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Testing generator system

F

fourswild

New User
MF 65, Generator, Delco/Remy "A" Voltage Reg (4 wire).
The Ammeter reads neutral when running (any speed), but will show "-" when I put on lights. I also periodically have to recharge battery after using tractor several times. Here"s what I"ve tried:
1.Polarized Generator
2.Tested good grounds for regulator and generator
3.Grounded "F" @ gen and run +Amps and >35volts @ "A" terminal
4.Jumped regulator "A" to "Batt" while running; no change
5. Jumped reg "A" to "F" while running; no change
6. Checked all wiring for correct connections

I"ve looked through previous posts on this site for similar problems. From all I"ve read, the results from test #3 above would indicate generator is good; but it doesn"t seem to charge properly and regulator doesn"t test bad. I also took the generator to an auto electric place and it tested good there as well.

I"m out of ideas, can anyone help? Thanks
 
What is the age and condition of the battery?

>35 volts at the "A" terminal with the "F" terminal grounded indicates something wrong with the generator.

What kind of a voltmeter was used to measure the > 35 volts? Newer digital meters don't always like the transients present and will read erroneously.

What detailed process was used to "tested good grounds for regulator and generator"?
 
(quoted from post at 14:20:48 08/28/14) MF 65, Generator, Delco/Remy "A" Voltage Reg (4 wire).
The Ammeter reads neutral when running (any speed), but will show "-" when I put on lights. I also periodically have to recharge battery after using tractor several times. Here"s what I"ve tried:
1.Polarized Generator
2.Tested good grounds for regulator and generator
3.Grounded "F" @ gen and run +Amps and >35volts @ "A" terminal
4.Jumped regulator "A" to "Batt" while running; no change
5. Jumped reg "A" to "F" while running; no change
6. Checked all wiring for correct connections

I"ve looked through previous posts on this site for similar problems. From all I"ve read, the results from test #3 above would indicate generator is good; but it doesn"t seem to charge properly and regulator doesn"t test bad. I also took the generator to an auto electric place and it tested good there as well.

I"m out of ideas, can anyone help? Thanks
Click to expand...
o #3 & #4 simultaneously.
 
# 4. is the connection used to polarize the generator. But it is done BEFORE the engine is started.

What is the actual process used in # 1. It should be the same as # 4. except the engine is not running.
 
Correct. Jumping from A to Batt with engine stopped was used to polarize. #4 is a test recommended for the regulator and is done running.
 
I used an analog voltmeter. It showed less than 50 volts, more than the next lower designation. I didn't look for a precise number because the test protocol indicated an unregulated generator could put out in excess of 50 volts. I believe it used the term unlimited.

Grounds were tested with continuity test light. I checked the regulator, base to block (where it's attached); the generator, case to bracket, bracket to block.
 
(quoted from post at 15:25:49 08/28/14) Correct. 3 and 4 were done at the same time, just listed separately
Click to expand...
hat would mean that you had 35 volts across battery (not likely) unless you didn't really have a good connection all the way to the battery!
 
Sorry, I wasn't clear. That test was generator only. Neither gen terminal had their normal wires connected. Test called for "F" grounded, Voltmeter between terminal "A" and ground. Battery therefore wasn't in the circuit.

Were you referring to a different test?

Thanks for your help
 
(quoted from post at 15:40:16 08/28/14) Sorry, I wasn't clear. That test was generator only. Neither gen terminal had their normal wires connected. Test called for "F" grounded, Voltmeter between terminal "A" and ground. Battery therefore wasn't in the circuit.

Were you referring to a different test?

Thanks for your help
Click to expand...
ow much clearer can I get? Jumper field to ground AND jumper Arm to BATT, simultaneously, while running at speed.
 
You are referring to the terminals on the regulator, correct?
What result am I looking for? Increase on Ammeter?
 
(quoted from post at 16:16:23 08/28/14) You are referring to the terminals on the regulator, correct?
What result am I looking for? Increase on Ammeter?
Click to expand...
es, charging indication on ammeter.
 
Thank you for your patience. Test completed. While "F" grounded and "A" to Batt, the ammeter indicated charge.
 
(quoted from post at 16:40:39 08/28/14) Thank you for your patience. Test completed. While "F" grounded and "A" to Batt, the ammeter indicated charge.
Click to expand...
he cut out inside VR is the set of contacts that connect ARM to BATT & it appears that such is not happening.
Just to confirm, you can repeat same test & remove field to gnd & if still charging then field ckt ok & you can then remove batt to arm jumper & if charging stops then you will know that cut out function is no good.
 
Thanks again for the help.

I did remove the field to ground, but the charging stopped at that point. Does that indicate ground problem for VR, or am I getting ahead of myself?
 
(quoted from post at 17:04:44 08/28/14) Thanks again for the help.

I did remove the field to ground, but the charging stopped at that point. Does that indicate ground problem for VR, or am I getting ahead of myself?
Click to expand...
he voltage regulator function normally provides ground to gen Field when ever charging is called for & removes that ground when battery is fully charged and cycles those 'grounding' contact at in-between needing full output & fully charged. So I might suspect that VR case is not properly grounded or both the voltage control fn & cut out function have failed or that in your last test, that the battery is so fully charged that it needs no more. You did leave the BATT to Arm jumper in place when you removed the field to ground jumper, didn't you?
 
If you take the time to work down through my Troubleshooting Procedure it can help diagnose charging problems. In Para 5 it tells you how to effectively by pass the VR functions (full field the genny) to see if non charging is the fault of the Genny or the VR. Also it explains the Motor Test.

BOTH the genny and VR need good grounds to work

NOTE The open unloaded output of a genny doesn't tell everything, ITS TO WHAT VOLTAGE IT RAISES A BATTERY AND HOW MUCH CURRENT IT PUMPS INTO A BATTERY THAT COUNTS.

A good charging system at high RPM should raise a 12 volt battery to at least 13 and up around 14 volts, half that on 6 volt systems.

Run my procedure and test the genny UNDER A LOAD (battery connected) and see what happens....

John T
John Ts Charging Troubleshooting
 
I believe I did, but only momentarily - just long enough to peek at the ammeter. I'll redo the test (a storm was about to roll through), but you have given me enough to understand what is taking place in the VR and I'm leaning toward that as the culprit.

You have been more than patient in handling this problem and I really appreciate all you've done. Thanks ever so much for your help.
 
(quoted from post at 17:33:28 08/28/14) I believe I did, but only momentarily - just long enough to peek at the ammeter. I'll redo the test (a storm was about to roll through), but you have given me enough to understand what is taking place in the VR and I'm leaning toward that as the culprit.

You have been more than patient in handling this problem and I really appreciate all you've done. Thanks ever so much for your help.
Click to expand...
ou are welcome. Be sure & let me/us know the outcome. I expect you are correct in that the VR is the culprit, assuming you do in fact have a good ground from generator to metal case of VR. It is clear that the generator will output/charge.
 
Just wanted to let you know how things went. I repeated the test and ammeter showed charge. Sure enough, when I removed the field ground, ammeter went negative. I've tested the VR enough to determine the cutout isn't working. So on to a new VR.

I have a new post concerning that, this one has gotten unwieldy.

Again, thank you for all your help.
 

Somehow I missed your original post, but thank you for your help. Actually I printed off your testing procedures a year or so ago because they were so clear and comprehensive. I have followed them especially for checking the overall flow from generator to battery and ignition, though I will admit I'm not sure I always understood the results I was getting. I believe I've now confirmed the VR is bad and I'm sure I've got good solid grounds and contacts.
 
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