Any small power-miser fans that would run in a stored boat?

[mastreb]

I'm going to stick my neck out and guess that the difference between inside and outside is actually mostly due to luminous intensity and not wavelength mix. I'll find someone who knows something about optics and run the calc and report back...

It's all about luminosity.

[Sumner]

....I'm going to learn more about your MPPT controller. I seem to recall you mentioning they are vastly superior......

Not really vastly, but enough so that I think if you are really trying to live on the boat for extended times that they make good sense as you only have room for so many panels. May as well make maximum use of them. I also keep all of the wiring from the panels to the charge controller and on to the batteries sized for less than a 3% loss at max. panel output, which would be even less when the panels are not producing max. amps.

I had a hard time getting my head around why the MPPT is more efficient than the PWM controller and why they are so much more. Basically the PWM just connects the panel to the battery in pules of different widths. If the battery is discharged down to 12 volts then the panel that is putting out about 17 volts drops down to 12.

Take an 80 watt panel that is 17.2 volts and puts out 4.65 amps at that voltage...

http://www.solarblvd.com/Solar-Panels-& ... _info.html

... 17.2 X 4.65 is 79.98 watts or 80 watts. If the panel connects to the battery and is now 12 volts at 4.65 amps then it is producing 55.8 watts (12 X 4.65 = 55. and that is what you are going to get with the PWM controller. The panels voltage can change but it can't produce more than 4.65 amps.

The MPPT controller can take the panels output and raise the amps at a lower voltage. So it will change the panels 4.65 amps into 6.66 amps at 12 volts and you will then be producing 80 watts again. Its circuit to make the amperage change is more expensive to make than the PWM's simpler switching circuit.

Of course the above figures are ideal and it isn't quite that efficient. If you are charging a battery that is down you will see the voltage rise as the battery comes up to full charge. As the charge voltage rises the difference in efficiency between the two controllers becomes closer together.

If we are charging with the gen-set we usually stop when the amps going in gets down to about 10 amps and/or the voltage starts getting up over 14 volts. It takes a long time running a gen-set to top the batteries off. The panels are really good at that.

For the MPPT controller to really work it is best that all the panels or the same. In our case we run three different wattage panels at the same time, but they put out the same voltage and the cell type is the same. That is key to using one of these.

Not sure if any of the above makes sense...maybe google it or this might help...

http://windsun.com/ChargeControls/MPPT.htm

On another matter looks like we are a little over 700 miles apart. I have the shop full with sewing projects now, but if it wasn't you would be more than welcome to use it,

Sum

Our Endeavour 37

Our Trips to Utah, Idaho, Canada, Florida

Our MacGregor S Pages

Mac-Venture Links

[Kittiwake]

I'm going to stick my neck out and guess that the difference between inside and outside is actually mostly due to luminous intensity and not wavelength mix. I'll find someone who knows something about optics and run the calc and report back...

It's all about luminosity.

I agree with Mastreb, Catigale: I think you and I are talking about the same thing by different 'names':
From Wikipedia:
"luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye."
Although one could perhaps rationalize indoor-vs-outdoor photocell observations without invoking UV light effects, I would be surprised if (invisible-to-humans) UV is not a major contributor since it is largely blocked by windows.

Kittiwake

[seahouse]

Hi All!

Connecting one computer fan to another is great for illustrating first principals of generator=motor and motor=generator, but I would be very surprised to find that, because of gross inefficiencies and lack of control circuitry, there would be a practical real world application for it. Not unlike the electric motor made from a nail.

Sum’s MPPT circuitry is practical for wind turbines as well as PV cells. If you are a sceptic, click here http://www.youtube.com/watch?v=0TE38SOd ... r_embedded for a good illustration of this fact, and of the efficiency benefits MPPT offers. PWM is the common control now, so I am looking forward to seeing more MPPT circuitry in the future. It has benefits when the source is at a low output over PWM.

Obviously the intensity of the light is a factor with power output of photovoltaics. Less obvious (and, after all, the less obvious facts are the ones really worth knowing aren’t they) is that PV cells are designed for specific light wavelengths, and can not currently be manufactured broad-spectrum sensitive, which is one source of their inefficiency. The solar cells in your solar-powered calculator that work well under indoor light (although it is also a low current load) are sensitive to different wavelengths than ones made for outdoor use.

- Brian.

[Kittiwake]

I'm not sure what the point is to blowing air into the ballast tank. It gets yucky and I add a chlorine tab when I fill it."[/i]

Right Russ. My interest in drying out the ballast tank was not related to growth of organisms in a wet tank.
It was a manifestation of my obsessive nature: wanting to minimize (hypothetical) permeation of water from the ballast tank along the fiberglass strands to just underneath the outer hull gelcoat ... and hence blistering and eventual hull damage. As one will note from this thread, there is considerable debate surrounding whether this is a realistic concern. The winter liquid sunshine here in BC has left me a bit twitchy about the possibility though (ie. in the winter, things don't dry here very well).

