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Tahoe / Yukon Service Manual

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. Refer to the link below under Reference Information for 12 V Battery Usage tables. Battery Type selection START/STOP AGM is ONLY for testing the small auxiliary battery in the trunk on some vehicles equipped with Auto Stop/Start (KL9) and not all vehicles with Auto Stop/Start. For vehicles with Dual Batteries the batteries MUST be isolated and charged separately. 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. Reference Information Description and Operation Battery Description and Operation Electrical Information Reference 12 V Battery Usage Battery State of Charge

  1. Be sure all electrical loads are turned OFF.
  2. Determine whether the battery has been used in a vehicle or charged within the past 12 hours. If the answer is no, the terminal voltage will be stabilized and no action is necessary before reading the voltage. Skip to step 3. If the answer is yes, terminal voltage will not be stabilized and you should wait 12 hours since the last time the battery was used.
  3. Estimate the battery temperature by determining the average temperature to which the battery has been exposed for the past 12 hours.
  1. Measure the battery voltage at the battery terminals. Refer to the following table to determine the state of charge according to the estimated battery temperature:
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

  1. Ensure that all of the battery terminal connections are clean and tight.
  2. Connect the charger positive lead to the battery positive terminal on the battery or the remote jumper stud underhood.
  1. Connect the negative charger lead to a solid engine ground or to a ground stud in the engine compartment that is connected directly to the battery negative terminal, but away from the battery. If the negative battery cable is disconnected and a terminal adapter is being used, connect directly to the adapter.
  1. Select ”Charging,” “Diagnostic”, “In Vehicle” when setting up the charger.
  1. Select the proper battery type, FLOODED, AGM, AGM SPIRAL or START/STOP AGM (small auxiliary battery in trunk), Enter the CCA as shown on the battery label or Refer to: 12 V Battery Usage.
  2. Follow the on screen instructions to compete charging. Battery Charging with EL–52800 DCBS E-XTEQ
  3. Ensure that all of the battery terminal connections are clean and tight.
  4. Connect the charger positive lead to the battery positive terminal on the battery or the remote jumper stud underhood.
  1. Connect the negative charger lead to a solid engine ground or to a ground stud in the engine compartment that is connected directly to the battery negative terminal, but away from the battery. If the negative battery cable is disconnected and a terminal adapter is being used, connect directly to the adapter.
  1. Use the VIN Scan feature or manually select the proper battery type: Flooded, or AGM.
  2. Verify the CCA as shown on the battery label.
  3. Select “Fast Charge” (rabbit icon).
  4. Select appropriate location of charging clamps (Battery Terminals or Jump Start Post).
  5. Follow the on screen instructions to compete charging.