voltage at battery with engine running

I'm still fighting overcharging. I had the generator checked today and it was good. With the engine at about 1800rpm the battery was showing 15.3 volts. At idle it was 13.3 volts. We cleaned the ground to the voltage regulator before we started.

I think you are worried over nothing. Unless you have an agm type battery, then get back to lead acid and forgettaboutit!

That voltage is too high. 14.3 running is ideal. While the 1 volt extra seems like not much, the battery will be much hotter and the electrolyte will boil/evaporate much faster. Much shorter battery life. The voltage regulator is the problem. Test another system with the same meter to verify meter accuracy.

I agree with the Bus Driver, the VR is set at too high a voltage. If you are very good reading and following electrical procedures from an old book on gen systems, I would recommend you replace the VR. JimN

The vr is new. I tested another tractor and it read 14.6 v

(quoted from post at 19:02:12 11/28/09) The vr is new. I tested another tractor and it read 14.6 v

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Did you test the voltage regulator in the other tractor as well? Remember, things are made in China and the new vr should be suspect as well.

The voltage regulator is called a "voltage regulator" for a reason . . . it regulates voltage. If it's good as you say, it will maintain proper voltage around 13.8 to 14.8 VDC.
It works by sensing battery voltage and cuts back current flow when that voltage reaches whatever level it is ajusted to. It will do the same regardless of what tractor you put it on, so you've got some other factors in this equation.

15.3 VDC is high, but not enough to hurt a conventional flooded lead battery (as the other poster stated) unless you're running 8 hours a day, 7 days a week.

The other tractor has a altenator instead of a generator and has a different type of regulator.

A good battery, after setting overnight, will read 12.6 volts. A good alternator, under full load (on a car we run the AC, fan on high, with lights on) needs to read 14.6 volts, or something is not right. Greg

Couple questions. First, what are you measuring voltage with? Cheap digital meters will often give erroneous readings when used with engines having point type ignitions & copper plug wires due to noise pickup on the leads. The fact that it reads correctly on another engine with an alternator doesn't guarantee it'll read correctly on the one you're concerned about. A good analog voltmeter is a very useful tool for working on these old systems.

Second, if the generator is in fact putting out 15+ volts, the regulator probably needs to be adjusted. The fact that its new doesn't mean it was adjusted correctly, particularly if it came from China. Newer electromechanical regulators have three coils; a voltage relay, an overcurrent relay, and a cutout relay to disconnect the battery when the generator's not turning.

Voltage is adjusted by changing the spring tension on the voltage relay...less spring tension gives lower voltage. Voltage regulation is accomplished by this relay switching a resistor in & out of the field line to control field current.

However, before tinkering with the regulator, I'd make sure that the measured voltage is in fact correct.

Keith

I have nothing but trouble from the chinese VR's but if you take the VR off, take the cover off, under the first coil is an adjusting screw that lets the spring get tighter or looser. This can also be accomplished by bending the hook on the spring back and forth to achieve the same results. Some guys do it while running but with my messed up hands I am afraid of letting the smoke out of the system. As a consequence I am charging my six volt at 8 volts instead of 7.2. A Generator usually can be set at 13.8 for a 12 volt system. Thats what is happening on my 12 volt tractor for the laast 5 years. Henry

a older fluke multimeter.

troll?

I don't think so. I'm just trying to fix an old tractor like many other posters.

I would consider trying another battery. Have
had this happen to me every now and then. I
have no idea why trying another battery seems
to occasionally correct the problem

If you're not running the tractor day after day putting 8 to 10 hours of use on the engine I wouldn't worry about overcharging the battery. Keep an eye on the battery acid to see if it's boiling away. I had a 1972 Ford with the 429 engine and I had the Ford manual on it and they said the charging voltage should be 15.2 volts. Never had any battery problems or with the points. It was the only car I ever had when you ran the AC it never affected the engine speed. I drove it to SC several times and it was a good road car. Hal
PS: Make sure you have a ballast resistor or NAPA's coil IC14SB between the ignition switch and coil.

tractor is diesel. Forgot to mention that.