Charging A Very Low or Completely Discharged Battery

The following procedure should be used to recharge a very low or completely discharged battery:

Unless the procedure is properly followed, a perfectly good battery may be needlessly replaced.

1. Measure voltage at battery terminals with a digital voltmeter. If below 11 volts, then charge current will be very 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 ammeters used on chargers.
2. Set battery charger on high setting. On Battery chargers with a regular setting and a maintenance-free setting, use the regular setting as this is generally a higher setting.

3. Some chargers feature polarity protection circuitry which prevents charging unless the charger leads are connected to the battery terminals correctly. A completely discharged battery may not have enough voltage to activate this circuitry, even though leads are connected properly, making it appear that the battery will not accept charging current. Therefore, follow the specific charger manufacturer's instruction telling how to bypass or override the circuitry so that the charger will turn on and charge a low-voltage battery.

4. Battery chargers vary in the amount of voltage and current they provide. The time required for the battery to accept measurable charger current at various voltages may be as follows:

Charger Voltage Hours

A. 16.0 or more Up to 4 hours
B. 14.0-15.9 Up to 8 hours
C. 13.9 or less Up to 16 hours

If the ammeter on the battery charger indicates that the battery is still not accepting a charge at the end of the charging times, the battery should be replaced.

If the charge current is measurable during the charging time, the battery is considered to be accepting charge and charging should be completed in the normal manner.

5. It is important to remember that a completely discharged battery, must be recharged for a sufficient number of ampere hours (AH) to restore it to a usable state. As a general rule of thumb, using the reserve capacity rating (RC) (refer to Section 6D of the appropriate Service Manual) of the battery as the number of ampere hours of charge will usually bring the green dot into view.

For example, if battery is rated at 75 RC minutes, it would be completely recharged as follows:

10 ampere charge x 7-1/2 hours = 75 AH or

25 ampere charge x 3 hours = 75 AH, etc.

6. It is required that any battery recharged by this procedure be LOAD TESTED to establish serviceability.
RATINGS

A battery has two ratings:

1. A cold rating at -18~C (0~F) which indicates the cranking load capacity (see battery label or specifications chart at the end of the Battery Section for specific battery ratings.

2. A reserve capacity rating at 27~C (80~F) which is the time a fully charged battery will operate the car with no generator operation.

COLD CRANKING AMPERAGE

The "Cold Cranking Amperage" rating is expressed at a battery temperature of O~F. The current rating is the amperage, which must be delivered by the battery for 30 seconds at the specified temperature, while meeting a minimum voltage requirement of 7.2 volts. This rating is a measure of cold cranking capacity.

The battery is not designed to last indefinitely; however, with proper care, it will provide many years of service.

If the battery tests good, but fails to perform satisfactorily in service, for no apparent reason, the following are some of the more important factors that may point to the cause of trouble:

1. Vehicle accessories left on overnight.

2. Slow average driving speeds for short periods.

3. The vehicle's electrical load is more than the generator output, particularly with the addition of aftermarket equipment.

4. Defects in the charging system such electrical shorts, slipping fan belt, faulty generator, or faulty voltage regulator.

5. Battery abuse, including failure to keep the battery cable terminals clean and tight, or loose battery hold-down.

NOTE: Properly assembled cables are air tight and do not require cleaning.

6. Mechanical problems in the electrical system, such as shorted or open wires.

RESERVE CAPACITY

The "Reserve Capacity" is the maximum length of time it is possible to travel
at night with minimum electrical load and no generator output.

Expressed in minutes, it is the time required for a fully charged battery, at a temperature of 80~F, being discharged at a constant current of 25-amperes, to reach a terminal voltage of 10.5 volts.

FIGURE 3 - CHARGING ADAPTER:

BATTERY CONNECTIONS

Load testing requires the use of battery side terminal adapters the same as with charging to ensure good connections (See Figure 3).

VISUAL INSPECTION

Check for obvious damage, such as cracked or broken case or cover, that is permitting loss of electrolyte. If obvious damage is noted, replace the battery. Determine the cause of damage and correct as needed. If battery terminals are severely damaged, such as loose, burned, or broken; replacement of the battery is required. Evidence of small amounts of electrolyte leakage, especially around the vent holes, does not necessarily indicate the battery is bad - leakage could have been caused by overcharging or by excessive tipping of the battery.

FIGURE 4:

READING BUILT-IN HYDROMETER

Look down into the built-in hydrometer (clean and use a flashlight if necessary) to observe its reading (Refer to Figure 4).

^ Green Dot Visible - Any green appearance is interpreted as a "green dot" and indicates that the battery is 65%, or above, in state of charge and is ready for use or testing. A fully charged battery should read 12.6 or more volts.

^ Dark, Green Dot Not Visible - Indicates the battery is below 65% state of charge and needs charging prior to testing.

^ Clear or Light Yellow - This means the fluid level is below the bottom of the hydrometer. This may have been caused by excessive or prolonged charging, a cracked or broken case, excessive tipping, or normal battery wearout. Whenever this clear or light yellow appearance is present while looking straight down on the hydrometer, always tap the hydrometer lightly with a small screwdriver to dislodge any gas bubbles that may be giving a false indication of low electrolyte level. Replace battery. Do not charge, test or jumpstart. A dark reading may be misinterpreted as a clear or light yellow when inspecting a Freedom II battery. This is caused by light filtering through the new translucent case. Shake the battery to determine the fluid level and shield the battery sides from light to determine the true reading before replacing the battery.
BATTERY LOAD TEST

Before testing a battery, it is important that the battery has a proper charge.

1. Connect a digital voltmeter and a battery load tester across battery terminals.

2. Apply 300 ampere load for 15 seconds to remove surface charge from battery.
Remove load.

3. Wait 15 seconds to let battery recover and apply specified load as indicated on battery label. Read voltage after 15 seconds, with specified load applied, then remove load.

4. Temperature of the battery will change the minimum voltage to pass the load test. To properly determine minimum voltage, estimate temperature battery has been exposed to for the last several hours, i.e., room temperature or outside ambient to within 10~F. If voltage is equal to or above minimum voltage listed in the chart below, the battery is good and should be returned to service. If voltage is less than minimum requirement, replace battery.

Temperature (21~C) (10~C) (-1~C) (-10~C) (-18~C) Below
70~F 50~F 30~F 15~F 0~F 0~F
Above

Minimum Voltage 9.6 9.4 9.1 8.8 8.5 8.0

CAUTION

All batteries generate hydrogen gas which is highly flammable. If ignited by a spark or flame, the gas may explode violently, causing spraying of acid, fragmentation of the battery, and possible severe personal injuries. Wear approved eye protection. Battery fluid is a corrosive acid. Flush any contacted area with water immediately and thoroughly.