Battery
Battery
NOTE: To prevent contact corrosion, only approved screws, nuts, discs etc. should be used. These elements have a special surface coating and must be stored separately.
The battery is one of the most important electrical components in the vehicle. Fault-free functioning of the battery contributes greatly to customer satisfaction. To guarantee long and efficient operation, the battery must be checked and maintained according the versions.
Besides the start function, the battery also has the tasks of butler and supplier of electrical energy for the entire vehicle electrical system.
Battery - handling notes
NOTE:
- Battery terminals should not be greased.
- The battery terminal clamps should only be attached without force to prevent damage to the battery housing.
- The tightening torque for the battery clamps is 5 Nm (4 ftlb.).
- If the battery is to be reconnected, proceed according to, refer to, to work instructions after disconnecting the battery.
- To guarantee that the battery does not leak it is necessary that the original plug accompanying the battery is screwed into the battery openings.
- In the case of loss or damage, only original plugs of the same design should be used.
- The plugs must be fitted with an O-ring seal.
Warning notes and safety regulations for hydrocyanic acid batteries
1. -1- Fire, sparks, naked flames and smoking are forbidden:
- Avoid sparking when using cables and electrical devices
- Avoid short circuits.
- In batteries with central venting, there is an increased detonating gas concentration. The venting hose should not be bent or blocked by dirt.
2. -2- Wear eye protection
3. -3- Keep children away from acids and batteries.
4. -4- Danger of causticization:
- Battery acid is highly caustic, therefore wear protective gloves.
- Do not tip battery, acid can emerge from the venting opening.
NOTE: First aid: Rinse acid splashes to the eyes immediately with clear water for a few minutes. Consult a doctor immediately. Neutralise acid splashes to the skin or clothing immediately with soap suds and rinse again with plenty of water. If acid has been drunk unintentionally, consult a doctor immediately.
5. -5- Observe information on the battery, in the Driver's Manual.
6. -6- Danger of explosion:
- A highly explosive detonating gas mixture occurs when charging batteries.
7. -7- Disposal:
- Hand in old batteries at a collection point.
8. -8- Never dispose of old batteries in the domestic rubbish!
Removing and installing battery
NOTE:
- The battery is located in the radiator tank.
- In order to avoid triggering the alarm siren (installed on right next to the battery) of vehicles with M 536, the battery must be disconnected with the ignition on!
- All loads must be switched off beforehand! Remove ignition key!
- Never disconnect battery with engine running!
- Never start engine without securely connected battery!
- The battery terminal clamps should only be attached without force to prevent damage to the battery housing.
- Battery terminals should not be greased.
- Check that the battery is seated correctly after installation. Other dangers exist with a loose battery such as: - Reduced service life due to vibration damage. - Damage to the grid plates of the battery. - Damage to the battery housing through the retaining bracket (possible acid leak, high subsequent costs). - Inadequate crash safety.
Functioning of central venting
NOTE:
- Batteries of the latest generation are fitted with central venting.
- The gas occuring during the charging, emerges centrally through an opening on the upper cover side. The backfire protection is integrated into the same position which prevents the ignition of the combustible gas present in the battery.
- In batteries with hose/pipe for the central venting, ensure that the hose is not disconnected. Only then can the battery freely degas.
- In batteries without a hose/pipe for the central venting, ensure that the opening is not blocked on the upper cover side of the battery.
Removing battery
1. Switch ignition off and remove ignition key.
2. Open turn-lock fasteners -A-.
3. Remove battery cover.
4. First disconnect the ground strap of the battery on the negative battery terminal. Unscrew hexagon nut and remove terminal.
5. Undo hexagon nut on the positive battery terminal and remove terminal.
6. Pull off venting hose -A- and fix in a suitable position with insulating tape.
7. Unscrew fastening screw -B-.
8. Remove battery.
Installing battery
NOTE: Refer to "Removing and installing battery".
