For better performance
of Inverter Battery it is always recommended to follow the procedure as given
below:-
There are following ways
to increase the life and Performance of lead acid batteries:-
1. The most important part is the care during
initial filling and charging which determines the life & performance and
knowledge about how a lead-acid battery works
2. There
should be appropriate followed up proper and regular routine and preventive maintenance of the
battery banks.
3. To take corrective
measures, one must have the knowledge of the normal failure modes of lead- acid
batteries & the reasons for the failure.
4. If any one is conversant
of the failure mode and the reason for same, then will be in a position to
rectify / prevent before it is too late.
|
Initial
filling and Charging a Battery
|
||
|
General requirement
1.
Room in
which batteries is kept should be clean, Dry, cool and properly illuminated and
well ventilated. Batteries should be well cleaned before filling.
2.
Constant current of same rating as per
requirement should be used which should be capable to supply requisite volt
& amps designed to give at 6% rate of charge up to 2.75 VPC at to charging
voltage.
3.
Sufficient quantity of battery grade
sulphuric acid of 1.220 + 0.005 sp. Gravity at 27ºc conforming to be 266
& battery grade water conforming to be 1069 should be available. Some
stock of 1.400-sp.gravity sulphuric acids at 27ºc for adjustment after full
charging, if required.
4.
Don’t use the blind plugs supplied with
batteries. Keep the vent plugs loose in position, to avoid explosions.
5.
Never ever use a Metallic vessel while
filling always use plastic vessels and protective wears.
6.
Never take open flame near Batteries.
7.
Never connect the cable loosely with the
cells / batteries to avoid sparks & chance of explosion / melting.
|
||
|
General
requirement: Making dilute Acid
1.
If dilute acid prepared from concentrated
acid at site, care to be taken. Do not use wooden or any other metal stirrer
but to use plastic/lead instead of wood only to avoid contamination.
Compressed air can be used for mixing but care should be taken to trap oil
acid to be used.
2.
To
follow all laid down safety rules for diluting acid from 1.840-concentrated
acid.
3.
The
acid to be used after cooling, specific Gravity corrected to 27ºc.
4.
Use
‘acifil pump’ or siphoning with spring loaded control lever trap, during acid
filling to avoid spillage and surface / earth leakage.
|
||
|
Acid Filling Procedure:
1.
The battery should be checked physically for any
damages/visible cracks and cleaned prior to filling of acid. Which may
otherwise leads to explosion sometimes if there is problem in battery.
2.
Check the specific Gravity of acid prior to filling.
3.
Pour cool dilute battery grade sulphuric acid of 1.220/1.190
sp. Gravity up to the max. Level by ‘acifil pump’, siphoning pipe or with
funnel & jug carefully. Do not over fill to avoid spillage.
|
||
|
Polarity check & Rest period Procedure:
1.
Just after acid filling, to check polarity of the cells by
checking the voltage of all the cells, if any cell wrongly reverses
assembled. The voltage observed is not that important at this point. Also
check for any leakage visible after filling.
2.
Allow 12 hours rest for the cooling; allow the plates &
separators to soak acid, but not more than 24 hours. Top up again with acid,
same as filling- in sp. Gravity.
|
||
|
|
||
|
Putting on First
Charge Procedure:
1.
Use only DC ‘constant current’ charger only
for initial charging of batteries.
2.
Ensure the charger in working condition and
capable of supplying requisite volt & amps required for the batteries to
be charged.
3.
Take care of polarity and connect the pos.
Terminal of batteries with the pos. & neg. Terminal with neg. Of the
charger, respectively.
4.
Charging may be done in 2 steps or single
step. In our tropical country advisable to charge in single step, especially
in summer
- For ‘2 step charging’ the initial current to be 12% of the C10 capacity of battery upto 2.36 VPC and followed by 6% of the C10 rated capacity of the battery upto 2.75 VPC. (For 500Ah battery 60 amps & 30 amps respectively). - For ‘single step’ charging, the battery to be charged continuously at the current 6% of the C10 rated capacity of the battery upto 2.75 VPC, till the end of charging e.g. 30 amps upto 2.75 VPC for a 500 Ah battery till end. |
||
|
Condition of Fully
Charged Procedure:
|
||
|
To
continue DC charging at ‘constant current’ till the following conditions of
fully charged cells are observed:
1.
All cells are gassing freely at voltage, 2.75
VPC at 6% - the finishing rate.
2.
No rise of voltage for 3 to 4 consecutive
hourly readings, after reaching 2.75 VPC
3.
No rise of specific Gravity for 3 to 4
consecutive hourly readings, after reaching 2.75 VPC
4.
Theoretical Ah input to be kept at the back
of the mind- the input to be approx. 4.5 to 5 times of the Ah capacity of the
battery i.e. For a 500 Ah battery the total Ah input to be 2250 Ah to 2500
Ah. (approx. time 75 to 85 hours)
|
||
|
Checks & Record
during charging Procedure:
1.
The electrolyte temperature should not be
allowed to increase beyond 50ºc, during charging if the temperature goes
above 50ºc, the charging to be suspended till the temp. of electrolyte comes
down to 40º c, then only start the charging again.
2.
Record the readings of sp. Gravity, voltage
and the electrolyte temp. of cells, initially every 4 hourly and every
hourly, after the cell voltage reaches 2.4 VPC.
|
||
|
First C10 Capacity
test Procedure:
|
||
|
Batteries
now charged ready - give a rest period of 12 hours for cooling & settling
but not more than 24 hours.
