Battery Charging

Special Tools

GR8 EL–50313 Midtronics Battery Charger/Tester

DCBS EL–52800 E-XTEQ Battery Charger/Tester

For equivalent regional tools, refer to Special Tools.

Diagnostic Aids

  • The correct Battery Type MUST be selected when setting up the test. Selecting the incorrect Battery Type may lead to a false “Battery is bad” result for a good battery.
  • Battery Type selection START/STOP AGM is ONLY for testing the small secondary battery on some vehicles equipped with Auto Stop/Start (KL9) not all vehicles with Auto Stop/Start.
  • Vehicles equipped with Diesel Engines or Dual Battery Option (K4B,) or (TP2) are not for Auto Stop/Start (KL9).
  • The charging area should be well ventilated.
  • Do not charge a battery that appears to be frozen. Allow the battery to warm to room temperature and test it using the before charging.
  • An AGM battery may be damaged if charged to more than 14.5 V.
  • A Flooded Cell battery may be damaged if charged to more than 16.5 V.
  • Vehicles with dual batteries must be charged individually which will result in two printouts.
  • (If Equipped with Autostop/Autostart) If you accidently blind charged the battery by connecting the battery charger directly at the battery terminals, Autostop/Autostart will be disabled. Disconnect and Reconnect the Battery Sensor Module to enable Autostop/Autostart.

Battery State of Charge

Note: Using voltage to determine the batteries state of charge is only accurate after the battery has been at rest for 24 hours. This is enough time for the acid in each cell to equalize. If the battery has been charged or discharged in the past 24 hours, the battery state of charge will only be an estimate.

The maintenance-free batteries state of charge is estimated by reading the voltage of the battery across the battery terminals. Because the voltage is affected by current flow into or out of the battery, the engine must be stopped and all electrical loads turned OFF, including parasitic loads, when checking the voltage. The voltage can also be affected if the battery has just been charged or discharged, so it is important to consider what has happened to the battery in the time just before testing. Use the following procedure to determine the battery's state of charge:

Battery Voltage

% Charge at 0°C (32°F)

% Charge at 25°C (75°F)

12.75 V

100%

100%

12.7 V

100%

90%

12.6 V

90%

75%

12.45 V

75%

65%

12.2 V

65%

45%

12.0 V

40%

20%

Use the state of charge information as follows:

  • A battery with a state of charge that is below 65% must always be recharged before returning it to service or continuing storage.
  • A battery with a state of charge that is 65% or greater is generally considered to be charged enough in order to be returned to normal service or in order to continue storage. However, if the battery is being used in slow traffic or with short drive times, or if the temperature is very hot or very cold, the battery should be fully charged, to at least 90%, before returning it to service or continuing storage.

Charging Time Required

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

  • The battery charger capacity—The higher the charger amperage, the less time it will take to charge the battery.
  • The state of charge of the battery—A completely discharged battery requires more than twice as much charging time as a half charged battery. In a discharged battery with a voltage below 11 V, the battery has a very high internal resistance and may only accept a very low current at first. Later, as the charging current causes the acid content to increase in the electrolyte, the charging current will increase. Extremely discharged batteries may not activate the reversed voltage protection in some chargers. Refer to the manufacturer's instructions for operating this circuitry.
  • The temperature of the battery—The colder the battery is, the more time it takes to recharge the battery. The charging current accepted by a cold battery is very low at first. As the battery warms, the charging current will increase.

Charging Procedure

Warning: Batteries produce explosive gases. Batteries contain corrosive acid. Batteries supply levels of electrical current high enough to cause burns. Therefore, in order to reduce the risk of personal injury while working near a battery, observe the following guidelines:

  • Always shield your eyes.
  • Avoid leaning over the battery whenever possible.
  • Do not expose the battery to open flames or sparks.
  • Do not allow battery acid to contact the eyes or the skin.
    • Flush any contacted areas with water immediately and thoroughly.
    • Get medical help.

Caution: 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 ECM/PCM or other electronic components.

Caution: Refer to Fastener Caution.

When charging side-terminal batteries with the battery cables connected, connect the charger to the positive cable bolt and to a ground located away from the battery. When charging side-terminal batteries with the battery cables disconnected, install the battery side terminal adapters and connect the charger to the adapters.

Battery Charging with EL–50313 GR8 Midtronics: Battery Charging with EL–52800 DCBS E-XTEQ: