D.Battery Charging

A battery must show a green dot before load testing. If a green dot is showing, proceed to Section II, Step E, Page 7, to load test the battery. If the built-in hydrometer appears dark, the battery must first be recharged as follows.

When charging a battery, the following guidelines should be followed:

^ Do not charge battery if hydrometer is clear or light yellow. Replace battery.

^ If the battery feels hot, 125~F (50~C) or violent gassing or spewing of electrolyte through the vent hole occurs, discontinue charging or reduce charging rate.

^ Do not charge a frozen battery (batteries may freeze at temperatures of +20~F or colder if the state of charge is very low). If it is suspected that a battery is frozen, move the battery indoors to a heated area for at least two hours before charging.
1. Battery Fast Charger Recommendations

The following specifications are recommended for battery chargers. No special equipment is required for Maintenance-Free or Freedom Batteries.

^ 40-50 amperes minimum charge rate capability for discharged battery.

^ To prevent overcharge, a timer (one or two hour) or voltage regulator (18 volt maximum) to stop or reduce the charge rate as battery is recharged.

^ Ammeter or charge indicator. (Extremely cold and some completely discharged batteries may appear not to accept a charge on this meter. In reality, some small current is being accepted and the meter is not sensitive enough to register it. Continue charging and a charge rate will begin to show in time.)

^ Automatic polarity protection. Some of these devices require some activating voltage to become operational, therefore, a by-pass or override feature is desirable for totally discharged batteries with extremely low terminal voltage.


2. Charging Procedure

a. Batteries with green dot showing do not require charging unless they have just been discharged (such as in prolonged cranking of the vehicle).

b. When charging sealed-terminal batteries out of vehicle, install adapters (AC Delco P/N ST-1201 or equivalent), or use approved alternate procedure. (Refer to Section II, Step C, Page 3).

c. Make sure all charger connections are clean and tight.


d. For best results, batteries should be charged while electrolyte and plates are at room temperatures. A battery that is extremely cold may not accept current for several hours after starting charger.
e. Charge battery until green dot appears. (Refer to Step 3, CHARGING TIME REQUIRED, below.) Battery should be checked every half-hour while charging. Slight tipping or shaking of the battery may be necessary to make green dot appear.

f. After charging, battery should be tested as outlined in "LOAD TESTING", Section II, Step E, Page 9.


3. Charging Time Required

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

^ Size of Battery - a completely discharged large heavy-duty battery requires more than twice the recharging as a completely discharged small passenger car battery.

^ Battery Temperature - a longer time will be needed to charge any battery at 0~F than at 80~F. When a fast charger is connected to a cold battery, the current accepted by the battery will be very low at first, then in time the battery will accept a higher rate as the battery warms.

^ Charger Capacity - a charger which can supply only 5 amperes will require a much longer period of charging than a charger that can supply 30 amperes or more. Charge rates as high as 50 amperes are generally satisfactory as long as spewing of electrolyte out the vents does not occur and the battery does not feel excessively hot (over 52~C, 125~F).

^ State-Of-Charge - a completely discharged battery requires more than twice as much charge as a half charged battery. Because the electrolyte is nearly pure water and a poor conductor in a completely discharged battery, the current accepted by the battery is very-low at first. Later as the charging current causes the electrolyte acid content to increase, the charging current will likewise increase.
4. Charging A Very Flat Or Completely Discharged Battery (Off The Vehicle)

The following procedure should be used to recharge a very flat or completely discharged battery. Unless the procedure is properly followed, a good battery may be needlessly replaced.

a. Measure voltage at battery terminals with an accurate voltmeter. If below 10 volts, then the 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 built into many chargers.

b. Set battery charger on high setting.

c. 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 by-pass or override the circuitry so that the charger will turn on and charge a low-voltage battery.

d. Battery chargers vary in the amount of voltage and current they provide. Thus the time required for the battery to begin to accept measurable charger current will also vary.

REMEMBER, EVEN WITH CHARGER ON HIGHEST SETTING, IT MAY BE SEVERAL MINUTES BEFORE CHARGING CURRENT IS MEASURABLE. HOWEVER, THE CHARGING CURRENT WILL THEN INCREASE RAPIDLY TO NORMAL VALUES IF A GOOD FAST CHARGER IS USED.

Figure 5 - Load Test Temperature Correction:

e. 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 Figure 4, page 11) 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, the green dot should show when recharged as follows:

10 ampere charge x 7-1/2 hrs. = 75 AH or
25 ampere charge x 3 hrs. = 75 AH, etc.

In any case, the battery should be checked every half hour, and charging should be reduced or discontinued when the green dot appears.

f. It is recommended that any battery recharged by this procedure be LOAD TESTED to establish serviceability.