Kohler 5ECD 150V

Hey guys, just seeing if anyone has had this issue. Boat is a 2006 290 Sundancer, generator has 372 hrs on it. Ran flawlessly until now...in fact the engine runs perfect. No codes or anything like that, but over the weekend I killed my starboard battery running the generator all night. Turns out fuse F6 was blown, but I had the main battery charger on. Which should have kept everything charged. Turns out the battery charger was shutting off due to the input voltage being 149V.

So I replaced fuse F6 and so far that seems to be working...I was able to adjust the ADC2100 controller settings to get the voltage to come down. But I have the coarse voltage setting turned all the way down just to keep it around 125V. And it's not as near as stable as it use to be. I can probably play with the stability settings but I don't see how any of this would have changed. Makes me thing the SCR module is going bad...anyone else have a issue like this? I know these Kohler 5ECD gensets can be a pain. But this one runs so good I'd like to get it fixed. Thanks!

Ryan

Don’t think F6 has anything to do with it. I’ve replaced F6 several times eventually blows. F6 is is what charges the battery which isn’t needed if you have an onboard charger.

Coz said:

Don’t think F6 has anything to do with it. I’ve replaced F6 several times eventually blows. F6 is is what charges the battery which isn’t needed if you have an onboard charger.

Click to expand...

I agree...I was able to get the 12V battery charger to work. But I’m hoping the SCR module is the only thing bad. Everything else checks out ok. Guess we’ll find out.

Hmm, tricky problem since multiple components act together in a closed loop. Note I have a electronics background, but not so much practical experience with typical failures of generators. But I'll give you my best guess.

If you want to do more debugging, maybe try setting external 12VDC excitation voltage to the rotor to see if the output voltage is at least steady. That would tell you the rotor brushes are good. You could then even measure the stator feedback voltage to the ADC (P15 connector) and check if its consistent.

Or just start throwing parts at the likely culprits: SCR, RIB, ADC. Starting with the SCR sounds plausible. Perhaps one or more of the SCR gates is not switching off and just rectifying the full AC sine wave causing excessive excitation voltage. However in this case, I don't understand why you would actually be able to adjust it at all with the ADC setting.

Second idea is the RIB board which has a Flash Relay which forces +12VDC excitation voltage onto the rotor. I think it's meant for startup only, although I'm not positive. I'm thinking if that relay was shorted and constantly setting +12VDC the excitation voltage would be the normal SCR's chopped sine output but then when it was expected to be off, it would then also get the +12V from the failed RIB relay causing excessive excitation voltage and lead to a high voltage. Worst case it's the ADC control.

How much is a SCR and RIB? I know the ADC is a lot $1k.

Thanks for response! SCR module was $50...I found the test procedure for it. But I’d have to buy a resistor to test it. So for $50 I figured I’d try that first. I figure since I was able to make changes through the ADC I’m praying the ADC is good. I’ll check on the RIB board as well. I think I read something in the service manual about it being for startup as well. But what you say makes sense...so I’ll check it out. It will probably be next week before I can install the new SCR module. But I will update this thread. Thanks guys!

Well guys...I finally bit the bullet and bought a new ADC 2100 for my Kohler. I was able to set the controller to the lowest it would go on the voltage set point and keep it around 135V-140V. But before I burned anything up in my boat, I decided to fix it once and for all. Called Colburn Power Systems and they were very helpful with a final diagnosis on the generator. In the end we decided it had to be the ADC. Sure enough, I ordered a new ADC controller and installed it this past Friday. Set the controller up properly and adjusted voltage in the driveway on the water hose. She put out a steady 120V no problem. Took the boat out for a long weekend, ended up putting 36 hrs on the generator and the new controller never missed a beat. She purred right along and kept the voltage perfect all weekend...wished I didn't have to spend $1050 on a controller. But I do love my A/C on these hot summer days