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EXIDE POWERSAFE VRLA STATIONARY
RANGE OF BATTERIES
- AN OVERVIEW
D.SEN CHOUDHURY
R&D CENTREEXIDE INDUSTRIES LIMITED
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ACTUAL SERVICE IN INDIAN CONDITIONS
FACTORS FOR CONSIDERATION
• PROLONGED STORAGE BEFORE COMMISSIONING.
• WIDELY VARYING OPERATING TEMPERATURES.
• FREQUENT DISCHARGE.
• PERIODS OF UNDERCHARGE.
• PERIODS OF OVERCHARGE.
• INADEQUATE ATTENTION / MAINTENANCE.
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DESIGN OBJECTIVES
• ADEQUATE DESIGN MARGIN.
•CHOICE OF POSITIVE ALLOY WITH RESPECT TO OPERATINGCONDITIONS.
• MORE ELECTROLYTE PER Ah ALONG WITH MAXIMISED
HEAT DISSIPATION SURFACE AREA.
• IMPROVED CYCLIC CAPABILITY WITH ENHANCED CHARGE
ACCEPTANCE.
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0
20
40
60
80
100
0.5 1 1.5 2 2.5
Sn % = 1.6
C o r r o s i o n %
0
10
20
30
40
50
60
70
80
90
100
G r i d - A M b
i n d i n g t e n s i o n %
Grid-AM binding tension % Corrosion %
50
60
70
80
90
100
110
0.05 0.06 0.07 0.08 0.09 0.1
Ca % = 0.06
C o r r o s i o n %
50
60
70
80
90
100
110
T e n s i l e S t r e n g t h %
Tensile Strengt Corrosion
OPTIMISATION OF Ca & Sn CONTENT IN POSITIVE ALLOY
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BOTTOM SUPPORT
SPACE FOR GROWTH
ANCHORED
TO POLE
EXIDE POWERSAFE
VRLA HAS A UNIQUE
ONE-FOOT GRID WHICH
ALLOWS FOR THE
GROWTH OF THE GRIDDURING THE SERVICE
LIFE TIME.POSITIVE
PLATE
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SELF DISCHARGE & STORAGE
DESIGN CHOICES THAT DETERMINE RATE OF SELF-DISCHARGE
• GRID ALLOY COMPOSITION.
• PURITY OF ALL PARTICIPATING COMPONENTS.
• DESIGN SPECIFIC GRAVITY.
• PLATE PROCESSING METHODOLOGY.
• OPERATING TEMPERATURE.
• EXIDE POWERSAFE EPST & MST/NMST RANGE OF CELLS HAVESELF DISCHARGE RATE OF LESS THAN 2 C!" CAPACITY PER
MONTH AT 2#$C. THIS HAS BEEN SUBSTANTIATED REPEATEDLY
DURING TEC TYPE APPROVAL.
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STORAGE PERIOD VIS-A-VIS COMMISSIONING CHARGE
DURATION
STORAGE TEMPERATURE% 2 - '" $C
STORAGE PERIOD LENGTH OF
INITIAL CHARGE
UPTO ' MONTHS NIL
UPTO ( MONTHS ) - !# H*+.
UPTO , MONTHS 2 - '" H*+.
UPTO !2 MONTHS ) - #2 H*+.
)V MST """Ah AT BIHARSAMSTIPUR CIRCLE 01 INSTALLED
AFTER !! MONTHS GAVE !"" CAPACITY AFTER #2 HRS FLOAT0
ON FIRST CYCLE.
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THERMAL RUNAWAY:
THERMAL RUNAWAY IS A STATE OF OPERATION WHERE THE
RATE OF HEAT GENERATION INCREASES FASTER THAN HEAT
DISSIPATION. THE RESULT IS AN ACCELERATED INCREASE OF
THE TEMPERATURE UNTIL THE BATTERY IS DESTROYED.
THE MAIN CAUSE IS THE ACCELERATION OF CHEMICAL
REACTION RATES WITH TEMPERATURE ACCORDING TO THE
ARRHENIUS RATE EQUATION.THIS ACCELERATION CAN BE
TRIGGERED BY ANY ONE OF THE FOLLOWING PARAMETERS%
INCREASED BATTERY TEMPERATURE. HIGHER CHARGE VOLTAGE.
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Thermal Runawa Test !ata
0
20
40
60
80
0.02 0.04 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3
!uration "#rs.$
% a t t e r T e r m
i n a l
T e m
& e r a t u o C
1 2.45 V T =25±3oC
2 2.25 V T =75 ±3oC
3 2.40 V T =75 ±3oC
!"tter#T#$e%
&MST 1000
1
'
(
Test Conditions
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SUMMARISED PRODUCT FEATURES OF EXIDE
POWERSAFE ‘VRLA STATIONARY RANGE
• WIDE RANGE STARTING FROM "Ah TO """Ah.• C!" CAPACITY BY DESIGN REQUIRED TO MEET !.) VPC END CUT-
OFF.
