[Public-list] weight distribution and electric power

J Bergquist jbergqui at gmail.com
Fri Sep 29 07:40:17 PDT 2006


I have no idea how Dan is planning to recharge while sailing, but solar
panels are not the only way to do this. 2 other examples are wind generation
and water turbine generation.

Water turbine generation was used by Gelinas during his round the world
cruise. It basically uses a propeller as a turbine, connected to a shaft
which drives a generator. Since a motor and a generator are physically the
same thing, most electric motors can be used as generators, and in fact,
most electric launches are set up in exactly this way.

Regenerative braking in hybrid cars works exactly the same way. This
technology is well established and frankly much older and more mature than
photovoltaic solar power.

I don't know much about efficiency numbers, but if Dan figures he's motoring
for 15 minutes to a half hour to get out of the harbor, followed by several
hours of sailing, I am guessing that since the generator is running at least
10 times longer than the motor (assuming 2.5 hours of sailing for every 15
minutes of motoring), he probably is not going to have a problem replacing
whatever juice he took out.

Plus he'll have a sweet way to recharge his house batteries and replace the
juice taken out by his lights and refrigeration and electronics and whatever
else.

I wouldn't use the system while racing, though...that pesky 2nd law...no
free lunches and all that.

JB

On 9/29/06, John Boor <mahseer at kos.net> wrote:
>
> > yes john, no gasoline.
> >   i was told i can motor 25 to 50 mile before empty. supposedly th batts
> > will recharge as i sail. the system has "smart" chargers that i am to
> > plug in while at the dock. i wont know until next springs sea trials how
> > well any of this works.
>
> Dan
>
> I am looking in to solar panels to recharge my house batteries(4x 225Ahr
> 6volt batteries) my concern is that 2 80watt panels at about 30x48in each
> will just keep my batteries charged when I use my refridgeration (2.5Amps
> per hour) this is with full sun (no shadows on the panels)all day. With
> your 48 volt system and limited sun hours I cannot see your bateries beind
> charged very much while sailing. I hope you have resolved this problem.
>
> John Boor
> MAHSEER #380
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