Honda GX620 not charging battery

[losttheplot]

I have a 20hp Honda GX620 on my Norwood mill. It has the 20amp charging system.
Initially I was running it without a rectifier/regulator and using a separate battery charger.

I purchased a Rectifier from Honda, unfortunately once hooked up it is not providing a charge to the battery.  :(

I have 35 volts A/C coming from the charge coils.
There is no continuity to ground through the charge coils.
The resistance across the charge coils is 1 ohm.

The battery voltage stays at 12.5 right up to 3600 rpm.
There is one fuse in the system and it is fine.

Does anyone have any suggestions on what to check next ?

LTP.

[Kbeitz]

Could be a weak or missing magnet in the flywheel...

[losttheplot]

I pulled the flywheel and the magnets all look OK...........

[47sawdust]

I run a Honda GX670 on my LT30.I have no advice except to call a small engine shop that sells Honda's.My local shop has always been very helpful.
I recently installed a 3 groove pulley on mine and installed a 75 amp external alternator for some added hydraulics.
Can you do a test on the rectifier?
Best of luck.

[esteadle]

Seems like the charger is doing the right thing, and the rectifier / Voltage Regulator is new, yes? Did you check the battery itself yet? Charge it with a trickle charger on a bench, and see if it holds?

[losttheplot]

Thanks for the thoughts.
The last battery died from running it flat every time.
New battery shows 12.5 volts with or without the motor running.

If I probe the harness before the battery it shows battery voltage with the motor running.
If I disconnect the output wire from the rectifier with the motor running I get 4-5 volts at idle and it drops to 1 volt at 3600.

Tempted to replace the charge coils, but I hate changing parts to try and fix a problem.

[Kbeitz]

It's gotta be that or the magnets.

[sawguy21]

There is nothing wrong with the charge coils or magnets if it is putting out 35VAC. Disconnect the charge wire from the battery and check output, you should get 14.5VDC. If not start working backwards, there has to be a bad connection in the system.

[losttheplot]

The rectifier is not putting out 14.5 volts.
I get 4 or 5 at idle and it drops to 1 or less at wot.
That is with the white charge wire disconnected from the wiring harness.
with the charge wire connected I get battery voltage back to the rectifier.
I have 35 volts ac going into the rectifier.

This says to me that the rectifier is not working, but it is new. ???

[sawguy21]

Is it mounted to a clean metal surface on the engine? Some avr's need to be externally grounded through the housing.
Is it OEM or aftermarket? Unfortunately, there is no warranty on electrical components from most suppliers.

[47sawdust]

When I removed my rectifier after adding the ext. alternator it was indeed mounted to a shiny surface.

[Ox]

I had the same symptoms on an old lawn tractor with the old cast iron Kohler engine.  Didn't make any sense.  It ended up being a bad rectifier.  A known good rectifier solved the problem.  I'm guessing it's either your new rectifier (it happens more frequently these days, getting a bad new part) or a wiring problem of some sort.  I would try a new rectifier myself.  If you're getting good AC from the coils and nothing much after the rectifier, it sort of has to be the rectifier, right? 

[losttheplot]

I talked with the honda service manager.
He tells me it is very rare to get a defective part.
He asked if the gap between the fly wheel and the coils was dirty or corroded.
I said no, but I dont think that would cause a problem to a magnetic field  ???

I have come to the conclusion that although the charge coils put out the correct voltage they are not putting out the correct amperage.
I don't have an ammeter that measures over 10 amps.

I am going to purchase a new set of charge coils, I just have not got around to it yet.

I will be sure to update this thread for the benefit of others

[losttheplot]

I installed a new set of charge coils and I have 14.5 volts with the engine running 
Unfortunately I also have a 1.2 amp draw when the key is in the off position  :(

[Ox]

Geez!  Two steps forward and 1 step back, huh?  I don't have a suggestion for the battery draw.  It's out of my league.  If this were mine, I'd put a blade switch in the positive cable and completely disconnect everything when done for the day and call it a success!  Sorry for your troubles, bud.

[losttheplot]

I picked up a toggle switch this afternoon.............. ;)

I can only think a diode is allowing current flow both ways in the rectifier?

[Ox]

Hmm.  That makes sense, doesn't it?  Just because it's brand new doesn't mean it isn't defective.  It would be worth a shot if you could take back the brand new one for a refund if it doesn't fix your problem.  Some places won't take back electrical parts.  I usually tell a little fib and say I found the problem before I had to install the new part.  Just don't get any grime on the new part!  :laugh: