10/12si Hybrid Alternator

[Expunge]

So we have several remote sites that are battery powered and after fighting dump loads and etc I was struck with an idea.  Thought I'd run it by the people here and see if this was a possible way to eliminate the headaches.

If a person were to take apart a 10si style alternator and replace the stator with a fine wound stator like the DC540 from Wind Blue, could you retain the internal regulator and rotor to provide a regulated output but start charging at lower speeds like a PMA?  Basically, it would be a standard alternator with a fine stator, so the question is, would it work similar to a PMA as far as the power curve?  We had a DC 520 PMA running at one site and it worked great other than the fact we were always fighting with having excess power and dump loads and and and...   My thought was leave the internal regulator and when the battery voltage gets up to whatever the regulator voltage is set at, it quits exciting itself just like in a car.

I am well aware that it won't be efficient, won't be ideal, etc... But we are looking for a simple solution to mass deploy and not have to fight diversion loads in wind systems.  Input would be appreciated.

[kell]

Car alternators use a series regulator.  When the batteries get up to voltage, you get an open circuit at the alternator.  Then the wind turbine would run free.

So, even though you've been having trouble with dump loads, you'll still need a load of some sort and a car alternator voltage regulator doesn't provide that.  I know from experience the 10/12 SI family of alternators uses series regulation, and I suspect it's pretty much universal among cars to use series regulation.  

Instead, you need shunt regulation.  Some motorcycles come with permanent magnet alternators and the voltage regulator in the stock design is typically a shunt regulator.  Harleys, for example.  Depending on the year of the bike, it might have single-phase or three-phase rectifiers.  Anyway, if you look for a stock regulator from a modern Harley with a high-amp electrical system, you might be able to use that with your DC-520 and avoid all the headaches.  I haven't yet done any searching for specs of the bike voltage regulators, but from looking at the dc-520 I thik it puts out less power than a modern Harley alternator.  

Even into a dead short, the dc-520 maxes out at only 25 amps.  That's less than what the typical late-model Harley alternator is rated to put out (and not into a short, either).  

One caveat -- the bike regulators are designed to have a lot of air flowing over them.  You'd have to take that into account when considering thermal management issues.

[wdyasq]

"But we are looking for a simple solution to mass deploy and not have to fight diversion loads in wind systems"

Some time back zubbly (RIP) sent TomW, one of the moderators of this board, a conversion of his ans told him to 'run it to destruction'. That was several years ago. To my knowledge, the mill is still running.

If you are not looking for extreme output, I think a 1/4 or 1/3 HP 3 phase motor could be converted to a PMA unit with the 'Ungrounded Lightening Rod' method of magnet placement and a blade-set with too many blades for top efficiency could be carved. Thus converted this motor would be a mill that is reasonable in cost to build, could be mass-converted and even have a bit larger bearings put in.

If you would be interested in doing this I could be persuaded to help design and even build them.

Ron

[valterra]

What's so 'hard' about dump loads?  Hook up some resistors and GHurd's controller and walk away.  Set it and forget it.  Where's the 'fight' in that?

[TomW]

valterra;

What's so 'hard' about dump loads?  Hook up some resistors and GHurd's controller and walk away.  Set it and forget it.  Where's the 'fight' in that?

Excessive ponderance of the plumbing.

Thats my story and I am sticking with it.

Tom

[Flux]

You are in a strange position with having too much output. Must be a very good wind location.

If you replace the pm rotor with a standard one you will need to supply about 40W to the field. That is 40W gone before you produce anything. If you can tolerate that then you can use the wound rotor.

The internal regulator is a more serious issue, it works by reducing field to maintain constant charging voltage. Firstly you will have trouble sensing that voltage on the end of a long line so you will limit voltage at the alternator and the line resistance will drop your charge rate right down. More seriously the regulator will shed load from the alternator and unless your prop has a pitch control mechanism or air brake it will run wild, become incredibly noisy and likely dangerous.

Like the others I can't see any problem with a dump regulator. What you want to do is possible but will involve far more work, less output and serious risks unless you control the unloaded speed.

Flux

[valterra]

TomW:

I KNEW something like that was coming!

Use wire that is too thick and your voltage drops...  takes 2 cycles to flush all of those electrons don't-ya-know.  Classic problem.  Happens to me all the time, especially at remote locations.

Is that too much of a stretch?

[Expunge]

Flux,  thanks for the input, you answered the main part of my question I guess as to what the parasitic loss would be as compared to a PMA.  The issue with dump loads is we are using wind power for some remote radio locations and usually combining with solar.  Most of these sites are a radio and some batteries inside a box just barely big enough for all of that, no real place to dump the heat.  The only place we can put the heat is outside our little boxes and we really don't have space for all of that, not to mention the fact that we are fighting some serious weather extremes.  All of our wind setups are designed to furl and the blades are excessively strong so I don't see a real overspeed issue.  

The biggest issues are space, reliability and simplicity/cost.  It actually would take less $$$ to convert a standard alternator with just a finer stator than it takes to convert to PMA, so savings there.  Don't have the expense of a dump load and don't have to get rid of the heat.  Heat can be great when it is -10F but when it's 110F, it's really hard to keep your load cool, and your fan fails, so does your load, batteries overvolt, cook, done.  If the alternator were to fail, 99 times out of 100 they just quit putting out power instead of overvolting.