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QT 16 Short Still Persists


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#1 chieffan ONLINE  

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Posted August 01, 2016 - 04:17 PM

On my third regulator and still have the short when the B+ wire is plugged to the regulator with the stator wires attached and the ignition switch is turned to the run position.  Stator checks out OK with 27.9 V AC at full throttle.  Light switch and attachment switch are both unplugged.  B+ wire does not show a short when checked end to end.  With the B+ wire and one stator wire attached to the reg. it is OK.  As soon as I touch the second stator wire I get the short.

 

These are aftermarket regulators so the terminals are 3 in a row and not two on top and one on the bottom.  With this configuration I can plug the B+ in the right terminal and the two stator wires on the other two and do not get the short.  Afraid to start and run the engine that way in fear of blowing the stator and/or regulator.  I have thought about rewiring the whole tractor, which isn't that much but I don't think I would gain anything.  Open to any and all suggestions.



#2 29 Chev OFFLINE  

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Posted August 01, 2016 - 07:49 PM

On most three terminal regulators the terminals are marked - B+ for voltage out and two marked with a curved line to indicate A/C current from stator wires in so I assume yours is marked and hooked up correctly.  Make sure the body of the regulator is grounded as floating / intermittent grounds can cause problems.  I would suggest hooking up the two A/C in wires from the stator after you make sure the regulator is grounded to the negative terminal of a good working 12 volt battery that is not connected to any of the tractor wiring (this will be a second battery).  Then hook a 5 or 10 amp fuse or circuit breaker to the B+ terminal and hook up the positive probe of the DC voltmeter to the fused wire and the negative probe to the second battery ground and observe the voltage after you start and run the engine for a few minutes.  If you are getting 13 - 14 volts DC and nothing gets hot try hooking up the fused wire to the positive terminal of the second battery - use a push pull switch so you do not create any sparks at the battery post.  See if the voltage output stays correct or changes and if anything gets hot or the fuse blows.  The fuse should prevent any serious damage to the regulator or wiring.  If everything checks out then I would think it is a problem with the wiring or battery in the tractor - just a suggestion.  Batteries can still start garden tractors but be bad internally and cause damage to electronic parts.   


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#3 chieffan ONLINE  

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Posted August 01, 2016 - 08:28 PM

I agree fully with the regulator markings.  Unfortunately, none of the ones I have used so far have any marking on the spades or the case to indicate which is which.  I also found another wiring diagram for the QT 16 first run.  It shows a different internal ignition switch connection that the one I have been using.  I also found a wiring diagram  that shows the right terminal as B+ and the center and left as stator.  Gets more confusing all the time.  The Onan number and Bolens number for the rect/reg are not the same.  But I guess that is understandable as two different companies handling the same part?

 

As for the battery it is a new Interstate about 2 months old at the most.

 

Why would I want to connect an AC source to the negative terminal of a DC battery?  AC and DC don't mix without the AC  going through a rectifier.  What am I missing here?  I follow your thinking in part by wanting to separate the tractor electronics but the reg/rect has to be grounded to the battery being used.



#4 29 Chev OFFLINE  

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Posted August 01, 2016 - 08:53 PM

Sorry - you do not want to hook up the A/C source to the negative post of the battery - the two wires off the stator go to the two A/C in terminals but make sure you hook up the ground connection from the battery negative terminal to the regulator case first before you hook up any other connections.  I would suggest you contact the place you got the regulator and verify which terminals are which to make sure you are connecting the terminals properly.  Not saying your battery is bad but I have seen cases where batteries would output current and voltage to start small engines but have high resistance internally when it comes to charging - the regulator sees the battery as needing to be charged and constantly keeps outputting full current in an attempt to charge the battery and self destructs - charging systems are not meant to be battery chargers but rather battery maintainers - put in current for a short time period of time to recharge what current was removed during starting and then maintain status quo. I am suggesting to eliminate the battery as a possible problem use a second battery to test the charging part of the stator and regulator with a second battery that is not connected to the tractor - that way you can start and run the engine off the battery in the tractor and still do your tests using the second known good battery to verify that the regulator and stator are working correctly  - again just a suggestion.     


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#5 chieffan ONLINE  

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Posted August 01, 2016 - 09:09 PM

OK, Thanks.  That makes a lot more sense.  The place I got the reg. from tells me that the center terminal is the B+.  This makes sense as it would not make any difference if the plug got turned over it would still be connected correctly.  I agree that the charging systems are maintainers and not chargers.  I have a couple small battery maintainers that I move around to different tractors to keep the batteries full all the time.  Will do some more checking tomorrow and se what happens. 
Thanks for the clarification.



#6 chieffan ONLINE  

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Posted August 02, 2016 - 08:53 AM

Sorry - you do not want to hook up the A/C source to the negative post of the battery - the two wires off the stator go to the two A/C in terminals but make sure you hook up the ground connection from the battery negative terminal to the regulator case first before you hook up any other connections.  I would suggest you contact the place you got the regulator and verify which terminals are which to make sure you are connecting the terminals properly.  Not saying your battery is bad but I have seen cases where batteries would output current and voltage to start small engines but have high resistance internally when it comes to charging - the regulator sees the battery as needing to be charged and constantly keeps outputting full current in an attempt to charge the battery and self destructs - charging systems are not meant to be battery chargers but rather battery maintainers - put in current for a short time period of time to recharge what current was removed during starting and then maintain status quo. I am suggesting to eliminate the battery as a possible problem use a second battery to test the charging part of the stator and regulator with a second battery that is not connected to the tractor - that way you can start and run the engine off the battery in the tractor and still do your tests using the second known good battery to verify that the regulator and stator are working correctly  - again just a suggestion.     

This may be all well and good when checking for charging.  But I cannot start the engine until I get rid of the short in the on position.  I don't think a week/bad battery would have anything to do with this problem.  Some place, something is going to ground when it should not.  THAT is what I need to find.






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