For the house bank on Moonshadow, I am using eight Hella Endurant six-volt, deep cycle lead acid batteries, wired in series/parallel. I purchased and installed these in Auckland, New Zealand in 1999. This gives us a total of 880 amp hours at 12 volts, or about 440 usable amp hours.
When we are passaging or on the hook, I normally charge every day. The generator charges through a Heart Interface Freedom 25 Charger/Inverter controlled by a Heart Interface Link 2000 battery monitor. To speed up the charging process, I have programmed the charging voltage pretty high at 14.5 volts, but normally only charge the batteries to about 85% of their rated capacity, or about 138 amp hours down from full.
If we are motoring or motor sailing and as a backup to the generator charging system, we have a Leece Neville 160 amp cruising alternator belted to the main engine. It runs through a Heart Interface Incharge 3 stage regulator.
When we are plugged into shore power, I have a Professional Mariner Promatic 50-3 three-step automatic charger that keeps the batteries topped up to 13 volts. The nice thing about this charger is that it can be wired to accept either 110 or 240 volts, depending on the local electrical supply.
On the hook, we normally burn through about 200-250 amp hours a day. We’ll never be accused of being conservative in our usage and also have a 12-volt refrigeration system. This translates to about two hours of genset time per day. While we are running the genset we can also make fresh water, heat water, fill SCUBA tanks, do a few loads of wash or if it’s a hot day, run the aircon while we’re below cooking a meal. Under sail our usage is higher, 300-350 amp hours a day, due to the added loads of the autopilot, radar, electronics, nav lights, sideband radio, CD stacker, etc.
I estimate that my current house battery bank has done about 350-400 cycles and expect (hope and pray) that I can get about 1500 cycles out of it with regular maintenance and conditioning.
For the start bank, we’re using two heavy-duty gel cell, service free batteries. Both the main engine and the genset have small alternators dedicated to topping up the start bank, and there’s a set of crossover switches in the event that I need to use house batteries for starting, start batteries for electronics or house functions, or either charging system to charge either or both of the battery banks.