The lead acid storage battery provides the power source for starting small boat engines and other types of small and medium size engines. Most starting motors for the engines in small craft are rated for 24 to 28 volts. To supply the required current for starting, four individual 6-volt batteries are connected in series.

For maximum efficiency and long life of the storage battery, periodic inspections are essential. Batteries that serve to start boat engines are subjected to moderately heavy use and may require frequent charging in addition to the charging provided by the engine generator or alternator.

MONITORING THE CHARGING SYSTEM

As an operator, you should be aware of the condition of the charging system of the engine. You can use the ammeter to monitor the charging system. An ammeter is a device that is wired into the electrical circuit to show the current flow to and from the battery and is mounted on the gauge board (panel) along with the other monitoring gauges. After the engine is started, the ammeter should register a high charge rate at the rated engine speed. This is the rate of charge received by the battery to replenish the current the battery has used to start the engine. As the engine continues to operate, the ammeter should show a decline in the charge rate to the battery. The ammeter will not show a zero charge rate since the regulator voltage is set higher than the battery voltage. The small current registered prevents rapid brush wear in the battery-charging generator. If lights or other electrical equipment are connected into the circuit, the ammeter should show discharge when these items are operating and the engine speed is reduced. Information on the electrical devices we have discussed is presented in detail in Navy Electricity and Electronics Training Series (NEETS), modules 1 through 5 (latest editions).