Servicing Battery System

Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

characteristic charging curve and battery chargers must be designed to detect the end of
charge conditions for the specific chemistry involved. In addition, some form of
Temperature Cut Off (TCO) or Thermal Fuse must be incorporated to prevent the battery
from overheating during the charging process.

Fast charging and quick charging require more complex chargers. Since these chargers
must be designed for specific cell chemistries, it is not normally possible to charge one cell
type in a charger that was designed for another cell chemistry and damage is likely to
occur. Universal chargers, able to charge all cell types, must have sensing devices to
identify the cell type and apply the appropriate charging profile.

Note that for automotive batteries the charging time may be limited by the available power
rather than the battery characteristics. Domestic 13 Amp ring main circuits can only deliver
3KW. Thus, assuming no efficiency loss in the charger, a ten hour charge will at maximum
put 30 KWh of energy into the battery. Enough for about 100 miles. Compare this with
filling a car with petrol.

It takes about 3 minutes to put 90 KWh of energy into the tank, sufficient to take the car
300 miles. To put 90 KWh into a battery in 3 minutes would be equivalent to a charging
rate of 1.8 Megawatts!!

Charge Termination Methods

The following chart summarizes the charge termination methods for popular batteries.
These are explained in the section below. See Table 1.

Termination Methods

SLA Nicad NiMH Li-Ion

Slow Charge Trickle OK Tolerates TrickleTimer Voltage Limit

Fast Charge 1 Imin NDV dT/dt Imin at Voltage Limit

Fast Charge 2 Delta Charge dT/dt dV/dt=0
TCO

Back up Termination 1 Timer TCO TCO TCO

Back up Termination 2 DeltaTCO Timer Timer Timer

Table 1.

TCO = Temperature Cut Off
Delta TCO = Temperature rise above ambient
I min = Minimum current

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

Charge Control Methods

Many different charging and termination schemes have been developed for different
chemistries and different applications. The most common ones are summarised below.

Controlled charging

Regular (slow) charge

 Semi constant current Simple and economical. Most popular. Low current therefore
does not generate heat but is slow, 5 to 15 hours typical. Charge rate 0.1C. Suitable for
Nicads

 Timer controlled charge system Simple and economical. More reliable than semi-
constant current. Uses IC timer. Charges at 0.2C rate for a predetermined period
followed by trickle charge of 0.05C. Avoid constantly restarting timer by taking the
battery in and out of the charger since this will compromise its effectiveness. The
incorporation of an absolute temperature cut-off is recommended. Suitable for Nicad
and NiMH batteries.

Fast charge (1 to 2 hours) (see Figure 2.)

 Negative delta V (NDV) Cut-off charge system

This is the most popular method for rapid charging for Nicads.

Fig.4 Nicad and NiMH Charging Characteristics

Batteries are charged at constant current of between 0.5 and 1.0 C rate. The battery
voltage rises as charging progresses to a peak when fully charged then subsequently
falls. This voltage drop, -delta V, is due to polarization or oxygen build up inside the cell
which starts to occur once the cell is fully charged. At this point the cell enters the

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

overcharge danger zone and the temperature begins to rise rapidly since the chemical
changes are complete and the excess electrical energy is converted into heat. The
voltage drop occurs regardless of the discharge level or ambient temperature and it
can therefore be detected and used to identify the peak and hence to cut off the
charger when the battery has reached its full charge or switch to trickle charge.

This method is not suitable for charging currents less than 0.5 C since delta V becomes
difficult to detect. False delta V can occur at the start of the charge with excessively
discharged cells. This is overcome by using a timer to delay the detection of delta V
sufficiently to avoid the problem. Lead acid batteries do not demonstrate a voltage drop
on charge completion hence this charging method is not suitable for SLA batteries.

o dT/dt Charge system NiMH batteries do not demonstrate such a pronounced
NDV voltage drop when they reach the end of the charging cycle as can be seen
in the graph above and so the NDV cut off method is not reliable for ending the
NiMH charge. Instead the charger senses the rate of increase of the cell
temperature per unit time. When a predetermined rate is reached the rapid
charge is stopped and the charge method is switched to trickle charge. This
method is more expensive but avoids overcharge and gives longer life. Because
extended trickle charging can damage a NiMH battery, the use of a timer to
regulate the total charging time is recommended.

o Constant-current Constant-voltage controlled charge system. Used for
charging Lithium batteries which are vulnerable to damage if the upper voltage
limit is exceeded. Special precautions are needed to ensure the battery is fully
charged while at the same time avoiding overcharging. For this reason it is
recommended that the charging method switches to constant voltage before the
cell voltage reaches its upper limit.

Fig.5 Constant-current Constant-voltage

The charge voltage rises rapidly to the cell upper voltage limit and is subsequently
maintained at that level. As the charge approaches completion the current decreases

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

to a trickle charge. Cut off occurs when a predetermined minimum current point, which
indicates a full charge, has been reached. Used for Lithium and SLA batteries.

Note: When Fast Charging rates are specified, they usually refer to the constant
current period. Depending on the cell chemistry this period could be between 60% and
80% of the time to full charge. These rates should not be extrapolated to estimate the
time to fully charge the battery because the charging rate tails off quickly during the
constant voltage period.

 Voltage controlled charge system. Fast charging at rates between 0.5 and 1.0
C rate. The charger switched off or switched to trickle charge when
predetermined voltage has been reached. Should be combined with temperature
sensors in the battery to avoid overcharge or thermal runaway.

