- Battery condition
- Idle current, idle voltage and battery voltage:
•
•

Battery tester
Battery tester

Information
Some of the functions of a battery tester (e.g. measuring battery voltage and closed-circuit current) can
also be carried out using the
•

9900 - PIWIS Tester 3 or

•

charger (see operating instructions for the relevant charger)

if necessary.
Part No.:

999. ⇒ Battery (capacity: 70 Ah)
999. ⇒ Battery (capacity: 80 Ah)
999. ⇒ Battery (capacity: 95 Ah)

References:

⇒ Workshop Manual '270689 Battery trickle charge'

Checking the battery
CAUTION
Ignition of the AGM battery during charging.
•

Danger of injury and risk of damage to materials coming into contact with battery acid when charging the AGM battery.

Þ
⇒

Never enter rooms in which batteries are being charged while holding a naked flame or smoking. Gases produced by the
charging process in the batteries are highly flammable.

Information
Document the following steps and the respective results carefully.
The battery temperature must be at least 10 °C (50 °F) when carrying out the checks.
Checks:

The following checks are carried out on the battery for diagnostic and error analysis purposes:
1

General data relating to the vehicle, battery (see below) and vehicle mileage per year.

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Figure 1
⇒ The specifications on the battery (in the vehicle) may differ from the specifications shown in Figure 1
Þ Figure 1) serves only as an example.
⇒ Illustration (⇒

2

3

•
•
•
•
•

Þ Figure 1 -Item A-),
Battery type: Rating in Ah (⇒
Þ Figure 1 -Item B-),
Date of manufacture of the battery (stamped on negative terminal): ⇒
Þ Figure 1 -Item C-),
Battery I-No. (for 2D code: ⇒
Þ Figure 1 -Item D-) and
Item number (⇒
Þ Figure 1 -Item E-),
Battery manufacturer (⇒

•

Þ Figure 1 -Item F-).
Safety instructions and warnings for handling the battery (⇒

Visual inspection of the battery:
2.1

for damage to the housing,

2.2

corroded and/or loose terminals and

Check the battery using a battery tester (see ⇒ Technical Information '270689 Recommended
chargers and tools'):
⇒ Battery charge state before and after charging.

4

Charge the battery using a suitable charger (see chapter ⇒ Technical Information '270689 Recommended chargers and tools', but with a current rating of at least 40 Ah ⇒ Observe minimum charging
time and operating instructions for the charger).

If the previous diagnostics
- clearly indicate a defective battery and
- There are no problems between the problem and the customer statement,

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Þ Replacing the battery (see ⇒ Workshop Manual '27061900 Removing and installing battery').
⇒
End of remedial action.
Information
In the event of technical problems, e.g.
- measurement and test results and/or diagnosis indicate that the battery is defective despite having handled
the battery carefully and
- having trickle-charged the battery,
⇒ the following fault finding/diagnostic steps
must be performed in the entire vehicle electrical system in addition to replacing the battery:
5

Measure the battery voltage using a voltmeter/voltage tester ⇒ Workshop Manual '270601 Checking
battery with battery tester':
- Battery idle voltage,
- Battery voltage with engine running at idle speed and
- Measurement at an engine speed of approx. 3,000 - 4,000 rpm with active loads (light, heating, air
conditioning).
⇒ The PIWIS Tester can also be used for these measurements.

6

Measure closed-circuit current, see ⇒ Workshop Manual '9X00IN Closed-circuit current measurement'
(if the measured value is greater than 30 mA ⇒ determine the cause).

7

Generator test - Measure generator voltage and charging current:
- Generator voltage with engine running at idle speed and
- Generator voltage at an engine speed of approx. 3,000 - 4,000 rpm with active loads (light, heating,
air conditioning).
- Charging current on the generator with engine running at idle speed (measurement using commercially available clamp-on ammeter) and
- Charging current on the generator at an engine speed of approx. 3,000 - 4,000 rpm (measurement
using commercially available clamp-on ammeter).
Other test methods:
7.1

Using PIWIS Tester II ⇒ Go to GFF (“Guided Fault Finding”) ⇒ Generator test: Document
“2722” (power supply - control system - supply voltage - charging system) or

7.2

With the PIWIS Tester II ⇒ In the”control unit overview” select the DME control unit.
The generator voltage is displayed in the “Nominal values” overview, or

7.3

Alternatively, the voltage can even be measured directly at terminal 30 on the generator in some
cases, depending on the vehicle model.

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Voltage drop measurement (max. 0.6 V per line):
- Measured on positive side ⇒ between battery positive terminal and generator positive and
- Measured on negative side ⇒ between battery negative terminal and generator housing.

9

The following values (see table) can be read out using PIWIS Tester II 9818:
9.1

Connect PIWIS Tester to the vehicle.

9.2

Switch on ignition.

9.3

Select the relevant vehicle in the “Diagnostics” menu.

9.4

Select the “Gateway” control unit in the “Control unit overview” menu and switch to the “Actual
values/input signals” menu.

9.5

Answer •YES“ in response to the VAL (Vehicle Analysis Log) prompt.

9.6

Read the campaign information instructions and confirm by pressing •F12“.

9.7

In the “Actual values/input signals” overview, select “Battery” and “Battery charge state
history” and press •F12“ to confirm.

9.8

In the “Actual values” overview, select the following actual values:
charge-related ... %

Battery ageing

performance-related ... %

Battery internal resistance

Actual ... mOhm

Battery charge state

... %

Open-circuit voltage

... V
(Acid) ...

Battery temperature

(Terminal) ...

Closed-circuit current

Below limit value (Duration) ... min.
Limit value exceeded (Duration) ... min.
Battery charge state 0 ... 25%

Battery charge state History

Battery charge state 26 ... 50%
Battery charge state 51 ... 75%
Battery charge state 76 ... 100%

9.9

Press •F12“ to confirm your selection.

9.10

Read off and document actual values.

9.11

Press •F11“ to exit the display.

9.12

Press •F11“ to go back.

End of remedial action.
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Additional references, summary
References:

Further technical information about the installed battery type can be found in the relevant Driver’s Manual.
Forms:
Battery trickle charge:

⇒ Technical Information '0X0000 Recommendations and measures for vehicle storage (26/09)'
Testing and checking the battery:

⇒ Workshop Manual '2706IN General information on AGM vehicle battery'
⇒ Workshop Manual '9X00IN01 Measurement of idle current'
Disconnecting and reconnecting the battery / removal and installation or replacing the battery:

⇒ Workshop Manual '9X00IN Work instructions after disconnecting the battery'
⇒ Workshop Manual '27061900 Removing and installing battery'

Labor time
Labor time:

27060100: Checking the battery

Labor time: 20 TU

27068950: Charging the battery

Labor time: 20 TU

27061900: Removing and installing battery

Labor time: 15 TU

27065500: Replacing battery

Labor time: 50 TU

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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