Late season summary

I have spent some time in September redesigning the DC electrical system.

Heavy electric usage, charging the dinghy motor battery from the static inverter and operating the refrigerator while cruising this summer, pointed up the fact that the alternator and the shore power charger were both undersized.

I had already purchased a new charger, so I installed it early in September. I intended to install a remote monitoring panel, but I had bought the charger so long ago that its model is now superseded, and I couldn't find the panel at any distributor.  The panel has been back ordered, and I shall install it in mid-October.

I found a new alternator which could be bolted onto the Westerbeke engine, from Electromaax, a company in Canada.  Its capacity is 120 amps instead of the 50 amps of the Mitsubishi alternator originally installed.  Of course, the larger alternator will need better cables, because its currents will be larger.  It will call for a new ammeter for the engine control panel, because the scale of the present one is limited to  60 amps.  I think it needs an external regulator, to protect the batteries from overheating and premature failure; I will install temperature sensors on the two batteries and alternator.

In addition to the expanded electrical demands, the alternator is a substantial mechanical load on the engine, so it cannot be driven by the single 3/8" belt used by Westerbeke.  I found a serpentine belt conversion kit from Electromaax, so I shall replace the pulleys on the engine crankshaft and its coolant pump with serpentine pulleys.

All of the alternator modification is very simple, except that the centerboard pendant runs in a pipe only about 3/4" from the coolant pump pulley.  Removing that pulley will require disconnecting the pendant and moving the pipe, which can't be done while the boat is floating. Therefore, the alternator installation will have to be deferred until after the boat is hauled.

The one job I completed in September was to replace the single-circuit battery selector switch with a dual-circuit one.  With the dual-circuit switch, the engine battery is connected to its starter separately from the circuit from the house battery to its loads.  I hope that this will prevent the radar and GPS from being rebooted when the engine is started.

Charging the batteries could be a problem since they are now not on the same circuit.  The shore power charger can charge both batteries independently, so they will be brought to full capacity alongside the pier.  When using the engine the alternator is connected only to the engine battery, but I have an automatic cross-connect relay, which connects the two together when the voltage applied to one or the other exceeds 13.6 volts.

I also installed the fuses now required to be within 7" of the batteries on clever fuse holders designed to be bolted onto the battery terminal clamps.  I selected 200-amp size, because the starter is supposed to require 150 amps.  The documentation of the engine starter capacity was quite vague, though,so it's not completely clear that these are large enough.