• SELF-DISCHARGE LESS THAN 2 C!" PER MONTH AT 2 C.
• 2" YRS DESIGN FLOAT LIFE .
• CYCLE LIFE%
)" D$D - !2"" CYCLES.
" D$D - !)"" CYCLES.
2" D$D - """ CYCLES.
• THERMAL STABILITY% #2 HRS MINIMUM AT # C.
EPST RANGE COVERS !"A# TO !""A#.
MST$NMST RANGE COVERS %""A# TO """A#.
ALL CELLS COME IN 'VOLT CONFIGURATION.
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NMST
THE NMST CONCEPTUALLY INVOLVES
• A MA3OR BREA4 THROUGH IN SIGNIFICANTLY IMPROVING
ACTIVE MATERIAL UTILISATION.
• THIS HAS BEEN ACHIEVED BY VERY ADVANCED PLATE
MA4ING 4NOW-HOW.
• THE SAVINGS IN SPACE ACHIEVED BY THE ABOVE IS
UTILISED TO PROVIDE MORE SEPARATOR AND HENCE MORE
ELECTROLYTE1 BESIDES FURTHER PROTECTION AGAINST
SHORT-CIRCUIT.
NMST(( THE ADVANCED VERSION OF MSTDESIGNED
• FOR LOWER FLOOR LOADING.
• FURTHER ENHANCEMENT IN ABILITY TO WITHSTAND HIGH
TEMPERATURE ENVIRONMENT.
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!)V-*"""A# +NMST,
STACING OPTIONS
)**T %ATT+R, )-**R.R/0T "m
'$ 1+/G#T "T$ -*A!/0G "T2m
'$
3ST-4M'()ST *ST(+ 1335 530 1689 0.707 1.802 2.5
4ST-3M'()ST 1780 530 1298 0.943 1.819 1.9
6ST-2M'()ST 2670 530 1689 1.414 1.852 1.3
%ATT+R, !/M+0S/*0S "mm$ARRA0G+M+0T
-+0GT# 1/!T# #+/G#T
COMPARISON OF MST WITH NMST +!)V-*"""A#, :
STD ARRANGEMENT
,''T !ATT-/ ,'' ,''T !ATT-/ ,''
&T *32+ 4-GT *T+ 'A(&G *T)3
2+ &T *3
2+ 4-GT *T+ 'A(&G *T)3
2+
MST 0MST
0.707 1.991 2.8 0.707 1.802 2.5
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HOW TO GET THE BEST OUT OF A D.C SYSTEM
• GOOD OPERATING PRACTICE STARTS FROM THE
COMMISSIONING CHARGING.
• MAINTAINING THE RECOMMENDED CHARGING SCHEDULE
• CARRYING OUT PERIODIC MAINTENANCE DISCHARGE &
CHARGE.
• 4EEPING THE BATTERY AS MUCH AS POSSIBLE PROTECTED
FROM DIRECT HEAT & DUST.
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GOOD OPERATING PRACTICES
STORAGE BEFORE COMMISSIONING
• PREFERRED STORAGE TEMPERATURE% ! - ' C.
• CELLS TO BE STORED AND PROTECTED FROM RAIN1 DIRECT
SUNLIGHT AND DUSTY ATMOSPHERE. AVOID STORAGE AT
AMBIENTS ABOVE "C.
• FRESHENING CHARGE MUST BE GIVEN ONCE IN ( MONTHS
DURING LONG STORAGE TO OBTAIN FULL PERFORMANCE AND
LIFE. FOR REGIONS EXCEEDING "C1 FRESHENING CHARGE HAS
TO BE GIVEN ONCE IN ' MONTHS.
• RECOMMENDED FRESHENING CHARGE%
2.V - !" HOURS / 2.2'V - 2 HOURS.
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OPERATING GUIDELINES
FLOAT VOLTAGE TO BE SET AT EXACT LEVEL AS GIVEN IN
THE OPERATING MANUAL. 5.6 AT AN AVERAGE AMBIENT
TEMPERATURE OF '"C1 FLOAT VOLTAGE FOR A )V
SYSTEM SHOULD BE '.7".V.
CURRENT IN AMPS SHOULD BE LIMITED TO A MAXIMUM OF
! OF THE RATED C!" Ah CAPACITY. 5.6 FOR A MST !"""
CELL LIMIT CURRENT SHALL BE SET AT !" AMPS.
RECHARGE SHALL BE ON FLOAT MODE ONLY.
MAXIMUM DISCHARGE CURRENTS TO BE LIMITED TO
! MIN% ' 8 C!" AMPS SEC% ( 8 C!" AMPS.
IN-BUILT LOW VOLTAGE TRIP ABOUT !.#VPC0
RECOMMENDED.
