Fully charge 12-volt vehicle electrical system battery.
Then create another VAL and check the gateway
control unit again for existing fault memory entries
analogous to step 5.

The charging current is <5 A.

12-volt vehicle electrical system battery is overcharged.
Continue with Step 11.

The charging current is <5 A and the “Battery
deep discharge” battery status was read out
beforehand.

Replace 12-volt vehicle electrical system battery.
For instructions, see: ⇒ Workshop Manual '270655
Replacing battery'

11 Switch off and disconnect the battery charger.
Then allow the 12-volt vehicle electrical system battery to rest for 24 hours.

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Information
For a 2nd generation 12-Volt vehicle electrical system battery (FinDreams), ensure that the battery
temperature is below 70 °C (158 °F). For information on battery generations, see the “Technical background” section.
12 After 24 hours of rest, measure the voltage at the 12-volt vehicle electrical system battery with a
suitable measuring device.
Assessment

Action

The voltage of the 12-volt vehicle electrical system
battery is <13 V.

Connect the battery charger and fully charge the
12-volt vehicle electrical system battery.
Then create another VAL and check the gateway
control unit again for existing fault memory entries
analogous to step 5.

The voltage of the 12-volt vehicle electrical system
battery is 0 V.

For a few seconds, connect a voltage of 14.4 V
directly to the 12-volt vehicle electrical system
battery. If necessary, the separating element can
be closed (for LG and A123 batteries, a single
clicking noise is audible).
•

If the separating element closes, charge the
12-volt vehicle electrical system battery via
the external starting points using a suitable
charger.

•

If the isolation element does not close or
opens again directly after removing the power
source, the 12-volt vehicle electrical system
battery must be replaced. For instructions,
see: ⇒ Workshop Manual '270655 Replacing
battery'

Technical background
Information:

In the lithium-ion battery, there is a battery control unit, a battery sensor and a separating element (for
batteries of the 1st generation, a relay, and for batteries of the 2nd generation, an electronic switch). This
control unit monitors the charging and discharging of the battery and opens the separating element in the
event of overcharging, deep discharge or overheating, for example, by interrupting the power supply to
the battery. As a result, there is no voltage present at the battery terminals. Therefore, no voltage can be
measured at the battery terminals (value is between 0 V - 2 V).
If the separating element is open, the vehicle is de-energized. This may be perceived as a battery fault, for
example.

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Information
With the launch of the 911 (992II) GTS T-Hybrid, a new generation (2nd generation) of 40Ah-12V LiFePo
batteries from FinDreams Battery was presented. These batteries will also be used in other vehicle variants in
the future.
•

1st generation: Manufactured by LG and A123 (Cayenne (9YA/9YB) and 911 (992): 60 Ah, Taycan
(Y1A/Y1B/Y1C): 40 Ah)

•

2nd generation: Produced by FinDreams Battery

The opening conditions for the separating element vary for the two battery generations.
Opening conditions for the separating element (LG and A123)
Information
The voltage values given below are internal battery voltage values that cannot be read or measured.
The status in the current VAL is always decisive for a battery diagnosis.
The overview is only intended to provide information about the behavior of the 12-volt on-board power
supply battery and its separating element.
The separating element opens reversibly if:
•
•
•
•

The separating element opens when the charge state (SoC) drops below 15% or the battery voltage
drops below 10 V.
The separating element opens when the battery voltage exceeds 16 V.
The battery overheats.
There is a short circuit. A classification document for the 12 V lithium-ion battery is stored in the PCSS,
see ⇒ Workshop Manual '2X00IN Classification of lithium-ion battery'.

The separating element opens irreversibly if:
•
•

The battery voltage exceeds 18 V.
The battery voltage drops below 6.5 V.

