T&T: Wiring diagram for adding inverter to DC system

[David&Joan]

John:

You first have to decide on your cruising profile: how many days at anchor 
vs motoring and how long you are going to motor to the next anchorage.

Most boats with refrigeration, will use about 125 amphours per day. So if 
you are going to be at anchorage for two days you will need say 125 x 2 x 2 
= 500 amphours of battery capaciy. The first 2 factor is days and the second 
2 factor doubles the battery capacity so you don't discharge below 50% for 
best battery life.

Then the maximum alternator you can install is 1/4 the battery capacity or 
125 amps, maybe a bit more if you have all AGM batteries. Then see if the 
number of hours cruising to your next anchorage will replace the 250 
amphours. If not add more battery capacity.

There are practical limits to this. The largest large case alternator is 
about 200 amps. Your 1" serpentine belt will probably handle this load. But 
you would need 800 amphours of flooded cell battery capacity to absorb all 
of those amps safely.

For wiring, go to the Xantrex site and download the manuals for their 
inverters. They will give you several wiring options.

David