Electrical sleuthing

[Clint S]

"'You mention that the cables look like they are "standard auto 12 volt sized cables" - if they are, they should be heavy enough since a 12v car system needs just as suitable cables as a tractor does.''

This above info is not correct.
'' standard 12 volt car cables'' are not fine. Undersized cables are the NUMBER ONE cause of slow cranking farmalls. The cables were undersized from the factory.
0 0/0 are what you need. Heed DJ54's words and change the cables. The smaller cables just will not flow the juice. Not saying the starter or battery is not worn, but if you are keeping the tractor and keeping 6v change the cables. I have seen cables only get slightly warm if they are not big enough.
Unless the starter was ''rebuilt'' and changed farmall did not make a 12 v starter that would fit that A. The alt if it is self exciting needs a diode in front of it or it will draw the battery down. It's a simple system so get a meter and start checking.
Disconnect everything and try a 12 volt battery see if that works

Edit I see what I think is a voltage reg on the alt. The excite field may be stuck open causing the drain. There are only a few things that draw on that machine so check them . (ignition, charging, lights)

 

[bcp]

I remember when 12V cars first came out. Battery cables went from finger size to pencil size. Modern small engines look like they have matchstick sized cables.

Many auto parts places no longer have larger sizes in stock. Try a large equipment/forklift dealer for cables. Or make them from welding cable and separate ends you add.

Bruce

 

[jeffgreef]

Here's a good article on 12v conversion on a Farmall with distributor.

Yesterday's Tractors - Step by Step 12-Volt Conversion

He puts a resistor before the coil to knock down the voltage to 6v. Can you replace the coil with a 12v?

Here's a link to a wire supplier that will sell you just a few feet of USE 1/0 for 2.35 a foot. USE is underground service entrance wire, it has very thick insulation.

USE-2 / RHH / RHW-2 Copper Wire | Wire & Cable To Go

 

[Clint S]

12 volt coil with 3.5-4ohms would do the trick.

 

[DJ54]

I can't remember where I posted the link to this business that makes up custom length battery cables in the past couple of weeks. There have been several threads on a similar issue. But the business listed below has prices on battery cables that are hard to beat, at least locally for me. It has a cost calculator for length of cable, plus types of ends you need. I'll probably be ordering a set from him later in the month, just to try them. MUCH less than what I paid at NAPA..!! The Shopping Cart : Tinned Marine Wire, The power behind it all

 

[DJ54]

As for the resistor ahead of the coil, I'm wondering if that is already what you have on yours. All I've seen available for tractors is the porcelain type, like what was on the old Case I had to replace. Being me, I'd have to untape that rascal, and see exactly what it is.

 

[SPYDERLK]

View attachment 460795

Here's a good article on 12v conversion on a Farmall with distributor.

Yesterday's Tractors - Step by Step 12-Volt Conversion

He puts a resistor before the coil to knock down the voltage to 6v. Can you replace the coil with a 12v?

Here's a link to a wire supplier that will sell you just a few feet of USE 1/0 for 2.35 a foot. USE is underground service entrance wire, it has very thick insulation.

USE-2 / RHH / RHW-2 Copper Wire | Wire & Cable To Go

Isnt that a resistor shown in the pic?

 

[LD1]

Here's a good article on 12v conversion on a Farmall with distributor.

Yesterday's Tractors - Step by Step 12-Volt Conversion

He puts a resistor before the coil to knock down the voltage to 6v. Can you replace the coil with a 12v?

Here's a link to a wire supplier that will sell you just a few feet of USE 1/0 for 2.35 a foot. USE is underground service entrance wire, it has very thick insulation.

USE-2 / RHH / RHW-2 Copper Wire | Wire & Cable To Go

Dont use service entrance cable for battery cables. TOO stiff. The individual strands of of wire are much larger diameter. Go with welder cable as others suggest, as it has much finer strands and a softer insulation that make it alot more flexible. Just did the battery cables on my backhoe with 3/0 welder cable and I am happy with the results.

As for whats in front of the coil, take the tape off. Could be a resistor, allthough with a 6v battery already I dont know why.

Not sure if an analog meter is sensitive enough to tell the difference between 6v and 6.2v. Personally I would get a cheapy digital. And if you can find one, a DC amp clamp is nice. Clamp it on a battery cable when attempting to start and see how many amps that starter is trying to pull.

Lots of stuff to check out. But for sure get some heavier cables. As someone mentioned earlier, if you own a good set of jumper cables, connect them as if running a second pair of battery cables and see if it makes a difference. Then continue with the rest of the stuff.

 

[Soundguy]

Uh.. Do you need a diagram?

12v bat, wire it neg grnd.

Starter and switch or relay from bat hot.

Charge side of alt to one side of ammeter, other side to bat hot. Alt side of ammeter to ignition switch, from switch to real 12v coil lil a Napa ic14sb.

#2 on alt jumped to charge stud.

Wire from coil side of key, thru a 194 or other similar marker lamp to #1 on alt.

Key on, lamp on, after starting, move rpm past 400, lamp out and charging.

If you want lamps, go from alt side of ammeter to fused lamp switch, then to lamps.

These early tractors are so basic to wire up, no diagram is needed.

 

[jeffgreef]

Yeah service entrance cable will be stiff. Fine strand is better. DJ's connection to battery cable supplier is probably the way to go.

I'll unmask the mystery box ahead of my coil soon as I can, and send a photo. But why would they put one on when they were keeping 6 volt?.......