For 1990-2009 cars

# Battery and Generator Diagnostics

Subject: | Service Information on Battery and Generator Diagnostics

Models: | 1991-1997 Saturns

### Purpose:

The procedure used for diagnosing batteries and generators has been revised. The new diagnostic procedure for the battery and generator is being provided in the form of a flow chart contained in this bulletin. Also, 2 copies of the flow chart are laminated and included with this bulletin these laminated charts contain the battery testing procedure on one side, and the generator testing procedure on the other side, along with specifications for all versions of generators used on Saturn vehicles. Please attach one laminated chart to each electronic system tester for quick reference.

Important: The specifications provided with this bulletin supersede the specifications available in prior versions of the Electrical Service Manuals.

It is important to note that whenever testing or charging a battery outside of the vehicle, appropriate battery terminal test adapters should be used. If the proper adapters are not used, test results may be invalid and/or battery charging time may be greatly increased.

Saturn STRONGLY recommends the use of battery terminal adapters whenever testing or charging a battery out of the vehicle. One set of battery terminal adapters, SA9807 (AC Delco ST-120), has been sent with this bulletin to all Saturn Retailers. Additional sets of terminal adapters can be purchased through the Saturn special tools catalog.

### Battery Testing

Battery state of charge can be estimated by observing the battery's built-in hydrometer. If the green dot is visible, the battery state of charge is over 65 percent. If the eye appears black, the battery state of charge is too low and the battery must be recharged before being returned to the customer. The hydrometer provides an estimate of the battery state of charge based on one of six cells within the battery. It does NOT indicate whether the battery is good or bad, The Saturn electronic system tester SA9154 must be used to determine whether the battery should be replaced. Refer to the battery testing flow chart included with this bulletin for the complete battery testing procedure.

### Battery Charging

Battery Charging times are affected greatly by the extent of discharge of the battery, temperature, charger capacity and battery size. The Saturn battery is a Delco Freedom, 75-60 CCA, with a 90 minute reserve capacity. Charging time for a completely discharged battery will be greatly increased due to increased internal resistance. This is because the battery charger must overcome the battery's internal resistance and can be seen by the low current that is produced when charging an extremely discharged battery. Charging time for a completely discharged battery can be roughly estimated by dividing the Reserve Capacity rating (90), by the actual charger output (the charger's rated output. Example: Using a charger with an actual charging rate of 10 amps, the estimated charging time would be 9 hours.

1. Properly connect the battery using the SA9807, if out of vehicle, to a charger.
2. Set the charging rate to the high setting and charge the battery. For best results, use a charger with an end of charge voltage of 16 volts.
3. Check the hydrometer indicator hourly for the green dot. Gently tap on the hydrometer to eliminate the possibility of the hydrometer ball sticking. Continue charging until the green dot is visible.
4. Monitor the battery for spewing, severe gassing or case temperature above 52°C (125°F). If this occurs, discontinue charging until the battery cools then resume charging at a educed rate.
5. When the green dot appears and remains, the battery is sufficiently charged.
6. Unplug the charger, disconnect the charger from the battery.

### Replace the Battery Under the Following Conditions:

• | Clear or yellow hydrometer, indicating that the electrolyte level is low.

• | Leaking, mutilated or distorted battery case.

• | Loose battery terminals or damaged threads which would prevent an adequate electrical connection

• | Battery open circuit voltage is below 11 volts with the green dot showing in the hydrometer.

• | The green dot does not appear in the hydrometer even after charging for 2 times the estimated charging tome. Reserve Capacity divided by the average charger output.

• | Battery test procedure results in BAD BATTERY being displayed on the Saturn electronic system tester.

### Charging System Testing

Refer to the charging system testing flow chart included with this bulletin for the complete generator testing procedure.

### Generator Noise Evaluation

Whenever a generator is producing current, a slight high-pitch noise can be heard and is completely normal. This noise is referred to as magnetic noise and results from the rotating magnetic forces which induce mechanical vibrations within the generator. The generator typically has several machine resonances throughout its operating speed range. Magnetic noise can be distinguished from other types of noises in that it becomes loudest within small RPM ranges, and is more pronounced at lower generator speeds near engine idle. To identify magnetic noise, disconnect the 4-way connector at the generator. If the noise is magnetic noise, it will not be heard with the generator disconnected. Other bearing, belt or interference type noises will likely continue when the generator is not charging. Whenever evaluating a magnetic noise complaint, be sure to test the vehicles battery. A damaged or discharged battery will cause an excessive load on the generator, thus increasing the amount of normal magnetic noise.