Electrical Systems - Manufacturer Requirements

Hydrogen gas is very explosive. Boat design and battery installations that permit the accumulation of hydrogen gas must be avoided since batteries emit hydrogen gas. Even "sealed" batteries have venting provisions and therefore must be considered vented batteries.

Hydrogen gas will disperse rapidly and will seek to exit through any opening, particularly through overhead openings, since the gas is lighter than air. Pockets above the battery that could trap and hold the hydrogen gas must be vented. Likewise, a battery box whose cover forms a pocket over the battery must be vented.

Particular attention must be paid to battery installations in special, isolated compartments that are not part of ventilated compartments. These areas may require special ventilation considerations to accommodate battery installations.

If in doubt about gas accumulation in the boat, a test may be conducted by charging the battery in the boat. The boat should be equipped as it would be in normal service, particularly in terms of normally supplied means of ventilation. A gas analyzer may be used to check areas above the battery where hydrogen gas accumulation is possible. If there are no dangerous quantities of gas found, then the installation should be acceptable.

The best practice is to install batteries in well ventilated locations.

The integrity of the battery terminal connections is very important to prevent sparking and overheating of the terminal. Failures of a battery terminal connection could result in a fire and explosion hazard.

By prohibiting spring-type battery terminal connectors, the regulation requires the use of mechanical connections that are not likely to loosen due to vibration.

There are two types of battery terminal connections in prevalent use. They are the clamp type, and the bolt-on type. Figure 17 depicts these types, as well as a spring-type which is
PROHIBITED.

FIGURE 17 - Battery Terminal Connections

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