Battery - Overview: Diagnosis BMW Z3 E36 рестайлинг

Battery Testing

There are four steps to follow in testing an automotive battery

1. Inspection.
2. Removal of Surface Charge.
3. State-of-Charge Test.
4. Load Test.

Inspection

Visual inspection is important for the detection of obvious problems

1. Loose Generator Belt.
2. Low Electrolyte Level.
3. Corroded Cable or Terminal Clamps.
4. Loose Hold-Down Camps or Cable Terminals.
5. Damaged Battery Case. NOTE: The proper electrolyte level is just covering the plates, not all the way to the top of the battery inspection holes.

State-of-Charge Test

OPEN CIRCUIT BATTERY VOLTAGE SPECIFICATIONS

Use the table to determine the battery's State-of-Charge.

Pay special attention if the DVOM measurement of OCV is equal to

1. 0 volts - Indicate an open cell.
2. 10.45-10.65 volts - Indicates a shorted cell.

For non-sealed batteries, check both specific gravity (SG) in each cell with a temperature compensated hydrometer and battery OCV, without the engine running.

For sealed batteries, measuring the battery's OCV (without the engine running) with an accurate DVOM is the only way to determine the state-of-charge.

Batteries with a built-in hydrometer measure the state-of-charge in one cell only. If the indicator is clear or light yellow, the battery has a low electrolyte level and should be refilled before proceeding or replaced.

A state-of-charge reading BELOW 75% using SG, voltage measurement or dark indicator in batteries with built-in hydrometers, indicates the battery must be recharged before proceeding.

Replace the battery if one or more the following conditions are met

1. More than 0.050 difference in the specific gravity readings between the highest and lowest cell (There is a weak or dead cell).
2. The battery will not recharge to 75% or greater state-of-charge or the built in hydrometer does not indicate good (green indicates 65% or better).
3. DVOM reading indicates 0 volts (Open cell).
4. DVOM reading indicates 10.45-10.65 volts (Shorted cell).

Load Test

A battery which has a state-of-charge of 75% or greater or has a "good" built-in hydrometer indication may be load tested.

With a battery load tester properly installed, load the battery for 15 seconds to one of the following

1. One-half (1/2) the CCA (Cold Cranking Amps).
2. Three (3) times the AH Rating (Amp Hour Rating).

The voltage on a good battery will NOT drop below 9.7 volts during the battery load test. After the load is removed, wait 5 minutes, the battery should bounce back to 50% or greater state-of-charge. If a battery drops below 9.7 volts during the load test, does not bounce back or fails to start the engine, the battery should be replaced. Batteries which pass this test should be recharged to restore peak performance.

Load Test Conditions

Tests assume electrolyte temperature of 80° F, 26.7° C.

If the electrolyte temperature is above 80° F add .1 volt for every 10 degrees up to 100°.

If the temperature is below 80° F subtract .1 volt for every 10 degrees to 40°.

Testing A Battery for Sulphation

A battery which fails the load test should be tested for sulphation. To test a battery for sulphation, place it on a battery charger for three minutes with the charger set on 40 amps. After three minutes check the OCV, if the reading is greater than 15.0 volts the battery is sulphated. Batteries which indicate a sulphated condition should be recharged slowly and retested before being discarded.

Closed Circuit Current Draw Testing

Increased closed-circuit currents may occur permanently or intermittently and cause the battery to discharge prematurely. The increase in closed circuit current may be caused by a faulty control unit or by the installation of a non-approved accessory.

In a situation where a vehicle has broken down due to a discharged battery, for diagnostic purposes it is important not to disconnect the battery. The control unit may reset if the battery is disconnected. Following a reset, a faulty control unit may start functioning correctly again, making accurate diagnosis impossible.

Tools Needed

1. Closed Circuit Current Measurement Adapter.
2. MoDic Adapter.
3. DISplus, MoDic or DVOM.

To correctly measure closed-circuit current, measurement adapter 61 2 300 (P/N 90 88 6 612 300) should be used. This tool provides a bridge to ground, before the negative battery terminal is disconnected, and this prevents the control units from being reset.

The additional use of MoDiC adapter 61 2 310 (P/N 90 88 6 612 310) provides a method for current measurements over an extended period of time.

The measuring device needed depends on the situation.

The DISplus may be used in situations of suspected high current draw.

The 1000 amp probe measures AC and DC current from 0 to 1000 amps. It is a self calibrating inductive pick-up. (Use this pick-up with current draws over 10 amps) The DISplus, through MFK 1 is capable of measuring up to 2 amps.

The MoDic is particularly suitable for extended measurements and provides a graphical readout of recorded measurements over time. It is recommended for the situations where the use of a multimeter provided insufficient information for problem diagnosis.

The DVOM may be used for measurements up to 10 amps either with the measurement adapter or alone.

Note. It is extremely important that the battery is NOT disconnected during the installation of test equipment. Disconnection of battery may cause faulty component to function normal.

Performing Closed Current Draw Test

1. Select proper measuring device (DISplus, MoDic or DVOM) Remember amperage draw in excess of 10A will damage DVOM. Use inductive amp probe of DISplus when amperage draw is high. When using DISplus inductive probe, clamp on negative battery cable with: Arrow pointing away from battery. Switch off all consumers. (It is not necessary to disconnect B- from body when using inductive probe).
2. Connect (-) test lead to negative battery terminal and (+) test lead to a known good ground.
3. Ensure all systems are OFF !
4. Be sure DVOM is on and set in proper mode.
5. Disconnect battery ground lead from body.
6. Observe meter reading, wait for vehicle to enter sleep mode.
7. Identify faulty circuit by disconnecting fuses, relays, control modules or connectors, observing meter readings.
8. Defective circuit is found when current is below maximum closed current for vehicle being tested.

Scheme 41

MAXIMUM CLOSED CURRENT BY VEHICLE

Note. Refer to appropriate article for complete instructions to perform closed circuit current measurement using measurement adapter and MoDIc adapter.