Batteries & charging system

BATTERIES & CHARGING SYSTEM

BATTERIES

- LEAD ACID BATTERIES

- MF BATTERIES

- MAINTENANCE, CHARGING & TESTING

- DIAGNOSING BATTERY FAULTS

BATTERIES & CHARGING SYSTEM

CHARGING SYSTEMS

- REQUIREMENTS OF CHARGING SYSTEM

- CHARGING SYSTEM PRINCIPLES

- ALTERNATOR & CHARGING CIRCUITS

- DIAGNOSING CHARGING & SYSTEM FAULTS

BATTERIES

PURPOSE OF THE BATTERY

The three main functions of the automotive battery are to :• Supply power to the starter and ignition system.• Supply the extra power required when vehicle's electrical load

requirements exceed the supply from the charging system.• Act as a voltage stabilizer in the electrical system.

BATTERIES

LEAD ACID BATTERY• Positive plate - lead peroxide ( Pb O2 )• Negative plate - sponge lead ( Pb )• Electrolyte solution - mixture of sulfuric acid and• water ( H2 SO4 )• Produced - 2.1 to 2.5 volt

BATTERIES

OPERATION

Plate positive (PbO2) + sulfate (SO4) electrolyte + hydrogen = water (H20).Plate negative (Pb) + sulfate (SO4) = Plumbum sulfate(PbSO4) @ ‘Lead sulfate’Plate positive and plate negative = Plumbum sulfateElectrolyte = water

-+

Pb O2

Pb

H2SO4

H2SO4

Cathode plate (change sulfate)

Anode plate (change sulfate)

BATTERIES

OPERATIONCharging

Plate positive and plate negative + water = ElectrolytePlate positive = lead peroxide and plate negative= spongy leadCharging gas oxygen and gas hydrogen * chemical action

Charger -+

-+

PbSO4 PbSO4H2 O

H2 OCathode plate (change sulfate)

Anode plate (change sulfate)

BATTERIES

BATTERY CONSTRUCTION

Vent plug

Shell connectors

Grids

Separators

Plates Container and cover

BATTERIES

BATTERIES

BATTERY CAPACITIES• Battery capacity is the amount of current that a battery can deliver

for a certain length of time at a certain temperature.• There are two terms used to express battery capacity: slow

discharge capacity and high discharge capacity.

BATTERIES

SLOW DISCHARGE CAPACITY• The electric power of a battery, when used for low-consumption

loads, is called the slow discharge capacity.

Ah = A x h

BATTERIES

High-discharge capacity can be expressed as:

(1) the length of time that a battery can output a heavy current when it discharges at a constant rate

(2) the voltage after the battery has been discharged at constant heavy current for a certain length of time.

BATTERIES

INTERNAL RESISTANCE

A battery not only creates electromotive force but also acts as a

resistant, due to the internal resistance of its electrolyte and plates.

V = E-lr

BATTERIES

CONNECTING METHODS

SERIES CONNECTION

E0 = E1 + E2

BATTERIES

PARALLEL CONNECTION

E0 = E

BATTERIES

SELF-DISCHARGEThe amount of self-discharge is indicated in terms of a percentage of the battery capacity, and is approximately 0.3 to 1.5 % per day at electrolyte temperatures of between 20 and 30°C (68 and 86°F). A battery will become fully self-discharged in 1 to 3 months if not used or recharged. The amount of self-discharge is larger when the battery temperature is higher. Therefore, batteries should be stored in a cool, dark place when not in use.

BATTERIES

Self-discharge can be caused by any of the following:a. Metal impurities (such as iron or manganese) mixed in with the

electrolyte or adhering to the plates. This is why distilled water, rather than tap water, is used in batteries since it contains minimal impurities.

b. Antimony used in the plates.

