Maybe it's because this thing sounds like it has so much juice it's hard to imagine having any problems- although I can remember cruising on a boat with a similar setup and waking up the first morning without enough juice anywhere to crank an engine
, a generator
, or hoist the anchor
One thing I find handy on my boat, which has a much smaller and much simpler setup than the one you describe, is that the battery
bank is switched so that it is in three zones of equal amp/hour capacity. You can run off one zone, any two, or all three at once. I don't remember seeing any battery
switches on the market that allow you to switch between three batteries (or three groups of batteries). A previous owner of my boat made this setup by using two separate battery switches.
It works out that each zone pretty much has enough capacity to handle the boat for 24 hours at anchor
. This is very useful for cruising. If the voltage starts to get low, I can switch to another zone and still have one zone untouched for starting the engine
later. That way I don't have to wake up the wife or other passengers for charging
All three of the zones are the same kind of deep-cycle batteries. I don't have a separate battery for cranking.
If you set up the batteries this way, you might want to try to plan your appliances
and usage so that a typical 24 hours of consumption
is no more than 1/6 of your total battery bank's amp/hour capacity. (You shouldn't draw your batteries below 1/2 capacity, and each zone would be 1/3 of the total amp/hour capacity in the bank.)
Although it sounds like you have three independent sources for charging
the batteries (two engines and a generator), you might want to consider adding some solar
as a backup. I did feel pretty silly sitting out in the anchorage in that trawler
with an engine room full of dead batteries.
A lot of cruising sailors try to set up enough solar
generation to meet, or nearly meet, their 12 volt demands while on anchor. But most of the trawlers I see out there seem to rely on primarily on their generators for charging while at anchor.
Also, for what it's worth, I didn't exactly plan all this setup out in advance. It took a a year or so of fiddling with loads, wiring
, batteries, charging schemes, etc., before I sort of learned what the boat would do and settled into a happy balance. In the beginning, I was a bit baffled and frustrated by it all.
Hope this is of some help.