When it is necessary to charge the battery, the following basic rules must be used.
- Use a constant voltage power supply with end of charge voltage of 16.0 volts equipped with a voltmeter that is accurate within 1%.
- If more than one battery is to be charged, the preferred method of charging batteries is to connect them in parallel with each other (+ to +) (- to -).
- Ambient (surrounding) temperature should be 15°C to 38°C (60°F to 100°F). A battery that is extremely cold may not accept current for several hours after starting the charger.
- The charging area should be well ventilated.
- Do not charge the battery if the hydrometer is clear or light yellow. If a cranking problem exists, replace the battery.
- Do not charge a battery if it seems to be frozen.
- Batteries with a green dot showing in the hydrometer do not require charging unless they have just been discharged (such as in cranking the vehicle).
Charging Procedure
Notice: Turn OFF the ignition when connecting or disconnecting the battery cables, the battery charger or the jumper cables. Failure to do so may damage the PCM or other electronic components.
When charging a battery in a vehicle, proceed to the first step. If charging side terminal batteries out of the vehicle, install the adapter kit (AC Delco part number ST-1201, GM part number 12303040 or equivalent).
The adapter should be tightened against the lead terminals of the battery to keep resistance between the adapter and the battery terminals to a minimum.
- Make sure all charger connections are clean and tight.
- Charge the battery using the charger setting for 12-volt batteries that gives the highest charge rate to the battery. (Do not use charger settings for jump-starting vehicles to charge the battery. Refer to the charger manufacturer instructions.) The battery should be checked every half-hour while charging. Tap the hydrometer lightly on the top to dislodge any air bubbles that may prevent a correct indication.
- If the battery feels hot, 52°C (125°F), or if violent gassing or spewing of electrolyte through the vent holes occurs, discontinue charging or reduce charging rate.
- After charging, the battery should be tested. Refer to Battery Load Test .
Charging Time Required
The time required to charge a battery will vary dependent upon the following factors.
| • | Size of Battery -- A completely discharged large heavy-duty battery requires more than twice the recharging time as a completely discharged small passenger car battery. |
| • | Temperature -- The colder the battery, the more time it takes to recharge. When a fast charger is connected to a cold battery, the current accepted by the battery will be very low at first. In time the battery will accept a higher rate as the battery warms. |
| • | Charger capacity -- The higher the charger amperage, the less time it will take to charge the battery. |
| • | State-Of-Charge -- A completely discharged battery requires more than twice as much charge as a one-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 also increase. |
Any battery discharged by parasitic loading, and then allowed to stand in this condition for a period of time, may not accept a charge readily. However, if recharged long enough, many batteries will return to a good usable condition.
If the battery remains in an extremely discharged condition for a prolonged period, it can become permanently damaged. This damage can be accelerated by high temperatures. Batteries which are extremely discharged can freeze at temperatures as high as -7°C (+20°F) and be permanently damaged.
To prevent battery damage and recharge problems, vehicles which are not going to be in service within a 20 day period should have the ground cable disconnected to remove the constant drain on the batteries. If this is not possible, batteries should be recharged periodically every 20-45 days until the green dot is visible or an open circuit voltage of 12.4 volts is obtained.
