battery overcharging

[ritcheyvs]

When the engine is reved up to about 1500 rpm I am getting 17.5. At idle it is 15.3. This is after letting the motor run for about 5 minutes.

Assuming your meter is OK, these voltages are WAY too high and will boil off the battery electrolyte. Ideally, you should see 14.x volts max as the battery reaches full charge. The bad news is your alternator is expensive (like $300). The good news is that the alternator is probably OK but the voltage regulator is probably sick and it's much cheaper (like $60) and easier to replace. It's item #1 in this diagram:

OEM Parts

Without a schematic I can't be certain that this is your problem but that's my guess. But this part is labeled "old version" in the drawing so make sure you get the right part for your specific serial number machine. In the old days the voltage regulator was separate from the alternator; originally, it was actually a relay that quickly opened and closed to regulate current to the alternator rotor based on output voltage, Later, solid state (transistor) versions were used. Today, almost all regulators are built into the alternator; some are easy to replace and some aren't. So the trick will be to get the right regulator for your machine.

 

[Coyote machine]

Assuming your meter is OK, these voltages are WAY too high and will boil off the battery electrolyte. Ideally, you should see 14.x volts max as the battery reaches full charge. The bad news is your alternator is expensive (like $300). The good news is that the alternator is probably OK but the voltage regulator is probably sick and it's much cheaper (like $60) and easier to replace. It's item #1 in this diagram:

OEM Parts

Without a schematic I can't be certain that this is your problem but that's my guess. But this part is labeled "old version" in the drawing so make sure you get the right part for your specific serial number machine. In the old days the voltage regulator was separate from the alternator; originally, it was actually a relay that quickly opened and closed to regulate current to the alternator rotor based on output voltage, Later, solid state (transistor) versions were used. Today, almost all regulators are built into the alternator; some are easy to replace and some aren't. So the trick will be to get the right regulator for your machine.

The parts diagram lists two number ones, the second one with an exclamation mark in yellow triangle; this new part supersedes the original 'old' part. Still verify it to your tractor's serial number.

Does anyone read what has already been written in this thread?
The voltage regulator has been deemed dead probably 5 different times by now!
Get a new one/ replace it in/with the original alternator and report back the results.

 

[murphy1244]

The parts diagram lists two number ones, the second one with an exclamation mark in yellow triangle; this new part supersedes the original 'old' part. Still verify it to your tractor's serial number.

Does anyone read what has already been written in this thread?
The voltage regulator has been deemed dead probably 5 different times by now!
Get a new one/ replace it in/with the original alternator and report back the results.

I said the regulator was bad in post 8. I don't understand the rest of this.

 

[Coyote machine]

I said the regulator was bad in post 5. I don't understand the rest of this.

Dittto Murph! Guess people aren't really paying attention to what's already been said!?:confused2::thumbsup:




VOLTAGE REGULATOR!! Replace it. post back results. Note: battery still may have been damaged! have it checked by a professional!

No one has said to throw it out...just to be cautious because it could explode, and to verify it stands up under load test.

 

[marler]

battery checked ok. replaced voltage regulator, now I am getting 14.5 volts while the tractor isrunning. thanks for all the help. bought an alternator I did not need but it was cheaper than having it hauled to the shop.

 

[murphy1244]

Well how about that?!!! Shazam! Good job...

 

[ritcheyvs]

Thanks for the feedback. I love it when a plan comes together.

FYI, overcharging isn't that harmful to lead-acid batteries as long as the electrolyte stays above the plates. Of course, hydrogen and oxygen gas (explosive) will out-gas but only during overcharge. Chronic undercharge, on the other hand, will eventually kill a battery