Polar Power...

[mobile_bob]

Steve:

don't get too wrapped up in the hype about the polar being a DC machine, it is no more
a DC machine than the alternator on your car

if it were a classic DC Generator it would have a commutator and brushes, or possibly some sort of
electronic commutation scheme other than a rectifier bank, which in the polar case is remotely mounted.

what they are trying to relate in a very broadly applied manner is the fact that eliminating conversion stages
increases efficiency. i don't have any problems with them stating the obvious but i do have issues with obfuscation
which they are boardering on heavily.

basically is is a brushless alternator with remote bridge rectification,, it has a 6 phase stator which makes a bit lower ripple
and a bit more efficiency, and what they gain with the pm excitation they have to give back with the buck section of the alternator
in order to gain control for regulation.

overall not a bad piece of engineering, but it is not the holy grail in my opinion. even though they would have you believe that it is just that
in their ad copy.

personally my bet is you could meet or exceed their efficiency claims with an STC 3 phase head that is rectified and uses an off the shelf VR that can do true 3 stage charging,, interestingly their 3 stage is not truely a 3 stage unit.

the big plus they have going for them is compact size, which is very desirable in military or marine equipment, but not much of a concern
for the offgrid crowd.

if you really want to do such an animal, look to the telecom boys
i know generac built or builds some belt driven 6kwatt alternators that are 6phase, remote rectifier, and are 24 volt nominal and they also make a 48 volt nominal unit as well,  you get all the bells and whistles, and can find them very inexpensively surplused with very low hours on the clock.

bob g

[oliver90owner]

 high voltage DC (~120 vdc)

Personally, I would avoid 120DC if you are considering more than a store to feed an inverter.

120DC can be very lethal (whatever that might mean ) and just a jolt from it is much more serious than one from 120AC.

Regards, RAB

[compig]

"If I have seen a little further it is by standing on the shoulders of Giants"

isaak newton


"and there really isn't anything new under the sun"

unknown by me its origins


everytime we think we have a new idea, after looking a bit further we find it has all be done before by someone, time after time.

standing on the shoulders of giants?

i'm just happy to dabble around in their shadows
(that last one is mine, er... i think its mine?)



bob g

Hmmm , I can think of a few things that are new and not previously done in history :-

http://en.wikipedia.org/wiki/Nanorobotics

http://en.wikipedia.org/wiki/Carbon_nanotube

[mobile_bob]

technically speaking
the nanorobots wouldnt exist had someone not invented the microscope, and someone else hadn't
invented robots to start with

same with nano tubes, i would guess

not much that just comes out of nowhere that can't trace its lineage to something or someone else.

usually there is a very large family tree



bob g

[AdeV73]

technically speaking
the nanorobots wouldnt exist had someone not invented the microscope, and someone else hadn't
invented robots to start with

same with nano tubes, i would guess

not much that just comes out of nowhere that can't trace its lineage to something or someone else.

usually there is a very large family tree

Whilst it's true that nanorobots couldn't exist without the microscope, it's not true to say that the development of the microscope ipso facto leads to development of nanorobots...

With carbon nanotubes, it's entirely possible that they exist in nature, but cannot be seen without microscopes; or assembled into something useful without nanobots.


It's undisputably true that the achievements of notable people - Albert Einstein, Neil Armstrong, Niels Bohr, Ernest Rutherford and many many many others - absolutely rely on the accumulated work of hundreds, thousands, perhaps even tens of thousands of people before them.

To say, however, that "nothing is new" is entirely incorrect. Physics (in particular) but also chemistry & biology are continuously leading to new discoveries, or new inventions; and while it's generally true that any new invention will rely on X previous inventions; sometimes, something comes at you from totally left field. Who, for example, could ever have predicted superconductivity?

[compig]

I think super conductivity was probably predicted in physics & mathematics but the hardware to confirm experimentally had to be developed when technology and materials allowed.

My definition of something new in the man made world is when no previous form of object X has ever existed. So , things like the transistor for example , had never existed before it was actually invented and also could never have previously existed until the science had been developed. Same applies to nanobots and carbon nanotubes.

However ,plenty of mechanism's and manufactured goods applauded as being 'new' have been done at least once if not many more times before.

