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Discussion Starter · #1 ·
Already replaced once. Issues again. Did a diode test. 2 of the 3 phase read 157 while the 3rd went to short. Melted tail lights, positive battery terminal, melted rectifier/stator connection. This all started when I noticed a loose + battery terminal. Could this have caused a diode to fault in the rectifier?
 

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I think you've got a something more serious that just a rectifier issue. it sounds like there is a short somewhere. that is allowing more current to move than a fuse should.
 

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^^^^^Agreed!!! Time to test that stator.
 

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Discussion Starter · #4 ·
Don't I need to supply power to the stator to test it? I have a new battery, rectifier and connector for the stator. How do I test this without burning up the new parts? Do I just say Heck and replace the stator too? I've never done a stator before. I'm pretty sure on a 2015 Sportsman 570 , the housing is oil filled. I have no problem trying it but would just need to order one and get a hold of a fly wheel puller. Any ideas on testing existing stator without damaging anything else would be appreciated. Thx
 

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You're looking for 0.2ohms between the coils and an open circuit from coil(s) to ground.
 

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Discussion Starter · #6 ·
Did a diode Test on the regulator rectifier and found a fault in 2 of the diodes. Stator passed ohms Test and there is no short to ground. At idle the stator put out about 20VAC and went up as the rpms increased. So I replaced the R/R and the connector on the stator side. Tie wrapped the entire harness as far from the motor as length would allow and since I had all the plastics stripped off, went over with a fine toothed comb. Cleaned up all grounds and hot connections. Put dielectric grease where I could. Seems to be running fine. Greased all her fittings, changed the oil, cleaned out the air box and changed the air filter. Yellow 3 phase wires are getting pretty warm still but I wonder if they should be a heavier gauge. Oh well, I’ll keep an eye on her.
 

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It's normal for the wires to get warm (caused by current (amps)) - the rec/reg will get warm too (changing AC into DC) - the higher the voltage output of the alternator (stator) the lower the amperage flowing through the wires.

20 VAC from the stator will not charge the battery - the 20 volts AC (peak to peak) is cut in half by the rectifier (10 volts peak to peak but the negative going peaks are now positive going peaks and the pulses are closer together (pulsating DC) raising the average voltage to approximately 8 VDC) - most alternators will have a 35 VAC or higher output at about 2000 rpm - the job of the regulator is to limit the DCV going to the battery to about 14.8 volts (typical regulator turns off about 14.6 to 14.8 volts and turns back on at about 12.8 to 13.2 volts).

What happens when the battery is fully charged and the voltage regulator turns off the current to the battery? The current is shunted off to ground through a resistor. The alternator continues to generate voltage, the rectifier continues to convert the AC into DC, the internal resistor in the regulator simulates the internal resistance of the battery and excess current is drained to ground. The resistor emits heat and the rec/reg housing gets hot dissipating the heat to the air.

Now - a permanent magnet generator/alternator/stator produces AC voltage continuously - the voltage output will rise and fall dependent on engine speed, but typically at about 2000 RPM it will have an output of no less than 28 volts AC and may be as high as 45 VAC. As engine speed increases, the voltage will rise, but usually never above 50 or 60 VAC. Keep in mind this type of charging system is not designed to "charge" a battery, but is designed to maintain the charge on a battery.

The best way to burn out a rec/reg and/or stator? Install an under charged battery and attempt to charge it by operating the vehicle or install a bunch of high wattage lights or other accessories that draw more amperage than the alternator is capable of supplying power for. In this case, the lights or accessories draw off the battery and charging system draining the battery while operating. The charging system is operating at maximum capacity continuously (which is not what it is designed for) and components start to fail. The first failure is usually the connector between the stator and the wiring harness - it heats up and as it heats up it's resistance increases which creates more heat - eventually the connector melts. At the same time, the regulator is not shutting off supplying a charge to the battery continuously - the rec/reg overheats and the diodes fail (either opening like a fuse or shorting out) - if the diodes open, current flow stops and the parts cool down - if the diodes short, AC voltage is passed through from the stator to the battery damaging the battery. Sometimes when the diodes short there is an AC voltage surge high enough to burn out lights and other electronic equipment. It takes a while for the AC to kill the battery. In a severe case, the stator, rec/reg and the battery all need replaced at the same time. Sometimes only the rec/reg needs replaced. The stator and the battery are pretty durable and while they may be slightly damaged, they may continue to function satisfactorily for several years before giving up completely. Generally a damaged stator will outlive a damaged battery.

