| Subject: | Battery Charging and Testing Diagnostic Tips |
| Models: | 2007 and Prior Chevrolet W-Series Medium Duty Tilt Cab |
| 2007 and Prior GMC W-Series Medium Duty Tilt Cab |
| 2007 and Prior Isuzu N-Series Commercial Models |
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 04-06-03-009 (Section 06 -- Engine/Propulsion System).
Isuzu has provided the following diagnostic tips to aid technicians in properly charging and testing a battery. Replace the battery only when the following tests have failed.
Common Causes
The following are some common causes that may contribute to a weak or dead battery.
| • | The vehicle headlights and accessories are left on for an extended period of time. |
| • | A condition with the vehicle charging system. |
| • | The electrical load of the vehicle exceeds the generator capacity (such as Bodybuilder add-on power equipment). |
| • | Extended slow speed driving with many accessories turned on. |
| • | Loose or poor battery cable to post connection or corrosion. |
| • | There may be conditions in the electrical system (such as shorted or pinched wires). |
| • | There may be a faulty starter or cranking circuit. |
| • | Slow, extended or no engine cranking. |
| • | Vehicle stored for a long period of time (See Service P&P Manual, Article 2.2, page 2, paragraph b) (In Canada, Article 2.3.2, paragraph b). |
Caution: Batteries produce explosive gases, contain corrosive acid and supply levels of electrical current high enough to cause skin burns. Therefore, to reduce the risk of personal injury when working near a battery, always shield
your eyes and avoid leaning over the battery whenever possible. Do not expose the battery to open flames or sparks. Avoid spilling the battery fluid (electrolyte). Flush any contacted area with water immediately and get medical help if eyes are affected.
Battery Charging Tips
If the vehicle is equipped with more than one battery, disconnect the cables to inspect/charge/test each battery separately in a well ventilated area.
| • | Most batteries are maintenance-free and have a Hydrometer built-in for a visual check. |
| • | Green dot = 65% or above state-of-charge; sufficient for load test |
| • | Dark = Below 65% state-of-charge; charging required |
| • | Clear or Light Yellow = Low fluid level. This may have been caused by excessive or prolonged charging, a broken/damaged case, seal leak, tipping over or normal battery wear-out. Replace the battery. Do not attempt to charge, test or jump start the
battery. |
| • | Charging rates between 3 and 50 amps are satisfactory as long as no spewing of fluid or the battery does not feel excessively hot over 51°C (125°F). If any of these conditions occur while charging, it will be necessary to reduce amperes or
temporarily stop to cool down. |
| | An automatic charger will monitor the charger output based on the battery status in order to protect the battery from overcharge/overheat, but still should be checked every 30 minutes. |
| • | The time required for a charge will vary. This is usually measured in hours. For instance, 25 amperes charging rate for two hours would be 50 ampere-hours charged to the battery. |
| • | Battery Size -- A completely discharged large, heavy-duty battery would require charging more than twice as long as a small passenger car battery. |
| • | Temperature -- A longer time will be needed to charge any battery at -17°C (0°F) than at 21°C (70°F). A warmer battery will accept more charging current. |
| • | State-of-Charge -- A completely discharged battery will require charging more than twice as much as a half-charged battery. |
| • | Charger Capacity -- A charger that can supply only 5 amps will require a much longer time than a 30 amp charger. |
Battery Testing Tips
If the vehicle is equipped with more than one battery, disconnect the cables to inspect/charge/test each battery separately in a well ventilated area. Be sure that the battery is properly charged and the Hydrometer has a Green dot visible before testing.
Test the battery using a Vehicle Charging/Starting System Tester, commonly known as VAT40 or Snap-on MT1552, or equivalent.
- Connect the positive lead of the tester to the positive (+) post of the battery, and the negative lead of the tester to the negative post of the battery.
- Connect the round current-probe cable of the tester onto either power lead to measure the current draw.
- Determine the Cold Cranking Amps (CCA) rating of the battery.
- Apply ½ CCA rating load for 15 seconds and take a voltage reading at the end. Turn off load and wait for 15 seconds to allow the battery to recover before repeating test, if necessary.
- Depending on the battery temperature, if the voltage does not drop below the minimum voltage as shown in the reference table below, then the battery is good and should be returned to service.
Temperature
| Minimum Voltage
|
21°C (70°F)
| 9.6
|
10°C (50°F)
| 9.4
|
-1°C (30°F)
| 9.1
|
-10°C (14°F)
| 8.8
|
-18°C (0°F)
| 8.5
|
Refer to Section 6D-Engine Electrical of the Service Manual for more details.
Warranty Information
Isuzu OEM battery is covered under the New Truck and Chassis Warranty for 12 months/Unlimited mileage.
