[VAL] Building your own generator - not so expensive after all

["Tom" <thomm@xxxxxxxxxxxxxxx>]

This is what I've found so far about building your own power generator for a
travel trailer like our Airstreams.  This could be done quite simply -- I
think -- at this point in time.  It is an interesting thought process none
the less and maybe one of us will actually "do it" as the Nike commercial
says. ;)

I would need:
5000W peak, 4000W continuous generator head - $389.99
8 Horse power engine - Tecumseh Engine - Cast Iron Sleeve - 8 HP - $279.99 -
for the same HP but with a Honda engine with gear reduction instead $754.99
Direct drive shaft coupler assembly 7/8" $11.95
   (use with 5,000W generator head)
Frame and sound proofed cover with fans if air-cooled
Inductive Tachometer to measure the engine RPM

For around $682.00 - $1157.00 plus the cost of the inductive tachometer, a
welded frame, material for a secure locking box/cover and some other small
electronics such as an electric fan or two for cooling this 5,000W generator
could be built.

Considering the fact that this amount of power would run all the things
aboard the Airstream I think it is certainly doable.  On the low end you'd
have a Tecumseh engine and on the high end you'd have a Honda and we all
know how dependable those engines are by now.

If you went with a diesel engine the cost would go up but I doubt if it
would be over the higher end cost of $1200.00 but I could be wrong.  I still
have to look into the cost of the small diesel engines.

If you went with a 9 HP engine you could go with a bit larger generator
head.  In fact, it doesn't cost much more to go up to KW or even more doing
it "this way" - buying the parts and assembling it yourself.

Since our tow vehicle is a Power Stroke diesel engine I'd be inclined to at
least check out the small diesel engines so they could both sip from the
same tank.  I'd also be inclined to go with a small water-cooled diesel
engine if I built this system for myself.

Typical Gas engines rate their horse power at 3600 RPM.  A diesel engine
could be run at half that speed or 1800 RPM due to it's torque rating.
Running a diesel at half the speed of a gas engine would probably last the
life of the trailer if you took great care of it and did all the maintenance
required when or before it needed it.

If the motor is used at speeds below that rating, the engine does not
develop full rated output torque and horse power. However, running an engine
at a lower RPM increases fuel efficiency and decreases wear and tear so
there are always trade offs.

You should also note that these small engines output shaft rotates in
counter clock wise direction as viewed from the output shaft side of the
motor. Because most engines are rated at 3600 RPMs, you will note that many
generator heads are also designed to be rotated at  3600 RPM.

If you attempt to run the AC generator head a speeds below the rated RPM of
3600 in this case, the AC output voltage will not be 120 volts, but will be
a lower value. Some equipment you intend to power may be more forgiving
about the lower voltage, some equipment might be damaged, so it is critical
that you spin the generator at the correct RPM.