Sorry to wait so long to offer a few suggestions and challenges:
The first challenge is to seriously question the philosophy of using batteries separate from the main house bank for thrusters/windlasses. This question has been discussed with intelligent arguments against the use of separate batteries since the 80's. The argument boils down to the concept
that with your proposed system design the weight of cabling from your house bank to the windlass
and thruster will be less than the weight of your added batterys. If you have the room put the extra batteries into your house bank thereby decreasing the source resistance and increasing the voltage under load of the bank for all uses. In addition, the cable weight will be distributed rather than lumped into a place which will probably add to the pitch
moment of the vessel.
The necessity of using a manual ac switch to select between shore and inverter power is obviated by the selection of an inverter/charger which is capable of internally (and automatically) transferring the entire 30A shore power
. With a good remote
control for the inverter/charger you can choose to enable or disable either "auto-invert" or "auto-charge". With "auto-invert" disabled if the vessel is unattended and the shore power is removed then no heater loads will deplete your battery bank without your knowledge.
Do you have the ability to mount a large frame (9inch dia.) high output alternator in addition to the existing one?
What is the stall current rating of your starter motor
? This determines the selection of a fuse rating from the battery. I am opposed to the inclusion of a fuse between a start battery and the starter. Any nuisance opening of the fuse is potentially dangerous when you need to have that engine
in an emergency
. ABYC allows for no fuse with short cabling distance and good wiring
practices. Yes, you would still fuse a cable from the start battery to any other switch or item other than the starter.
Yes, you should have a "real" battery monitor
for your house bank.
Consider designing in either an isolation transformer preferably the new "switch-mode" light-weight one that Mastervolt has introduced for the US market or at least one of the torroid transformer types that are lighter and smaller than the old technology non-torroid types (new winding machines have enabled the production of high power torroids that did not exist several years ago thereby making them more affordable as well as more efficient). We need to realize that ABYC may "dictate" that existing galvanic isolators are not acceptable without so much internal electronics
for monitoring the integrity of the device that the cost of such a product will approach that of an isolation transformer. In addition, with the inclusion of an isolation transformer the necessity of ground-fault monitoring may be simply accomplished with branch circuits like in the galley
. Any consideration for external ground-fault monitoring only needs to be between the dock
and the end of the shore power cable at the boat, and in the future dock
power boxes may be required to have them built in.
Before commenting on any other details regarding your system design it is necessary to make decisions about these basic considerations because the details beyond these basic ideas will follow from them.
Design attributes which make automatic power transfer and switching (ac as well as dc) when done properly removes the requirement of anyone having to be schooled about when and where switches must be thrown and under what conditions. There will be a lot of comments about this philosophy, especially that "KISS" thing which I hate to hear anymore as though one equates "automatic" or "more involved" with a lowering of reliability
which innately is untrue. In fact the concept
of "KISS", as is generally interpreted, is actually a logical fallicy.
An an example, I have set up a few boats so that someone relatively uninitiated with the electrical system
can connect or disconnect the shore power cord at any time with or without throwing any breakers and have no problems result. They can use the microwave, toaster, hairdryer, 120V TV/DVD tied into a 120VAC sound system and not be concerned about throwing switches with or without shore power. If the owner is not aboard and there is no shore power available she can tell a guest aboard to use the conveniences at will merely noting an illuminated bar on the battery monitor/inverter/charger controller. If the "bar indicator" turns from green to amber turn on the engine
and let it run until the bar turns green again and then turn off the engine. No swiches have to be changed,nothing else has to be done. If the shore power returns or goes away it not matter. No one has to understand what is an "Amp-hour" or what voltage means what. Think about it.