Brian Teitelbaum wrote:
Hi boB,
The issue is whether the generator is rated for use as "prime power" or rated as
"back-up power". Prime power units will get considerably more run-time hours on them then
generators used in back-up. At least that is what the generator manufacturers think.
Once upon a time it didn't matter. The engines were heavy cast iron, and
running at slow speeds, usually 1800RPM, but sometimes as low as 1200RPM, and
lasted for thousands of hours of run time. As the manufacturers switched to
cheaper aluminum engines running at 3600, the amount of hours before a major
rebuild was required decreased. Honda, and others, were able to bring aluminum
engines back up to fairly long life-spans, but they are still not as rugged as
those old hunks of iron. Emission regulations further destroyed the old iron
engines, unless you get one big enough to have 4-cylinders.
There is no reason, other than cost, for Kohler to not make a 4-cylinder, cast
iron, 1800RPM, prime-power unit, but maybe they feel that there just isn't
enough of a market for them to build it. I think that they are wrong, but I
don't know the true numbers.
The real problem is that the generator manufacturers don't understand how
off-grid systems work these days. 20 years ago, you could expect an off-grid
generator to rack up considerable hours in a short time. These days, we get PV
to do that, and the genny is just used for back-up. If the system is designed
properly, the genny should get minimal hours per year, and the manufacturer
should be able to warranty them. They need to be educated.
Brian Teitelbaum
AEE Solar
Thanks Brian. Yes, I do believe they need to be educated that these
days, their generators, even backup rather than prim power classes, are
more of
a backup. If they wanted to, they could just use the run time meter to
decide if it is warranty or not, maybe.
Thanks again,
boB
-----Original Message-----
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Tuesday, March 30, 2010 12:07 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Kohler Generator Issues
Nick Soleil wrote:
Hi Jeff:
I have had some similar issues with the Kohler generators in
recent years, after installing hundreds of air cooled and water cooled
generators from them. I have heard that they are less reliable now,
and the company is harder to deal with now.
Recently, I tried a Generac in an off-grid project, which I have
found is even more difficult to work with. They don't warranty the
product for off-grid applications, it requires hard wiring a battery
charger, and it starts and stops based on utility sensing, which
required installation of a relay to switch the sensing circuit on and
off. It was a pain to deal with, and required a few more trips to the
site than I would have liked.
On a similar note, Xantrex provided the Auto Gen Start module, but
it did not support 2-wire start! Isn't that the most common gen start
configuration? The newer versions do offer that now.
Is this "no warranty if used off grid" in writing from these
manufacturers, or is it just some salespeople saying this ?
Why would you need a generator if you have grid available ?
boB
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
------------------------------------------------------------------------
*From:* Jeff Yago <jry...@netscape.com>
*To:* RE-wrenches <re-wrenches@lists.re-wrenches.org>
*Sent:* Mon, March 29, 2010 7:53:18 AM
*Subject:* Re: [RE-wrenches] Kohler Generator Issues
Although we have specified and included Kohler RES models in all our
off-grid and battery based solar projects for over 15 years, we have
seen a real decline in the suitability of the Kohler line in the past
few years for use in solar/battery/generator applications. First they
killed off the 1800 RPM units under 15 kW. We had many older systems
that would not work when we replaced an aging 1800 RPM unit with their
same kW size new 3600 RPM units, which made inverters go nuts with
under-voltage and over-current errors.
Then several years ago they got rid of the battery charging alternator
or whatever that re-charged the battery when the generator was running
as a way to reduce costs, so now the only way to keep the battery
charged was to plug in a full time float charger. This 24/7 electrical
load is not a good idea for smaller off-grid systems and requires
another set of wires out to the generator to supply this outlet.
Finally, Kohler added a diagnostic electronics panel that adds another
24/7 electrical load. We "kill" this off during installation on any
off-grid application as we cannot justify this 24/7 standby load.
There is a software switch to do this, but its not easy to find in the
instructions.
Funny thing was the other day I received a call from the main Kohler
factory about some marketing issues and I finally let loose with the
above rant. I really complained that so far they have done everything
they could NOT to serve this very large and growing off-grid market,
and I pointed out that most of their recent design "improvements" made
their generators LESS suitable for this market, not better. This guy
was absolutely dumb-struck, and it appears to me that they have made
no effort to understand this market. Their more recent efforts to
void warranties is just another reason to look for a different
generator supplier.
Has anyone on this list had any contact from Kohler central office
about finding out what features this industry needs? The guy I talked
with may be just blowing smoke, but he promised to have a followup
call in next few weeks to learn more about what they can do.
According to him, he thinks they can add a software "switch" in the
programming for little or no cost like "on/grid - off/grid" that we
could access during setup that would adjust generator parameters and
standby losses when used in an inverter-battery application. In case
he really does followup, are there any other rants I could include
from you guys that have been a problem for you when using Kohler
generators. I will assume we are limiting this to their non-water
cooled units under 15 kW.
While ranting on generators, the main reason we liked to use Kohler
was the easy 2-wire start/stop connections you can connect to the aux
relay in most inverters, while many other generator brands were not
easy to remote start from an inverter or required multi-step starting
relays. Has this changed, and are there now other brands of
generators in the 8 to 15 kW range that work well for backup of
solar/battery charging applications and the manufacturer does not have
warranty issues when used in off-grid applications?
Thanks,
Jeff Yago
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