By the way, I did sneak out this afternoon and tape/seal a 0.092 amp 12- volt DC computer fan over the collar surrounding the (open) V-berth ballast vent such that it blows entirely down into the tank (leaving the stern ballast valve open of course and screened against critters). Given my lack of success with the "1-watt" solar panel (as described above), I powered the fan with my house battery via a (fused) wiring loop.
Sum is right: a 40 watt solar panel would be a far more sensible (solar) choice that the "1-watt" item with which I was experimenting.

Kittiwake

[ronacarme]

For the last decade or so we have wintered our X in southwest Michigan under inexpensive blue plastic tarps.
Bilge ventilation is by a 5 watt solar plate (Harbor Freight on sale @ $40) driving a computer fan (Hosfelt Electronics 12v dc, 160 mA, 45cfm) thru a 12v regulator (Hosfelt 12v 1 amp, 45 cents) to protect the fan from being overpowered on a sunny day. Fan is mounted in a hole in the riser of the fwd dinette seat and draws thru the bilge from near the transom. Works during sunny or cloudy days, not at night. To eliminate the regulator, experiment with a higher amp draw fan.
Cabin ventilation by a 3" Nicro day/night solar vent in the forehatch. Enuf light comes in thru the blue tarp to drive the vent fan during the day (have not checked at night), assuming no heavy snow load stays on the sloping blue tarps.
A second 5 watt plate keeps the house battery at full charge.
Same plates and fans work during the sailing season as well.
Ron

[Kittiwake]

For the last decade or so we have wintered our X in southwest Michigan under inexpensive blue plastic tarps.
Bilge ventilation is by a 5 watt solar plate (Harbor Freight on sale @ $40) driving a computer fan (Hosfelt Electronics 12v dc, 160 mA, 45cfm) thru a 12v regulator (Hosfelt 12v 1 amp, 45 cents) to protect the fan from being overpowered on a sunny day. Fan is mounted in a hole in the riser of the fwd dinette seat and draws thru the bilge from near the transom. Works during sunny or cloudy days, not at night. To eliminate the regulator, experiment with a higher amp draw fan.
Cabin ventilation by a 3" Nicro day/night solar vent in the forehatch. Enuf light comes in thru the blue tarp to drive the vent fan during the day (have not checked at night), assuming no heavy snow load stays on the sloping blue tarps.
A second 5 watt plate keeps the house battery at full charge.
Same plates and fans work during the sailing season as well.
Ron

That is impressive Ron ... and sounds quite relevant to my situation.
I must admit, the possible need for a regulator had not occurred to me: more food for thought.
Do you worry that the 5 watt solar panel could over-charge the house battery when left for months on end?
Kittiwake

[mastreb]

Hi All!
Connecting one computer fan to another is great for illustrating first principals of generator=motor and motor=generator, but I would be very surprised to find that, because of gross inefficiencies and lack of control circuitry, there would be a practical real world application for it. Not unlike the electric motor made from a nail.
- Brian.

Try it. You'll be very surprised. It's about 60% efficient, which means that for every 5 turns of the wind powered fan, you'll get 3 turns of the slave fan. Considering that it's free power and that you only need to drive 1 cubic foot of air per minute to swap the cabin air out twice in a day, it's 100% cost efficient. Of course, using a turbine blade designed to catch the wind will work way better than a computer fan, if you happen to have one around, but if you don't any DC fan will work, the larger the better.

You guys are way over thinking this. DC motors are not sensitive electronics, they're about the most rugged electronic compnent there is. They wear out from rotatry motion--I bet you've never even heard of an electrial motor that was blown by being over powered. There's no need to protect a 12v fan with a voltage regulator from a 5 watt 12v solar panel. It's 5 watts max. It won't harm it even if it generates 18v for a few hours. Keep your house battery out of the loop--just hook the panel up to the fan, and when there's sun, the fan will move. More sun, faster movement. It's really that simple.

[ronacarme]

Our old 26D connected a 5 watt plate to the house battery from 1988 to when we sold the D in 2000, with the house battery (still original as I can best recall) still working well. However, the D house battery was very lightly used....mostly FM and VHF radios, rare cabin and nav light use, manual start motor.

A 5 watt plate has been connected to our 2001 X house battery since 2001 , tho I did replace the battery 2 years ago. The battery does start our 9.9 Honda and run its power tilt so has more work to do than the house battery on our old 26D.

Thus, we have seen no evidence of overcharge of our house batteries by their 5 watt plates.

Moreover, 5 watts/12.6 volts = about 0.4 amp, which I believe would be a relatively small maintenance or trickle charge at most, and so unlikely to overcharge the house battery.

Ron

[mastreb]

Moreover, 5 watts/12.6 volts = about 0.4 amp, which I believe would be a relatively small maintenance or trickle charge at most, and so unlikely to overcharge the house battery.
Ron

You don't need to worry about anything below a 12v/2 amp (25 watt) solar panel damaging your battery. Above that you definitely need a charge controller and voltage regulator, because you're beyond what the battery chemistry can smooth out on its own.

[Kittiwake]

Very informative and useful input.
Thanks all.
Kittiwake