 V- Taper controlled charge system Similar to Voltage controlled system. Once
a predetermined voltage has been reached the rapid charge current is
progressively reduced by reducing the supply voltage then switched to trickle
charge. Suitable for SLA batteries it allows higher charge level to be reached
safely. (See also taper current below)

Failsafe timer

Limits the amount of charge current that can flow to double the cell capacity. For
example for a 600mAh cell, limit the charge to a maximum of 1,200mAH. Last resort if
cut off not achieved by other means.

Pre-charging

As a safety precaution with high capacity batteries a pre-charging stage is often used.
The charging cycle is initiated with a low current. If there is no corresponding rise in the
battery voltage it indicates that there is possibly a short circuit in the battery.

o Intelligent Charging System
Intelligent charging systems integrate the control systems within the charger with
the electronics within the battery to allow much finer control over the charging
process. The benefits are faster and safer charging and battery longer cycle life.
Such a system is described in the section on Battery Management Systems.

Note

Most chargers provided with consumer electronics devices such as mobile phones and
laptop computers simply provide a fixed voltage source. The required voltage and
current profile for charging the battery is provided (or should be provided) from
electronic circuits, either within the device itself or within the battery pack, rather than
by the charger. This allows flexibility in the choice of chargers and also serves to
protect the device from potential damage from the use of inappropriate chargers.

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

Voltage Sensing

During charging, for simplicity, the battery voltage is usually measured across the
charger leads. However for high current chargers, there can be a significant voltage
drop along the charger leads, resulting in an underestimate of the true battery voltage
and consequent undercharging of the battery if the battery voltage is used as the cut-
off trigger. The solution is to measure the voltage using a separate pair of wires
connected directly across the battery terminals. Since the voltmeter has a high internal
impedance there will be minimal voltage drop in the voltmeter leads and the reading
will be more accurate. This method is called a Kelvin Connection. See also DC Testing.

Charger Types

Chargers normally incorporate some form of voltage regulation to control the charging
voltage applied to the battery. The choice of charger circuit technology is usually a
price - performance trade off. Some examples follow:

Switch Mode Regulator (Switcher) - Uses pulse width modulation to control the
voltage. Low power dissipation over wide variations in input and battery voltage. More
efficient than linear regulators but more complex needs a large passive output filter to
smooth the pulsed waveform. Component size can be reduced by using higher
switching frequency. Switching heavy currents gives rise to EMI and electrical noise.

Series Regulator (Linear) - Less complex but more lossy - requiring a heat sink to
dissipate the heat in the series, voltage dropping transistor which takes up the
difference between the supply and the output voltage. All the load current passes
through the regulating transistor which consequently must be a high power device.
Because there is no switching, it delivers pure DC and doesn't need an output filter. For
the same reason, the design doesn't suffer from the problem of radiated and conducted
emissions and electrical noise. This makes it suitable for low noise wireless and radio
applications.

With fewer components they are also smaller.

o Shunt Regulator - Shunt regulators are common in photovoltaic (PV) systems since
they are relatively cheap to build and simple to design. The charging current is controlled
by a switch or transistor connected in parallel with the photovoltaic panel and the storage
battery. Overcharging of the battery is prevented by shorting (shunting) the PV output
through the transistor when the voltage reaches a predetermined limit. If the battery
voltage exceeds the PV supply voltage the shunt will also protect the PV panel from
damage due to reverse voltage by discharging the battery through the shunt. Series
regulators usually have better control and charge characteristics.

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

o Converter. They have high efficiency and low heat losses. They can handle high output
currents and generate less RF interference than a conventional switch mode regulator. A
simple transformerless design with low switch stress and a small output filter.

o Pulsed Charger. Uses a series transistor which can also be switched. With low battery
voltages the transistor remains on and conducts the source current directly to the battery. As
the battery voltage approaches the desired regulation voltage the series transistor pulses the
input current to maintain the desired voltage. Because it acts as a switch mode supply for part
of the cycle it dissipates less heat and because it acts as a linear supply part of the time the
output filters can be smaller. Pulsing allows the battery time to stabilize (recover) with low
increments of charge at progressively high charge levels during charging. During rest periods
the polarization of the cell is lowered. This process permits faster charging than possible with
one prolonged high level charge which could damage the battery since it does not permit
gradual stabilization of the active chemicals during charging. Pulse chargers usually need
current limiting on the input source for safety reasons, adding to the cost.

o Inductive charging - Inductive charging does not refer to the charging process of the battery itself.
It refers to the design of the charger. Essentially the input side of charger, the part connected to the AC
mains power, is constructed from a transformer which is split into two parts. The primary winding of the
transformer is housed in a unit connected to the AC mains supply, while the secondary winding of the
transformer is housed in the same sealed unit which contains the battery, along with the rest of the
conventional charger electronics. This allows the battery to be charged without a physical connection to
the mains and without exposing any contacts which could cause an electric shock to the user.

A low power example is the electric toothbrush. The toothbrush and the charging base
form the two-part transformer, with the primary induction coil contained in the base and the
secondary induction coil and the electronics contained in the toothbrush. When the
toothbrush is placed into the base, the complete transformer is created and the induced
current in the secondary coil charges the battery. In use, the appliance is completely
separated from the mains power and since the battery unit is contained in a sealed
compartment the toothbrush can be safely immersed in water.

The technique is also used to charge medical battery implants.

