Re: 100 amp charger on sm2k

David Vogel

Greetings all,


I have a top-of-mizzen Rutland 1200, installed 2018, cost to purchase-and-install ~$2,200-. The running count for the wind-gen since it was last reset 920 hours ago Arriving on-anchor, La Playita, Panama), is 547Ah contributed to battery charge; =~ 0.6Ah per hour, =~ 15W average per.hour contribution.  Since last reset, we have been in a typical steady wind, but not-so-windy location.  Previously, when in windy locations (meaning, wind in general blowing always 18 knots, but often 20-30), we were seeing easily double, sometimes triple this, on-average.


These overall production figures are somewhat BELOW what would otherwise be seen in a stand-alone wind-gen set-up (without solar), because at mid-day +/-2.5H when your solar cells pumping it in, or when the batteries are sensed as fully charged, the wind-gen switches off.


Also, when you are on genset (or motoring), sometimes the wind-gen senses this and shuts down also.


But when the wind-turbine is spinning, the output is within 5% of the manufacturers curve (case: windy at night, no solar in competition, for example).


Overall, with the solar and wind-gen, my need to run the genset whilst on anchor is reduced to about 50% of what is was before (no solar or wind).  On longer offshore passages, we have only a few days here and there, so not really able to say.  So I am still planning fuel burn for offshore work on the pre-wind/solar basis of 2 x 1.5 hour genset runs per day.  I am happy with ‘free’ power from the shaft gen – enough to cover the NAV Station – when STW >7 knots.  I switch the shaft-gen off if I really need to squeeze for speed, as I estimate that the shaft-gen pulls the STW down by between 0.5 and 1.0 knot. For really long-distance work (say, >3,000nm), that 1knot pull-down relates to an extra 2 days passage-time.  There is always a trade-off.


I am glad to have the redundancy provided by solar and wind in combination, although this is only partial at best.


We are not at this time considering a second wind-gen.  We are thinking to increase the solar to 800-1,200 watts.  The panels themselves will pay for themselves over time, but the capital expense of the arch is harder to reconcile.





SM#396, Perigee


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