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Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

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Page 1: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste
Page 2: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Lead-Acid Battery Construction

Page 3: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Lead-Acid Battery Construction Cont’d

Page 4: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Chemistry of lead acid battery

Pbo2 + Pb + 2H2SO4 PbSO4

+ PbSO4 +2H2O+e

Page 5: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Why does a battery die?Antimony

Acid

Temperature

Page 6: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Components of lead acid batteryPositive plate: Lead peroxide on lead

antimony/calcium grid.

Negative plate: Spongy lead paste on lead antimony/calcium grid.

Separator: PVC, fiber glass layered PVC material.

Electrolyte: Very weak sulphuric acid

Page 7: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Types of lead acid batteriesCranking Batteries: C20 rated

Stand-by Batteries: C10 rated

Traction Batteries: C5 rated

Page 8: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

VRLA/SMF Batteries: C10/C20 rated

Solar/Wind/Renewable Energy Support Batteries: C10/C20 rated

Page 9: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Cranking Batteries Batteries with pasted positive and pasted negative

plates at C20/C10 rating.

For cranking 2 wheeler, 4 wheeler engines, aircraft, diesel engines and DG sets.

Capable of delivering very high one shot current equivalent to 5 times the rated capacity.

Page 10: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Stand-by Batteries With tubular positive and pasted negative plates,

generally rated for C10 rate of discharge.

Designed to deliver steady current for a definite duration with a defined end voltage.

Generally used as emergency support batteries in power generating stations, electrical sub stations and for all stand-by power requirements.

Page 11: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Traction Batteries Compact cell assembly with tubular positive and

pasted negative plates, rated at C5 rate of discharge.

Used in all electric vehicles, electric material handling equipments and for all traction applications.

Page 12: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Valve Regulated Lead Acid(VRLA) / SMF Batteries Batteries with pasted positive and pasted negative

plates with an absorbent type separator and a starved electrolyte design, rated C10/C20.

Designed to support stand-by applications such as UPS systems and also to meet brown-out requirements.

Page 13: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Solar/Wind/Renewable Energy Support Batteries Tubular positive with pasted negative, rated C10/C20

rate of discharge.

Designed with minimum self loss and best chargeacceptance qualities.

The battery grid is made of lead-calcium alloy tominimize heat generation, thus preventing water loss.

Page 14: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Improper initial charging.

Continuous usage of the system without focus on local generation.

Long duration of low charge level in the battery.

Why does a battery die in a solar installation?

Page 15: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Abuse in the form of external loads on the battery.

Having no alternative charging facility available at site.

Lack of preventive maintenance.

Page 16: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Types of Charging systemsTrickle charging

Float charging

Boost charging

Equalizing charging

Page 17: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Trickle ChargingGiven to cells when there is no permanent load on the battery bank.

Page 18: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Float ChargingSelected when there is a

permanent DC load. This charger continuously compensates the self loss of the cells and also takes care of the permanent DC load.

Page 19: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Boost ChargingBoost charger will have the facility of boost charging and trickle charging and also comes with float mode and boost mode depending up on the load pattern in the station.

Page 20: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Equalizing ChargingEqualizing charger is used once in a year

while correcting the imbalance in the specific gravity readings in a battery bank.

Generally the capacity of a boost charger will be to charge the batteries at max 5% rate of the capacity of the battery bank.

Page 21: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Voltage Setting for the Charger Trickle Charging:

2.16 to 2.25 volts per cell depending up on the type of battery selected. This charger cannot manage permanent DC load

Float Charging:

2.16 to 2.25 volts per cell depending up on the type of battery selected which accommodates a flow of 10% of the capacity of the battery plus the total DC permanent load in the station.

Page 22: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Boost Charging:

Boost charging mode will be capable of building the cell voltage from 2 volts per cell to a maximum of 2.75 volts with a maximum current of 15% of the capacity of the battery. This mode recharges a fully discharged battery.

Page 23: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Why and what is specific gravity imbalance?All cells record uniform specific gravity

reading above 1200 at room temperature.

All cells record low gravity less than 1200.

Some cells are ok but some cells low gravity.

All/some cells record high specific gravity beyond 1200 going up to even 1300.

Page 24: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

High temperature effect on batteries

Battery is hot to touch.

