Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsBattery Diagnosis and ServiceMedium
A technician is connecting a battery charger to a vehicle battery that is still installed in the vehicle. To prevent damage to sensitive electronic components, which connection sequence is generally recommended?
- ANegative charger clamp to a good chassis ground away from the battery, then positive charger clamp to battery positive.
- BPositive charger clamp to battery positive, then negative charger clamp to battery negative.
- CPositive charger clamp to battery positive, then negative charger clamp to a good chassis ground away from the battery.
- DNegative charger clamp to battery negative, then positive charger clamp to battery positive.
Show answer & explanationAnswer & explanation
Correct answer: C. Positive charger clamp to battery positive, then negative charger clamp to a good chassis ground away from the battery.
Connecting the negative charger clamp to a good chassis ground away from the battery minimizes the risk of a spark occurring near the battery, which could ignite hydrogen gas emitted during charging. This is especially important for the final connection.
Why the other options are wrong
- A. This sequence is incorrect and poses a spark risk at the positive terminal.
- B. Making the last connection (negative) directly to the battery negative terminal increases the risk of a spark near the battery.
- D. This sequence is incorrect and poses a spark risk at the positive terminal.
Battery Charger Connection Safety
When connecting a battery charger to an installed battery, always connect the positive lead first, then the negative lead to a chassis ground away from the battery as the last connection.
- Connect positive (+) first.
- Connect negative (-) to chassis ground last.
- Avoid sparks near battery to prevent hydrogen gas ignition.
- Ensure charger is off before connecting/disconnecting.
Memory trick: Positive First to Power, Ground Away to Guard.