Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsBattery Diagnosis and ServiceMedium
A technician is testing a sealed, maintenance-free battery. Which of the following tests is typically NOT performed on this type of battery compared to a conventional flooded lead-acid battery?
- AParasitic draw test.
- BOpen-circuit voltage test.
- CBattery load test.
- DSpecific gravity test.
Show answer & explanationAnswer & explanation
Correct answer: D. Specific gravity test.
Specific gravity testing involves using a hydrometer to measure the density of the electrolyte, which directly indicates the state of charge. Sealed, maintenance-free batteries do not have removable caps to access the electrolyte, making a specific gravity test impossible to perform. The other tests (OCV, load, parasitic draw) are applicable to all 12-volt automotive batteries.
Why the other options are wrong
- A. Parasitic draw testing measures vehicle current consumption, not battery type specific.
- B. Open-circuit voltage can be measured on any battery type.
- C. A load test is essential for assessing the cranking ability of any battery.
Specific Gravity Test
A test that uses a hydrometer to measure the density of the electrolyte in a flooded lead-acid battery, providing a precise indication of its state of charge.
- Only for flooded (serviceable) batteries
- Higher specific gravity = higher state of charge
- Readings vary with temperature
- Requires access to individual cells
Memory trick: Sealed means no peeking inside for specific gravity.