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Looking for charging failure explantion from you smart tractor guys


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In the summer of 2020 I used the battery and charging circuit on my HB112 to power a custom made rear mounted weed sprayer.  The sprayer came with a 10 amp in-line fuse.  As a precaution and test before I used the sprayer the first time I substituted a 5 amp fuse that promptly blew...as did a 7 amp fuse.  I put the original 10 amp fuse back in and ran the sprayer with no problem.  The electrical configuration stayed the same for summer 2021 but this time things smelled  "hot" quickly and the ammeter stopped registering. However, the in-line 10 amp fuse didn't blow. I finished what little remained of the spraying job on just the battery. After following tips on this site  and YouTube on how to test the generator part of the starter generator and upon taking the starter-generator apart it was readily apparent some windings had burned.  The tractor is used only occasionally for mowing around the lake place and doesn't need to start/stop repeatedly.  I've decided, since the starter still works (and I'm too cheap to fix/replace the unit) that I'll just charge the battery before each use. For spraying I'm planning to mount and use a 12v deep cycle battery I have.

The Delco Remy spec sheet I found on-line for the 1101689 starter generator says it's rated for 12 amps so I'm surprised it wouldn't handle a 10 amp draw.  Also, why didn't the 10 amp fuse blow before the generator windings failed. Can you wiser, more experienced tractor guys explain this for me??

Thanking any and all responders in advance.

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Not an expert by any stretch of the imagination, but the problem could have been a faulty voltage regulator that allowed the S/G to produce more amps than it was rated for. 

It also might be that as S/Gs age, they become more susceptible to heat failure as the thin coatings on the wires in the field coils start to break down and there's some shorting in the coils and they can't produce max amps without failure. 

I am curious what @BLT's thoughts on your issue are. 


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From the article Bill linked above:

" Since these SGs are a combo and only have one generator field coil they only produce about 5 to 10 amps max.  If the regulator contacts stick and keep the F term grounded at all times [called full fielded] the SG overheats and the generator field burns out.  We replace these commonly. NOTE: If they are burned out most commonly the regulator caused it. HAVE IT CHECKED HOOKED UP TO THE STARTER GENERATOR!!!  "

Also verify the regulator is the correct one for the application, others look the same but can do the same thing as your problem, by allowing to many amps to be drawn.

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