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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12592
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have 2 craftsman lawn tractors they both have 15.5 hp

Customer Question

hi i have 2 craftsman lawn tractors they both have 15.5 hp briggs and stratton engines they both have a dual circuit alternator, my problem is when the tractor is running at full rpm for 20 min or so the battery voltage goes up to 20 v dc, i know this isnt normal, i even changed multimeters to make sure. i dont get why it charging so high.
Submitted: 6 months ago.
Category: Small Engine
Expert:  JohnF2015 replied 6 months ago.
Hi, my name is***** will be assisting you.Does your engine or machine have a regulator on it? If so the regulator is most likely your issue, it is causing voltage spikes which it should not be doing. I have seen this happen on several occasions and normally replacing the regulator will solve your issue. The only other thing that I have seen occur is the wiring from the alternator get shorted together and cause it.
Customer: replied 6 months ago.
nope they do not have any voltage regulators
the wiring was all checked and so was the fuse and holder
Expert:  JohnF2015 replied 6 months ago.
The wiring under the flywheel coming off of the stator or alternator was checked as well?
Customer: replied 6 months ago.
yes it was i removed the flywheel and checked everything everything is good
Customer: replied 6 months ago.
08 May 2016 09:14
yes it was i removed the flywheel and checked everything everything is good
Customer: replied 6 months ago.
now today i have rechecked after 20 min of running and its at 16.2 volts
Expert:  JohnF2015 replied 6 months ago.
Can you provide the model and type numbers from your engine so that I can look at diagrams of the engine to better assist you?Does the battery get warm or hot after running the machine for a little while? If it is overcharged normally the battery will get hot.
Customer: replied 6 months ago.
the engine model is 31c707 0230 e1 030625za
the second one is 31a607 0741 b2 100216zdthe batterie does not get hot at all even at 20 volts it dint get hot, batteries arent boiling either
starting to think this is normal for these thats probably why batteries dont last very long in lawn tractors.
Expert:  JohnF2015 replied 6 months ago.
According to the parts diagram for the 31c707 it has a voltage regulator on it. I would suspect that the regulator is bad if you are getting that kind of charging voltage back to the battery. It should normally be somewhere between 14 - 15 volts.And the 31a607 also shows to have a voltage regulator as well in the parts diagram.They both utilize the dual circuit stator or alternator.
Customer: replied 6 months ago.
where is this regulator located cause ive searched the entire tractor inside of frame and evrything
Expert:  JohnF2015 replied 6 months ago.
The regulators are normally mounted right to the side of the engine. The wiring from the alternator(normally yellow wires) plugs into it and then there will be another wire(normally red wire) running from it back to the solenoid or ignition switch. It is a square block about 2".
Customer: replied 6 months ago.
checked again today there is none, the 2 wires comming from the stator are red and one is black, the red one has a diode in it and the black one is pure ac for lights, both wires go into the harness and go to the ignition switch.