Heavy acid smell in battery room.

High gravity in cell.

Battery looks bulged.

Drinks more distilled water.

Page 25: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Low float voltage effect on cellsBattery remains cool – no gassing, no

bubble.

Battery looses specific gravity gradually – 1200 – 1190 – 1150 – 1130 – nil.

When loaded voltage dips below 2 volts per cell and refuses to take the load.

“Sulphation” sets in.

Page 26: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Health check of a battery Check float voltage in the charger.

Check specific gravity of the battery – all the cells.

Check physical appearance of the battery – ok –swollen – hot – top dirty – white formation on terminals – smell of acid in the room.

Subject the battery bank for boost charging and record the time taken to attain maximum voltage on charge.

Discharge the battery at the rate of discharge recommended based on the type of battery.

Page 27: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

The right battery room Battery room should have proper ventilation in the

form of air inlet and outlet system.

Should have a running water system.

Should have acid proof tiles on the floor and up to 6 feet in the wall.

The lighting and fan fixtures should not be vertically above the battery bank, that is the roof and should be on the side walls.

All metal portions like door knobs and windows should be painted with acid proof paints.

Page 28: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Cell configuration for 110 volts system If 55 cells are selected to provide 110 volts DC system –

2.25 volts X 55 cells = 123.75 volts.

This is more than the maximum DC tolerance on the load side. The maximum DC voltage required is 110 +/-10% = 121 volts.

Hence, the number of cells commissioned for 110 volts DC system is 110 volts / 2.25 volts = 53.77 cells. Therefore maximum cells can be 53 cells.

Page 29: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Cell configuration for 220 volts system If 110 cells are selected to provide 220 volts DC system

2.25 volts X 110 cells = 247.50 volts.

This is more than the maximum DC tolerance on the load side. The maximum DC voltage required is 220 +/- 10% = 242 volts.

Hence, the number of cells commissioned for 110 volts DC system is 220 volts / 2.25 volts = 107.55 cells. Therefore maximum cells can be 107 cells.

Page 30: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

What happens if floated at 2 volts per cell?No current will flow into the cells.

Battery slowly discharges and sulphation starts.

Will refuse to take load when needed.

If floated for long at 2 volts per cell, the battery bank dies.

Page 31: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

What happens if floated at higher voltage beyond 2.25 volts per cell?Cells get overcharged.

Temperature shoots up.

Heavy gassing and water evaporation and records high specific gravity.

The battery bulges.

Battery room smells of acid.

Battery bank dies prematurely.

Page 32: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Hydrometer – Why is it needed?

Page 33: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste
Page 34: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

What happens when the battery is under fed?

Discharged Battery:PbSo4(positive)+PbSo4(negative)+h2O+0e

Fully Charged Battery:

Pbo2+Pb+H2So4 PbSo4+PbSo4+H20+e

Page 35: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Battery Terminals

• Positive Terminal diameter is bigger.• Negative Terminal diameter is smaller.

Page 36: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Battery Terminal Cables• Copper multi strand cable to be properly soldered to the terminal.

• Any loose strands leads to loss of energy and heat generation at the terminal.

• Further leads to corrosion and sulphation.

Page 37: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

What is Sulphation?

White formation on the terminals.

Green formation on the terminals.

Electrolyte turning milky white.

Positive and negative plates having white spots/flakes.

Page 38: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Causes for Sulphation

A discharged battery kept unfed for long

Dead short in some of the cells.

Topping up with tap water, borewellwater, mineral water.

Foreign material falling into the cell like nuts or bolts.

Page 39: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Remedies for Sulphation

Immediate recharging removes sulphation from the cells.

Removal of the foreign body from the cell and feeding energy till it is fully recovered.

Removal of the impure electrolyte from the cell and topping it up with distilled water and recharging the cell.

Page 40: Lead-Acid Battery Construction - mgired.kar.nic.in · Components of lead acid battery Positive plate: Lead peroxide on lead antimony/calcium grid. Negative plate: Spongy lead paste

Storage of Battery A dry and uncharged battery is electrically

inactive and can be stored for a long period.

Addition of electrolyte begins the life of the battery.

A wet battery should be kept fully charged and should be on trickle charge mode always.

A discharged battery should not be kept without feeding. This will terminate the life of the battery.