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An open circuit voltage, no load test will show the state of charge in a battery. Also, if it will pass a load test of 50 percent of the battery cold crank rating. Refer to Battery Load Test. If a battery has an open circuit voltage reading of 12.4 volts or greater, and will not pass a load test, it is defective and replacement would be required. To test open circuit voltage, perform the following operation:

(1)Remove both battery cables, negative first. If the battery has been boosted, charged, or loaded just prior to this operation, allow the battery a few minutes to stabilize.

(2)Using a voltmeter connected to the battery posts and measure the open circuit voltage (Fig. 7).

A fully charged battery must have reserve cranking capacity. This will enable the starter motor and ignition system enough power to start the engine over a broad range of ambient temperatures. A battery load test will verify the actual cranking performance based on the cold crank rating of the battery.

WARNING: IF BATTERY SHOWS SIGNS OF FREEZING, LEAKING, LOOSE POSTS, OR EXCESSIVELY LOW ELECTROLYTE LEVEL, DO NOT TEST. ACID BURNS OR AN EXPLOSIVE CONDITION MAY RESULT.

(1)Remove both battery cables, negative first. Battery top, cables and posts should be clean. If green dot is not visible in indicator, charge the battery. Refer to Battery Charging Procedures.

(2)Use a suitable Volt Ammeter Load tester (Fig.

9)connected to the battery posts (Fig. 10). Check the open circuit voltage of the battery.

Voltage should be equal to or greater than 12.4 volts with the green dot visible in test indicator.

Fig. 12 Load 50 Percent Cold Crank Rating

After 15 seconds, record the loaded voltage reading and return the load control to the off position.

(6)Voltage drop will vary according to battery temperature at the time of the load test. Battery temperature can be estimated by the temperature of exposure over the preceding several hours. If the battery has been charged, boosted, or loaded a few minutes prior to the test, the battery would be slightly warmer. Refer to Fig. 13 for proper loaded voltage reading.

(7)If battery passes load test, it is in good condition and further tests are not necessary. If it fails /load test, it should be replaced.

BATTERY CHARGING

A battery is considered fully charged when it will meet all the following requirements:

²It has an open circuit voltage charge of at least 12.4 volts (Fig. 8)

²It passes the 15 second load test (Fig. 13)

²The built in test indicator dot is GREEN (Fig. 5)

CAUTION: Disconnect the battery negative cable first (Fig. 14) before charging battery to avoid damage to electrical systems. Do not exceed 16.0 volts while charging battery. Refer to the instructions supplied with charging equipment

Fig. 14 Disconnect Negative Battery Cable

Battery electrolyte will bubble inside the battery case while being charged properly. If the electrolyte boils violently, or is discharged from the vent holes

while charging, immediately reduce charging rate or turn off charger. Evaluate battery condition. Battery damage may occur if charging is excessive.

Some battery chargers are equipped with polarity sensing devices to protect the charger or battery from being damaged if improperly connected. If the battery state of charge is too low for the polarity sensor to detect, the sensor must be bypassed for charger to operate. Refer to operating instructions provided with battery charger being used.

CAUTION: Charge battery until test indicator appears green. Do not overcharge.

It may be necessary to jiggle the battery or vehicle to bring the green dot (in the test indicator) into view.

After the battery has been charged to 12.4 volts or greater, perform a load test to decide cranking capacity. Refer to Battery Load Test. If the battery will endure a load test, return the battery to use. If battery will not endure a load test, it must be replaced. Properly clean and inspect battery hold downs, tray, terminals, cables, posts, and top before completing service. Also refer to Group 8B, Battery/Starter/ Alternator Service.

CHARGING TIME REQUIRED

The time required to charge a battery will vary depending upon the following factors:

² SIZE OF BATTERY

A completely discharged large heavy-duty battery requires more than twice the recharging time as a completely discharged small capacity battery (Fig. 15).

Fig. 15 Battery Charging Time

²TEMPERATURE: A longer time will be needed to charge a battery at -18°C (0°F) than at 27°C (80°F). When a fast charger is connected to a cold battery, current accepted by battery will be very low at first. In time, the battery will accept a higher rate as battery warms.

²CHARGER CAPACITY: A charger which, can supply only five amperes will require a much longer period of charging than a charger that can supply 30 amperes or more.

