Kohler 18kw standby generator

Location
Mackinaw il.
Occupation
Electrician
I recently got a new customer who has a Kohler stand by whole house generator 18KW 100amp breaker. It's mfg date 09/12. The last electrician replaced the motherboard in the board in the transfer switch twice the issue is when the power goes out the generator is not starting automatically automatically he has to go out and manually switch it. When he hits the run button on the generator it starts right up every time does its job it's just not automatically transferring.Even after the motherboard and the transfer switch was replaced the issue was still there so now I'm jumping in after another electrician and the only thing I can think of is it's the controller on the generator itself I called Kohler and since I'm not a licensed distributor with color they were limited on what information they could give meOn the generator the low voltage DC end there's AB which are the 2 communication wires and then there's power and common on the power I'm getting 14 V I've taken the battery off batteries fine cause the generator starts up on run when I go to test B I'm getting 3 V I'm pretty sure I should be getting 14 V on B and then when the generator kicks on I should be getting 14 V on a and nothing on B. My problem is I'm trying to determine if it's the motherboard againOr if it's the top side control on the generator it's a generator. The Is top side control is $1300And the motherboard and the transfer switch is only 500 I really don't want this customer spending all this money on a new controller if that's not the issue you I'm having a hard time How to determine if it's the motherboard in the transfer switch or the controller on the generator itself. Is any in all advice is much appreciated thank you.
 

Buck Parrish

Senior Member
Location
NC & IN
Personally, I'd leave it to a Koehler tech to work on. I remember years ago Koehler wouldn't warranty it unless a tech done the initial start up after inspecting it.
 
Location
Mackinaw il.
Occupation
Electrician
The warranty is up. I was thinking same thing about getting a tech out from Kohler, he called them first and it was going to be 2 weeks before anyone could get out there. Just figured I would try and see what I could do to help him out.
 

tom baker

First Chief Moderator
Staff member
I understand you have this new customer, good for business. But if you replace any boards and it does not work, then you own it. Does the kohler tech warranty his parts?
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
I have done very few Kohler residential generators, so I’m not familiar with the “A” and “B” terminals. On commercial Kohler transfer switches, it’s two terminals on the switch, and it’s just a contact closure to signal the generator to start. Once the voltage is acceptable to the switch, it transfers. With Generacs, the generator makes the decision to transfer, that is why they have more control wires.
 

Barbqranch

Senior Member
Location
Arcata, CA
Occupation
Plant maintenance electrician Semi-retired
Two years ago I installed a 20 KW Kohler at our mountain "cabin". There are two wires that go to the transfer switch that when connected together tell the generator to run. When voltage is stable, the ATS transfers the power source. And transfers it back when POCO is stable. Generator then runs until temperature drops to a certain value. I don't know if this is true on the 18 KW unit, but I expect it is.
 

ATSman

ATSman
Location
San Francisco Bay Area
Occupation
Electrical Engineer/ Electrical Testing & Controls
The warranty is up. I was thinking same thing about getting a tech out from Kohler, he called them first and it was going to be 2 weeks before anyone could get out there. Just figured I would try and see what I could do to help him out.
Can you send a pic of the ATS nameplate showing model and serial# so I can dig up the schematic for this unit. Then we can Talk Turkey.
 

ATSman

ATSman
Location
San Francisco Bay Area
Occupation
Electrical Engineer/ Electrical Testing & Controls
Forgot to mention:
I normally work on 3 phase systems but I think the engine start circuits are similar.
Sounds like the 14 VDC is coming from the gen start battery (12V.) If this is a 2 wire gen start setup then the batt voltage
appears across the gen start wires because it is an open circuit. When the ATS controller sends the signal to start the gen
a contact in the controller closes, the voltage goes to zero and the gen starts. I would do a point to point check of these
2 wires from the ATS to the gen, there may be a break somewhere that could be causing the problem. Once you identify
the wires at the ATS controller you can jumper them at the controller terminals there and see if the gen starts.
If it does not start there is a break or loose conn in the wires from ATS to gen. If it starts then the controller is bad.
To further verify this, measure the 14VDC at controller start terminals
when the normal power is removed from the ATS or when the Test feature is initiated at the controller.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Forgot to mention:
I normally work on 3 phase systems but I think the engine start circuits are similar.
Sounds like the 14 VDC is coming from the gen start battery (12V.) If this is a 2 wire gen start setup then the batt voltage
appears across the gen start wires because it is an open circuit. When the ATS controller sends the signal to start the gen
a contact in the controller closes, the voltage goes to zero and the gen starts. I would do a point to point check of these
2 wires from the ATS to the gen, there may be a break somewhere that could be causing the problem. Once you identify
the wires at the ATS controller you can jumper them at the controller terminals there and see if the gen starts.
If it does not start there is a break or loose conn in the wires from ATS to gen. If it starts then the controller is bad.
To further verify this, measure the 14VDC at controller start terminals
when the normal power is removed from the ATS or when the Test feature is initiated at the controller.
That’s what I’m thinking, but being a residential unit, they seem to do some funky control schemes to save money in manufacturing. 2012 though, Kohler should be still using the same controls as the commercial units.
 
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