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Kohler 6.5 controller A-245701


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  #1  
Old 03-13-2019, 11:20:56 PM
Kenny Crenshaw Kenny Crenshaw is offline
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Default Kohler 6.5 controller A-245701

I got my generator running after an infusion of about $1,000 in parts. Runs great, no smoke or blowby, sucks gas like it was free. Anyway, I am looking for a schematic on the controller, which is a single phase 220-240 volt with a 12 volt start system. My main concern now is with where the electric Sisson choke hooks up. The wiring is unmollested, but there is not an obvious wire that would go to it. Any help would be appreciated.
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  #2  
Old 03-14-2019, 09:25:27 AM
gnucklehead gnucklehead is offline
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Default Re: Kohler 6.5 controller A-245701

This thread should interest you.. Wiring diagram attached to post #10
https://www.smokstak.com/forum/showthread.php?t=141715
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Old 03-15-2019, 02:12:57 AM
dkamp dkamp is offline
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Default Re: Kohler 6.5 controller A-245701

Hey Kenny-

Should be Terminals 2 and 3 (polarity irrelevant)... but two things...

Get a modern silicon bridge rectifier and replace that selenium rectifier stack before it fries and kills your field windings... Seleniums were the common technology for the day, but they tend to have a limited life, and when they die, it's not a happy death. A 20A 1000v bridge is about six bucks, and is a whole lot smaller. There's four connections- two for AC, and one for field +, the other for field -. Only two that are critical are - and + polarity of the field side- If you hook them up wrong, it won't regulate properly (you'll put a load on, and voltage will fall off rapidly). Hook 'em up right, and it'll stay regulated nicely.

And for what it's worth, your L600 should NOT be thirsty... make sure the timing is correct, and that your magneto's impulser is working properly (it provides both spring-impulse retard for cranking, and advance for running).

While I don't think it'd really suck lots of fuel, your selenium rectifier might be leaking a bit, causing the excitation load to be higher, thus eating crankshaft HP.

Does it seem like it's laboring or running really rich?
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Old 03-15-2019, 01:45:06 PM
Vanman Vanman is online now
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Default Re: Kohler 6.5 controller A-245701

Very good stuff. Just a couple of extra points.

In the case of a selenium rectifier failing open, it is the compounding transformer that will be ruined (by very high voltage) if there is a load on the generator. Still a big deal as these are not an off the shelf component, and must instead be rewound.

If the rectifier were to leak or short, nothing would be effected except for the loss of compounding. The voltage would droop under load. But it's my understanding that these fail open. So definitely replace it before it ruins your compounding transformer.

Keith
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Old 03-15-2019, 09:02:04 PM
Kenny Crenshaw Kenny Crenshaw is offline
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Default Re: Kohler 6.5 controller A-245701

Wow, thanks guys. I am going to have to process all of that. The timing is nearly dead on. My timing light shows the "S" mark is at about 20 degrees, it is supposed to be at 16, I set it at 18 according to my adjustible timing light. The compression is around 110. When I say thirsty, it can drink over a gallon an hour (estimate) with no load. It has 8 new valves, I reground the seats to spec. There us no smoke or blowby. New pounts, condenser, and coil. New plugs and plug wires. I had accidentally put $1,000 in new parts in it.

Ok. So I found the rectifier in the parts book. The thing with all the fins. Where do I get one of those?

Also, the battery charger part is putting out 10 amps at 16 volts. Is that normal? The big wire wound resistor on the back of the controller gets too warm to touch. Is that normal?
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Old 03-15-2019, 10:40:30 PM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 6.5 controller A-245701

Quote:
Originally Posted by Kenny Crenshaw View Post
Also, the battery charger part is putting out 10 amps at 16 volts. Is that normal? The big wire wound resistor on the back of the controller gets too warm to touch. Is that normal?
Sounds high on the voltage. The resistor might get too hot to touch without there being a problem though, but “too hot to touch” is a bit of an arbitrary measurement.

I’d try to lower that voltage a bit if you can, ideally something more around 14 volts or so.

Bill
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Old 03-16-2019, 12:00:50 AM
Kenny Crenshaw Kenny Crenshaw is offline
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Default Re: Kohler 6.5 controller A-245701

How do you lower the voltage?
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Old 03-16-2019, 01:03:32 AM
Vanman Vanman is online now
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Default Re: Kohler 6.5 controller A-245701

That sounds like a stuck or failed voltage regulating relay. It is a voltage sensitive relay with a normally closed contact in series with the larger battery charging resistor (the one that's getting hot).

When the battery voltage comes up, the relay picks up, and cuts out the high charge current, leaving only a smaller, higher resistance resistor in the charging circuit.

The exciter runs around 30 volts, and your battery wants to be 13 ~ 14, so these resistors drop the voltage / limit the charge current.

Most likely the contacts are stuck, but it's possible it's coil is burned out, or otherwise not getting power.

Keith
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Old 03-16-2019, 12:16:12 PM
Kenny Crenshaw Kenny Crenshaw is offline
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Default Re: Kohler 6.5 controller A-245701

Keith, how do I test that relay, or do I just replace it?
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Old 03-16-2019, 08:24:08 PM
jack0 jack0 is offline
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Default Re: Kohler 6.5 controller A-245701

On the fuel consumption.

Something is not right. You could burn 1g. at full load.
3 weeks ago we lost power for 7 hours. I ran one of my L600 5K units.
The outage occurred at night, so the plant was lightly loaded running
the boiler, frig, freezer, TV and necessary lighting.
The next day I measured how much fuel I used. It was .45 gph. I was running prem. non-eth. gas at stock timing. I could probably do better with a little more advance.
Not bad for a flatty.
Your results should be similar.
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Old 03-17-2019, 08:50:20 PM
Vanman Vanman is online now
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Default Re: Kohler 6.5 controller A-245701

Quote:
Originally Posted by Kenny Crenshaw View Post
Keith, how do I test that relay, or do I just replace it?

To start with, I'd remove the cover and have a look. It may well be that the contacts are merely stuck, and in need of a good dressing / polishing. Remember they are normally closed, so operate the relay by hand to test them.

If the contacts aren't stuck, I'd start up the plant, with a voltmeter on the battery. When the voltage goes up above 15 or so, I'd see if the contacts are open. If not, manually push in the relay, and the voltage should begin dropping.

Beyond that it would be a matter testing the relay coil and that it is getting power.

Keith

Last edited by Vanman; 03-17-2019 at 09:37:49 PM.
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