[RE-wrenches] Kohler Generator Issues

Brian Teitelbaum bteitelbaum at aeesolar.com
Tue Mar 30 13:20:44 PDT 2010 

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




-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at 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 <jryago at netscape.com>
> *To:* RE-wrenches <re-wrenches at 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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