Generator Update [RE-wrenches]

Fri Nov 25 18:10:52 PST 2005

We installed a Kohler 12RES just over a year ago for an off grid client.
For the money it's a fine unit.  From the testing that we put it through it
had outstanding voltage and frequency regulation plus it's really quiet.
Quieter then most 1800 RPM units I've been around.  I'm heading up to
service it next week.  I speak to the customer often and it's been doing a
fine job for them.

Its only wart is that its electronics will run the battery down in no time.
I believe we lost two starting batteries before we figured out what was
going on.  It was easily resolved by removing the jumper which lets the
electronics turn off after a period of non use (24 hrs?) and installing a 15
watt solar panel dedicated to the generator battery.  The lack of an
alternator for charging for its starting battery was a surprise but really
not an issue.  From what I've seen every manufacturer recommends block/ and
or carb heaters for temps below ~40f.  We've also got several 1800 RPM
Kohler installed which don't use the carb/block heaters and so far we've had
no problems with any of the them starting in the winter.  It rarely gets
below 10f around here.

I visited a new customer last week who had an earlier version of the 12RES
with same engine.  I was totally shocked to see that it had over 8500 hrs on
it and still ran like a top!  I swear, I saw it with my own eyes.  The
customer told me that all he had ever were the PM's, no serious repairs had
ever been made to it.  It was the sole power source for years before added
solar.

We frequently use our Yamaha 2800i at job sites and are quite happy with it.
We've tested on DR's, SW's and Outback's and they all love the voltage and
frequency.  Several customers have the Honda inverter units and are very
pleased with them.

Best,
Travis Creswell
Ozark Energy Services

-----Original Message-----
From: Allan Sindelar [mailto:allan at positiveenergysolar.com] 
Sent: Friday, November 25, 2005 12:31 PM
To: RE-wrenches at topica.com
Subject: Re: Generator Update [RE-wrenches]

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Ray,
Re the Kohler: we'll know soon what's up. A newly transplanted offgrid
client contacted us looking for an inverter to use with his newly-purchased
generator to run his trailer and housebuilding project. The generator is a
Kohler 12RES. I immediately told him of the issues that had been discussed
in the previous thread about small Kohlers. I printed out the whole thread,
of which I had saved the key posts, and gave it to him. I explained that we
had stopped selling Kohlers because their smaller units just weren't
appropriate for offgrid backup charging any more. He had also purchased a
240V AC well pump, so we designed a PS2/VFX3648/X240 system with a
Tri-Metric monitor and a single "temporary" string of 8 T-105s. We'll finish
the installation next week, after the propane co has set an LPG tank and run
the line to the generator.

The 12RES installation manual claims (this is from memory) 192 AC input
watts for the battery charger (which I assume is continuous), plus a
carburetor heater and something else -a block heater?- for a total draw of
340 watts from grid AC.

Here's what I predict:
1. The gas company will hook up the generator and it'll start and run just
fine. The generator starting battery will go dead in about two days. We'll
figure out the continuous draw, change that jumper to allow the controller
to power down eventually, and figure out what it'll take to make this system
work.
2. I have warned him not to use his RV 5th-wheel trailer's onboard battery
charger or keep the trailer plugged into the power system as if on RV-park
hookups, which it's designed for. We'll see how quickly this lesson is
learned.
3. He will add PV to the system much sooner than he originally planned, as
he lives for awhile with this arrangement. The system we are installing is
purposely designed to grow into a full home system once he has a home with a
load profile and more educated user. The golf carts are intended to be a
quickly-used-up-and-recycled "starter set", his cheapest storage medium for
the short term.

I'll let this list know if we learn any good solutions to the Kohler issue.

Re the inverter-generators: Subaru's 5100 model, which I believe is rated at
4300 watts continuous, is now available in an inverter configuration. I
found the same unit to be cheaper under the "Baldor" name. And I think Honda
has a model out that's larger than 3kW. Yamaha is also supposed to be
releasing a 4kW version, but we haven't received anything from them yet.

Allan at Positive Energy