One , which greatly surprised me a few years ago was oval cylinder bores in an internal combustion engine. Honda launched a motorcycle , the NR750, with oval cylinders , well rectangular with radius-ed ends !! They claimed this was a first. Well , maybe in a PRODUCTION engine it was but Triumph motorcycles had made a running engine with an oval bore in the 1920's !!  Machine tools were just not sophisticated enough to produce them economically.

[Doug]

I just read this thread.

Summer of 92 My old boss George and I discussed something along this line....

So this guy is making them eh?

Not sure if I am impressed or amused

[Quinnf]

Don't laugh too hard.  There's a whole generation of geeky kids who have (re)discovered nixie tubes.  http://tubehobby.com/store.php?cat=1

Quinn

[Quinnf]

To say, however, that "nothing is new" is entirely incorrect. Physics (in particular) but also chemistry & biology are continuously leading to new discoveries, or new inventions; and while it's generally true that any new invention will rely on X previous inventions; sometimes, something comes at you from totally left field. Who, for example, could ever have predicted superconductivity?

I suppose it depends on how you choose to define "new."  Much of what we call new is, in a strict sense, a refinement of existing technology.  New ways of doing old things.  New twist on an old idea.  I think what Solomon was talking about was how little there is that is really, fundamentally new.  I think he was a little depressed. 

Modern day incarnation of the idea can be found in Douglas Addams' character, Marvin, "the paranoid android," from the Hitchhiker's Guide to the Galaxy trilogy (consisting of 5 books at last count).  Brain the size of a planet, and he's tasked with being a servant to humans, performing menial tasks which so bores him that he's morbidly depressed. 

Now, take Galileo.  There was a guy who seemed to think far outside the box.  You see some of his inventions involving gears?  And that helicopter-thing?  That was REALLY new in his day.  I read a Sci-Fi book long ago that had it that an advanced civillization would exile their political dissidents by transporting them to a time and place where they could live out the remainder of their lives and pose no threat to the ruling regime.  Galileo was forever trying to jump-start technology so he could get back and continue his "community organizing."   

Quinn

[Doug]

I have to admit those tubes are kinda cool but I sideburns and tail fins are stylish......

[apogee_man]

Bob,

Thanks for the telecom tip...

Stumbled across this cute little thing while searching:

http://www.alibaba.com/product/mrmay-11886880-11137816/Microgen_DC_Generator_For_Telecom_Shelters.html

Steve

[mobile_bob]

at least they started with a real alternator
that is a working half of a 110-555jho prestolite/leece neville, which was formerly the large frame motorola
alternator that was around 30 years ago.

what they did was throw away the front case, and make up their one that doubles as a bellhousing to fit the engine
and the internalized the fan and made it direct drive so it shares the front brg with the engine main brg.

i have been preaching about the 555 alternator for years, it is used by many as a basis for a generator such as these folks have done.

what this all means is if you can find one of these units surplus, repair parts for the alternator are commonly available and not proprietary
except for the front hsg of course, fan and drive coupler all of which should never fail anyway.

very cool indeed

and likely pretty darned efficient as well, or it certainly could be depending on whether they have done it right or not.

bob g

[lowspeedlife]

anyone thought of using a surplus elevator motor/generator, basically an electric motor driving a dc generator. the motor could be disabled or removed or used as a/c power at the same time you were charging batteries.

   Scott

[rcavictim]

anyone thought of using a surplus elevator motor/generator, basically an electric motor driving a dc generator. the motor could be disabled or removed or used as a/c power at the same time you were charging batteries.

   Scott

I have been searching for such a beast.  I want a large diameter open frame unit, many poles, out of an Egyptian Pyramid or just a bit newer.  Not the newfangled junk.  My desire is to wind/create a really low speed alternator.

[Cowboy Billy]

The old gas powered welders had 30-35 vdc generators in them. And my brother was just given a old old dc welder that was driven by a 3 phase ac motor to a 30 vdc generator. He is going to hook the dc generator to a 6-1 lister. We have 120 acres off grid in Michigan's UP. We have been using a chingfa powered generator up there. This summer we got a 24v forklift battery and 5000 watt power inverter that we run off of and are using a big battery charger running of of the chingfa to charge it back up.

The good thing of running 48v into a inverter is that you 1/2 the amps for the same power that a 24v inverter needs.

The bad thing is that a 48v inverter is  4-5 times the price of 24v inverter for the same output.

I payed $469 for my 5000 watt 24v inverter including shipping.

Billy