Lucas Generator output voltages

[MillvaleMurph]

Hi I'm looking tho find the output voltage range of a 12 volt lucas generator. Anyone one with any info?

 

[Travelover]

It might help to give a little more information, but most 12 volt systems show 14.5 volts or so with the generator charging..

 

[MillvaleMurph]

Thanks That's what I'm looking for. The lucus generator is producing but I'm not sure how well. It only puts out approx. 12 volts. It's controlled by a mechanical regulator mounted on the firewall. Before I take a closer look at the regulator I thought I'd see what voltage I should be seeing ie. 12.5-14.5v.
I'm new to lucas generators and wanted to make sure they don't top out anywhere near the 12 volts. Thanks again!

 

[Travelover]

That 12 volts may be from the battery, not the generator. You can buy an inexpensive ammeter and hook it up between the generator and the battery to read the current output - this is basically what the ammeter in the gauge cluster does on a tractor or a truck equipped with an ammeter.

 

[number two]

A fully charged 12 volt battery will show 12.6 volts-2.1 volts per cell. I recently repaired a Ford 4000 with a Lucas generator with help from TBN,especialy from Soundguy. Diagnosis tips from TBN led me to replace the firewall mounted voltage regulator,which I purchased from the CNH dealer for $48,although a less expensive source was suggested in this forum.Sounds like you're in a similar situation.I'm not computer savvy enough to post the link,but it was titled (Ford 4000 not charging)about 4-5 weeks ago.Good luck!

 

[MillvaleMurph]

HI All,
Thanks for the help so far! I cleaned up my commutator and brushes and now have 14.6 volts going to my field windings and the generator is producing 14.6 volts. My battery still reads approx. 12.4. All of the terminals on the regulator are showing 14.6 to ground even "E". Other than the two "B" terminals that are showing 12.4. This regulator is less than a year old and all the contacts, connections, and coils "look" fine. Should my "E" terminal have 14.6volts to ground? Prehaps I have a shorted wire in the harness? Also is the indicator light on the dash in series or parallel? It doesn't light up and I hope it's not as simple as current is feed thought it on the way to the battery. Any ideas?

 

[Soundguy]

Look in the service manual for your tractor.. you don't mention what model you have.. but if it's lucas.. I'm guessing 2000-3000-4000-5000 between 65 and 75.

I just rebuilt my lucas gen on my 5000.. at hi-idle I get about 14.1v.. and as high as 14.5 at pto rpm.

Use a analog volt meter.. the consumer grade digitals don't like the brush noise.

that unit is B-Circuit.. IE.. the field coil in the genny is grounded, and it expects field power controlled by the regulator.

Full field by jumping bat to field.. if that makes your battery votlage come up.. then the field circuit in the reg is bad.

If not, then bypass the cutout and jumper from armature to battery... see what you get.. you can also full field while doing this test.

CNH sells a new reg for this genny... .. the old lucas regs are prone to get dirty sticky contacts.


Polarize the genny by jumpering bat to field.


Motor test by slipping the belt off.. jump bat to field and bat to armature... if the genny spins.. it will likely charge... Most gennies that charge, will spin.. most gennies that spin, will charge.

soundguy

 

[MillvaleMurph]

Got another kick at it last night. Found why I had voltage on "E" (ground)
terminal....short in the wiring harness. Regulator is only sending down 5 volts. When I bypass with direct battery voltage, to the field, I run right up to 14 plus volts. Looks like the regulator didn't like the dead short. All the contacts are free and unpitted so I'm thinking one of my coils/resisters may be burnt. One more quick test and I'll grad a new regulator. I still have one question to answer why do I have to polarize my field isn't it externally excited from the battery? If it is self excited I'd understand the need to polarize and insure a level of residual magnetism. Any thoughts. Thanks for all the help so far!

 

[Soundguy]

The genny field pieces should retain residual magnetism once polarized.. this will determine output polarity.. it's always good to repolarize after swapping polarity, rebuilding the genny.. or long periods of non use.

Just swapping your reg.. you shouldn't need to repolarize.

And to answer your question.. no.. technically your field current comes from the armature, and is merely fed back via the regulator thru a vibrating contact and a field resistor.

soundguy

 

[Jackfr]

Had the same problem with my 5000. Found a main harness plug up over the fuel tank had corroded and was pulling apart. Just had to clean it and put it back together the charging circuit then worked fine. I put a cable tie around the plug so it wouldn't come apart again.