user errors and the high accuracy of capacity and voltage measurement of battery monoblocks of proposed solution are presented.
Article
Full-text available
The major cause of deterioration in lead-acid batteries is sulfation. There are patents on the use of high-frequency pulse desulfators to desulfate lead-acid batteries. Also, many products available in the market worldwide claim to use this technique to effectively desulfate lead-acid batteries that deteriorate due to sulfation. But there are little or no systematic studies to evaluate the performance of these products to know whether they do what their manufacturers claim. This research, therefore, aims at empirically evaluating one of such products. Four fully charged 100 Ampere-hour Valve Regulated Lead-Acid Gel batteries were discharged with an electronic-load battery discharger to ascertain their capacities. Thereafter, a high-frequency pulse desulfator was connected to desulfate the battery bank consisting of the four batteries. The battery bank was connected to be charged at the same time by a photovoltaic system. The desulfation experiment lasted for ten weeks but the batteries were tested to know their capacities after two, six, and ten weeks. The results show that the desulfation device works in desulfating lead-acid batteries as there are different degrees of improvement on the capacity of all the batteries. The percentage improvement in the capacity of the batteries is 89.5%, 75.9%, 1.6% and 1.4%, for batteries 1, 2, 3 and 4, respectively.
Patent
Full-text available
A system and method for monitoring the status of a system of battery strings is described. The system includes a current sensor for each of the battery strings, and a controller configured to compute the average current from the measured currents. The state of the battery system is determined as being fully charged, discharging or charging, and the individual battery string currents are compared with the average measured current to determine if the currents are within a threshold value. An alarm indication is provided when one or more of the currents exceeds a threshold difference. The system may provide a local indication of status and may also interface with a communications network to provide for remote monitoring.
Patent
Full-text available
Systems, apparatuses, and methods for managing battery circuits in systems such as wireless communications service base stations are disclosed. An example apparatus includes a battery circuit having multiple strings of one or more serially connected batteries. The apparatus may be configured to rotate between battery strings such that one or more strings are maintained at or near an upper threshold while other string(s) are disconnected from the maintained string(s). The apparatus may also be configured to charge the battery circuit, to test the battery circuit, and to handle power failures.
Book
The lead-acid battery is the workhorse of the rechargeable battery systems. Although many new systems may challenge its position, its reliability, low cost, and good operational life make replacement by other battery systems many years in the future. The lead-acid battery is the single most-used battery system worldwide. A comprehensive summary of lead-acid battery science and technology, this book describes the technology as it exists today in the lead-acid battery industry. The fundamental principles and practical operations of the lead-acid battery are presented. Stress is placed on basic principles of battery operation. The functioning of the lead-acid battery is presented from the viewpoint of thermodynamic principles, electrochemical kinetics, and molecular structure. Sound engineering principles are applied to the practical processes of electrode manufacture. 381 references, 127 figures, 108 tables. (RWR)
DC Power System Design for Telecommunications
  • W D Reeve
W. D. Reeve, DC Power System Design for Telecommunications. Hoboken, NJ, USA: Wiley, 2007.
The changing face of backup
"The changing face of backup", Bestmagazine, Energy Storage Publishing, no. 39, Winter 2013 [Online]. Available: www.bestmag.co.uk
Automatyzacja oraz zdalne badania baterii akumulatorów w obiekcie telekomunikacyjnym
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P. Godlewski and B. Regulska, "Automatyzacja oraz zdalne badania baterii akumulatorów w obiekcie telekomunikacyjnym", Przegląd Telekomunikacyjny, vol. 8-9, p. 1260, XXVIII Krajowe Sympozjum Telekomunikacji i Teleinformatyki KSTiT, Warszawa, 2012 (in Polish).
Battery Optimization Services. A guide to optimize your battery maintenance. Emerson Network Power and FOCUS Consulting
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Handbook for Gel-VRLA-Batteries, part 2: Installation, Commissioning and Operation
"Handbook for Gel-VRLA-Batteries, part 2: Installation, Commissioning and Operation", Industrial Energy, Technical Support, Rev. 5, Dec. 2003, Deutsche Exide GmbH, Büdingen, Germany.
The keys to extended battery life
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B. Blohm, "The keys to extended battery life", Electrical Construction & Maintenance (EC&M), 2002 [Online]. Available: http://ecmweb.com/content/keys-extended-battery-life