Over-sizing gen head

[Ray C]

Hello, my name is Ray and I'm a generator-aholic  .

OK, I'm hooked!    -That said, I'm going to build a house addition next year and plan to incorporate a lister-type engine for occasional backup power and/or heat in the winter.  I've been analyzing my old utility bill and have been taking readings with a Kill-A-Watt meter.  I'm doing lots of reading about how to size the generator, especially as it relates to using the generator in it's "sweet spot" of efficiency.  That said, I have a couple more basic questions to add to the ones I posted here:  http://listerengine.com/smf/index.php?topic=1319.0

It's very likely that a 6/1 engine will (more than) adequately meet my needs.  Is there anything terribly wrong with using a 10kw ST head with a 6/1 engine?  Obviously the engine could never drive the generator to it's full potential but, once something is too small, it will always be just that:  -Too small.  A larger gen-head gives me the option of upgrading the engine later on.

Also, can anyone comment on the fuel consumption rate differences between the 6/1 and the 8/1?

As this project progresses, I'd like to consider using battery packs and DC inverters... Can someone post some links to some of teh common places that carry this equipment?

.... Thanks ....


Ray


(PS:  Oh man, this is one addictive/fun topic.  It appeals to just about everything I love and enjoy).

[biobill]

  Hi Ray.

    I'll let someone more qualified answer your generator question but I do have some alternative energy links for you. Just the tip of the iceberg.

     http://www.backwoodssolar.com

    http://www.newenglandsolar.com

  And if you don't already get it you need Home Power magazine

    http://www.homepower.com

   Have Fun,  Bill

[Procrustes]

Fuel consumption figures:

http://www.indiamart.com/ashwamegh/#diesel-engine

Likely these have been handed down from the beginning of time, so I've no idea how accruate they are.

[dkwflight]

Hi In my opinion larger is OK.
The gen head will run cooler. and I don't think it takes much power to turn a larger gen head.

Dennis

[aqmxv]

Everything I've read or heard suggests that your 3.5 kw continuous (about 4.5 kw surge) 6/1 would drive a 10 KW head quite well.  The change in efficiency between 20% and 100% of continuous rated output on a gen head isn't very large.  Further, you do get some advantages from oversizing:  The head will be cool, which both means less internal resistance and longer life for all components, and the larger field rotor will contribute some inertia, which is good for frequency stability.

In any case, I'm a big believer in ignoring "surge" ratings.  My gen head (which I got cheap) is a 3600 RPM 4 KW belt drive head with no surge rating.  If somebody were to put a surge number on it, it's probably in the neighborhood of 4.5 KW or so, which should be sufficient to get everything I need to make go moving, if not all at once, and the continuous 3.5 KW or so the listeroid can provide seems a good fit.

Go for it.