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Larry Larry is offline
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First recorded activity by BoatBanter: Jul 2006
Posts: 5,275
Default Power inverter vs. portable generator?

"Duffer2" wrote in
:

Thinking about installing a 2000watt Power Inverter to run a 1000W
(1350W @ 120vac consumed) microwave oven and to heat my hot water
tank 1200W @ 120vac not at the same time.


Well..........

1200 watts divided by 12V (just to keep it simple) equals 100 amps, if the
inverter were 100% efficient, which it's not, but close enough.

100 amps X 12V for 20 minutes, not seconds like starting a diesel, is
probably way enough to warp the hell out of the house battery plates,
wouldn't you say? I would....they have little cooling for long hard pulls,
even the wetcells will get really hot.

One good battery explosion should just about convince you this is NOT a
good idea unless you have a battery rated for 100 amps for most of its
discharge time, which it's not. (Look under the seat of an electric fork
lift truck at what will. You probably won't want to float it.)

Actually, the fork lift batteries aren't a very good example, either. They
get the current down to a safe level by running 24 or 48 or 96 volts with
lots of cells in series to higher voltage traction motors. The Toyota
Prius, for instance, takes this notion even further putting so many cells
in series to get the current down low they run 400VDC or something like
that.

Nothing's funnier than watching a boater with a new, $4000, 4KW inverter
walking down the dock with an electric heater in his hand and a big smile
on his face.

The microwave works good for a couple of minutes, though, on an inverter.

So, you need a generator to do the job at a reasonable weight.

If it's just 1500 watts, this one will work:
http://www.hondapowerequipment.com/M...elName=eu2000i
It's a very quiet 2KW inverter running off a 1 cyl, computer controlled gas
engine whos actual engine speed has nothing to do with making 60 Hz. The
alternator in them looks like your outboard motor's high frequency stator
coils inside the magnet-encrusted engine flywheel. You can't hurt it like
a regular genset, either. If you overload or short it, its computer simply
shuts off the load and drops the engine to idle until you shut it off and
restart the engine after pulling the load off it. It will stand a short
overload over its rated output, warning you by turning the output light
from green to yellow to red, when it shuts it down. At only 46 pounds,
it's very portable and easy to store....

I have two of them, the EU1000i, the little 1KW brother to the 2KW. But, I
needed more power for my stepvan electronics shop so I got this one:
http://www.hondapowerequipment.com/M...lName=eu3000is
the big brother to the 2KW suitcase.

There is a BIG difference between the plastic suitcase gensets and the
3000is, however. The two little gensets have tiny, compact, FAST TURNING
little engines that, I predict, will wear out quite quickly at your 1350
watt load, working hard to pull it. The EU3000is, on the other hand, has a
much BIGGER, stouter, SLOWER TURNING and QUIETER engine with a much lower
running note. It's just larger, as you can see at 134 pounds. It also has
a MUCH larger STEEL fuel tank that will pull two 8000 Btu window air
conditioners and my little bar fridge and soldering equipment for over 8
hours on ONE tank that's REALLY easy to fill through the HUGE, strainered
gas cap made of STEEL, not plastic. The whole case is steel, not plastic.
The EU3000is is the finest genset I ever owned at any price, even the
diesel ones. One neighbor asked if that was my air conditioner outside
unit running...it's THAT quiet! Electric start comes from a separate
internal AGM lead acid battery built right into the case under the control
panel. Your boat's 30A shore cable plugs right into its twist-lock 30A
connector. It also puts out 12A from a completely separate winding to
charge your boat batteries while its running....12V at 12A charging only.

Because all of these gensets are a really nice, rugged inverter, the
engines have an Econo mode, switch selectable. I've never figured out why
they'd want to switch it to full speed...?? Pulling a 1500W electric
heater and a 1200W calrod hot plate with both thermostats switching these
big loads on and off don't wiggle an AC voltmeter (not included) monitoring
its output...the 3000is. Very save for computers and electronics.

The 3000is turns 1200 RPM in Econo mode until the total load is over about
1950 watts. That's SLOWER by 1/3 a big 4-pole 60 Hz commercial alternator-
direct genset. I don't know how long it will last. Mine only has about
2200 hours on it, estimated, and uses no oil at all. I change the oil at
around 100 hours, about every other week. It only holds a little more than
a quart and that's real easy from a little door on the opposite end from
the control panel. It has a drain plug and a filler with dipstick. It
also has Oil Alert and will shut itself down if it's low on oil. No oil,
it won't even start. It has a recoil manual starter to pull, but mine is
mounted against the back door of the van. Open petcock, pull choke
(manual) and turn key works every time, even UNDER THE TWO AIR CONDITIONERS
AND FRIDGE compressors coming on all at once!

It's a helluva great genset.

PLEASE INSTALL A CARBON MONOXIDE ALARM IN YOUR CABIN IF YOU GET A
GENSET....thanks.