12V Conversion questions

[RobertN]

Yes, this is true; it's not like there are 30 wires /forums/images/graemlins/wink.gif

I think of more importance than the number of wires, is the reengineering for low rpm function. Yes, a Jeeper could overdrive the alternater with pulley ratios to have it charge at lower crank rpms. But, most also have low gears and rev a bit on the road. Then, it would really be overdriven /forums/images/graemlins/shocked.gif

That is more the coorelation with old tractors; my Farmall-A revs out at 1500rpm or so, like your Ford.

The caveat is, most tractors don't need 150A altenators /forums/images/graemlins/shocked.gif

 

[upgw]

FYI: I got a hygrometer and checked the battery, all three cells were at the highest level of green (fully charged). The ammeter showed just below 15 amps for the entire 1 hour run on Sunday, with water being boiled out the top again. At least this time, she cranked pretty well and fired right up. So basically, I have no idea why it barely cranks most of the time.

- Patrick

 

[Soundguy]

</font><font color="blue" class="small">( Per the manual, looks like I have an 'A' circuit generator..Two wires from the generator to the regulator )</font>

Just because it has two wires won't mean it is an a-circuit. Does the manual actually specify a-circuit?

The a & B circuits polarize differently.. so you don't won't to have it backwards when you polarize.

</font><font color="blue" class="small">( was up at tractor supply and while they were out of 6V batteries, they did have 8 volt ones... strange.
)</font>

8V batteries are bad bandaids for a bad 6v system.. or a worn starter/engine.. or one in need of a tuneup.

Sure 8v spins the 6v starter over better.. and makes the sparks hotter.. but also increases current flow in the primary of the coil.. reducing the coil lift.. and reducing the points life. Besides.. the condensor is rated at a specific size and capacitance for that 6v system.. and may not be matched for the 8v system.. allowing the points to burn and pit prematurely. Also.. most 6v gennies won't charge a 8v battery -well-. What you will have is a system that runs.. but a battery that is always about 25% discharged. Some gennies and regulators are adjustaable.. either bu adjusting a 3rd brush on the genny.. or by changing tension on a vibrating contact... but tweaking vr's is almost voodoo.. if you don't know what you are doing.. leave it alone.. or have a shop adjust it for you.

8v is also hard on 6v lights.

What is the regulator doing that makes you think it has a problem?


Soundguy

 

[Ramon]

Just out of curiosity from a newbie, how are you guys measuring RPMs. Do you have a gauge for it on the tractor or are you using an external gauge of some sort?
Thanks

 

[Soundguy]

</font><font color="blue" class="small">( The ammeter showed just below 15 amps for the entire )</font>

I'm still guessing either wrong regulator or the field wire is grounded somewhere.. I guess though.. the field contacts could be stuck ( or welded ) together in the regulator.. and no vibrating like they should.

Once you deffinatively find out what type it is.. ( if it is a-circuit ).. then it is real easy to check.


Assuming a-circuit ( which is what I think it is too.. as an a-circuit generally overcharges due to a shorted external field contact.. )
First of all.. remove the field wire at the regulator.. if the charge rate stays high.. then follow that wire.. it may be shorted somewhere before it gets to the field tab. If not.. remove the field wire from the genny.. if charge rate stays high.. I would guess the insulation where the field tab passes through the genny casing has shorted.. and the genny is full fielded to ground right there. Generally it is a phenolic grommet/washer that.. and they do get brittle and brake. Fortunately.. very easy to repair... probably do it right on your bench.

Soundguy

 

[Soundguy]

Some of my tractors ( 51 and newer fords ) have a proofmeter ( tach ) on them.

The others are guestimates based on rpm specs of the engine ( high and low.. ) and how it sounds.

Also.. some have picked up the small watch battery electronic tachs that use a small wire wrapped around the #1 cylinder wire. Lawnmower shops sometimes sell them as well as fleamarkets. Easy to slap on with doublesided tape..

Lotsa ways.. engina anlyzer.. etc. Guess you coul even use an osciloscope with a highly attemuated probe and an inductive pickup..

Soundguy

 

[Soundguy]

</font><font color="blue" class="small">( But, most also have low gears and rev a bit on the road. Then, it would really be overdriven
)</font>

True.. if you used pulley ratio to get low rpm charging then at high engine rpm.. the alternator will be really turning. I soppose as long as the bearings are rated for the speed.. it would be ok... but have no direct data on that.

That is another reason why the 1 wire jobs are simply not desireable. Worring about low rpm exciting shouldn't be an issure.. that is one of the nice things about the externally excited 3 wire jobs.

Soundguy

 

[upgw]

The manual says A circuit explicitly. I have the original shop manual for the tractor. Doesn't sound like an 8V conversion is the way to go... except for the possible over-charging, the old girl is behaving right now.

 

[jrepp]

<font color="blue"> </font> except for the possible over-charging, the old girl is behaving right now. <font color="black"> </font>

upgw:
If you are using a VR make sure you are using a good quality one, the ones that most auto parts stores sell are of poor quality and may overcharge.

 

[Soundguy]

If you know it was OEM A-circuit.. and that the genny on it now hasn't been swapped, then it is easy to check.

Pull the field wire right at the vreg.. and the charge should stop. If it doesn't, disconnect the field wire at the genny. If it doesn't stop then, the field is shorted at the stud ( bad insulator ) or just inside the casing.

This -MAY- be something you can pull apart and fix.

If it does stop charging when you pull the wire at the vr, put it back on and giv ethe vr a good whack with a screwdriver.. might be field contacts stuck closed.

If that doesn't help.. shut it down and repolarize it.. jumper arm and battery terminals. try it again.

If it still charges too much, pry open the vr and see if the contacts are welded together. If they are.. I doubt you will be lucky to pry them apart and it still work. The spring tension is very precise.. perhaps it is surface rust that can be dressed by sliding a piece of brown paper grocery sack back and forth thru the points with them held lightly together... That dresses them better than emory paper. I wouldn't file either.. unless you specifically have a points file or stone.

If they are stuck and gone.. new VR time. Remember to polarize the new vr and genny when you install it.. before starting the tractor.

As a jury rig.. I've heard of putting a power resistor in line with the field terminal to ground when a vr conked out at a time when a farmer couldn't get tot he store for a few days. Might have to try different vallues between 1.8 and lower . And of course.. this will be a fixed charge rate.. justr a lower rate than a shorted field contact.

Your vreg should be an on the shelf item at a farm store. There are probablt a few other vregs that would fit it.. including 48-52 ford tractr vregs that are a circuit as well.

Check it with those tests before plunking down 30-40$ first though.

Also.. to go along with the other poster... make sure you get a decent vreg.. and install it good. If it is meant to be grounded to the chassie, make sure there is good metal to metal contact.. not just paint. These vregs need good clean ground reference.

Soundguy