Assuming you are planning on venturing onto the deep blue sea you have to design for the worst case scenario. It is the middle of the night and you have been motoring for far too long because the wind you were counting on never showed up. If you are lucky the batteries are strong enough to start your genset. The panels didn't do much because it has been cloudy for the last couple of days. There is no wind but there is a current pushing you towards the rocks or a bridge or other hard objects. Now the genset has to provide all the power to the 8.5 KW motor. That's the rated output (shaft). The input power would be easily 11 KW because of motor and drive losses. If you want to recharge your batteries at the same time you have to add another 2 KW to 3 KW. We are getting close to a 15 KW genset. This is a hard pill to swallow but you have to be honest with yourself. Thanks. Steve S.
--- In electricboats@yahoogroups.com, "v40beth" <mrkgillis@...> wrote:
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> Eric and Steve-
> Thank you so much for responding. I can make my own plumbing and sew my own sails, but this hybrid stuff is new to me. A number of people are pressuring me to get the Beta genset which is rated at 9.5 KW. Eric, my calculations were along what you did, And I was thinking that on batteries alone I could pretty well do everything I wanted to do, but the genset will be there for extended times on the hook and for those little things that tend to drive the volts down in the batteries. ( I will be using AGM's BTW) As I have read Nigel's study on this, I need a genset sized to the average draw, not the acute draw of a panic move on the motor, or 10 minutes on a stove etc. My battery set needs to be big enough, but if I have the genset just to top it off, or run through slack water (dead calm) in the ocean, why do I need a 500 lbs flesh eating monster? (the smaller genset is 210 lbs)
> But you guys have been there and done that. I am only speaking theory. I have the bucks to do either, but I do not want to turn my boat into a large party boat where the fun never stops (ie entertainment via electricity)
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