If you have any questions after reading this, I will do my best to answer them. I am not an electrical engineer, but I do have a technical degree in electronics.
 

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Discussion Starter · #8 ·
Latebird, thank you for the reply and sharing your knowledge. I’m going to keep a close watch. I do not run a ton of accessories. I have a winch and that’s all. I think the stator maxes out at 55-60 VAC when getting the rpms up. I’m just bummed that this is the 3rd R/R and 3rd battery in 3 years. I have 640 miles on the machine. I’m half tempted to replace the stator now because that is the only piece of the charging system that has not yet been replaced. Honestly, once I get this issue kicked, I am thinking about trading the 570 in and getting a UTV. My main purpose is to take care of my 30 acre farm so I need this tool to operate as it should. Frustrating?!!!
 

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Sounds like you have great knowledge of these electrical systems. I have an old Ranger that just burned up/melted. It started to melt and then continued to melt even with the engine off until I unplugged it, then immediately stopped. This occurred while I was running about 1/2 throttle continuously for about a 2 mile stretch. this Ranger typically stays on my very small yard and rarely gets the throttle opened up for more than a minute due to the small operating area. Battery is old, but it always starts. I did replace the rectifier once before a few years ago chasing a separate issue, but that was not the "cure" for the previous issue. That previously replaced rectifier did however have a "hot spot" on it's back side which was the reason I replaced it chasing that previous issue. The ranger started to sputter and then stalled right when the rectifier went up in smoke. But then it actually started after I unplugged the entire thing and was able to limp home. By limp home I mean it ran nicely (driving back at just 10 or 15mph or so) but then died after about a mile. towed it back, then let it sit for a few hours and I was again able to start it to get it loaded back on the trailer.

Does this sound like just a bad rectifier or do I need to look elsewhere to see if there is a separate culprit taking out the rectifier?
 

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It's normal for the wires to get warm (caused by current (amps)) - the rec/reg will get warm too (changing AC into DC) - the higher the voltage output of the alternator (stator) the lower the amperage flowing through the wires.

20 VAC from the stator will not charge the battery - the 20 volts AC (peak to peak) is cut in half by the rectifier (10 volts peak to peak but the negative going peaks are now positive going peaks and the pulses are closer together (pulsating DC) raising the average voltage to approximately 8 VDC) - most alternators will have a 35 VAC or higher output at about 2000 rpm - the job of the regulator is to limit the DCV going to the battery to about 14.8 volts (typical regulator turns off about 14.6 to 14.8 volts and turns back on at about 12.8 to 13.2 volts).

What happens when the battery is fully charged and the voltage regulator turns off the current to the battery? The current is shunted off to ground through a resistor. The alternator continues to generate voltage, the rectifier continues to convert the AC into DC, the internal resistor in the regulator simulates the internal resistance of the battery and excess current is drained to ground. The resistor emits heat and the rec/reg housing gets hot dissipating the heat to the air.

Now - a permanent magnet generator/alternator/stator produces AC voltage continuously - the voltage output will rise and fall dependent on engine speed, but typically at about 2000 RPM it will have an output of no less than 28 volts AC and may be as high as 45 VAC. As engine speed increases, the voltage will rise, but usually never above 50 or 60 VAC. Keep in mind this type of charging system is not designed to "charge" a battery, but is designed to maintain the charge on a battery.

