Overcharging on C-175 (Kohler KT17)

[Jeff-C175 7,207]

End of last year I notice my ammeter running consistently half way up scale on a fully charged battery.  I knew something was wrong...

 

Put a voltmeter on it yesterday (FINALLY!, yes, I'm a procrastinator) and found it was charging at 17.3 V ... great... probably 'cooked' the battery.

 

I first pulled the ignition switch to check it and found good connection on all but one of the terminals.  Measuring from the B (Battery) to the R (Regulator) terminal was bouncing all over the place, from good connection all the way to open connection.  OK, switch is bad...

 

Nothing to lose, needs replaced anyway, I decided to open it and have a look.  CAREFULLY!!!! (it's white metal and EASILY broken) and slowly I went around the edge and unrolled the metal where it crimped the terminal board in.

 

Knowing there are springs and detent balls inside I carefully popped the back terminal board off... nothing went flying... good so far.  This thing was so full of 'schmutz'... dirt and grease... I was surprised ANY of the contacts were making.

 

I did NOT pull the plastic actuator out of the switch since that's where the balls and springs are, if you try this at home, be very careful that part stays in place.  If anything goes SPRANG and pieces fly, give up.

 

After cleaning the schmutz off the terminal board and wiper contacts, I put the terminal board back in and with small ball peen hammer, went around tap tap tap and crimped the board back in place.

 

After this, it WORKS GREAT!  Clean contact, no intermittent... good deal, for 3 hours of time, I saved $12!  What a deal! 

 

Chapter 2 next................

[WH nut 553]

How many beers went in the 3 hours?

[Jeff-C175 7,207]

After switch was reinstalled, I started machine and voltage went to about 14.6 and hung there for about 3-4 minutes and then dropped back to 12.7 for a few seconds, then up to 14.6 ... lather rinse repeat... cycled between the two voltages as though it was doing what it should be, charging the battery...  fixed!  or so I thought... the plot thickens...

 

During this test, engine was running around 2500 RPM, halfway between turtle and rabbit.

 

I pushed the throttle all the way to rabbit and after a second or two, BLAM! the voltage popped up to 17.3V again.  Ran throttle all the way to turtle and voltage dropped to about 15.5V.

 

NOT fixed.

 

Regulator must be fried.  There's an intermittent inside it, and probably temperature related.  Works fine when cool, but after a few minutes of charging something craps out.  Could be vibration related too I suppose.

 

Going out now to check it again while cool.  Going to let it run at medium speed to see if it continues to work, because I suspect that it may also be a voltage related failure.  When engine runs slower, voltage from stator not as high, works OK... raise voltage to regulator, maybe extra voltage causes it to crap out.

 

More later...........

 

How many beers went in the 3 hours?

 

HA!  THREE before I even had the ballz to take the pliers to it and open it! 

[Jeff-C175 7,207]

And, don't think I'm not going to try and get that epoxy out of that bad regulator! 

 

Failure analysis is my game!

 

I have no doubt that the bad connection in the switch caused something to fry in the regulator.

[WH nut 553]

LOL sounds like it was time well spent then

[Jeff-C175 7,207]

Any excuse to down a six of Sam is a good one! 

[WH nut 553]

LOL didnt realize you even needed an excuse

[Jeff-C175 7,207]

No, yer absholtely carreck!  No excuse needed... It's 5 o'clock somewhere!

 

There's definitely something whacked with that regulator.  When I first started it cold, the the ammeter was bouncing all over the place, the voltage was following it.  17 for a half a second, 13 for a half second, up down, up down, ...  after about 10 minutes or so it seemed to settle down but still jumped every now and then.

 

Double checked and cleaned all the connections again, all OK.  Checked the stator output, steady as a rock.  Maxes out about 38 VAC at 3600 RPM, about 18VAC at idle.

 

Ordering a new one tonight, will dissect the old one if I can soften the epoxy somehow after the new one gets here.  I guess I'll order a new switch too.

 

Anybody have any idea how to soften old hardened epoxy potting compound?

[WH nut 553]

SOI has explored the regulators so maybe he will chime in.

[Jeff-C175 7,207]

I've read several of the other voltage regulator threads... that's sorta what inspired me to finally look into this one.  One of the threads had a schematic of the regulator... forget who drew it, but after studying it for a while I finally understood how it works (or is SUPPOSED to work).

 

I'm wondering if putting the regulator in like a 250° oven will soften the epoxy so it can be picked out without damaging the components too badly.

[DoctorHfuhruhurr 137]

Got a heat gun? 

[Save Old Iron 1,573]

I'm wondering if putting the regulator in like a 250° oven will soften the epoxy so it can be picked out without damaging the components too badly.

 

Make certain you unsolder the SCR leads from the circuit board as the SCR body is press fit into the heat sink assy (second image down circled in red).

 

The potting material in the reg i disassembled was more a polyurethane type material than rigid epoxy. I thought I had included a photo of the material in my original post. Just incase ...

 

 

 

 

[SousaKerry 503]

I pulled one apart once cause I was bored I guess...   I wouldn't recommend it  unless you like a challenge,

[Jeff-C175 7,207]

 

Got a heat gun?

But of course!  That's probably going to be tried after I get kicked out of the kitchen for baking wheel horse parts in the oven.

 

That white potting compound looks nothing like what's in this one... mine is hard and black... oh crap, did I just type that?  Really looks like an epoxy.

 

I do like a challenge, but masochism come to mind also!

[Jeff-C175 7,207]

Steve, is that a small transformer I see on the circuit board behind the casing?

 

That isn't the same type of regulator as on the KT engine and I don't believe there's a transformer in it... but sure does look like one in yours!

[Jeff-C175 7,207]

I got the new regulator in, works fine.

 

Dissected the old regulator... or TRIED to... nothing softens old hardened epoxy.  Only thing that would work is to burn it out with a torch.

 

Bottom line is that there isn't much left of the original regulator, but for now, the machine is fixed.