WaterMota Alternator

The WaterMota alternator is often fitted to Freeman Cruisers with the WaterMota crossflow petrol engine, and occasionally the pre-crosflow engine, to generate electricity for charging the battery.

How does an alternator work?

Alternators are a modern generator of sorts. Alternators convert mechanical rotation into electrical alternating current by means for rotating magnets, static coils and magnetic fields. The rotor, a rotating magnet, usually turns within the static stator, a collection of wire-wound iron core conductor coils. The magnetic field generated by the rotational process (the rotor is spun by the pulley and alternator belt via the engine) develops electromotive force in the stator conductors producing current.

The automatic voltage regulator inside the alternator provides a constant and stable current in order to run the electrical circuit and charge batteries whilst the engine is running.

Does my WaterMota engine have this alternator?

The WaterMota alternator largely took the place of earlier WaterMota Dynamo. In the early days positive earth circuits were popular for both cars and boats. Later, negative earth became the standard. This standard WaterMota alternator is for Negative earth installations which is the most common, especially on the Crossflow petrol engines. However, there are also positive earth systems so therefore check the polarity of your installation.

Is my WaterMota engine Negative or Positive earth?

Either polarity is possible on your boat. The most common is a negative earth system but it is important to understand your particular setup before replacing an alternator.

The easiest way to identify the polarity of your boat is to establish which terminal of the engine battery the "earth" wire leads to the earthing point - usually found on the engine itself. If the earth wire comes from the 'Negative' terminal then this is most likely a negative earth system. If the earth wire leads from the 'Positive' terminal then it is most likely a positive earth system.

My boat has a Positive earth system not a Negative earth system, what are my options?

If you have established that your system is a positive earth setup then please contact us as you will normally require further assistance.