battery overcharging

marler · Mar 9, 2012

I have a LK2554. I am getting 17.5 volts while the tractor is charging. I just replaced the alternator. Still getting 17.5 volts or better. Where else can I check?

SSdoxie · Mar 9, 2012

If the battery has a shorted cell it can cause an excess voltage draw so alternator would be put out extra volts trying to keep up.

murphy1244 · Mar 9, 2012

What is the battery voltage while the tractor is off?

JimRB · Mar 9, 2012

I had to jump my tractor. This was a few years ago but seem to recall that the charging voltage was way high. New battery and the charging voltage was fine. I would not put a new alternator on without having the old one bench tested. Way too much money to toss around.

marler · Mar 10, 2012

I just put my 2nd battery in two years in. The Alternator is brand new. I am getting 13.3 volts with the tractor off

Traxx · Mar 10, 2012

Most battery chargers now have a battery and alt test mode. I would look into one before a battery or alt. They are much cheaper and can be used on about any thing.
17volts does seem a little high. Should be more like 14/15volts.

marler · Mar 10, 2012

no more ideas?

murphy1244 · Mar 10, 2012

If your measuring voltage at the battery you should have 12.5 to 13.5 with engine off. Fire up engine and your voltage should jump to 15.5 or so volts. As the engine runs the voltage should drop to 12.5 to 13.5 volts. If your voltage does not drop after engine is running for a bit your voltage regulator is not working.

Coyote machine · Mar 10, 2012

17.xx is way too much output- enough to cause the battery to explode and throw acid all over you and everything else around it. While wearing safety glasses, long sleeved shirt and gloves, CAREFULLY remove the negative battery terminal and then the positive and place the battery in something safe, (HD plastic or wood crate or something similar, with a blanket or some such thing to cover it during transport). Have it load tested at a local facility after explaining what its been reading at 17.xx volts. Evidently the alternator is not your issue. By load testing the battery and checking the specific gravity of each cell you will be able to rule out the battery or find that it is indeed the problem. Report back results, and be careful; no one wants to experience a battery explosion under any circumstances.

marler · Mar 10, 2012

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.

murphy1244 · Mar 10, 2012

your voltage regulator is not working......

marler · Mar 10, 2012

is this attached to the alternator or is it a seperate part?

Is this something a parts house could check?

murphy1244 · Mar 10, 2012

some are and some are not. check your manual or have it tested.

Coyote machine · Mar 10, 2012

marler said:
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.

Your voltage regulator should limit output voltage to 14.25 Volts MAX. Anything higher is too much, regardless of load/RPMS etc.
If your voltage regulator is external to your alternator then just replace it. If its part of the alternator then you should have a qualified alternator repair shop check out both the original AND the new one to verify what they are outputting on a test bench. It is possible both the old one and the new one are defective, but highly unlikely. You still need to have your battery checked too.
BTW, Don't run the tractor anymore until this issue is resolved- because of the battery being overcharged.
One step at a time.

ritcheyvs · Mar 11, 2012

Methinks your voltage regulator is sick.

marler · Mar 11, 2012

in the wiring diagram there is a part called regulator. is this what I am looking for?

JimRB · Mar 11, 2012

marler said:
in the wiring diagram there is a part called regulator. is this what I am looking for?

Yes it is.

grsthegreat · Mar 11, 2012

me thinks you need to take the voltage meter your using and go test a few other batteries (car, boat) and see what readings your getting. Ive had bad meters before. Do this first before throwing out the battery.

Coyote machine · Mar 11, 2012

marler said:
in the wiring diagram there is a part called regulator. is this what I am looking for?

Does it show it as integral to the alternator or as a separate item?
You could test your multimeter to verify it is functioning properly, but I doubt it is faulty. Usual self test is to test for ohms reading with the leads opening and closing the circuit on that scale. What made you change out the alternator in the first place?

marler · Mar 11, 2012

The print is very small on the wiring diagram. I could not find the voltage regulator. So I ordered a alternator thinking the regulator was built in. I got the magnifying glass out today and found the regulator on the wiring diagram.