You are in the planning stages of replacing a battery charger, where an exact duplicate of the charger to be replaced is not available. Obviously the charger must be suitable for the battery to be charged. According to 46 CFR, Subchapter J (Electrical Engineering), which of the following is a true statement concerning battery chargers?

Correct Answer: Option B — Battery chargers incorporating grounded autotransformers must NOT be used, and if the charging voltage exceeds 20% of the battery line voltage, automatic protection against reversal current must be provided.

Per 46 CFR Subchapter J (Electrical Engineering), battery chargers incorporating grounded autotransformers are strictly prohibited due to severe shock and grounding hazards, and automatic reverse-current protection is mandatory when charging voltages exceed 20% of the battery line voltage.