Ford 3500 generator

[FarmerBlair]

Hi all, I have an electrical related question regarding a 1968 Ford 3500 diesel tractor I got recently. This is the same tractor I recently posted about for battery and fuel injection pump issues.
This will probably be a dumb question, since I am not very knowledgeable on things electrical.
I just got a 4dlt battery for this machine. I put a voltmeter on the battery at rest (unconnected to the tractor) and it reads 12.6 volts, which I think is full charge, or nearly full. With the battery connected and running, the voltage across the battery terminals drops a little to 12.55. I am assuming this means the generator is not working, right? However, the charge indicator on the dash light goes out when the engine is running, indicating it is charging. So is all okay?
This has an old Lucas generator and wiring looks okay as far as connections and no cracked wires. Does a 12 volt generator need to be polarized? All the previous posts I found only talked about polarizing 6volt generators. This tractor sat unrunning for 12 years before I got. I don't think it had a battery in it (or a charged one) for most of that time.
Btw... the previous owner put a smaller auto battery in it just before I first saw the tractor so he could get it to run. If you left that battery connected it drained the battery. I'm not sure how long it takes drain the battery, but before I got the 4dlt, I was working on this tractor once a week and the auto battery would be pretty weak from sitting connected for that period of time. I don't see any spark when connecting the battery terminals so maybe there isn't a short (for what it's worth, I could see a small spark on my 8N when I had that problem). THanks

 

[souNdguy]

Sure,polarize it.. Its not just for 6v jobs.

You can bypass the reg field ckt and full field the Genny too. Bat to field. And bat to arm

 

[FarmerBlair]

(quoted from post at 20:51:04 02/27/16) Sure,polarize it.. Its not just for 6v jobs.

You can bypass the reg field ckt and full field the Genny too. Bat to field. And bat to arm

Thanks Soundguy. You went a bit over my head. Could you spell it out a little more if possible. Like I said, I'm barely literate as far as electrical stuff. So I should make a contact (spark) between the battery (positive pole?) to the field on the generator? Then do the same between battery to armiture? Also, not sure which terminal on the generator is field vs armiture I don't want to let the smoke out of anything which I'm likely to do. Trying to post a pic. May not work. Thanks

 

[FarmerBlair]

Another attempt a posting at pic.

 

[FarmerBlair]

 

[souNdguy]

little wire on genny is field, big wire is armature.

I'd unplug field on the genny, and then jumper from bat hot to the armature and field ( leaving field unplugged ).

then plug back in and check.

 

[sotxbill]

AND... the genny will not charge at an idle.. must be reved up a bit and then you should see the voltage slowly come up....


if you watch the volt meter when you "polarize it" you should see the voltage go up a lot as your putting the gen in "FULL CHARGE" MODE.... do not leave the jumper in very long as you can damage the generator at full charge. The voltage regular actually will limit the max current so that you dont melt the solder out of the armature windings.

 

[Little Billy]

.
.
Yes, polarize it ...... you'll find many 'Utubes' showing exactly where to hook up......
only takes a second to hit the connections on the voltage regulator.

In the voltage regulator dept., take the cover off of it,
and check for condition. If it's original, you'll probably find
plenty of rust/corrosion inside, enough to consider replacement.

Lastly, the generator will not put out enough at idle to make
much of a difference in voltage at the battery......
check when RPM is at running speed (1500-2000 RPM)

.

 

[FarmerBlair]

SouNdguy, Soxtbill, Little Billy,

Thanks for the responses. Actually, I did not see your posts before trying to figure out the generator problem this morning. I figured it was too much dumbing down to warrant time to get any more response from anyone! Anyway, I spent some more time searching the internet to try and figure it out. I found on another tractor website an old post with instructions that were pretty clear even for me. I would post a link here to it, but not sure it would fly with this rival website. Hopefully that posting was correct and here's what I did so far:

1) disconnected both field and armature wires from generator. Still not 100% sure which was which. (I found a description that the field is a spade connector and the other is threaded connection. However, both are spade connectors on my generator... one centered and one at the edge of the generator). I'm guessing the spade closer to the edge of the generator is field. Now that SouNdguy mentions it, I think maybe the center spade was slightly wider which I guess would suggest it is armature. Not at the tractor right now to check.
2) removed belt from generator.
3) ran a couple wires and connected both field and armature at the generator to the hot (+) battery post.
4) generator started spinning at a pretty good clip. Let it spin for maybe 30 seconds.
5) Started tractor and checked charge at battery. It still read 12.59-12.6 volts. Increasing engine rpm over 1000 (~2/3 throttle) did not change reading at battery.

When I did (3), I held the wires by hand to the generator field and armature contacts. Noticed I only had to touch the center armature spade to make it spin. If I then contacted the field spade while it was spinning, it caused the spinning to slow a bit. I assume this is normal. Hopefully I didn't mess up anything by experimenting.

