Dear Ray, Our ‘house’ battery bank, that runs all of the equipment on board, consists of 3 lithium batteries of 200 amp-hours each, so 600 amp-hours in total. The boat normally runs at about 15-16 amps consumed per hour. Whereas previous generation gel cell batteries could deliver about 50% of their capacity, the lithium batteries can deliver 70-80% of their capacity. Plus, with gel cell batteries, the voltage slowly goes down, and with the lithium batteries, the voltage is maintained until a precipitous drop off at about 80% depletion.

We have set our alarm on the battery monitoring at 40% capacity, to alert me to get the charging going. But we have diverse charging mechanisms. We have a big alternator on the engine, that can put out 250 amps. yet our combination of hydrogenerators, solar panels and wind turbine, can also keep the batteries going. In fact the hydrogenerator has delivered about 4 times the amount that the engine has delivered, and the combination of solar and wind have delivered about what the engine alternator has delivered.

The hydrogenerators can deliver 30 amps. So they can both run the current boat needs, plus charge the batteries slowly, and when we add in solar and wind, the combination can charge the batteries a bit faster. Yesterday, with sun, I ran all day with the wind turbine and the solar panels, and they maintained a steady state on the batteries. I did not use the hydro generators, because that is the one system that is at risk for hitting something in the water. So we won’t risk it if we don’t need it.

Question submitted by Ray, Philadelphia PA, USA