December 2023 - 28

TOOL BRIEFING
Today's battery and
electrical system service
Understand the proper procedures and tooling to
repair automotive battery and electrical systems.
By Ross Colket, Contributing Editor
in order to perform an accurate test. I have
had the occasional battery that if you load
tested it, it would fail but it would pass the
conductance test. Those batteries have been
the exception rather than the rule though.
The next step is to check the charging
system for proper operation and voltage. As
part of my charging system testing, I will
typically turn on all the major loads in the
vehicle and see where the voltage rests. If I
do find a problem, I will begin by voltage
drop testing the charging system. This is
the fastest way to locate any type of issue
you may have in the charging circuit.
p Chrysler dashboard illustrating the technology involved in today's vehicles.
Photo from Mitchell 1
W
hen it comes to today's
vehicles, stable voltage
is incredibly important.
On modern vehicles, just dirty battery
terminals can cause drivability concerns.
They can cause odd things with the vehicle's
operation, from stalling just from
poor contact at the battery terminals to
communication issues and multiple trouble
codes. When it comes to looking for
this, a simple voltage drop test can be the
best test to perform to find these types of
problems. Due to the number of computers
utilized in today's vehicles, it is increasingly
important to ensure proper charging
system operation as well.
DIAGNOSING
ELECTRICAL CONCERNS
Now, when it comes to diagnosing an electrical
concern you should always start with a
complete battery and charging system test.
I am going to show my age in my next statement.
I started so long ago that I learned to
test batteries with carbon pile testers. They
would load test the battery and generate
quite a bit of heat as part of the test, hence
the nickname toaster. Today's battery testers
(Figure 1) are conductance-type testers and
do not load test the battery, instead, they
test the internal resistance of the battery.
The benefit of this type of tester is that the
battery does not have to be fully charged
28 PTEN DECEMBER 2023 www.VehicleServicePros.com
THE MODERN
VEHICLE'S BATTERY
More and more vehicles are installing the
battery in the trunk. The reason for this is
to maintain the temperature of the battery
more consistently. Being installed in the
trunk, the battery is not exposed to the high
underhood temperatures of the engine. But
in doing so, the batteries have become more
difficult to access and replace. Make sure to
consult the labor guide for proper testing
times on these applications.
Also, more and more vehicles are coming
from the factory with AGM-style batteries.
As you can see from Figure 2, the
battery doesn't look any different from
a normal flooded LED cell battery, but
don't let this similarity make you forget
to reset the battery life cycle in the PCM.
The purpose of doing this is to ensure the
proper charge rate for the new battery. An
aged AGM battery is going to have a more
aggressive charge rate to maintain the
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December 2023

Table of Contents for the Digital Edition of December 2023
