Battery Charging
When charging a sealed battery, the following safety precautions must be followed:^ Do not charge battery if hydrometer is clear or light yellow. Replace battery if there is a cranking complaint.
^ 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.
BATTERY CHARGING CONNECTION PROCEDURE
Bolts alone, screwed into the side terminal, should not be used for the connection of battery charger cables since the mating threads inside the battery terminals provide a very small contact surface, which has high resistance to current flow. The high resistance can prevent adequate charging current from reaching the battery, creating the appearance of the battery not accepting a charge, or at the least, requiring longer charging time. It also explains why some batteries are called bad when they are load tested, but are obviously good batteries when checked with proper connections at the terminals.
There are two ways of connecting to the side terminals to charge a battery:
FIGURE 3 - CHARGING ADAPTER:
- By use of an adapter charging tool (See Figure 3). The number of this tool is AC-Delco ST-1201 or Borroughs BT-3572-2. The adaptor should be snugged up against the lead pads of the battery with pliers to keep resistance between the adapter and battery terminals at a minimum. This is the preferred method.
- By the use of a 3/8" bolt with standard threads (16 UNC) and 3/8" nuts with standard threads (See Figure 3).
a. Screw 3/8" nut onto 3/8" bolt (1-1/2" or longer).
b. Using fingers, screw bolt into each side terminal until it bottoms out, and then back off one full turn. (Do not tighten with wrench as bolts can be driven through case.)
c. Holding the bolt, screw the nut down on the bolt until the nut is against the battery terminal lead pad. Snug nut with pliers. (Do not overtighten as nut inside battery terminal could be pulled out.)
d. Attach the charger or tester leads to the 3/8" nuts and follow normal charging and testing procedures. The main charging or load test current will be carried through the lead pads of the battery terminals and not through the nuts inside the terminals.
1. Batteries with green dot showing do not require charging unless they have just been discharged (such as in cranking vehicle).
2. When charging side-terminal batteries, install adapter Kit AC Delco part number ST-1201 or Borroughs BT-3572-2. Refer to Figure 3.
3. Make sure all charger connections are clean and tight.
4. For best results, batteries should be charged while they are at room temperature. A battery that is extremely cold may not accept current for several hours after starting charger.
5. Charge battery until green dot appears (See Charging Time Required). Battery should be checked every half-hour while charging. Tipping or shaking battery may be necessary to make green dot appear.
6. After charging, battery should be tested as outlined in "BATTERY TESTING".
EQUIPMENT
A battery charger that is classified as a "Fast Charge" unit generally is considered sufficient, as they are usually capable of about an 18 volt output. When investigating a charger, the following items should be considered essential:
1. A 40-50 amp minimum charge rate.
2. To prevent overcharging, the unit should have a timer (1 to 2 hours) or a voltage regulator that would regulate a maximum of 18 volts.
3. An ammeter or charging rate meter.
4. An automatic polarity protector.
Some equipment that is available include the Associate No. 6001 and the Sun 720. Very few chargers have sensitive low voltage meters, therefore, separate voltmeters may be necessary.
FIGURE 5 - LOAD TESTER:
A suitable load tester such as the Sun VAT-40, shown in Figure 5 (or equivalent) is available and is a very useful tool to properly diagnose battery problems.
CARRIER AND HOLD-DOWN
The battery carrier and hold-down clamp should be clean and free from corrosion before installing battery.
The carrier should be in a sound condition so that it will hold the battery securely and keep it level. Make certain there are no foreign parts in the carrier before installing battery.
To prevent the battery from shaking in its carrier, the hold-down bolts should be tight, but not overtightened. The torque requirements are as follows:
Base Clamp 15-20 N-m (11-15 ft.lbs.)
Bar or Frame Clamp 2.3-4.5 N-m (2-3 ft.lbs.)
Side Terminal Cables 10-20 N-m (8-15 ft.lbs.)