HELP with 755 alternator and battery overcharging?

[Sundancer268]

The Battery is over filled. The liquid level should be below the split rings. The battery should have enough Acid to cover the plates prior to charging and then filled with distilled water to slightly below the rings.
12.6 Volts will be the normal reading for a fully charged battery after it has set for a while with no charge or discharge loads applied.
A properly functioning Alternator will put out a voltage between 13.6 to 15 volts with the output related to the ambient temperature. The colder it is the higher the voltage, At a normal summer time temperature of 70-80 degrees you should read about 14.6 Volts. This should not change very much as you add or remove loads like the head lights or other loads. If the voltage drops and does not recover you have a poorly operating or improperly sized alternator installed. If the electrical system has not been modified over the years with additional lighting the alternator should be of the proper size to handle the original electric system. If it can not handle the original electrical system, you have a problem with the alternator. The voltage regulator only controls the maximum system voltage at the current ambient temperature. If an internal coil winding is shorted, open or has a bad diode the alternator will not achieve its rated output and there for not keep up with the original load.

 

[Gator6x4]

The Battery is over filled. The liquid level should be below the split rings. The battery should have enough Acid to cover the plates prior to charging and then filled with distilled water to slightly below the rings.
12.6 Volts will be the normal reading for a fully charged battery after it has set for a while with no charge or discharge loads applied.
A properly functioning Alternator will put out a voltage between 13.6 to 15 volts with the output related to the ambient temperature. The colder it is the higher the voltage, At a normal summer time temperature of 70-80 degrees you should read about 14.6 Volts. This should not change very much as you add or remove loads like the head lights or other loads. If the voltage drops and does not recover you have a poorly operating or improperly sized alternator installed. If the electrical system has not been modified over the years with additional lighting the alternator should be of the proper size to handle the original electric system. If it can not handle the original electrical system, you have a problem with the alternator. The voltage regulator only controls the maximum system voltage at the current ambient temperature. If an internal coil winding is shorted, open or has a bad diode the alternator will not achieve its rated output and there for not keep up with the original load.

I concur.

 

[JD755]

I agree with everything Sundancer268 said. The problem looks to be simply an overfilled battery. I posted a picture from the 755 manual that shows the proper battery fill level. Having said that, there is still some small loss through the vents to be expected due to the bouncing and angles of operation for a tractor. Corrosion around the battery on JD tractors is very common, and there are lots of threads here about that. I also experienced those corrosion problems, but mostly solved them several years ago by adding a vent hose. The JD TY6192 battery comes with a second vent cap that can be used with a hose. Buyers usually just throw that cap away. If you still have it just add a hose and change over to that. Of course first make sure that battery fill level is correct.

 

[Jaymien]

So, alternator is working as it should which i thought would be the case. with that in mind, i tend to agree that it may be a simple battery issue. Wouldn't the battery fill level sort of self correct itself after it has leaked several times. the level in the battery now is close to what's shown in the manual, but again still had enough leaks over the weekend to get the tray wet, again! I think i'm going to the auto parts store for a sealed battery today and taking the JD battery back. I'm tired of cleaning up battery acid.

thanks for all the help troubleshooting this.
I'll post a pic of the new battery once i get it and results after a few days running the tractor.

damien.

 

[Jaymien]

so here is fix. went and bought a sealed battery that fit the battery tray. I took the JD battery back and the dealer looked at it and confirmed level in battery was okay, but dealer down in denver is pretty good to me, and they took it back with no problem. They said they would also test it and let me know what, if anything, was wrong with it. New battery was optima 34r which fits the battery tray perfect, post on correct sides and towards front end. this is way more battery than the tractor needs, and $40 more than the JD battery, but oh well. made a quick hold down bracket and after a full day of work...no more leaks.

dealer also suggested, the same vent and drain tube that JD755 showed, but also agreed the battery still shouldn't leak that much and you shouldn't need to drain anything from the battery.

photo of battery installed.

 

[Resourcerer]

I had a similar problem with a JD 755. battery acid overflowed. Voltages were almost identical. I installed a new battery... from JD dealer. I cleaned out battery compartment, used battery mats to soak up acid... no luck. Dealer indicated I needed new alternator (expensive). Same thing happened with new alternator and new battery. Same voltages as before. Spent time cleaning up acid and repainted everything. I ordered a gel battery and the problem went away. About 6 months later I traded the tractor in for 2720. Dealer did not want "old alternator" since it was used.

Which gel battery did you get? I'm having the same problem with new and old JDTY6192 batteries on different 755's. It's a problem with the acid batteries. Because this is a common problem JD has an alternative battery cap with a vent or discharge nipple to a tube, but that just exits the acid below, which could be on a mower deck. So I'm trying to get away from acid batteries altogether.