1. Insert battery.
2. Screw in fastening screw -B-, position battery and tighten the fastening screw.
Tightening torque: 23 Nm (17 ftlb.)
3. Push on venting hose -A-.
4. First connect the positive cable then the negative - otherwise there is a danger of a short-circuit!
Tightening torque: 5 Nm (4 ftlb.).
5. Put on the battery cover and lock with the turn-lock fasteners.
6. Refer to, Carry out work instructions after disconnecting the battery.
Visual inspection
Before measurements such as open-circuit voltage gravity of electrolyte or the battery load test are carried out a visual inspection of the battery must be performed.
Through this check, it can be determined:
- Whether the housing of the battery is damaged. Acid can leak out due to damage of the housing.
- Whether the battery terminal (battery line connections) are damaged. Contact of the line connections cannot be guaranteed if the battery terminal is damaged. This can cause a line fire and malfunctions in the electrical system.
Checking acid level
CAUTION:
- The accident prevention regulations must be observed when handling battery acids.
- Wear suitable protective clothing and protective glasses.
- Only illuminate the inside of the battery with a torch.
- Never illuminate the inside of the battery with a naked flame.
- Do not handle a naked flame or burning cigarettes near to batteries.
- Observe the disposal regulations for batteries when disposing of batteries and sulphuric acids.
NOTE:
- Use commercially available battery filling bottle.
- The correct acid level of the battery is an important factor for long and efficient operation of the battery.
- When the acid level is too low a capacity loss (performance loss) of the battery occurs which is caused by the cell plates drying out If the cell plates are not surrounded by electrolyte (battery acid), it will lead to corrosion of the lead plates, the plate bridges and the cell connectors. The result of the corrosion is that the function of the battery cannot be guaranteed. The battery will become useless.
- If the acid level is too high, damage can occur by the battery acid leaking out (sulphuric acid water mixture) outside the battery.
1. Switch ignition off and remove ignition key.
2. Remove battery cover.
3. Unscrew plugs of the battery.
4. Illuminate into the battery using a torch. The electrolyte level of the battery must be at the protruding "lug".
- If the acid level is too low, refill distilled water using the battery filling bottle.
5. Screw in plug of the battery again ensure that it is seated correctly.
6. Remount battery cover.
Checking gravity of electrolyte
CAUTION:
- The accident prevention regulations must be observed when handling battery acids.
- Wear suitable protective clothing.
- Observe the disposal regulations for batteries when disposing of batteries and sulphuric acids.
NOTE:
- Use commercially available battery acid tester. Refer to Workshop Equipment
- The gravity of electrolyte test provides information about the state of the battery in connection with the battery load test
- The temperature of the battery acid must be at least 10 degrees C.
The gravity of electrolyte must be checked in all battery cells as follows.
1. Switch ignition of and remove ignition key.
2. Unscrew all battery plugs (plugs of the battery cell).
3. Dip into the battery cell using the acid siphon or the pipette and take up the battery acid.
4. Read off the gravity of electrolyte in kg/cubic dm on the scale of the battery acid tester and compare with the following table.
Battery charging condition Spec. gravity in kg/cubic dm
in normal climatic zones
discharge 1.12
half charged 1.20
well charged 1.28
Battery charging condition Spec. gravity in kg/cubic dm
in tropical climatic zone
(hot countries)
discharge 1.08
half charged 1.16
well charged 1.23
The gravity of electrolyte must be at least 1.24 kg/cubic dm.
- If the gravity of electrolyte is too low, charge battery.
- After charging the battery, repeat the gravity of electrolyte test.
The measuring values for the gravity of electrolyte of the individual battery cells should not deviate by more than 0.03 kg/cubic dm from each other.
Example 1: The gravity of electrolyte in cell 4 is too low.
Example 2. The gravity of electrolyte in cells 4 and 5 is too low. The specific gravity of electrolyte deviations between the battery cells is larger than 0.03 kg/cubic dm.
- If the nominal values are not achieved, replace battery.
