Transcript Battery Testing & Service Chapter Battery Testing & Service  Objective: After studying this chapter, you will be able to summarize the most common methods.

Battery Testing & Service
Chapter
30
Battery Testing & Service
 Objective: After
studying this chapter,
you will be able to summarize the most
common methods for testing and
servicing batteries.
Battery Maintenance
The five (5) primary steps in maintaining an
automotive battery are:
 Checking the electrolyte level
 Cleaning the battery terminal connections
 Cleaning the battery top
 Checking the battery hold down and tray
 Inspecting for physical damage to the case
and terminals
Battery Maintenance
 Safety
Glasses must be worn at all times
Battery Maintenance
 The
best solution to correctly wash an
automobile battery is baking soda and
water.
Battery Maintenance
 A battery-terminal
test
1. Hold (-) lead to cable near clamp
2. Hold (+) lead to negative battery post
3. Disable ignition or injection system
4. Crank engine while watching voltmeter
Battery Maintenance
 A battery-terminal
test RESULTS
Voltmeter shows over .5 volts = FAIL
Means high resistance is present at cable
connection and cable end needs cleaning
or replacement.
Voltmeter shows less than .5 volts = PASS
Battery Maintenance
 Preventing Terminal
Corrosion
Coat the connection with petroleum jelly or
white grease, this will help prevent
corrosion from battery gasses.
Battery Maintenance
The automotive memory saver is designed to
maintain the memory of your on-board
vehicle computer when your battery is
disconnected.
Not to mention
the radio stations
and clock!
Battery Maintenance
 If
the cells of a
maintenance-type
battery are low, the
correct refill liquid is
distilled water.
Battery Safety
 Hydrogen
gas is both colorless and
odorless, but it is also extremely
flammable and explosive!
Battery Testing

The density of a liquid can be checked by
using a Hydrometer or Specific Gravity Tester.
Specific Gravity indicates the state of charge of the battery
Battery Testing
 A battery
with a
specific gravity
of 1.265 has a
higher state of
charge than a
battery with a
specific gravity
of 1.250
Battery Testing

the battery’s condition is defective if the hydrometer
readings vary 25 or more points between cells
Battery Testing


Battery Voltage Test
To check the open-circuit
voltage of your battery, first
disconnect the battery cables
so that no power is coming in
or going out. Set your
multimeter to read “DC volts”
(for meters without auto
ranging, set the scale to 20
volts), and touch the red
(positive) probe to the positive
battery terminal and the black
(negative) probe to the
negative terminal as shown
here.
Battery Testing
Percent Charge


Battery Voltage Test
100
RESULTS
90
80
70
60
50
40
30
20
10
0
11.80 12.00 12.20 12.40 12.60
Battery Testing

CELL VOLTAGE TEST.—
The cell voltage test
will let you know if the
battery is discharged or
defective. Like a hydrometer
cell test, if the voltage
reading on one or more cells is
.2 volts or more lower than the
other cells, the battery must be
replaced.
Battery Testing
battery drain test - looking for a parasitic drain.
 A parasitic drain is when an electrical device is
using battery power when the car is closed, and
the ignition key removed. Therefore, when doing
this test make sure that the dome light, under hood
light, trunk light, etc. are off. This normally is less
than 25-50 milliamps. More than that indicates a
battery drain problem and should be repaired.

Battery Charging
 A battery
charger transforms AC voltage
into DC voltage.
 It is NEVER safe to charge a frozen
battery because it WILL explode!
Battery Jump Starting




STEP 1: Connect one end of the Positive(+) cable to
the Positive(+) post of the dead battery.
STEP 2: Connect the other end of the Positive(+)
cable to the Positive(+) post of the good battery.
STEP 3: Connect one end of the Negative(-) cable to
the Negative(-) post of the good battery.
STEP 4: Connect the other end of the Negative(-)
cable to a good solid SHINY, NON PAINTED metal
part of the engine on the dead car. Usually a giant
shiny nut on the engine block will do. A painted, dirty,
or oily nut will not work. You usually want to avoid
placing the Negative(-) cable directly on the dead
battery to minimize the chance for explosions. You
should only use the ground post on the dead battery
as a last resort. On this step you'll get a normal spark
as you connect the ground and complete the circuit.
NOW START THE DEAD VEHICLE!
Battery Jump Starting
 Remove
cables in reverse order
CAUTION!
 If
polarity is reversed when attaching
jumper cables, serious damage to
the charging or computer systems
can occur to either vehicle. Watch
what you are doing!
Battery Jump Starting
A portable battery-pack is a safer and easier
method to jump-starting a vehicle if the directions
are closely followed.
 Failure to follow directions can cause the
same consequences as incorrect jump
starting, such as explosion or damage to
onboard computer systems.

Battery Load Test






A battery load test checks the battery under full current
load.
Most modern load testers have inductive type ammeter
connection leads.
During load testing, the automatic testers subject the
battery to three times the battery’s amp-hour rating.
For Example: A 110 amp-hour battery would be loaded to
330 amps.
Modern battery’s use the S.A.E. rating of Cold-CrankingAmps
If a 12 volt automotive battery shows 9.6 volts or more
during load testing, the battery is in good condition.
More Battery Tests
A 3 minute quick test will determine if a
battery is defective and no longer serviceable.
 A three-minute battery charge test checks for
a sulfated battery. This battery test requires
charging the battery at 40 amps for three
minutes, then checking the voltage across the
terminals with the charger on. If the voltage is
above 15.5 volts, the battery is not accepting a
charge and should be replaced.

Other Battery Problems
 If
all the battery tests are good, some other
areas to inspect for charging system
problems are:
 Defective charging system
 Battery drain
 Loose alternator belt
 Corroded, loose, or defective battery cables
 Defective starting system
Battery Replacement

To remove a battery, first disconnect the
cables. Then loosen the battery hold-down.
Using a battery strap or battery carrier,
carefully lift the battery out of the vehicle.
Warning! Always wear Safety Glasses!
Selecting a Replacement Battery
 CCA rating
must be at least equal to OEM
 Size of battery should fit into its tray
 Hold down should secure battery in place
 Terminals should be in correct location and
of same design as original battery.
Questions?
 Refer
 Or
to chapter 30 in the Duffy text.
see on-line:
Car Battery Myths & Facts