A high power example is a charging system used for EVs. Similar to the toothbrush in
concept but on a larger scale, it is also a non-contact system. An induction coil in the
electric vehicle picks up current from an induction coil in the floor of the garage and
charges the vehicle overnight. To optimize system efficiency, the air gap between the
static coil and the pickup coil can be reduced by lowering the pickup coil during charging
and the vehicle must be precisely placed over the charging unit.

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

A similar system has been used for electric buses which pick up current from induction
coils embedded beneath each bus stop thus enabling the range of the bus to be extended
or conversely, smaller batteries can be specified for the same itinerary. One other
advantage of this system is that if the battery charge is constantly topped up, the depth of
discharge can be minimized and this leads to a longer cycle life. As shown in the section
on Battery Life, the cycle life increases exponentially as the depth of discharge is reduced.

Charger Power Sources

When specifying a charger it is also necessary to specify the source from which the
charger derives its power, its availability and its voltage and power range. Efficiency
losses in the charger should also be taken into account, particularly for high power
chargers where the magnitude of the losses can be significant. Some examples are
given below.

Controlled Charging

Easy to accommodate and manage.

AC Mains

Many portable low power chargers for small electrical appliances such as computers
and mobile phones are required to operate in international markets. They therefore
have auto sensing of the mains voltage and in special cases the mains frequency with
automatic switching to the appropriate input circuit.

Higher power applications may need special arrangements. Single phase mains power
is typically limited to about 3 KW. Three phase power may be required for charging
high capacity batteries (over 20 KWh capacity) such as those used in electric vehicles
which may require charging rates of greater than 3 KW to achieve reasonable charging
times.

Regulated DC Battery Supply

May be provided by special purpose installations such as mobile generating equipment
for custom applications.

Special Chargers

Portable sources such as solar panels.

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

Opportunity Charging

Opportunity charging is charging the battery whenever power is available or between partial
discharges rather than waiting for the battery to be completely discharged. It is used with
batteries in cycle service, and in applications when energy is available only intermittently.

It can be subject to wide variations in energy availability and wide variations in power levels.
Special control electronics are needed to protect the battery from overvoltage. By avoiding
complete discharge of the battery, cycle life can be increased.

Availability affects the battery specification as well as the charger.

Typical applications are:-

Onboard vehicle chargers (Alternators, Regenerative braking)
Inductive chargers (on vehicle route stopping points)
Solar power
Wind power

Mechanical charging

This is only applicable to specific cell chemistries. It is nor a charger technology in the
normal sense of the word. Mechanical charging is used in some high power batteries such
as Flow Batteries and Zinc Air batteries. Zinc air batteries are recharged by replacing the
zinc electrodes. Flow batteries can be recharged by replacing the electrolyte.

Mechanical charging can be carried out in minutes. This is much quicker than the the long
charging time associated with the conventional reversible cell electrochemistry which could
take several hours. Zinc air batteries have therefore been used to power electric buses to
overcome the problem of excessive charging times.

Charger Performance

The battery type and the application in which it is used set performance requirements which
the charger must meet.

Output Voltage Purity

The charger should deliver a clean regulated voltage output with tight limits on spikes, ripple,
noise and radio frequency interference (RFI) all of which could cause problems for the battery
or the circuits in which it is used.

For high power applications, the charging performance may be limited by the design of the
charger.

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Information Sheet 5.1.1: Electrical safety in Charging Automotive Battery

Efficiency

When charging high power batteries, the energy loss in the charger can add
significantly to the charging times and to the operating costs of the application. Typical
charger efficiencies are around 90%, hence the need for efficient designs.

Inrush Current

When a charger is initially switched on to an empty battery the inrush current could be
considerably higher than the maximum specified charging current. The charger must
therefore be dimensioned either to deliver or limit this current pulse.

Power Factor

This could also be an important consideration for high power chargers.

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Worksheet 5.1.2: Apply Electrical Safety in Charging Battery

Learning outcomes:

5 Remove Automotive battery

Learning Activity:

5.2 Test on Apply Electrical Safety in Removing Battery

Select / determine the correct answer given below;

1. To detect the reconstitution of the active chemical is complete and to stop the charging
process before any damage is done.
a. Termination charging
b. Safe charging
c. Termination voltage
d. Charging voltage

2. A process in which the materials transformed in the charges transfer process are moved
on from the electrode surfaces.
a. charge transfer
b. mass transport or dilution
c. intercalation process
d. charging process

3. It is the actual chemical reaction taking place at the interface of the electrode with the
electrolyte.
a. charge transfer
b. mass transport
c. charging times
d. termination process

4. A DC power supply which in its simplest form may consist of a step down transformer
from the main with a rectifier to provide the DC voltage to charge the battery
a. constant voltage
b. constant current
c. taper current
d. pulsed charged

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Worksheet 5.1.2: Apply Electrical Safety in Charging Battery

5. It varies the voltage applied to the battery to maintain a constant current flow, switching
off when the voltage reaches the level of a full charge.
a. a. constant voltage
b. constant current
c. taper current
d. pulsed charged

6. Charging from a crude unregulated constant voltage source.
a. constant voltage
b. constant current
c. taper current
d. pulsed charged

7. Feed the charger current to the battery in pulses. The charging rating can be precisely
controlled by varying the width of the pulses.
a. a. constant voltage
b. constant current
c. taper current
d. pulsed charged

8. Uses pulse width modulation to control the voltage.
a. series regulator
b. shunt regulator
c. buck regulator
d. switch mode regulator