- If the nominal values are achieved, screw in the original plug again.
Open-circuit voltage measurement
NOTE: Use a hand-held multimeter to measure the battery voltage. Refer to Workshop Equipment
1. Switch ignition off and remove ignition key.
2. Disconnect ground strap on the battery.
NOTE: After charging and a waiting time of at least 2 hours during which the battery should neither be burdened or charged.
3. Measure the battery voltage with a hand-held multimeter.
- The battery open-circuit voltage should not fall below 12.5 V.
- If the hand-held multimeter shows 12.5 V or over, the battery voltage is OK.
- If the hand-held multimeter shows a battery voltage below 12.5 V: charge battery.
Battery load test
NOTE:
- The gravity of electrolyte test provides information about the state of the battery In connection with the battery load test.
- A battery test device is required for the load test. Refer to Battery test charge device, Workshop Equipment.
- The battery must not be removed or disconnected.
- The battery must be charged before the load test is performed.
Carry out battery load test:
1. Switch ignition off and remove ignition key.
2. Observe the information in the operating instructions of the battery test device.
3. Connect the pliers of the test lines to the battery terminal as described in the operating instructions of the test device.
- As the load current varies, the current must be set depending on the battery capacity (operating instructions of test device).
The load test currents can also be referred to in the following tables.
4. Carry out the battery load test according to the operating instructions and compare to the test result of the following tables.
- A minimum voltage is determined by the battery load test depending on the specified battery voltage.
Table:
Battery capacity: 80 Ah
Cooling test current 380 A
Load current 300 A
Minimum voltage (limit value) 9.5 V
5. If the minimum voltage is not attained, replace battery.
Remarks on battery load test:
- The battery voltage sinks during this test due to the severe load on the battery.
- If the battery is in order, the voltage value only reduces to the minimum voltage.
- If the battery is faulty, the battery voltage will sink very quickly below the specified minimum voltage.
- After the test has taken place, the low voltage value remains over a long period of time, the voltage increases again slowly.
Charging battery
WARNING:
- The battery plugs must always be screwed in correctly when charging and during the voltage measurement and the load measurement.
- Rooms in which batteries are being charged, should not be entered with a naked flame or when smoking. Gases form through the charging process in the batteries which are highly flammable.
NOTE:
- A battery charging device is required. Refer to Battery test charge device, Workshop Equipment.
- Observe Driver's Manual of charging device.
- The battery must have a minimum temperature of 10 degrees C.
- Do not charge batteries too quickly if possible as they can be damaged in this way.
- If totally discharged batteries are charged quickly, they will not take up a charge current or they will be expelled toe early as full by the so-called "surface charge".
1. Switch off battery charging device.
2. Switch ignition off and remove ignition key.
3. First disconnect the ground strap of the battery, then the positive battery terminal.
4. Connect positive line of the battery charging device to the positive terminal of the battery.
5. Connect negative line of the battery charging device to the negative terminal of the battery.
6. Set the charge current on the battery of the charge device according to the battery capacity.
7. Switch on battery charging device.
Method of procedure for loading totally discharged batteries:
- Batteries which are not in operation for a long period of time, discharge.
- A battery is totally discharged if the open-circuit voltage has sunk below 11.6 V, refer to "Open-circuit voltage measurement".
- In totally discharged batteries, the battery acid (sulphuric acid water mixture) consists of virtually only water, as the sulphuric acid proportion is considerably reduced.
- Totally discharged batteries sulphatise, i.e. the entire plate surface of the batteries harden.
- If totally discharged batteries are immediately recharged after an exhaustive discharge, the sulphatisation recedes again.
- If these batteries are not recharged, the plates continue to harden and charge take-up ability is limited. A reduction in the battery performance is the result.
- Totally discharged batteries must be charged with a low charge current as follows:
- Set charge current at maximum 5% of the battery capacity, ie. with a 80 Ah battery the charge current is a max. 4 A.
8. Charge battery.