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CHARGING FEATURES
MAX VOLTAGE RIPPLE% 2 RMS.
MAX CURRENT RIPPLE% AMPS PER !"" Ah C!" CAPACITY.
AS A RULE OF THUMB1 IF THE BATTERY NEGATIVE
TERMINAL TEMP. HAS A DIFFERENCE OF MORE THAN ' C
ABOVE THE ROOM TEMP THEN THE CHARGER IS LI4ELY TOHAVE A HIGHER RIPPLE CONTENT.
RECOMMENDED FLOAT VOLTAGES
AMBIENT RECOMMENDED FLOAT MAX. CHARGING
TEMP +C, VOLTAGE PER CELL +V, CURRENT +AMPS,- TO ! 2.2# 7 "."! ".! C
! TO 2 2.2 7 "."! ".! C
2 TO ' 2.2' 7 "."! ".! C
' TO " 2.2" 7 "."! ".! C
C% NOMINAL !" HR. CAPACITY AT 2# C
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MAINTENANCE PRACTICES
OBSERVE INDIVIDUAL CELL VOLTAGES AT LEAST ONCE IN
A MONTH.
INDIVIDUAL CELL VOLTAGES AFTER COMMISSIONING MAY
VARY WITHIN A BAND OF 7 "."V ON FLOAT.AFTER ABOUT
2/' MONTHS INDIVIDUAL CELL VOLTAGES SHOULD VARYWITHIN A BAND OF 7 "."2V.
CELLS WITH ABERRANT VOLTAGE READING SHALL BE
MONITORED ON A WEE4LY BASIS. IF THE PROBLEM
PERSISTS OR DETERIORATES THE CELL MIGHT HAVE
DEVELOPED A DEFECT. REPLACEMENT OF ONE OR TWO DEFECTIVE CELLS WITHIN
YEARS OF SERVICE LIFE WILL NOT AFFECT STRING
PERFORMANCE.
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MAINTENANCE PRACTICES
FULLY CHARGED CELLS SHOULD DRAW A MAXIMIUM
STEADY CURRENT OF '"-"9A/!""Ah OF C!" CAPACITY IN
NORMAL FLOAT CONDITIONS AT 2#C0
5.6 MST !""" CELL AT 2#C SHOULD DRAW ".'-".AMPS UNDER FLOAT CONDITIONS. FLOAT CURRENT
APPROX. DOUBLES FOR EVERY !"C RISE IN TEMPERATURE.
CHARGING SYSTEM SHOULD HAVE THE PROVISION FOR
MEASURING THE FLOAT CURRENT MAX AMPS0
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ANNUAL MAINTENANCE PRACTICES
• TEST DISCHARGE AT C!" RATE FOLLOWED BY A
RECHARGE. THE MEASURED C!" CAPACITY IS THE MOST
ACCURATE ESTIMATION OF STATE OF HEALTH.
• TEST DISCHARGE AT C RATE FOR !" MINUTES -INDIVIDUAL CELL VOLTAGES SHOULD BE !.,V. THIS GIVES
AN APPROX. IDEA OF THE STATE OF HEALTH.
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STATE-OF-THE-ART MANUFACTURING
TECHNOLOGY
EIRICH PASTE MIXING MACHINE%
CONTROLLED PASTE MIXING DONE UNDER HIGH VACUUM TO ENSURE
PERFECT CONSISTENCY BETWEEN BATCH TO BATCH IN TERMS OF MOISTURE
CONTENT1 DENSITY & OTHER PARAMETERS.
OSI CURING OVENS%
AUTOMATIC HYDRO-SETTING CYCLE WITH INCONTROLLED HUMIDITY
AND TEMPERATURE CONDITIONS FOR EXCELLENT BONDING OF THE PASTE TOTHE GRID AND GENERATION OF TETRA BASIC LEAD SULFATE IN THE PASTE.
PULSE CHARGING FOR 3AR FORMATION%
A PROPRIETARY COMPUTER CONTROLLED PULSE CHARGING METHODOLOGY
FOR VERY FAST AND COMPLETE ACTIVATION OF PASTE MATERIAL. !""
BATTERIES VOLTAGE & CURRENT DATA ARE DATALOGGED AND MONITORED
PRIOR TO DESPATCH.
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FULLY AUTOMATED SHIN-OBE ASSEMBLY LINE
: ROBOT CONTROLLED STAC4ING.
: !"" GROUP COMPRESSION CHEC4.
: AUTOMATIC BOXING.: !"" SHORT-CIRCUIT TESTING.
: ARGON ARC BASED TIG-WELDING.
: AIR LEA4 TESTING.
: DOUBLE PROTECTION RESIN SEALING.
: HIGHLY RELIABLE HELIUM ION TESTING.
: VACUUM CONTROLLED ACID FILLING.
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