The last states mentioned are irreversible; the battery needs to be replaced.
Opening conditions for the separating element (FinDreamsBattery)
The separating element opens reversibly if:
•
•
•

The charge state (SoC = State of Charge) drops below 15%, or the battery voltage drops below 8 V.
The battery voltage exceeds 15.6 V.
The battery temperature has not exceeded 75 °C (167 °F).

The separating element opens irreversibly if:
•
•

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The battery voltage exceeds 18.4 V.
The battery voltage drops below 6 V.

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The battery temperature exceeds 80 °C (176 °F).

The last states mentioned are irreversible; the battery needs to be replaced. A classification document for the
12 V lithium-ion battery is stored in the PCSS, see

⇒ Workshop Manual '2X00IN Classification of lithium-ion battery'

Charging 12-volt vehicle electrical system battery
•
•
•
•
•

Use a suitable battery charger
Set the correct charge voltage and charging current
Work procedure for a discharged battery
Work procedure for an overcharged battery
Work procedure for a totally discharged battery

NOTICE
Important!
•

Only use Deutronic charger VAS 5908.

Þ
⇒

Battery chargers that are not suitable for lithium-ion batteries cannot be used.
To prevent damage to the battery and vehicle electrical system, a charger that is suitable for lithium-ion
batteries must be used - Battery charger 90A. The charger must also be set correctly. To do this, change the
charging values as shown below.
Information
If the battery charging current is lower than the power consumption of the vehicle, the contactor will open if
the system voltage drops.
When the contactor opens, non-certified chargers can cause voltage peaks above 28 V. This can damage the
battery.

Information
In most cases, the charging values must be changed.
Detailed information can be found under Special tools in the PPN or in the Workshop Manual/operating
instructions for the charger.
Set charging values as follows:
Voltage:

14.4 V

Maximum charging current:

90 A

Trickle charge voltage:

13.5 V DC

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Cut-in voltage:

5.0 V DC

Trickle current:

5.0 A

Capacitive charging current:

5.0 A

Work procedure for a discharged battery
Information
If the battery is discharged, charge the battery as described and set the charging values specified above.

Questions & Answers
Is it possible to jump-start a vehicle with a lithium-ion battery?
See relevant section in the Owner’s Manual of the vehicle.
What happens if a standard AGM battery is installed in the vehicle instead of the specified lithium-ion
battery?
Installing a standard AGM battery is not permitted in vehicles equipped with a lithium-ion battery.
If a standard AGM battery is installed in the vehicle, a warning message will be displayed because there is no
LIN communication. The power supply network switches to emergency operation.
Can customers charge the battery at home?
The 12-volt lithium-ion battery can be charged using the Porsche Charge-o-mat Pro.
For further information, refer to the operating instructions for the charger or contact Porsche Tequipment.

Warranty
Information
In order to invoice Porsche AG for work for diagnosis and, if necessary, for replacing the 12-volt lithium-ion
on-board battery, the Standard Form PNA 000 162 QM—Lithium-Ion Battery Checklist – Lightweight
battery 60 Ah, must be completed and attached to the relevant PCSS line. Otherwise, we reserve the right
to reject or charge back the claim.
For documentation and warranty invoicing, enter the working position and PCSS encryption specified below
in the warranty claim:
APOS

Labor operation

03350050

On board diagnostic

03350053

On board diagnostic - Create VAL

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I No.

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APOS

Labor operation

27060154

Vehicle electrical system battery check

27065500

Vehicle electrical system battery replace

2706

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I No.

PCSS encryption:
Location (FES5)

27060

Vehicle electrical system battery*

Damage type (SA4)

4000

Electrical faults

* PID 27050 Battery sensor, must not be used as this is only relevant for models with a separate battery
sensor and not for the 12-volt lithium-ion battery

Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training courses. They are
written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special tools may be necessary in
order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the safe operation of your vehicle, and
may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and safely. Part numbers listed in these bulletins
are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a discrepancy, the work procedures in the PIWIS Tester
are the ones that must be followed.

© 2026 Porsche Cars North America, Inc.

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