Athena 38: General Info

[morningstar10]

I'm thinking 157 ft. might be a tad optomistic. Did you mean 57 ft.?

[Crak]

Yes

17.30m / 57ft

[Rapanui]

I have a 2003 FP Athena and am trying to understand how the charging from the port engine works on the house bank. From observation, when the port engine is running it preferentially charges the so called 'port' starter battery. At a certain point, it then seems from observations of the voltage to start charging the house service 'starboard' bank, which would imply to me there is a voltage sensitive relay involved but it seems to achieve about 0.5 v less than the starboard engine charge voltage in charging the house service bank which would imply a diode splitter is involved. I believe the set up is as it left the factory and have the circuit diagram ATH.ELEC.01 but no specifications for the parts.

On the circuit diag there is a relay 'Relais de couplage de puissance' which I translate as 'Battery power coupling relay' which parallels the starter battery with the service house bank activated by either alternator via another relay which provides the windlass control voltage. However, as the windlass only works with the port engine, I deduce that the diagram is wrong and is really fed from just the port alternator.

Has anyone got to the bottom of how the Athena charging circuit works? I would be very grateful if they could publish a circuit diagram. Thanks in advance. I have attached the electrical diagram from FP.

[Crak]

You can start any engine first, but as the STBD engine is closer to the start battery it is wise to start the STBD engine first. When the alternator charge voltage builds to 12v, (either engine) solenoid "O" closes and parallel’s both the start and house battery's so they all charge together from both engine alternators. (That is the loud “clunk” you hear just after the engine starts) Stopping both engines closes solenoid "O" isolating the start battery from the house bank. Either engine must be started before the windlass can be operated as the windlass gets it's sense voltage from solenoid "O".

[Rapanui]

Thanks for the reply Crak very helpful. I think the link from the starboard engine has been disabled as only the port engine running allows the windlass to operate which is explained in the manual. However, the manual is inconsistent with the wiring diagram which shows feeds from both engines. I am wondering if relay 'O' has gone high resistance which would explain the voltage drop. Will do a test next time I'm on the boat

[Crak]

The windlass (L) is connected to the STBD engine switch and either engine should enable it to work. Check to see if the SBD diode spade connector has not come loose and disconnected. Check to see if you have a volt drop across solenoid "O" and open / clean or replace it if it is too high. Good luck.

Regards,

Craig