I keep my boat on a mid-river mooring
in the Hamble River, and when I'm out cruising, I spend most nights at anchor
. As a result, I am not very often connected to shore power
My power system works very well and I really don't worry too much about electrical
power, either AC or DC. I have 420 amp/hours * 24 volts of Trojan batteries, a Victron 3kW, 70 amp charger/inverter, and a Kohler 6.5kW heavy-duty generator
. On the hook, one (or at most, two) charging
run a day for a couple of hours is generally enough to keep us in electrical
power and hot water
, even with five people on board as we had for this year's summer cruise
I am especially pleased with the batteries, which have been abused by being run out dead flat two different times and left for weeks like that (once a stupid mistake of mine, another time a shore power
failure when the boat was on the hard
being refit). At the moment, they are testing better than they did when new with my Argo capacity tester, and they just go and go, despite living a very hard life. I do avoid discharging them below 50%, and I do equalize them from time to time, but without shore power, they are not brought up to 100% charge very often. They are Trojans, not the true heavy duty ones, but the 12v ones which look suspiciously like car batteries/leisure batteries (these were the only ones which would fit my battery
Now I'm back on the boat for a few days getting her cleaned up and ready to be left alone for a month while I go back to work. And here's my puzzle:
Say you are charging
from a generator
, and not from shore power, like I am. You do not want to run your generator 24 hours at a time, or even 10 hours at a time, as this is a waste of diesel fuel
hours. You are trying to gradually get your batteries up near 100% charge before leaving the boat for a month. How do you do it? Run the genset for 10 hours (or whatever to really get them to 100%, them top them up just before leaving? Or is it better to charge them a little bit at a time every several hours?
It seems to me that the batteries are accepting more charge per hour of genset run if I charge them a little bit at a time. It seems to me that the surface charge dissipates between runs, extending the bulk phase of charging. The less charge being accepted, of course, the less efficient is your genset run.
I do have a small Honda
petrol generator which I bought specifically to put a finishing charge on the batts the last day before leaving the boat. However, the carburetor is clogged again (I bought from a guy who had let it sit unused for five years) and I really don't have time to faff around with it.
I'll be interested in your views on this.