Checking The Battery
- Danger of injury and risk of damage to materials coming into contact with battery acid when charging the AGM battery.
→ Do not smoke near or expose an open flame to the gases produced by the charging process. These gases are highly flammable.
Information
Work through the Battery Checklist while carrying out the following steps and document the results carefully in the Checklist.
The battery temperature must be at least 50° F (10° C) when carrying out the checks.
Checks:
The following checks are carried out on the battery for diagnostic and error analysis purposes:
- General data relating to the vehicle, battery (see below) and vehicle mileage per year.
=> The specifications on the battery (in the vehicle) may differ from the specifications shown in Figure 1
=> Illustration (> Figure 1 ) serves only as an example.
- Battery type: Rating in Ah (-Item A- ),
- Date of manufacture of the battery (stamped on negative terminal): -Item B- ),
- Battery I-No. (for 2D code: -Item C- ),
- Item number (-Item D- ) and
- Battery manufacturer (-Item E- ),
- Safety instructions and warnings for handling the battery (-Item F- ).
- 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 > Recommended chargers and tools):
=> Battery charge state before and after charging.
- Charge the battery
using a suitable charger (see chapter > 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,
=> Replacing the battery (see > Refer to the appropriate service information ).
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:
- Measure the battery voltage using a voltmeter/voltage 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.
- Measure closed-circuit current
, see > 9X00IN MEASUREMENT OF CLOSED-CIRCUIT CURRENT
(if the measured value is greater than 30 mA → determine the cause).
- 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.
- 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.
- 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:
Battery ageing charge-related... % performance-related... % Battery internal resistance Actual... mOhm Battery charge state ... % Open-circuit voltage ... V Battery temperature (Acid)... (Terminal)... Closed-circuit current Below limit value (Duration)... min. Limit value exceeded (Duration)... min. Battery charge state History Battery charge state 0... 25% 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 actual values and enter them in the Checklist.
- 9.11 Press F11 to exit the display.
- 9.12 Press F11 to go back.
End of remedial action.
> Refer to the appropriate service information