Generator light goes off, but no charge.

blue_tractor_man · Oct 15, 2017

My 1964 Ford 4000 tractor with a 12 volt generator and regulator just quit charging. When you turn on the key the generator light comes on. When you start the tractor the light gets dimmer and goes out like it always has. Nothing seems unusual. The voltage on the battery is 12.70 volts with everything off, 12.40 volts with the engine running, and 12.30 volts with the engine running and the lights on. What is broken? Thanks.

Mike(NEOhio) · Oct 15, 2017

The light dims and goes out as the generator voltage rises. Doesn't mean you are charging. Look for a bad connection in the charging circuit or cutout relay in the regulator

Janicholson · Oct 15, 2017

Determine if it is a B circuit Ford, or an A circuit. They are very different. The B circuit uses an internally grounded field, with the VR supplying voltage to make field magnetism. The A circuit has a field that is supplied with voltage internally and the regulator grounds that voltage to make the magnetism. Jim

blue_tractor_man · Oct 15, 2017

How will I know an A circuit from a B circuit, and what do I do when I determine that?

blue_tractor_man · Oct 15, 2017

Could it be a dirty contact in the voltage regulator?

Janicholson · Oct 15, 2017

From on line diagrams of the generator I believe it is the B type. The dash light is connected to a terminal o the regulator. It may not be directly related to charge rate. To see if the generator is putting out voltage, put a volt meter across the battery terminals. Running above idle, it should produce 14.2 to 14.6 volts. If battery voltage (about 12.6) it is not charging. Keep the volt meter connected. and positioned so you can see it from the generator. With the engine stopped, remove the Field wire from the generator. Protect the end of the wire so it touches nothing. With it running, use a jumper from the battery hot terminal to the F terminal on the generator. (do this temporarily, as in touching the terminal with the wire briefly) this will spark a little, but the voltage will go up on the meter. This indicates that the generator is working. I would replace the voltage regulator. If it does not go up, I would have the generator tested at a shop. Jim

Ozlander · Oct 16, 2017

First thing to do is to tighten the gen. belt.

JMOR · Oct 16, 2017

(quoted from post at 23:00:28 10/15/17) My 1964 Ford 4000 tractor with a 12 volt generator and regulator just quit charging. When you turn on the key the generator light comes on. When you start the tractor the light gets dimmer and goes out like it always has. Nothing seems unusual. The voltage on the battery is 12.70 volts with everything off, 12.40 volts with the engine running, and 12.30 volts with the engine running and the lights on. What is broken? Thanks.

f you are correct in it being 1964, then it would be 12 volt only if diesel from the factory. If 1964 & gas & 12v, then it has been converted & what generator & how it is wired is completely wide open. If you have not had it long, it could be 6v system & PO just stuck a 12v battery in it to sell it, with 6v gen/VR still there. ?????

Traditional Farmer · Oct 16, 2017

So why do they bother to put the light there in the first place,I think you're right just wondering why they do it?

Traditional Farmer · Oct 16, 2017

There is an easy and cheap fix for those folks like you and myself that don't really know about electrical systems,a one wire alternator for less then $60 you can buy an alternator off
ebay that'll put out 2X the current of your generator and be hassle free.And for all the Naysayers,No the tractor doesn't have to be run at a high RPM for them to charge and NO
they won't run the battery down.

JMOR · Oct 16, 2017

(quoted from post at 09:07:24 10/16/17) So why do they bother to put the light there in the first place,I think you're right just wondering why they do it?

ike most things in life, there are perhaps no absolutes, but many things come close & this is probably one of the latter. Boiled down to the basics, that light is connected between the battery & the gen armature & when those voltages are different it will light. At start up V-batt is greater than V-arm and it lights, then as V-arm increases to point that cut out closes, those closed contacts short out the bulb (now V-batt & v-arm are equal & you have same voltage on both sides of lamp) & no light. The 'absolutes' part comes in where under some circumstances/conditions/etc., the cut out doesn't close, but v-arm reaches v-batt and light goes out, but batt and gen are not connected. If this were to happen, the light should re-light as speed continues to increase, as v-arm will soon exceed v-batt, resulting in current flow thru lamp & once again giving operator a valid indication that all is not well. Not absolutely perfect, but pretty good, in my opinion.

rvirgil_KS · Oct 16, 2017

With one wire alternator you will lose the function of the charge indicator light

Get a 3 wire Delco, loop #2 pin down to output stud and connect generator/regulator end of the indicator light to the #1 pin on alternator

Traditional Farmer · Oct 16, 2017

Yea so what? I don't need a dummy light on a tractor anyway to see if its charging or not with the alternator it will be charging unless something major happens.

Mike(NEOhio) · Oct 16, 2017

Well, we call them idiot lights, don't we.

Ozlander · Oct 16, 2017

My ammeter tells me if it is charging or not.

Generator light goes off, but no charge.

blue_tractor_man

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