Every internal combustion engine has an alternator. This is a current generator driven by the engine. Today, alternators are actually always alternating current generators, often with built-in rectifiers and voltage regulators. The rectifier converts alternating current into direct current to charge the batteries. The voltage regulator provides a nearly equal output voltage (voltage), regardless of engine speed. If the alternator is not working properly, the boat's battery will not be recharged or will be recharged poorly. This will eventually lead to starting problems.<\/p>\n
First, an alternator must rotate properly with the engine to generate power. In inboard engines, the alternator is driven by a V-belt or multi-belt. This belt can break, causing the alternator to stop turning with the engine. Also, the belt must be properly tensioned. If it is too slack, the belt will slip and the alternator will not turn properly.<\/p>\n
It is often wise to check the simplest problems first. A loose wire, broken wire, or ill-fitting connection will obviously cause problems. Check that all wires on the alternator are tight. They should not move on the connection, nor should the wire itself move in the pinched eyes. If it does, this should be fixed first.<\/p>\n
For the alternator to work, it needs to be energized once. Thus, when the alternator starts running, it briefly needs a 12-volt current to become energized, after which the alternator will work and keep itself energized. If this excitation remains off, the alternator does not supply any current. Older boats often have a separate alternator control light on the boat's dashboard, often a red light. Through this light the excitation current goes to the alternator. When this light is broken, the alternator is no longer energized.<\/p>\n
To detect problems with the alternator, a number of things can be checked. Be extremely careful around rotating parts with hands, loose clothing, long hair, and so on.<\/p>\n
The charging current (amperes) can only be measured with the proper knowledge and tools. If you do not have this, it is better to omit this check.<\/p>\n