File in Section:
Bulletin No.:

Service Bulletin

Date:

06 - Engine
15-06-03-001B
April, 2016

INFORMATION
Subject:

Cold Weather and Long Stand Time Battery Maintenance and Testing Tips

Models:

2017 and Prior GM Passenger Cars and Trucks

Attention: This Bulletin also applies to any of the above models that may be Export vehicles.
This Bulletin has been revised to add 2017 Model Year and update the note for AGM charging
voltage and information for Manual Sections under Storage Tip. Please discard Corporate
Bulletin Number 15-06-03-001A.

The following diagnosis might be helpful if the vehicle
exhibits symptom(s), that include but not limited to, a
slow or no crank condition that may be caused by a
discharged battery.
Below is information that may be useful on diagnosing
batteries that have set for a long period of time and/or
set in cold weather climates and testing those batteries.

this condition is referred to as acid stratification (Figure
1). Since it is the concentration of the sulfuric acid that
lowers the electrolyte freeze point, the upper levels of
the acid (with low acid concentration) in this state can
begin freezing at or near 0°C (32°F).
Note: Stratification does not affect AGM type
batteries.

Effects of Long Stand Time

4052174
4052173

(1) = Normal Battery
(2) = Stratified Battery
Inside the battery, the electrolyte is generally composed
of 35% Sulfuric Acid and 65% water. When a lead acid
battery is inactive (not actively discharged and
charged), the acid, being heavier than water, will settle
toward the bottom. This leaves a low acid concentration
near the top, and higher concentration at the bottom,
Copyright 2016 General Motors LLC. All Rights Reserved.

(1) = Acid density is high.
(2) = Acid density is low.
(3) = Acid density is not distributed evenly.
In a low state of charge (SOC), lead sulfate will form on
the battery plates. This creates what is known as the
“Sulfated Battery” condition. The lead sulfate insulates
the plate’s reactive material, which reduces capacity
and decreases the battery’s ability to accept a charge.
Sulfation begins to occur below 80% state of charge in

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April, 2016

as little as two weeks. The longer the battery is left in a
low state of charge, the more lead sulfate forms.
Batteries that have been deeply discharged for periods
longer than 60 days may be permanently damaged.
Note: Long stand time causes sulfation, which may
result in customer no start events due to reduced
battery capacity. Thus, it is imperative to maintain
(charge) the battery every 30 days to ensure the battery
state of charge (SOC) remains greater than 80%.
Notice: Batteries that are deeply discharged will
take an extended time to recharge. Batteries that
are cold (below freezing) can falsely fail testing.
Batteries that are cold and deeply discharged must
first be warmed prior to testing & charging.

Cold Battery Testing – Battery Temperature at
Less Than 0°C (32°F)
When an automotive 12 Volt battery is cold, (below
freezing) its capacity starts to reduce. This can be
observed in the voltage level of the battery, as well as
measured cold cranking amps. A cold battery is also
resistant to charging. The colder the battery, the more
these characteristics are affected.
Depending how cold a battery is, it can fail testing using
any type of battery test equipment, including the
EL-50313 (GR8).
Important: It is impossible to calculate the core
temperature of a battery, so using external surface
temperature is not reliable. Warm the battery a
minimum of 12 hours prior to testing. Longer warming
times will be needed depending how cold the battery is.
Note: Cold batteries are resistant to charging even
when in use on the vehicle. They will not recover
quickly in subfreezing temperatures. Releasing a new
vehicle with a battery in a low state of charge puts the
customer at risk to a no crank event.

Battery Charging and Testing Tips
The majority of these tips apply to new vehicles in
inventory or relatively new batteries (less than 12
months old).
Batteries tend to recharge in the same manner as they
were discharged and temperature affects charge time:
• Cold Battery = Slow Recharge
• Slow Discharge = Slow Recharge
• Fast Discharge = Fast Recharge
Note: If you suspect that a battery may be frozen,
inspect the case for cracks prior to charging. Do not
charge a frozen battery.
Always warm a cold battery temperature to above 4°C
(40°F) prior to testing.

Bulletin No.: 15-06-03-001B

The EL-50313 (GR8) has a built in algorithm to limit the
length of time needed to recharge a battery. Because
cold batteries are resistant to charge, or it is deeply
discharged, it may calculate longer than reasonable
time to recover the battery and fail it. If you are working
with a newer battery that is most likely simply
discharged, select Manual Charge, Limit Current, 10
Amps, for 120 Minutes. Once that is complete, perform
another Diagnostic Charge.
Note: AGM batteries are sensitive to overcharging.
Maximum charging voltage should be limited to 14.5V.
Caution: Do not continue charging when battery
temperatures are above 49°C (120°F).
If a newer battery fails testing, allow it to rest overnight
and retest. It will often “soak” in the charge and test
good after a 12–24 hour rest.
Note: If the tool responds with “Unsafe to Charge” or
“Shorted Cell” message do not proceed.
Correct battery cold cranking amperage (CCA) ratings
and type are critical for proper test results when using
the EL-50313. Access to the battery specification label
which contains the CCA rating and type may be difficult
without component removal. Refer to the latest version
of PI1098 Battery Test Cold Cranking Amperage (CCA)
for Original Equipment Batteries and Testing Tips in SI.

Absorbent Glass Mat (AGM) Battery
Some vehicles (ex. Cadillac ATS and CTS Sedan VIN
A) are equipped with a 12 Volt Absorbent Glass Mat
(AGM) battery.
This battery is similar to current vehicle lead acid flood
batteries, except it uses glass mats that absorb
electrolytes that are pressed between the plates
instead of immersing the plates in electrolytes. This
allows for a smaller, lighter battery with the same
amount of power that is less susceptible to heat. The
maximum permissible voltage allowed for the
absorbent glass mat battery is 14.5 Volts at room
temperature.
The AGM battery requires different charging voltages
than conventional lead acid batteries. The essential
tool EL-50313 Midtronics® GR8 Battery Charger/Tester
has this algorithm built in. The EL-50313 Midtronics®
GR8 Battery Charger/Tester is the preferred charger for
use during a PDI, calibration updates or any other
repairs that requires the use of a battery charger. You
MUST select AGM when prompted or damage to the
battery will result. Make sure to select the proper
battery type: AGM and CCA during charger set up.
Incorrectly selecting "flooded" battery may cause
unnecessary battery replacements.
Refer to the latest version of PI1098 and 15-06-03-002
in SI for battery type and CCA rating if the battery label
is unavailable.

Bulletin No.: 15-06-03-001B

April, 2016

Storage Tip
Transport Mode – This is designed to help vehicles that
are not being used (In Transport or Storage) use less
battery energy. Vehicles with this feature are generally
shipped from assembly with this mode on. While in
inventory we recommend that this feature be on. Refer
to the latest version of Bulletin 11-08-49-001 for
instructions on how to turn the mode on/off.

Page 3

If you need additional information regarding warranty
coverage, please review GM Service Policy and
Procedure Manual Section 2.8.1 & 2.1.2 (b) and it is
also outlined in the latest version of Bulletin
03-06-03-004.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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