Based on the motoring, I think the generator should be OKAY?

What I am not sure about, is whether this process of motoring the generator effectively POLARIZED it, because the next instructions on the rival website said to then run a wire from hot (+) post on battery and briefly contact the field spade on the generator to polarize it. I thought I had already done that when motoring, but will do again just in case since I still am not getting any charging at the battery.

Thinking about getting a new voltage regulator to replace the old Lucas one since I read it often fails (New Holland or NAPA?). Or would you do this follow-up test of the voltage regulator (described at the same rival website posting). Again, checking with you guys for correctness:
a) start up tractor
b) connect wires to both armature and field spades on generator and connect to hot (+) post on battery
c) take a voltage reading at battery. If the generator is charging (13.5-15 volts(?)), then the problem is with the voltage regulator. (or, I guess it could potentially be a broken wire somewhere).

For these last instructions, it did not specify whether to disconnect the original field and armature wires at the generator before doing (b). Should they be disconnected?

Still not sure why the charging indicator light on the dash goes out when the tractor is running since it is definitely not charging at the battery based on the voltmeter readings. For what its worth, the tach doesn't work so maybe the rest of the dash isn't right. The oil light goes out also when running... maybe I shouldn't believe that for oil pressure either.

Thanks

 

[FarmerBlair]

Another potentally realllly dumb question. I just remembered that I charged the 4dlt battery before putting it back in the tractor. Resting voltage is 12.6. Would you still expect the generator to be putting out >13 volts to the battery even though the battery may be fully charged? Or does the generator continuously put out that voltage to the battery when the tractor is running regardless of battery state? What if I were disconnect the battery while the tractor is running, and then check voltage across the battery cables. What should it read? Thanks again.

 

[Sean in PA]

(quoted from post at 15:13:33 02/29/16) Another potentally realllly dumb question. I just remembered that I charged the 4dlt battery before putting it back in the tractor. Resting voltage is 12.6. [b:5c522de9e4]Would you still expect the generator to be putting out >13 volts to the battery even though the battery may be fully charged? Or does the generator continuously put out that voltage to the battery when the tractor is running regardless of battery state?[/b:5c522de9e4] What if I were disconnect the battery while the tractor is running, and then check voltage across the battery cables. What should it read? Thanks again.

The generator should put out much more than 13.5 volts. It is the voltage regulator that keeps the voltage at the battery around 13.5 when the system is charging. I'm not 100% sure, but don't think that disconnecting the battery while the engine is running is a good idea.

 

[souNdguy]

I'd be checking the field circuit on that genny

 

[JMOR]

(quoted from post at 00:36:27 03/02/16)

(quoted from post at 15:13:33 02/29/16) Another potentally realllly dumb question. I just remembered that I charged the 4dlt battery before putting it back in the tractor. Resting voltage is 12.6. [b:a7db5dc1d2]Would you still expect the generator to be putting out >13 volts to the battery even though the battery may be fully charged? Or does the generator continuously put out that voltage to the battery when the tractor is running regardless of battery state?[/b:a7db5dc1d2] What if I were disconnect the battery while the tractor is running, and then check voltage across the battery cables. What should it read? Thanks again.

The generator should put out much more than 13.5 volts. It is the voltage regulator that keeps the voltage at the battery around 13.5 when the system is charging. I'm not 100% sure, but don't think that disconnecting the battery while the engine is running is a good idea.

rue, it would not be uncommon for a fully fielded and unloaded armature to output 18v or more.

 

[FarmerBlair]

So I bought a new voltage regulator at New Holland and replaced the old one on the tractor.
With tractor not running, the voltage at the battery was 12.66. After starting the tractor, the voltage gradually rose to 15.5 volts at 1/2 throttle; and was about 13.7 at slowest idle.
So it's working! So much easier access to the regulator on this 3500 tractor than on an 8N or 800-series tractor!

Thanks for the input on this post.

Btw..... the voltage regulator at New Holland cost $28. NAPA gave me a price of $98. I was surprised by the price difference. The NH regulator was an after market and did not say where or who made it on the box. I forgot to look at the actual regulator before installing it. Thanks.

 

[JMOR]

(quoted from post at 18:03:52 03/03/16) So I bought a new voltage regulator at New Holland and replaced the old one on the tractor.
With tractor not running, the voltage at the battery was 12.66. After starting the tractor, the voltage gradually rose to 15.5 volts at 1/2 throttle; and was about 13.7 at slowest idle.
So it's working! So much easier access to the regulator on this 3500 tractor than on an 8N or 800-series tractor!

Thanks for the input on this post.

Btw..... the voltage regulator at New Holland cost $28. NAPA gave me a price of $98. I was surprised by the price difference. The NH regulator was an after market and did not say where or who made it on the box. I forgot to look at the actual regulator before installing it. Thanks.

lad to be of help.