John Deere 630 overcharging.

I need help with a John Deere 630 overcharging. The generator has been disassembled and checked by a repair/ rebuild shop and found to be ok. All tractor wiring has been replaced with a store bought harness (positive ground). The regulator was new and from the same place as the harness. The battery is new and shows almost 13 volts at rest. After putting it all back together and polarizing (gen/arm term to batt term) it seems fine for about 10 minutes then increases till the ammeter tops out at about half throttle (gauge only goes to 20). I opted to replace the reg again with one from a local auto parts supplier (crossed John Deere / Delco part #1118792 to Standard VR219) only to have the same problem. If I remove the field wire from the gen it drops to 0 amps, not charging at all which tells me I don't have an internal field short in the gen. The reg is mounted to the gen so the wires from one to the other are short, all visible with no short to ground. If I let it sit and cool for an hour or so or disconnect the battery, reconnect and polarize, it is ok for 10 minutes again. What's up with this? Bad 2nd reg ?

(quoted from post at 11:07:17 12/19/20) I need help with a John Deere 630 overcharging. The generator has been disassembled and checked by a repair/ rebuild shop and found to be ok. All tractor wiring has been replaced with a store bought harness (positive ground). The regulator was new and from the same place as the harness. The battery is new and shows almost 13 volts at rest. After putting it all back together and polarizing (gen/arm term to batt term) it seems fine for about 10 minutes then increases till the ammeter tops out at about half throttle (gauge only goes to 20). I opted to replace the reg again with one from a local auto parts supplier (crossed John Deere / Delco part #1118792 to Standard VR219) only to have the same problem. If I remove the field wire from the gen it drops to 0 amps, not charging at all which tells me I don't have an internal field short in the gen. The reg is mounted to the gen so the wires from one to the other are short, all visible with no short to ground. If I let it sit and cool for an hour or so or disconnect the battery, reconnect and polarize, it is ok for 10 minutes again. What's up with this? Bad 2nd reg ?

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What is the actual voltage at the battery(s) when it's "overcharging"?

How many charging Amps (measured with an accurate test meter)?

Unless you are REALLY unlucky and got two bad regulators I'm gonna say you've got a "bad" battery.

I've had up to 18 volts at the battery
at mid/high rpm. Amps to follow.

One battery or two in series?

Have you tried a different battery?

To start with I question that 13 volts?? A full charged lead acid battery AT REST AND STABILIZED should be around 12.6 volts NOT 13 which is more what Id expect when the genny is operating. After a longgggggg rest with nothing on check battery voltage again ?? Lets say perhaps that 13 isnt accurate ?? Id see if the voltage rises at fast RPM ?? If the battery and charging system were all good Id expect an accurate reading of at least 13 to 14+ or so subject to battery state and condition and charging system and RPM. An ammeter on the wire from BAT on the VR up to the ammeter is another good indication of actual charging amps, maybe that and another volt meter will show its all okay ???

If a VR's internals or the wire off the VR's FLD post (goes to FLD on Genny) was somehow shorted that can cause overcharging. If after long runs with no lights on the battery outgasses excessive and/or boils out water that's a sign of overcharging

NOTE BOTH the Genny and VR need good grounds, check the VR case/frame to genny connection for good contact.

You may what to check the battery including water levels and if there's a short or a bad cell it can draw excess current. A hydrometer check of each cell is in order including a load test. Look for any one cell that is off colored or milky gray ??

John T

"I've had up to 18 volts at the battery at mid/high rpm."

WOW thats highhhhhhhhh but if the battery is good ??? it would take one heck of a charging system (those old gennys arent all the strong) to raise a GOOD 12 VOLT BATTERY TO 18 VOLTS.

I question if the battery and volt meter are BOTH okay ???????

John T

Put a borrowed brand new ammeter that
reads to 60 amps in it. Voltage at
battery, tractor off 13.43, idle
14.31, at full throttle 18.37. Ameter
reads 2 to 4 at idle, 35 at full
throttle. That's 18.37 and 35 amps at full throttle!

One brand new 950 cca battery. Have to pull battery from my IH and try. Much smaller.

John T, my reply to Wore Out will answer your questions. Voltages and amps are accurate. Just got tractor back inside after switching to a different batt and same results.

Batt from other tractor, same results. Before I started with the 2nd battery, it's voltage was 12.48. Battery hasn't started anything in 2 days.

Have you adjusted the spring pressure on the regulator current points .
If the voltage is high , needs more spring pressure to hold the field contacts open .

I see no adjustment. From what I've
read it doesn't sound like something I
could do or should need to do.
Shouldn't the reg be set out of the
box?

You should not need to take the cap off a new regulator. What first entered my mind is a wire shorting after it is warmed up. It is the main reason a bad coil quits sparking after it warms up. A condenser will do the same thing. I suspect the regulator is the culprit and with the sketchy quality of replacement electrical parts today two bad regulators in a row is plausible.

When cold, first started. It seems
fine but at a steady rpm you can see
the amps increase slowly till the
gauge is at it's max. Takes only about
5 minutes.

(quoted from post at 18:50:19 12/19/20) I see no adjustment. From what I've
read it doesn't sound like something I
could do or should need to do.
Shouldn't the reg be set out of the
box?

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There is adjustment however the cheapskate production uses a bendable tab instead of a set screw .