9. A switching regulator which incorporates a step down DC-AC converter.
a. shunt regulator
b. buck regulator
c. pulsed regulator
d. inductive charging

10. Common in photovoltaic (PV) system since they are relatively cheap to build and simple
to design.
a. shunt regulator
b. buck regulator
c. pulsed regulator
d. inductive charging

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Worksheet 5.1.2: Apply Electrical Safety in Charging Battery

ANSWER KEY

1. C
2. B
3. A
4. A
5. B
6. C
7. D
8. D
9. B
10. C

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Information Sheet 6.1.1: Charging Automotive Battery

Learning outcomes:
6 Charge automotive battery

Learning Activity:
6.1 Charging Automotive Battery

Battery Charging

BATTERY BATTERY CHARGER

Two methods of charging the Battery

1. Slow charging – the battery is given a charge of a few amperes of several hours.

2. Quick or fast charge- a 30 amp charging rate up to 30 minutes.

For further charging reduce the charging rate to 20 amp or less for up to 3 hours longer.
Change a maintenance free battery until the green dot appears. To connect the charger to a
side terminal battery, it may be necessary to install bolts or adapters in the terminal bolt holes.
When charging a battery in a vehicle, disconnect the ground cable from the battery. This
protects electrical and electronic components from the high charging voltage.

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Information Sheet 6.1.1: Charging Automotive Battery

BE CAREFUL: Never connect the battery charge backward. The reverse polarity may
cause high current flow which would damage the vehicle electrical equipment.

WARNING:

Quick or fast charging the battery requires to monitored at all times and the
charging time must be controlled. Do not fast charge a battery longer than two
hours. Excessive fast charging can damage the battery. Do not allow the voltage of
a 12 volts battery exceed 15.5 volts. Also, do not allow temperature to rise above
125 F.

CHARGE RATE:

The charge rate required to recharge a battery depends on several factors:
1. Battery Capacity, High capacity batteries require longer charging time.
2. State of Charge
3. Battery Temperature
4. Battery Condition

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Worksheet 6.1.2: Determine the Procedure in charging Automotive Battery

Learning outcomes:

6. Charging Automotive battery

Learning Activity:

6.1 Test on Charging Automotive Battery

Select / determine the correct answer given below;

1. A method of charging in which the battery is given a charge of a few amperes for several
hours.
a. slow charge
b. fast charge
c. never charge
d. both a and b

2. For further charging reduce the charging rate to.
a. 20 amp or less for up to 3 hrs.
b. 30 amp or more.
c. 40 amp or less
d. Both a and b

3. A method of charging a battery, a charging rate given 30 amp up to 30 minutes.
a. quick or fast charge
b. slow charge
c. both a and b
d. none of the above

4. When charging a battery in a vehicle,
a. disconnect the negative cable first
b. disconnect the positive cable first
c. disconnect together both positive and negative cables
d. none of the above

5. In slow charging, the battery is given a charge of few amperes in several,
a. days
b. month
c. minutes
d. hours

6. If the battery charger terminal is connected backward or reverse, the result is:
a. high current flow
b. damage to the battery
c. damage to battery charger
d. all of the above

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Worksheet 6.1.2: Determine the Procedure in charging Automotive Battery

7. A typical fast charging is 30 amps charging rate up to
a. 30 hours
b. 30 seconds
c. 30 minutes
d. 30 days

8. Two methods of charging battery:
a. slow and fast current
b. quick and slow charging rate
c. slow and fast charge
d. all of the above

9. The purpose of disconnecting the ground cable from the battery during charging is to
protect the,
a. driver
b. battery
c. electrical and electronics components
d. battery charger

10. Excessive quick charging can damage the,
a. battery
b. charger
c. electrical components
d. all of the above

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Worksheet 6.1.2: Determine the Procedure in charging Automotive Battery

*ANSWERS KEY:

1. A
2. A
3. A
4. A
5. D
6. D
7. C
8. C
9. C
10. A

.

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Job Sheet 6.1.4 Determine the Procedure in Charging the Battery

Learning outcomes:
6 Test Automotive Battery
Learning Activity:
6.1. Determine/Perform procedure in charging automotive battery.

Charging a battery

The objective of this procedure is to show you how to correctly charge a battery using
battery charging equipment. Before charging a battery always carry out a visual
inspection of the battery to ensure there are no cracks or holes in the casing.
Part 1. Preparation and safety
Objective
 Correctly charge a battery using battery charging equipment.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and
equipment that is appropriate for the task and which conforms to your local safety regulations
and policies. Among other items, this may include:

 Work clothing - such as coveralls and steel-capped footwear
 Eye protection - such as safety glasses and face masks
 Ear protection - such as earmuffs and earplugs
 Hand protection - such as rubber gloves and barrier cream
 Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

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Job Sheet 6.1.4 Determine the Procedure in Charging the Battery

Safety check

 Make all connections between the battery charger and the battery to be charged
before connecting to the power supply or turning “ON” any switches.

 Never try to charge a 'frozen' battery.
 Make sure that the voltage used to charge the system never exceeds the system

design while charging. For instance if you connect two 12 volt batteries in 'series'
for charging you should use the 24 volt setting on the charger, however if you
connect the same two batteries in 'parallel' you should only use the 12 volt
setting on the charger.
 Never allow a spark or flame to get near the battery.
 Always use the markings on the battery to determine the positive and negative
terminals. Never simply use the colour of the cables to determine the positive or
negative terminals.
 Make sure that you understand and observe all legislative and personal safety
procedures when carrying out the following tasks. If you are unsure of what these
are, ask your supervisor.

