Just had my own experience and problem with one of those cheap ChiCom 2 stroke generators.

 I am helping do an engine swap on a 91 Caravan and we are using the
generator to power lights.  The problem seems to be that the gen really
doesn't like inductive loads as it ran the fluorescent lights or a metal
halide light separately but not both together.  With both on the voltage
drops and the lights just flash on and off while the engine just loafs with
no signs of being bogged down at all.  I need to know if I can use some of
the motor run capacitors I have laying around to power factor correct the
lights and make them all work at the same time.  The total load should be
about half of the 750 watts continuous that this one claims to supply.  As a
test I plugged in a small toaster oven and the engine bogged right down so I
know the gen is capable of supplying good power.

 

Your symptoms are consistent with having more inductive load than the
alternator can handle. Inductive loads do not load the engine but can cause
the voltage to drop excessively.  I would think the capacitors would permit
the system to work okay. Just try the smallest capacitor first, preferably
connected at the same time as the other loads, and increase if necessary.
Too much capacitance can raise the voltage too much and ideally you would
want the capacitor current to nearly equal the inductive part of the load
current.

Don Young

 
Although I was not at the location where the inductive lights are I tried
plugging in a 500 watt halogen light and then plugged in a 25 microfarad
capacitor and the halogen did get brighter.  The no load voltage on the
gen's built in meter is about 100v although it bounces around as the
governor hunts.  With the 25uF connected it raises to 120v and with 35
connected (25+10 dual run cap) it goes to about 150v.  I ordered my first
Kill-A-Watt off of Ebay and it should be here today or in a few days
(shipped the 22nd) so hopefully I can use it to get the power factor as
close to 1 as possible and check the frequency and volts at the same time.
Thanks

 On Mon, 25 Feb 2008 07:09:25 GMT, "Daniel Who Wants to Know"



A halogen light has a unity power factor so your cap isn't correcting any PF
problem
What it IS doing is affecting the field excitation and therefore the voltage
regulation point.  You can do the same thing by adding capacitance to the aux
excitation winding that already connects to a capacitor.

These harmonically excited generators don't like low power factors, lagging or
leading (what you're doing when you add capacitance to a unity PF load).  You'll
need
to adjust the PF for the running load with the mercury light attached.  The
problem
is, the PF of the light changes radically as the light warms up, assuming you
have a
regular PF light.  The PF is lowest upon ignition.  In fact, the VA draw remains
similar from ignition through full output.

High PF lights almost always have a capacitor in series with the lamp.  You might
give that a try if paralleling the cap across the input doesn't work well enough.

I do have to say that I've had more trouble trying to get mercury/HID lights to
run
on small generators and inverters than just about anything else I've messed
with.  A
400 watt merc light will extinguish itself after it is almost fully on even on a
1500
watt inverter.  The same light works fine on this same generator we're talking
about
but the generator won't pull very much of any other load.  I suspect that the
low PF
is affecting it but I haven't measured it yet.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
In theory, there is no difference between theory and practice.  In practice,
there is.

 
Got my KAW yesterday and the capacitors did work quite well on the
generator.  We ended up not using the metal halide (I think) light as once
the voltage was proper the fluorescent lights were bright enough for the top
stuff with an LED flashlight on hand for those dark spots underneath. We ran
an angle grinder with a cutoff wheel to grind through the exhaust flange
bolts and the gen ran it fine with the lights just dimming for a sec from
the turn on surge.  It was interesting to hear the engine note change with
changes in load from grinding through those bolts.  The final voltage,
frequency, and watts without the grinder on ended up being 140V, 64Hz, and
230W per the KAW as I ran the voltage on the high side because it was below
freezing in the garage and the fluorescent shop lights don't have cold
weather ballasts in them as at the normal 120 from either the grid power
before the house burned down or on the gen they flickered and wouldn't fully
light up.   I am wondering why the frequency was so high though as I didn't
touch the governor but did note that it has a row of holes for the spring so
it may be adjustable.

I must say that I don't remember anyone on here saying that the KAW beeps
when the buttons are pressed but it does.  It reported 76 watts @ 122V for a
75 watt 120V incandescent bulb in a clamp lamp on grid power and 0 watts and
195VA with just a 35uF capacitor plugged in. so it seems fairly accurate and
works properly.  Does anyone know what it will read with reverse power flow
through it such as supplying power instead of consuming it like a grid tie
inverter does?  I may have to make a male-male and a female-female cord to
find out.