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
On 05/24/2011 12:08 PM, John Green wrote:
I would like charging amps explained pls.
Posted by: "John Green" v_2jgree@operamail.com john_green1947
Date: Mon May 23, 2011 12:45 pm ((PDT))
Thanks, I got it. Great replies. Thanks for keeping it simple. I have to
make sure that I have a charge controller suited to the amps load
expected, am I correct?
I will have to wait and see what I end up with for a wind generator.
I am looking at a design called the Chispito, using a dc treadmill
motor, with 4 foot diameter blades.
I have a supplemental question, again regarding the
same/similar/relative subject, hence the retitling of the thread.
I prefer not to have max wind power generation all the time. It is a
liability issue, with blades whizzing around unattended achieving only
bearing wear once the batteries are fully charged.
I would like to have a secondary charging system, with very low amps
involved. Can I assume that I can manually switch the feed to the charge
controller (that will be selected/purchased for handling larger amp
loads) from a large windmill to a smaller one that will give a trickle
charge and will only be as dangerous as the average electric fan.
(maybe a solar panel might make sense, I hate the look of them, and my
room to mount them is almost non-existent, but I could maybe have it to
fold/stow when I am present and the larger wind power is running.)
My projected batteries will be low cost Walmart type marine or similar
so-called marine or floor cleaner batteries. I want to have no shore
dependency, expected initial boat use maybe 3 times a week.
I suppose I might be asking here, does a larger amp handling charge
controller consume power to a greater degree than a smaller one? ( I
don't want to end up consuming more power than the small windmill makes)
Maybe I can just use a diode to prevent the battery running the small
generator, in the same manner that the very low output solar panel
'battery maintainers' do? What happens if this ends up in overcharging?
Can I assume that if I choose a charge controller that is too low in
capacity, that the thing will just destroy itself?
The reasoning for asking this is that the easy way for me to go is to
spend a little extra, and get a charge controller that can handle larger
loads, but I would like to know if there are snags in doing that?
Again, I might be overthinking, I might just get a 'large' windmill
selected, and then I can experiment with the smaller one while taking up
rum drinking on sunset nights at anchor.
Thanks again,
John
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