Help With Ebay DC Generator Requested

[LowGear]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230489471008&ssPageName=STRK:MEWAX:IT

How does that dinky little rectifier pass all that current?

How long do you think the motor would last being turned at 3400 RPM?

Casey

[mobile_bob]

the rectifier will go full nuclear at about 10% of what they claim from that motor/generator
(unless you expect to charge a 240volt battery bank)

as for lifespan at 3400rpm?  probably measured in hundreds of hours, and in tens of hours
at anywhere over about 25% of claimed output.

at 15kwatt, it won't last an hour.

bob g

[Westcliffe01]

sounds like about 40 amps at 240v (14hp ~10kW ?)  So at that voltage the power dissipated in the diodes should be fine.  As the RPM are reduced total power is reduced too.  One would need to add a 10x to 20x reduction drive on the front of the thing to get the blade rpm anywhere near ballpark for 10kW.  Servomotors typically have a wide dynamic range and many run over 5000rpm, although this one is tagged at 3000rpm.

At close to $400 it is just an overpriced servomotor.

[LowGear]

So many stars and so much variance in answers. 

My plan is to hook my Witte up to some kind of DC program and see how good the Sunny Boy is with fairly clean DC.  Same hardware is the Windy Boy and my feeling is that windmill DC just ain't too purdy.

I need about 320 volts DC at about 4KW or (2) 2KWs.  Would a 400 hz unit deliver some very pretty rectified DC? 

I wonder if SMA has an extended warranty option?

Casey

[mobile_bob]

i get really negative about these ebay sellers of windpower schemes, mostly because they are so full of crap
that it boarders on being criminal.

that blade set coupled to that motor soon to be generator will be lucky as hell to ever make 300 watts in any reasonable amount of wind.

folks keep looking for a quick and easy wind generator, so they either buy one of the motors or worse one of the pm converted gm delco
car alternators and a set of plastic blades with a swept diameter of 6 or 7 ft, and think they are going to make power to sell back to the grid.

it just isn't going to happen, short of a hurricane
and that is when the grid is down anyway!

the seller goes on about this thing making 15kwatts, and shows a set of plastic blades, and will throw in a rectifier which under normal conditions might handle the 60 or 70amps, but will go quickly to hell unless it is on a good heat sink "and" the load and supply are stable, which is never the case with windpower.

load dump will kill that rectifier if it ever gets close to its rating.

yes i am very negative about these guys.

there has got to be a better alternative to connect the witte to the grid tie, maybe an stc head (3phase) rectified
at least the output would be stable and the head likely would outlive the ebay motor.

bob g

bob g

[billswan]

For what it is worth I will second what mobil bob just wrote. 

Billswan

[highwater]

Ok, its been awhile since I had anything constuctive to add to any topic, and this will likely not be so, but wind power is something that I am fasinated with, if that be the word.

I would love to work on one of these wind farms here in Oklahoma.
Beautiful if you ask me.
They are putting these things up by the hundreds in the western half of the state. I would say from my research on them 1.5Mwatt and up.

Friends and family know of my love for these things, so I get asked some questions, which if reading between the lines you can tell they are looking for my blessings on something like the ebay scam listed above. Yeh, lets go ahead and call it a scam.

So I answer these questions with a few questions of my own, and get the same answer.

Answer #1-------Well I don't know.

Questions go as follows.

Let's start with your residential consumption. How many kwatts do you use monthly and yearly?

Ok, what wind zone do you live in?

What is the average wind speed at your place?

Do you understand that 12mph wind in December is not the same as 12 mph in August ?

Do you understand net metering?

Not that your going to get a hefty paycheck from the power company; but just how much are they paying for backwash?

How much tower do you need?



As I said, I get the same answer.

Currently fighting a simular scenario with a solar panel desire.
A relative want to put a solar panel on top of the house.
Gonna buy one off the top of some guys travel trailer.
Says he runs the washer/dryer and AC from that thing.
Nope, can tell you just from hearing about it, he's not running the dryer and AC from the panel alone on a regular basis.


Randall