The electrical system .... where to start ....... it's a big topic on a boat like this.  I guess we should start at one end or the other, so let's start at the DC end and work our way to the AC mains.

Batteries & Charging
All batteries on the boat are Amalgamated Glass Mat (AGM) construction.  The House DC system is configured for 24v except where 12v is required for some equipment like radios and certain instrumentation.  The 12v is provided via Victron DC/DC conversion rather than have a separate 12V battery system, which would then need a 12v alternator or other form of charging.  The 12v breakers are all mounted on the main panel, in their own section, positioned between the 24v and 230v panels. 

I wanted plenty of reserve battery power to avoid continually having to run the generator every time we wanted to run a 230v appliance, so the house batteries have been sized at 2000A/hr providing approximately 20KW of useable power before they need charging (2000A/hr actually provides 24KW at 50% discharge, but I don't like to deep discharge batteries).  This is provided by two separate banks each of 12 x 2v cells at 1000A/hr each, which as well as powering much of the boat, also provides good balllast as they weigh 66kgs (145lbs) each!!

The house battery charge will be topped up during the day by solar panels on the flybridge hardtop and can be charged from the main engine 80A alternator, a separate 220A Balmar alternator driven via a hydraulic motor, which can be powered either from the main engine or generator, or from the generator itself via the 3 x 100A Mastervolt battery chargers.

The maximum charge on the batteries is 200A, which with such a large bank, requires several hours to complete the bulk charging phase alone when batteries are at a low level of charge.  Therefore, another switch has been added to allow the house banks to be isolated into two banks for bulk charging from the generator.  The 300A battery chargers charge one bank while the 220A hydraulic alternator charges the other.  The excess 100A on bank 1 and 20A on bank 2 allows for maximum charge while maintaining the ships services.

In reality of course, it is impractical to charge the batteries fully at every charge as the absorption phase can take endless hours and you end up running the generator for very small amperages, which is not only poor economics, but is bad for the generator as it will be running under low load.  It is therefore common to only charge to around 85%, as long as you bring the batteries to full charge regularly, which would be done while underway or on shore power.

Not only does this configuration halve the time required for the bulk phase of charging but it has the additional benefit of doubling the load on the generator.

For base load and absorption charging phase, 8 x 135W solar panels have been fitted to the hardtop and these should should provide between 150A and 200A per day at 24v (3.6KW to 4.8KW), depending on the amount of direct sunlight and the ships lattitude. 

As the hydraulic alternator can be driven from either the generator or the main engine it can also be used for providing a high level of power when using the 5KW inverter for 230v AC air conditioning or washing machine etc, while underway thus avoiding having to run the generator. 

We have made some 230v switching changes so that we can run the higher powered 230v services via the inverter without starting the generator.  Having a 5KW inverter, a large battery bank and a large alternator allows say the Pilothouse air conditioner to be run from the main engine while cruising or running the washing machine while at anchor, without having to run the generator.  It did not seem a good solution to have to run the generator for an AC service while underway, when there is more than enough power is already being generated. 

The battery chargers will provide plenty of charging capacity from shore power or additional charge when running the generator.  Chargers are Mastervolt and there are 3 x 100A for the house batteries and a separate 1 x 50A for the engine & generator starting batteries.  The 80A main engine alternator provides nearly a 2KW output, which is more than sufficient power for the general house keeping tasks while underway and this is augmented with a hydraulically driven 220A @ 24vdc Balmar alternator, which can be run as required.

The solar panels are particularly exciting.  Two sets of 4 panels each fit perfectly on the hardtop, allowing a 150mm (6") walkway down the middle for access to the radar mast.