The best way to burn out a rec/reg and/or stator? Install an under charged battery and attempt to charge it by operating the vehicle or install a bunch of high wattage lights or other accessories that draw more amperage than the alternator is capable of supplying power for. In this case, the lights or accessories draw off the battery and charging system draining the battery while operating. The charging system is operating at maximum capacity continuously (which is not what it is designed for) and components start to fail. The first failure is usually the connector between the stator and the wiring harness - it heats up and as it heats up it's resistance increases which creates more heat - eventually the connector melts. At the same time, the regulator is not shutting off supplying a charge to the battery continuously - the rec/reg overheats and the diodes fail (either opening like a fuse or shorting out) - if the diodes open, current flow stops and the parts cool down - if the diodes short, AC voltage is passed through from the stator to the battery damaging the battery. Sometimes when the diodes short there is an AC voltage surge high enough to burn out lights and other electronic equipment. It takes a while for the AC to kill the battery. In a severe case, the stator, rec/reg and the battery all need replaced at the same time. Sometimes only the rec/reg needs replaced. The stator and the battery are pretty durable and while they may be slightly damaged, they may continue to function satisfactorily for several years before giving up completely. Generally a damaged stator will outlive a damaged battery.

If you have any questions after reading this, I will do my best to answer them. I am not an electrical engineer, but I do have a technical degree in electronics.
Great Info thanks!

i am trying to button up my friends 2014 sportsman 570 and i originally thought the rectifier might be bad. i watched a few videos on testing the rectifier with a diode set multi meter and my findings are -
1. multi+ to battery + = OL
2. multi+ to battery - = OL
3. multi - to battery + = .4-.5
4. multi - to battery - = .773

any help would be greatly appreciated!!

thanks
bob
 

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Premium Member
2008 800 ho efi, 2019 850 SP premium
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10,142 Posts
Great Info thanks!

i am trying to button up my friends 2014 sportsman 570 and i originally thought the rectifier might be bad. i watched a few videos on testing the rectifier with a diode set multi meter and my findings are -
1. multi+ to battery + = OL
2. multi+ to battery - = OL
3. multi - to battery + = .4-.5
4. multi - to battery - = .773

any help would be greatly appreciated!!

thanks
bob
Welcome to the forum
 

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Premium Member
2008 800 ho efi, 2019 850 SP premium
Joined
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10,142 Posts
Sounds like you have great knowledge of these electrical systems. I have an old Ranger that just burned up/melted. It started to melt and then continued to melt even with the engine off until I unplugged it, then immediately stopped. This occurred while I was running about 1/2 throttle continuously for about a 2 mile stretch. this Ranger typically stays on my very small yard and rarely gets the throttle opened up for more than a minute due to the small operating area. Battery is old, but it always starts. I did replace the rectifier once before a few years ago chasing a separate issue, but that was not the "cure" for the previous issue. That previously replaced rectifier did however have a "hot spot" on it's back side which was the reason I replaced it chasing that previous issue. The ranger started to sputter and then stalled right when the rectifier went up in smoke. But then it actually started after I unplugged the entire thing and was able to limp home. By limp home I mean it ran nicely (driving back at just 10 or 15mph or so) but then died after about a mile. towed it back, then let it sit for a few hours and I was again able to start it to get it loaded back on the trailer.

Does this sound like just a bad rectifier or do I need to look elsewhere to see if there is a separate culprit taking out the rectifier?
Welcome to the forum
 

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I've got a 03 700 bought it new really had with for years until the crank bearing started going, first it took the magnets off the flywheel and stator was chewed too
So replaced everything but didn't know about the bearing at that time.
And a 5min ride turned a 500$ flywheel to a paperweight and another stator, good times!
After a year not looking at it
Replaced everything one more time + bearings, I got it running and now it's over charging, on 3rd voltage regulator/ rectifier original didn't work and burned one
And getting one in a few days
So after that if that doesn't work I'm at a loss
Any thoughts
 

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2008 800 ho efi, 2019 850 SP premium
Joined
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10,142 Posts
I've got a 03 700 bought it new really had with for years until the crank bearing started going, first it took the magnets off the flywheel and stator was chewed too
So replaced everything but didn't know about the bearing at that time.
And a 5min ride turned a 500$ flywheel to a paperweight and another stator, good times!
After a year not looking at it
Replaced everything one more time + bearings, I got it running and now it's over charging, on 3rd voltage regulator/ rectifier original didn't work and burned one
And getting one in a few days
So after that if that doesn't work I'm at a loss
Any thoughts
WELCOME to the forum
 
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