Points to note

 Slow charging a battery is less stressful on a battery than fast charging is.
 Always remove the negative battery terminal while changing a battery to reduce

risk to the vehicle, especially with today’s electronically intensive cars. Use a
'memory minder' to retain electronic settings.
 After charging the battery and reinstalling it, always clean the battery terminals
and posts.

Part 2: Step-by-step instruction

1. Inspect the battery
Carry out a visual inspection of the battery to ensure there are no cracks or holes
in the casing.

2. Connect the charger
Check the charger is unplugged from the wall and turned off. Connect the red
lead from the charger to the positive battery terminal. Connect the black lead
from the charger to the negative battery terminal. Turn the charger on. Check the
charger amperage output to ensure the battery is charging correctly. A slow
charger usually charges at a rate of less than 5 amperes. A fast charger charges
at a much higher ampere rate depending on the original battery state of charge
and should only be carried out under constant supervision.

3. Disconnect the charger
Once the battery is charged turn the charger off. Disconnect the black lead from
the negative battery terminal, and the red lead from the positive battery terminal.

4. Test the battery
Allow the battery to stand for at least 5 minutes before testing the battery. Using
a load tester or hydrometer, test the charged state of the battery.

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Information Sheet 7.1.1 Testing Functionality of Battery

Learning outcomes:
7 Check Functionality of battery

Learning Activity:
7.1 Test the Functionality of Battery

Car Battery Testing

The only ways to gauge a battery’s performance is to test the voltage output it is offering. The
Output voltage levels that is provides with and without load can give you an idea of battery
health.

So to test a car battery, yourself with a voltmeter and set the dials on the 0-50 V range.
Disconnect the battery from the car connections by following the details in the car manual to
the word. While doing so attach a 9V alkaline battery to the car PCM as otherwise it loses its
programmed settings.

Connect positive red lead of voltmeter to positive of battery terminal and the black lead to the
negative terminal. Check the voltage level. If in the range of 12.6 to 12.8, your battery is doing
well and adequately charged. Anything below that is like 10 V or lower means it is in need of
charging.

Now reconnect the battery and start the car. Keep in idling mode and check the voltage
reading between the same point again. If is around 10V, then the battery is okay. Anything
below 10 V means that either the car battery needs charging, or some other problems are
causing the voltage decline.

Next thing to check is the fluid level in the battery. To do this you must disconnect the battery
again of course. Open up the battery cover and peep into the compartments of cells inside.
The electrode plates should be submerged in the electrolytic fluid. If the are not, you must add
distilled water to the cell compartment only until the fluid level rises about a one fourth of an
inch above the plate. Another reason causing low battery charging may be, due to car
alternator problems. Get it checked with a mechanic as soon as possible.

Thus, you can check and test your car battery with ease, armed with just an humble voltmeter
and a discerning mind! Dealing with your car problem, on your own, is a satisfying experience.
(see Figure 1.)

.

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Information Sheet 7.1.1 Testing Functionality of Battery

Fig. 1

Voltmeter

voltmeter instrument used to measure differences of electric potential , commonly
called voltage, in volts or units that are multiples or fractions of volts. A voltmeter is
usually combined with an ammeter and an ohmmeter in a multipurpose instrument.
Most voltmeters are based on the d'Arsonval galvanometer and are of the analog type,
i.e., they give voltage readings that can vary over a continuous range as indicated by a
scale and pointer. However, digital voltmeters, which provide voltage readings that are
composed of a group of digits, are becoming increasingly common. Since an
oscilloscope is capable of giving a calibrated visual indication of voltage, it can be called
a voltmeter.

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Worksheet 7.1.2: Testing the functionality of Battery

Learning outcomes:

7. Test Functionality of Automotive battery

Learning Activity:

7.1 Test on Functionality of Automotive Battery

Select / determine the correct answer given below;

1. The only way to gauge a battery performance is to test the.
a. Voltage input
b. Voltage output
c. Voltage level
d. Both a and

2. Which of the following instrument is used to test the battery voltage?
a. Voltmeter
b. Multi tester
c. Ammeter
d. Both a and b

3. During voltage test in the battery, if the reading in the voltmeter range is 12.6 to 12.8 v,
your battery is
a. doing bad
b. doing well
c. inadequate charge
d. all of the above

4. While doing testing of battery voltage output, attach the 9v alkaline battery to the
a. car PCM
b. car radio
c. car wheel
d. none of the above

5. If the reading in the voltmeter during battery voltage test is below 10v or lower, this means
that the battery need to
a. Charge
b. Discard
c. Replace
d. None of the above

6. A voltmeter is usually combined with
a. ammeter
b. ohmmeter
c. tachometer
d. both a and b

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Worksheet 7.1.2: Testing the functionality of Battery

7. Most voltmeters are based on the galvanometer and are of the
a. analog type
b. digital type
c. pressure type

8. The output voltage level, with and without load, can give an idea of battery
a. Power
b. Condition
c. Health
d. All of the above

9. If the reading in the voltmeter is below10 v, this means that either the battery need
charging, or some other problems are causing the,
a. Voltage decline
b. Voltage higher
c. Both a and b
d. None of the above

10. The first step in testing the battery voltage by the use of voltmeter is to
a. set the dial on the 0-50 range
b. connect the red lead of voltmeter to the positive battery terminal
c. add first the electrolyte
d. none of the above

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 2

Worksheet 7.1.2: Testing the functionality of Battery

*ANSWERS KEY:

1. B
2. D
3. B
4. A
5. A
6. D
7. A
8. D
9. A
10. A

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 7.1.3 Determine the Procedure in Testing the Functionality of Battery
Learning outcomes:
7 Check Functionality of Automotive Battery
Learning Activity:
7.1 Check electrolytic level of automotive battery.