BATTERIES

MAINTENANCE FREE BATTERIES

BATTERIES

MAINTENANCE FREE BATTERIES

DIFFERENCES FROM ORDINARY BATTERIES

a. The amount of antimony in the positive and negative plate grids is either extremely small, or the antimony has been replaced with an other metal, such as calcium, for example.

b. The height of the ribs at the bottom of the case is reduced to increase the amount of electrolyte.

BATTERIES

REDUCED NEED FOR WATER REPLENISHMENTMaintenance interval batteries having low antimony and lead alloy grids or calcium and lead alloy grids so the rate of electrolyte loss is low.

BATTERIES

REDUCED SELF-DISCHARGING

Maintenance interval batteries use low-antimony plates or

calcium-lead alloy plates, the rate of self-discharge is reduced

substantially.

BATTERIES

ELECTROLYTE LEVEL AND SPECIFIC GRAVITY INDICATORExtended maintenance interval batteries are equipped with an indicator which allows easy inspection of the electrolyte level and specific gravity.

CONSTRUCTIONThe indicator contains two floats of different colors, having different specific gravities. Specific gravity is 1.150 for the blue float and below 1.0 for the red float.

OPERATING PRINCIPLE Low Electrolyte Level

BATTERIES

BATTERIES

Electrolyte Level Normal but Specific Gravity Below 1.150

BATTERIES

Electrolyte Level and Specific Gravity both Normal

BATTERIES

Battery Maintenance

1. Visual inspection

2. Cleaning the battery top, terminals and cable clamps.

3. Testing battery

4. Charging battery

BATTERIES

Visual inspection

1. CHECK BATTERY ELECTROLYTE LEVEL

2. CHECK BATTERY CASE FOR CRACKS

BATTERIES

IF BATTERY ELECTROLYTE LEVEL IS LOW,ADD DISTILLED WATER TO SPECIFIED LEVEL

BATTERIES

Visual inspection

4.CHECK BATTERY VENT PLUGS FOR DAMAGE OR CLOGGED

BENT HOLES

BATTERIES

Cleaning the battery top, terminals and cable clamps.

BATTERIES

Battery Testing

Testing determines if the battery:

1. Is in good condition

2. Needs recharging

3. Is defective and should be discarded

BATTERIES

OPEN CIRCUIT VOLTAGE TEST

BATTERIES

HYDROMETER TEST

BATTERIES

Measurement Result Possible Cause

Specific gravity too low in all cells alike.

Undercharged ... Charging system trouble, driving distance or speed too lowOvercharged ... Overload, insufficient generator capacity(Leaking ... Lack of cleaning, too much electrolyte)

Specific gravity too low in some cells.

Internal shorts ... lack of electrolyteImpurities in cells ... excessive self-discharge

Specific gravity too high. Sulfuric acid rather than water has been added

BATTERIESSpecific Gravity State of Charge1.265 - 1.299 Fully charged battery1.235 - 1.265 Three-fourths charged1.205 - 1.235 One-half charged1.170 - 1.205 One-fourth charged1.140 - 1.170 Barely operative1.110 - 1.140 Completely discharged

BATTERIES

LOAD TEST

BATTERIES

BATTERY CHARGING

BATTERIES

BATTERY CHARGING

1. Slow chargingSmall current 5 to 7 amps for long period 14-16 hours

2. Fast chargingHigh current 50-60 amps for short time 1-2 hours

3. Trickle chargingVery low current, less than 1 amps for wet batteries that must be kept for any length of time.

BATTERIESDiagnosing battery faults Fault Causeundercharging • Low alternator output, perhaps due to a slipping drive belt • Excessive use of the battery, which may be due to a short circuit • Faulty alternator regulator • Terminal corrosion• Overcharging • Defective cell in battery

(excessive gassing) • Faulty alternator regulator

• Low battery capacity • Internal or external short between cells • Sulphation • Loss of active material from plates • Low electrolyte level • Incorrect electrolyte strength • Terminal corrosion

BATTERIES

NEXT CHARGING SYSTEM

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