Hi, Kevin, thanks for the interesting mine of info on this.
Seems that it is not as easy as I thought.
Am I correct that you are saying that you have a wind generator that
produces
100 volts, and you feed this direct to the battery with no controller,
and the
'shorting' effect of the battery cushions it at roughly 12 volts?
Hmmm, if that's the case, might be better not leaving that running
unattended!
I have, in the few days since my last post, checked out my little
'battery top-
up' solar panel a bit more. It is about a single watt, as far as I can
remember.
You would think it would be written on it, but nothing, not even in
Mandarin.
Seems from my experiments that the volts do not go much lower when it is
faced even 45 degrees away from
direct sun.
I am not sure if panels get the power from the sun increasing the amps,
or just
the volts, but if it is solely the volts, I was getting 20 when facing
the sun,
and still as high as 17 or 18 when it was no longer direct. And I was
still
getting well over 14 volts even with no sun, just light, medium bright
day, but cloudy.
If this is the case, I could fit solar panels on the insides of the
cockpit
footwell when away from the boat. There is also a little room under
where the
hatch slides to when open. Again, my understanding is that provided I
get over
about 13.7 volts, I am good to go, just feed it into a charge
controller, and
bingo. I realise that a controller probably converts the extra volts
into more amps, so the higher the output the better.
I have to admit to have given up on the idea of a small trickle charging
windmill. Maybe something to experiment with later. I suspect solar
might be
better suited. Your experiences seem to back that up.
I am going to soon be wiring up for the bilge pump, and once the boat is
in the
water, will get a pair of batteries, one I can put on the car as a
second
battery to charge when doing the 30 mile or so drive to the boat, then
swap them
out each visit or as required. Or I might find that I have no need to.
My first electric drive experiment will hopefully be using a 24 volt 500
watt motor, on a
15 foot dinghy as a test bed. I will know more about that later this
week, I am
trying to gather parts locally to avoid massive shipping charges.
I probably will not pull out the Atomic 4 gas engine from the sailboat
this
season, but neither will I bother getting it running.
So, from what you are saying, windmills on boats are problematic.
I just might be able to get enough power from solar panels, bearing in
mind that
I will have only two batteries, not a big bank of them.
My understanding is that I can just add panels wired in parallel, and if
so, I can
build up a piece by piece system. And I can mix in wind power later as
well, I
assume, provided I have diodes so the power goes only one way. I know
that adding small panels is expensive, but it also gives greater
redundancy if a panel gets broken, and they can be hidden more,
especially on a small boat, where larger panels would look overpowering.
(no pun intended, but it was a good one!)
Another place for solar when away from the boat would be directly in the
windows, kind of against the
glass.
That would give me about 5 watts from a single square panel in front of
the
hatch, and another 4 watts total from the main windows, and I could
probably fit
another couple of 1 watt ones beside the mast. About 10 watts, but at
low
efficiency. Maybe another 5 watter vertically over the hatch door while
away.
Low efficiency, but quiet. And that is with only discreet mounting
places used.
Overall, I think after looking at what you have experienced, I ought to
be
getting a few solar panels first, then look into wind as a secondary
thing.
Even using 24 volts, I can charge 12 v singly, and have a changeover
system like
RV use, in their case charging the starting battery first, house battery
second.
Interesting that your experiences match my own reservations, with having
stuff whizzing around!
Of course, at the low levels of solar I am speaking of, maybe a mini
windmill or two makes a bit more sense.
My battery drain might not even be measurable most of the time. Just a
few minutes use for approaching and leaving a mooring. But, human nature
being what it is, the appliances get added later, or, laziness
encroaches, and the sails don't go up as often as they should.
It will be interesting to see what comparative results you get with a
'designed' prop.
Thanks again,
John
2a. Re: Re Charging controllers. amps - supplemental to 'amps explained'
Posted by: "Kevin Pemberton" pembertonkevin@gmail.com the_right_lane
Date: Fri May 27, 2011 2:21 pm ((PDT))
Hello John,
I have been playing around with the wind for a while. The wind-generator
I now play with trying to get things just right will produce over 100v
open circuit. Charge control can be accomplished by shorting the leads
coming from the generator, and is the most common way of limiting charge
current. 100 volts from a limitless supply could be a big problem when
shorted out, but because (like all natural supplies) the power behind
the circuit is so low. The battery bank will shunt the voltage down to
charging voltage without as much as a spark. Well ok a little one, but
the wires (12gauge) don't show signs of heat.
The generator I have built from parts (not a motor of any sort) is rated
close to 3hp (2000w). my last attempt proved poorly. It was an auto
alternator re-wired to produce 48v by using smaller gauge wire with more
turns. Installed were PMs on the rotor, but alas the generator would not
stop the blades in a blow so proved dangerous.
The blades purchased from the survival unlimited site are of such low
pitch that a stiff breeze is required to start turning. These are the
same blades I am now using on the latest attempt but I have changed the
pitch of the blade. With out the change the blades would howl loud
enough to wake people a mile away when unattended and the wind came up.
I am happy to report that using my oversized over-voltage (100+v open)
the windmill while charging is whisper quiet and operates at almost
stall while pumping 13v into my battery.
Today's test (gusts as High as 40mph) would not make the windmill over
spin even when running open. The 29 series battery used for the test was
topped from a starting voltage of 12.00v by 2PM. This is not bad
considering the blades were designed for higher speed usage and were
running at an almost stalled condition. To top this off changing the
pitch altered the effective foil from hub to tip.
What I didn't like about previous generator set-ups:
Unless you are on a mooring (not at anchor) when the wind picks up
enough for a wind-generator to produce useful current Anchor watch is
necessary. Add to the problem wind-age that affects the way the boat
lays, as well as strain on the anchor rode.
I once had to go to sea in a blow because I became exposed to the wind.
The wind generator kicked in as we were getting ready to head out.
Communication because of the noise became almost impossible.
Any anchorage windy enough for a wind generator is most uncomfortable,
making the anchorage undesirable or the wind generator, take your pick.
One more bit. notice the conditions for my test today. 20mph will get
most wind generators rotating. some will stay turning at speeds as low
as 7mph. Most will not produce as much as a 45w solar panel at that low
a wind speed. At 20mph the output is not that great. 40mph is as close
to gail force as I want to get on the water ever again. I have been
there, done that, and it made for a very long uncomfortable night as I
made unbelievable way on my passage.
McMaster Carr used to sell panel mounts for stanchions. now that is not
what they were made for but they worked great. I had two panels that I
could drop vertically when I wanted them out of the way. Boats house
electric may be the best use of solar panels to date. By my own
experience I don't thing wind generators are. By the way. My next
project wind generator is the manufacture of a classic style prop
designed for wind generators and a much lower RPM than other blades on
the market today, we will see how that goes. I am going to use an Oscope
to measure the RPM my generator puts out charging current and make the
blade based on that.
Kevin Pemberton
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