Honda Gennie Problem [RE-wrenches]

Thu Feb 3 16:32:23 PST 2005

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Wrenches,

Here's a one-of-a-kind problem for me, that one or another of you has
hopefully faced before.

Background: One of our favorite clients, an artist in his seventies with a
heart of gold, has lived offgrid since around 1985. Windy originally set
James up, and the basic 12V system is still in place with some upgrades over
the years.

His backup generator since 1987 was a 5.5 hp Honda engine running a 100A
truck alternator without internal regulation via belt drive (See HP
2:23-27). In 1998 we added a Mark VI field controller, built from the
HP42:28-32 article, which has worked well. The engine finally wore out (17
years!). His Trace 1512 inverter lacks a battery charger (they were an
option in the early days) and I just can't see that he needs a new inverter.
I had a dead Winco Tri-Fuel 6000 watt generator with a good 11 hp Honda
engine with electric start and propane conversion, so I had a local
welder/fabricator combine the two. We ran a propane line into the generator
shed with a shutoff valve. The generator uses a fuel solenoid with a manual
prime: open the valve, push a release button on the solenoid to let LP gas
into the intake, and turn the key; works well.

We're getting to the problem. James asked me if there was a way to
automatically shut off the LP gas supply if the the engine stopped for any
reason. He preferred the safety of an additional shutoff. No problem, I
thought. I purchased an automatic fuel solenoid kit from Winco, designed to
fit this generator. The kit consists of an ASCO electric LP gas fuel
solenoid that runs on 12VDC, along with a relay with an AC coil and a manual
pushbutton override. An AC cord plugs into the AC output of the generator.
To start the generator you push the override pushbutton, which opens the
solenoid using power from the 12V starting battery (in this case, from the
12V house battery, which provides the power for starting the engine as
well). Start the engine normally; the relay coil uses 120VAC power from the
now-running generator to allow 12VDC to keep the solenoid open as long as
the engine is running. If the engine stops for any reason, AC voltage is
lost, the relay opens and the solenoid closes. Simple system.

Here's the problem: We have no AC to plug into, as the AC generator is gone.
So I figured the simple solution was to replace the AC relay with a 12VDC
relay and use the engine's starting battery charging circuit to power the
relay, as this source would also stop if the engine stopped. What I
discovered only after hooking it all up is that the Honda engine puts out a
rectified pulsed DC current, rather than smooth DC, and the 12V relay
"chatters" -- that is, it opens and closes with each revolution of the
flywheel. The relay doesn't stay open and the gas doesn't flow.

Any ideas? I can't use straight battery power, as it is continuous. I could
use a voltage-based switch, but with the Concorde sealed batteries we are
using the voltage setting would be very sensitive and probably wouldn't
allow the generator to get the batteries completely full before the 14.2
setting would shut it off -- would that work well enough? I could use a big
diode on the output current to block backfeeding, but that sounds expensive
and kind of brutal. There must be some simple, elegant solution here. Can
anyone suggest a simple circuit to smooth out the power so that the relay
works?

Thank you for any responses.
Allan @ Positive Energy

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