Steps in checking electrolytic level of automotive battery using Hydrometer:

Figure: Test / Check electrolytic level of automotive battery

SPECIFIC GRAVITY TEST PROCEDURE (HYDROMETER)

 1. Wear suitable eye protection.
 2. Remove vent caps or covers from the battery cells.
 3. Squeeze the hydrometer bulb and insert the pickup tube into the cell closest to

the battery's positive (+) terminal.
 4. Slowly release the bulb to draw in only enough electrolyte to cause the float to

rise. Do not remove the tube from the cell.
 5. Read the specific gravity indicated on the float. Be sure the float is drifting free,

not in contact with the sides of top of the barrel. Bend down to read the
hydrometer at eye level. Disregard the slight curvature of liquid on the float.
 6. Record your readings and repeat the procedure for the remaining cells.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 7.1.3 Determine the Procedure in Testing the Functionality of Battery

Note: Hydrometer Measurements

When you measure the specific gravity (weight) of each cell, they must all
be within 50% of each other

1.28 Cell 1
1.26 Cell 2
1.24 Cell 3
1.22 Cell 4
Cell 5
1.2 Cell 6
1.18
1.16
1.14
1.12

1.1
1.08

Level

Given the above measurements, write down the specific gravity for each cell on
the table below and put your recommendation;

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 2

Job Sheet 7.1.3 Determine the Procedure in Testing the Functionality of Battery

No. of cells Scale Reading Dead Recharge Good
CELL 1
CELL 2
CELL 3
CELL 4
CELL 5
CELL 6

Average

Note: Specific gravity for each cell should be at least 50% for each other:
Overall recommendations: ____________________________________

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 3

Information Sheet 8.1.1 Replacing Battery

Learning outcomes:
8 Replace Battery

Learning Activity:
8.1 Replacing Battery

Replace Automotive Battery

While most new batteries last around five years, factors including climate, over or
undercharging, etc. can impact on the life of the battery. In most cases, if a battery is over four
or five years old. It should be replace. Auto mechanics and service facilities will install batteries
but it can be done by the car owner quickly and less expensively. The procedure itself is fairly
simple if certain details and safety rules are followed.

First, make sure that the battery purchased is the one made to fit the particular type of car. The
same type that is already in use may be adequate or another powerful or expensive battery
may be desired. However, do not exceed the voltage requirements for the car. Consult the
automobile owner’s manual for the specification or get assistance from the personnel at a
reputable auto parts store. (see Figure 1.)

Figure 1.

Make sure that proper safety measure are taken when installing a battery, since serious acid
burns to eyes and hands are possible. Use safety glasses and plastic glove to protect eyes
and hands. After installing the battery, discard the gloves.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page # 1
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Information Sheet 8.1.1 Replacing Battery

Disconnect the negative battery cable, then the positive cable. Remove the metal clamp
that holds the battery in the battery tray. If rust is found in the bottom of the tray, wash
plain water and let dry before installing the battery. After drying, put the new battery into
the tray and attach the metal clamps to secure the battery. These metal clamps should
also be checked for rust or corrosion.

Before re-attaching the battery cables, make sure that the insides of the cable
connectors are free from rust or corrosion. If present, use a thick paste of household
baking soda and water to scrub the insides of the cable ends. This same paste can be
used to clean the metal battery clamp. A small wire brush for scrubbing off this
corrosion may be obtained from an auto parts store. Then spray with WD-40. Spray
cable ends with WD-40 once every six months to guard against corrosion.

Make sure that cable wires are not frayed to insure a safe connection. Re-attach
positive and then negative cables to posts and tighten until firm but not over tight.

.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page # 2
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Worksheet 8.1.2 Replacing Battery

Learning outcomes:
8 Test Functionality of Automotive Battery

Learning Activity:

8.1 Test on Replacing Automotive Battery

Select / determine the correct answer given below;

1. Which of the following personal protection device is used in installing battery?
a. Safety glasses
b. Plastic gloves
c. Apron
d. All of the above

2. When replacing automotive battery disconnect first the.
a. Positive cable
b. Metal clamp
c. Battery tray
d. Negative cable

3. If rust is found in the battery tray, wash it with
a. Plain water
b. Gasoline
c. crude
d. thinner

4. Spray the ends of the battery metal clamp or cable ends with WD-40 once every
a. 2 months
b. 6 months
c. 3 months
d. Once a month

5. The WD-40 is used to guard against
a. Moisture
b. Dirt
c. Corrosion
d. Both a and b

6. Safety precaution is very important, when replacing the battery
a. to avoid accident
b. to avoid electric shock
c. to avoid damage to car parts
d. all of the above

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Worksheet 8.1.2 Replacing Battery

7. Safety eye glasses are used to
a. Protect your eyes
b. Protect your hands
c. Protect your body
d. None of the above

8. After installing the battery, the gloves that you used will be
a. Kept in your cabinet
b. Kept in your table
c. Discarded
d. All of the above

9. Before re-attaching the battery cables, make sure that the inside connectors are free
from
a. Corrosion
b. Rust
c. Moisture
d. Both a and b

10. When re-attaching the positive and negative cables of the battery post, tighten the bolts
until firm but
a. Not loose
b. Not over loose
c. Not over tight
d. Both a and b

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Worksheet 8.1.2 Replacing Battery

*ANSWERS KEY

1. D
2. D
3. A
4. B
5. C
6. D
7. A
8. C
9. D
10. C

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 3

Job Sheet 8.1.3 Determine the Procedure in Replacing the Battery

Learning outcomes:
8 Replace Automotive Battery
Learning Activity:
8.1. Procedure in replacing automotive battery.

