Can I test the amps from my alternator like this?

[jinman]

any ideas what could be causing that drop?

Thanks to your sending me the charging diagram, I absolutely do have an idea what is causing the drop. Remember, there are two places you should read battery voltage when the key is ON and one place when the key is OFF. With the key ON, you should read battery voltage at the yellow wire into the regulator and also at the 210red wire. With the key switch OFF, you should only read voltage at the 210red wire. My guess is that with the yellow wire having battery voltage, the VR is biased to ON and therefore becomes a voltage divider with the low resistance in the red wire. I would put a voltmeter on the red wire with the key OFF and then with the key ON to see if there is a difference in voltage. If the wire has 1 ohm of resistance and the VR has 12 ohms to ground when turned ON, then that would account for almost a full 1 volt drop due to the voltage divider effect. When the VR is OFF (key OFF), there should be infinite resistance internally and the full battery voltage should appear at the input.

Now, add to this equation that the engine is running and the alternator is supplying AC power to the rectifier/VR and things should change because now the VR should put out 14.5 volts at the red wire and all of that should be felt at the output of the VR and nearly all at the battery with full voltage as the battery becomes fully charged.

I'd love to see the circuit inside your regulator. I have a circuit inside a similar regulator on a Kubota, but I just don't want to put that VR schematic up here and have you or me or someone else put too much faith in it. For now, if we could know what the voltage is at the red wire before the key is turned on and afterwards, that will tell us a little more info.

 

[Soundguy]

are all the wires oem.. have any been replaced or downsized? if the charge line is undersized it will heat and drop voltage. a v check across the vreg output to the bat or wherever it hits to charge.. like the solenoid hot is a possible check.. can also show bad connections at crimp and molded connectors that may be hid by insulation..

soundguy

 

[jinman]

are all the wires oem.. have any been replaced or downsized? if the charge line is undersized it will heat and drop voltage. a v check across the vreg output to the bat or wherever it hits to charge.. like the solenoid hot is a possible check.. can also show bad connections at crimp and molded connectors that may be hid by insulation..

soundguy

Chris, do you remember back in 2006, you participated in a discussion of a Yanmar 1610 with a couple of EEs trying to reengineer the VR? I searched and found that discussion and figure this JD 4100/Yanmar tractor may be having similar issues. One of the fellows in that other thread was trying to get a Wells VR728 rigged to work on his Yanmar. I don't know what the resolution of Smitty's problem will be, but this electrical system has caused several TBN members grief in the past. Your suggestion of loose connections or undersized wiring is as good a guess as anybody else's. I'm just afraid that Smitty's new VR has now gone south. A high AC ripple on the output would sure seem to indicate that. An o-scope would sure be handy about now.

 

[Soundguy]

ditto that for sure. some rectifier somewhere is shorted... IMHO. too bad he ain't near a school with an oscope...

ifn't it was me.. I think I'd just throw together a series pass regualtor with some big silicon.. like 2n3055 drop the ac to dc,, then go from the varrying dc to regulated dc... I remember th thread that you mention.. and I'm not overly thrilled by rectifier/regulator packs as we are dealing with... too easy to do it with a diode trio and internal field current control regulator. I hung a hitachi alt on my old 1700 LOOOONG ago.. uses an old style chrysler external vreg

soundguy

 

[rsmith02184]

ok...i have some info from the weekend.

#1) I couldn't do the tests because I left the tech manual at work

2) I tried to test the amps on the red battery cable and a few other wires while the tractor was running and I think it showed 9amps (at medium throttle). I have a 20 amp alternator.

3) Here is the BIG NEWS: While I was doing the amp test, I was near the alternator and I noticed some arcing at the connector between the alternator and the wiring harness. I checked the terminals and it seemed that there was a loose connection there. I put a tool in the tightened down the crimped connectors. After that, all the wires were cool going into the VR.

Do you think this was the problem? Could that have been causing false readings at the VR?

I think I still blew this VR since it probably arced everytime I ran my tests.

 

[Treemonkey1000]

TA-DA!

 

[luscsmith]

I think it might be ready to go, I hope so.
I have enjoyed the thread.

Scott

 

[jinman]

TA-DA!

I think I here gongs going off. Too bad Smitty didn't find that problem before replacing his VR. I suspect this one will have to be sacrificed to the smoke god.

 

[rsmith02184]

I also have enjoyed the help that I have received on this thread but I haven't ENJOYED the problem that precipitated the thread!!!!

another question: if the VR is shot and it is putting out large amounts of DC voltage to the battery, what bad things could happen?
it might be putting out 15+ DC volts.

 

[Transit]

I also have enjoyed the help that I have received on this thread but I haven't ENJOYED the problem that precipitated the thread!!!!

another question: if the VR is shot and it is putting out large amounts of DC voltage to the battery, what bad things could happen?
it might be putting out 15+ DC volts.

The normal charging voltage is in the realm of 13.7 to 14.5. At about 14.7 and higher the battery will overcharge, "boil" off electrolyte [water] and shorten the batteries life.