Connect
the batteries with suitable load and conduct C10 capacity test at constant
current, upto ‘end voltage’ 0f 1.85 VPC e.g. For a 500 Ah battery at 50 amps
for 10 hours. Take hourly readings and record the volt, specific Gravity &
electrolyte temp. Of all cells. If any cell voltage comes to 1.85 volt before
10 hours, the cell to be recharged / checked before taking for commissioning.
|
||
|
Recharge after C10
Capacity test Procedure:
|
||
|
Recharge
the batteries immediately after discharge by constant current charging at 6%
of the rated Ah capacity of the battery upto 2.75 VPC, till the batteries are
fully charged- i.e. All cells are gassing freely, constant voltage, constant
sp. Gr., theoretical 130% Ah input given, when 100% of Ah
taken out during discharged.
|
||
|
Adjustment of Sp.
Gravity Procedure:
1.
After batteries are fully charged, the sp.
Gravity of the electrolyte of all cells to be adjusted to the service gravity
i.e. 1.210 /1.250 ± 0.005, at 27ºc. the batteries to be put on charge for
proper mixing.
2.
If sp. Gravity in cells more than service
gravity corrected to 27ºc. Take out acid and add battery grade water, when on
charge for proper mixing. adjust sp. Gravity to the service gravity corrected
to 270 c. As applicable with respective batteries.
3.
If the sp. Gravity of the cells less than
the service gravity at 270 c take out acid and add 1.400 sp. Gr. Acid by few
drops, on charge for proper mixing. Adjust the sp. Gravity to the service
gravity at 270 c as applicable.
4.
After adjustment of the specific gravity,
continue the charging for 1- 2 hours for proper mixing of the electrolyte.
Stop the charging and allow the batteries to cool, before commissioning.
|
||
|
The
normal failure modes of lead - acid batteries
|
||
|
Sulphation in cells
1.
Over discharge
2.
Allowing a battery to stand idle
3.
Starvation
4.
Allowing electrolyte to fall on earth
5.
Impurities in electrolyte
6.
Adding Acid instead of water.
|
||
|
Bucking of plates:
1.
Over discharge
2.
Continued operation with battery in starved
condition
3.
Charging at high rates
4.
Non- uniform distribution of current over
the plates, due to repeated deep discharge
|
||
|
Shedding of active
materials:
1.
Normal
Shedding
2.
Excessive
Charging rate or Overcharging.
3.
Charging sulphated plates at too high rate
4.
Charging only a part of the plate
5.
Deep discharge battery on normal charge.
6.
Freezing.
|
||
|
Container trouble:
1.
Rough handling: any storage battery to be
handled as if made of glass, though the containers made with hard rubber, SAN
or FRP. Heavy batteries should be handled by more than one person or by
mechanical handling and not to be dropped / dragged. This will lead container
crack/ damage.
2.
Explosion in cell: may cause due to open
flame, electrical sparks and clogged vent holes.
3.
Bulging of container: this is be due to
under curing of the container.
4.
Stacking should be restricted to max. 3
high, with hard board in between layers
|
||
|
Terminals/
connector corrosion:
1.
Too much topping water added to cells
2.
Battery poorly sealed
3.
Loose vent caps / float guide
4.
Electrolyte spillage
5.
Battery cable damaged, or loose
6.
Connecting bare wires directly to battery
terminals.
7.
Loose terminal connections
8.
Non application or renewal of petroleum
jelly for protection
|
||
|
Loss of capacity:
1.
Impurities in the electrolyte
2.
Sulphation
3.
Loose active materials
4.
Incorrect proportions of acid and water in
the electrolyte
5.
Separators clogged
6.
Shedding
7.
Low level of electrolyte
8.
Effect of age
|
||
|
Internal short
circuit:
1.
Worn out separators
2.
Lead run
3.
Foreign material
4.
Accumulation of sediment
|
||
|
Reversal of plates:
1.
Assembling of the cell in reverse direction.
2.
Charging a battery in wrong direction.
3.
Lagging / defective cell in battery bank
will be reversed if not taken care in time
|
||
|
Earth / surface
leakage in battery:
1.
Over filling of battery water.
2.
Careless hydrometer use, spillage of
electrolyte.
3.
Careless acid filling during initial filling
& charging.
|
||
|
Problems in
Electrolyte:
1. Higher specific
gravity of electrolyte.
2. Lower Specific
gravity of electrolyte.
3. High Level of
electrolyte.
4. Lower Level of
electrolyte.
5. Impurities in
electrolyte.
|
||
|
The importance of
equalizing charge:-
|
||
|
To
ensure that every cell in a battery bank is maintained in healthy state to
give enhanced life & performance it is advisable to give ‘equalising
charge’ atleast once in a year. Under ‘constant potential’ mode during
operation a passive layers form on the plates. This causes variation of
sp.gravity & voltage from cell to cell. To take care the battery bank to
be put on ‘constant current charging at 6% of rated capacity upto 2.75VPC,
followed by an extended charge for 12 to 24 hours on ‘constant current’
charging at 3% of rated capacity. By this the cells are rejuvinated with
fresh layer of active material, all the cells will show approx. Same sp.
Gravity & voltage. As low current was given during 3% rated amps of the
Ah capacity. This will not affect the activated portion of the plates, but
will remove the patches of sulphate from the plates back to the solution,
increasing the sp. Gravity of cells. so, it is mandatory to give equalising
charge, once in ayear,if not earlier.
|