Here is the procedure:

1. With the engine off, pop the hood and find
the battery. Detach the negative (black)
battery cable from the battery. First loosen
the nut with a combination wrench. A
better tool to use would be battery pliers or
a battery wrench.

2. Twist and pull up on the end of the cable
with your hand. If it does not come off
easily you may want to purchase a battery
terminal puller from your local auto parts
store. This will help prevent damage to
your battery or cables. It is not
recommended to use a screwdriver as a
pry-bar, this could break off your battery
terminal or cause other damage.

3. Detach the positive (red) battery cable
from the battery using the same method.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 1

Job Sheet 8.1.3 Determine the Procedure in Replacing the Battery

4. Using a combination wrench or a socket
and ratchet, remove the battery hold-down
clamp.

5. Take the battery out of the battery tray.
Batteries are heavy, so grab from the
bottom using both hands. If the battery has
a handle, use that instead.

6. Use baking soda mixed with water and a
wire brush to clean any corrosion from the
battery tray and the hold-down clam

7. Clean the battery cable connectors with a
wire brush. To remove heavy corrosion
from the connectors, use battery-cleaning
solution (available at any auto-parts store).

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 8.1.3 Determine the Procedure in Replacing the Battery

8. Place the new battery in the battery hold-
down tray and secure the battery with the
hold-down clamp. Spray both terminal
ends with anti-corrosion solution (optional).
Attach and tighten the positive battery
cable. Attach and tighten the negative
battery cable. Check that all cable
connectors are tight. If you can move them
at all, your car may not start.

Tips & Warnings
 Battery acid is extremely corrosive. Don't let it splash out. Take care not to spill any on your

hands, body or clothing, or on car paint.
 The old battery cannot go into the regular trash. Take it to a facility that accepts hazardous

material for recycling. You can also return the used battery to the auto-parts store where
you bought the new one.
 Make sure you're connecting the wires to the right battery terminal otherwise you can cause
damage to your vehicle.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 3

Information Sheet 9.1.1: Jump Start the Battery

Learning outcomes:
9 Jump Starting

Learning Activity:
9.1 Jump Starting Battery

Jump Starting a Car with a Dead Battery

When you are preparing to jump start a car, position the vehicles for an easy stretch of your
jumper cables. Be sure the cables attach securely to the battery post.

It’s easy to jump start if you have a dead battery. Batteries go dead for all sorts of reason, but
usually it’s your fault. This is a good thing, because that means a simple jump start will get you
back on the road with no permanent damage.

What You’ll Need:
1. Another car, running
2. Jumper cables
3. Safety glasses
4. Wire brush (optional for cleaning connections)

You’ll need to park the running car next to the dead car in such a way that the jumper cables
can reach both batteries. If you aren’t sure where the batteries are under each hood, take a
peek* before you park. (see Figure 1. below)

Figure 1.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page # 1
ALT723303 September 19, 2010 0

Information Sheet 9.1.1: Jump Start the Battery

Important TIP:

 *Never drive with your hood raised. Not only do you have no visibility, you could
damage your hood compartments or the hood itself.

 *You might be tempted to attach it to the”-“ side of the dead battery, but this isn’t
recommended. In the old days, batteries leaked small amounts of acid, which
would turn into flammable gas around the battery. This gas could explode if the
cable caused a spark just above the battery.

 *I have seen some people clamp the negative cable onto the rubber cable
covering of the positive side while they walk across to the other car. This is a NO
NO.IF one of those sharp teeth were to first pierce the rubber cover and reach
the wires inside, you could do serious electrical damage to one or both vehicles!

Starting the Car With the Dead Battery

Now that you’re all set up, it’s time to turn some keys. First the car with the good battery,
and leave it running. If the battery in the dead was really badly drained, it may help to
leave them connected for a minute with the good car running before you try to start the
dead car. This will allow a little charge to build up in the dead battery.

Turn key in the dead car to start and it should fire right up! As long as you don’t have any
issues with your alternator, you can disconnect the jumper cables right away.

Disconnecting the Jumper Cables:
Disconnecting the jumper cables doesn’t need to happen in any specific order, but be sure
you don’t let the red and black cables touch each other at the end when they are still
connected to one battery.

Important TIPS:
*f you want to be sure, you can disconnect the black (negative) cables first, then go

back and disconnect the red. Remember, the red (positive) cables are the ones that can
cause a short of they touch the car while they are connected to the battery

*If the dead car doesn’t turn over or turns over very slowly, check to see if your battery
or connections are corroded. If they are, sometimes a little wiggling while the cable clamp
is connected will make your connection better. Otherwise, it might be a good time to clean
your battery connections.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page # 2
ALT723303 September 19, 2010 0

Worksheet 9.1.2 Jump Start Automotive Battery

Learning outcomes:
9 Testing Functionability of Batery
Learning Activity:
9.1.2 Test on Jump Starting Battery

Select the correct answer listed below.