²STATE OF CHARGE: A completely discharged battery requires more charging time than a partially

charged battery. Electrolyte is nearly pure water in a completely discharged battery. At first, the charging current amperage will be low. As water is converted to sulfuric acid inside the battery, the current amp rate will rise. Also, the specific gravity of the electrolyte will rise, bringing the green dot (Fig. 5) into view.

WARNING: NEVER EXCEED 20 AMPS WHEN CHARGING A COLD -1°C (30°F) BATTERY. PERSONAL INJURY MAY RESULT.

CHARGING COMPLETELY DISCHARGED BATTERY

The following procedure should be used to recharge a completely discharged battery. Unless procedure is properly followed, a good battery may be needlessly replaced (Fig. 16).

Fig. 16 Charge Rate

(1) Measure the voltage at battery posts with a voltmeter accurate to 1/10 volt (Fig. 17). If below 10 volts, charge current will be low, and it could take some time before it accepts a current in excess of a few milliamperes. Such low current may not be detectable on amp meters built into many chargers.

Fig. 17 Voltmeter Accurate to 1/10 Volt (Connected)

(2) Connect charger leads. Some chargers feature polarity protection circuitry which, prevents operation unless charger is connected to battery posts correctly. A completely discharged battery may not have enough voltage to activate this circuitry. This may happen even if the leads are connected properly.

(3) Battery chargers vary in the amount of voltage and current they provide. For the time required for the battery to accept measurable charger current at various voltages, refer to Fig. 16. If charge current is

still not measurable after charging period the battery should be replaced. If charge current is measurable during charging time, the battery may be good, and charging should be completed in the normal manner.

GENERAL INFORMATION

A normal electrical system will draw from 5 to 30 milliamperes from the battery. This is with the ignition in the OFF position, and all non-ignition controlled circuits in proper working order. The amount of IOD will depend on body model and electrical components. A vehicle that has not been operated for an extended period of approximately 20 days may discharge the battery to an inadequate level. In this case, the Main Fusible Link Connector should be disconnected. The Main Fusible Link connector is located rearward of the battery on the engine wiring harness (Fig. 18).

Fig. 18 IOD Test

If the IOD is over 30 milliamperes, the defect must be found and corrected before condemning the battery. Usually, the battery can be charged and returned to service (Fig. 15).

IGNITION OFF DRAW (IOD) TESTS

VEHICLES WITHOUT ELECTRONIC AUTOMATIC TRANSMISSION/LOAD LEVELING SUSPENSION OR ALARM SYSTEMS

Testing for HIGHER AMPERAGE IOD must be performed first to prevent damage to most milliamp meters.

A standard 12 volt test light and a milliamp meter that is equipped with two leads will be used for the following tests. The milliamp meter should be able to handle up to two amps.

(1)Verify that all electrical accessories are OFF. Turn off all lights, close trunk lid, close glove box door, turn off sun visor vanity lights, close all doors and remove ignition key. Allow the Illuminated Entry System if equipped to time out in approximately 30 seconds.

(2)Verify the engine compartment lamp bulb is working by

opening/closing hood. Remove the lamp.

(3)Disconnect negative battery cable (Fig. 14).

(4)Connect a typical 12 volt test light between the negative cable clamp and the negative battery post (Fig. 18). The test light may be brightly lit for up to three minutes or may not be lit at all. This depending on the body model or electronic components on the vehicle.

(a)The term brightly used throughout the following tests. This implies the brightness of the test light will be the same as if it were connected across the battery posts. This would be with a fully charged battery.

(b)The test light or the milliamp meter MUST be positively connected to the battery post and the battery cable during all IOD testing.

(c)Do not allow the test light or the milliamp meter to become disconnected during any of the IOD tests. If this happens, the electronic timer functions will be started and all IOD tests must be repeated from the beginning. Clamp the test light at both ends to prevent accidental disconnection.

(d)After three minutes time has elapsed, the test light should turn OFF or be dimly lit depending on the electronic components on the vehicle. If the test light remains BRIGHTLY lit, do not disconnect test light. Disconnect each fuse or circuit breaker until test light is either OFF or DIMLY lit. Refer to the Front Wheel Drive Car Wiring Diagrams Service Manual. This will eliminate higher amperage IOD. It is now safe to install the milliamp meter without damage to the meter to check for low amperage IOD.

(e)Possible sources of high IOD are usually vehicle lamps trunk lamp, glove compartment, luggage compartment, etc..

(f)If test light is still brightly lit after disconnecting each fuse and circuit breaker, disconnect