So guess how many amps / day an autopilot uses? I don't know but assuming 5 amps / hour (I think that would be conservative) We're talking 125/day which even with a HO alternator would take an hour or two to put back. Two hours / day engine run time vs non with a wind vane. What's the cost of running the engine? And battery bank size is not important. It's cycles. Eveything you take out has to go back and that all adds up. You don't have to buy the "arguement". I'm not arguing only applying my observations. Batteries are aged by cycle life. Once one reaches the Pacific and 10 and 20 day passages are made it becomes more of an issue. The east coast and carib which one can do in all day hops is IMHO not offshore sailing. And compared to all the goodies that one has percentage wise it's not that important. Yet it still counts int he daily use and if you have to have a larger bank to take care of all the goodies then that cost must IMHO go into the equation.

Ciao