1. The following are the purposes of jump starting EXCEPT one.

a. to charge the dead battery
b. to go back on the road with no permanent damge.
c. to start the engine
d. to charge the alternator

2. The small amount of acid leak from the battery could turn into:

a. flammable gas
b. atmospheric pressure
c. flammable liquid
d. both a and b

3. When jump starting, start the car with a good battery.

a. leave it running for minutes
b. remove after starting
c. remain permanent
d. all of the above

4. Which of the following is important tip in disconnecting jumper cable.

a. disconnect the battery first
b. disconnect positive cable first
c. disconnect the negative cable first
d. all of the above

5. If the battery doesn’t turn the engine over or turn over very slowly, check the.

a. electrolyte level
b. battery connection
c. battery cell
d. starting motor

6. A simple jump start will get you go back on the road with no

a. Permanent damage
b. Permanent charge
c. Permanent power
d. Both a and b

7. The following are the materials used for jump starting EXCEPT one

a. Good battery
b. Jumper cables
c. Safety glasses
d. Electrolyte

8. After starting the car leave them connected for a minutes, this will allow a little charge
build up in the,

a. Dead battery
b. Good battery
c. Damage battery
d. All of the above

9. If the positive and negative cables are not properly disconnected, this can cause

a. Short circuit
b. Open circuit
c. Ground circuit
d. All of the above

10. Do not allow the red and black cables to touch each other, when they are still

a. Connected
b. Disconnected
c. Both a and b

Worksheet 9.1.2 Discuss the Procedure on how to Jump Start the Battery

*ANSWER KEY
1. D
2. A
3. A
4. C
5. B
6. A
7. D
8. A
9. D
10. A

Job Sheet 9.1.3 Discuss the Procedure on how to Jump

Learning outcomes:
9 Check Functionality of Automotive Battery
Learning Activity:
9.1. Jump Starting Procedure

Procedure in Jump Starting Battery;

Warning: Jump-starting a car can cause serious injury if you are not careful. If you are
unsure of what you are doing at any point, do not attempt to jump-start your car. Call
your friendly roadside towing service for help instead.

STEP 1: Read your owner's manual. Some
manufacturers do not allow jump-starts, and
some have fuses that need to be removed
before jump-starting, or other steps that
need to be taken before you can
successfully jump-start the car.

A number of manufacturers place the car
battery in a location other than the engine
compartment. In this case, your car will have
designated jump start terminals under the
hood. If you are uncertain what to look for,
always check your owner's manual!

STEP 2: Make sure the dead car and the
good car are not touching. They should be

close enough, however, so your jumper
cables can reach easily from battery to
battery.

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 9.1.3 Discuss the Procedure on how to Jump

STEP 3: Turn the ignition key in both cars to
the "off" position.

STEP 4: Put on eye-protection glasses.

STEP 5: Identify battery terminals or jump
start terminals, if your battery is not in the
engine compartment

POSITIVE HAS A PLUS SIGN (+)
NEGATIVE HAS A MINUS SIGN (-)

STEP 6: Lay the jumper cables on the
ground, making sure that the red and black

clamps aren’t touching each other. Be sure
to use cables that are SAE approved

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 2

Job Sheet 9.1.3 Discuss the Procedure on how to Jump

STEP 7: Connect a red (positive) cable to the
dead car's positive battery post or positive
jump start terminal

STEP 8: Connect the other end of the red
(positive) cable to the live car's positive
battery post

STEP 9: Connect one end of the black
(negative) cable to the live car's negative
battery post. Do not connect the other end of
the negative cable to the dead car's battery
post.

STEP 10: Locate an unpainted metal part of
the dead car's engine, away from the battery.
The engine manifold is a good location. You
can also use the air conditioner compressor
bracket or the alternator bracket (the bracket
is the piece of metal to which the compressor
or alternator is attached), but be careful to
avoid moving parts, such as belts

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 9.1.3 Discuss the Procedure on how to Jump

STEP 11: Connect the unused end of the
black (negative) cable to this location.

STEP 12: Start the good car's engine.

STEP 13: Start the dead car's engine. If it
doesn’t crank, wait for two or three minutes
and try again.

STEP 14: If it still doesn’t crank, you probably
have a bad connection somewhere. If the
dead car's engine fails to crank, turn off the
engine of the good car. Disconnect the
negative clamp on the dead car’s engine to
avoid sparks near the battery, then jiggle the
other three clamps to be sure they’re making
good contact with the battery terminals.
Reconnect the fourth clamp

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Sept. 19,2010 4

Job Sheet 9.1.3 Discuss the Procedure on how to Jump

STEP 15: Again, refer to your owner's
manual. As soon as the dead car starts, you
can disconnect the cables. Generally, you
should take jumper cables off in the reverse
orde that you placed them, as described
below, however, some owner's manuals
recommend a different procedure. If this is
the case with your car, do not follow the
instructions below; refer instead to your
owner's manual from this point forward.

STEP 16: Disconnect the black (negative)
cable connected to dead car's engine. be
careful not to drop this end

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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Job Sheet 9.1.3 Discuss the Procedure on how to Jump

STEP 17: Disconnect the black (negative)
cable from the negative terminal of the good
car's battery

STEP 18: Disconnect the red (positive)
cable from the positive terminal of the good
car's battery

STEP 19: Disconnect the red (positive)
cable from the positive terminal of the dead
car's battery

Code No. Servicing Automotive Battery Date: Developed Date: Revised Page #
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