12V conversions...what went wrong?

Sam1911

New User
Hi guys!

I've been following some of the archived threads here for guidance in switching my old Farmall Cub Lo-Boy to a 12 V system with a 10SI alternator using the attached
diagram.

Everything has gone just fine, got the alternator mounted well, belts on, all wires run, and then I figured I should test the starter out to see if I could get it to
turn over. Pulled the ignition switch and the new "charging" or warning light came on (good). Then hit the starter. Nothing at all. Pulled the starting switch
apart about four times and thought maybe I had it just a little off somehow, but couldn't get any response. So I removed the starter switch and tried simply
connecting the (now positive) battery cable (that was connected to the switch) to the contact on the starter (normally under the switch) to see if it would turn over
that way.

"CLICK." (No crank.) And the charging light died. Now I don't get the charging light on at all and it seems even deader than before.

I've gone over the diagram about 17 times and I can't figure out what I've got wrong. Any suggestions?

Many thanks!
a190007.jpg
 
My guess would be you have a bad (corroded) connection at the battery cables / posts , followed by a bad cable or battery. Also possibly a bad / loose connection where the ground cable connects to the tractor.
 
I agree with Jon bad connection at the battery or where the cables hook to ground or the starter switch
 
So you guys think that "pop" or loud click was just the circuit breaking at a poor connection?

I'll recheck everything tomorrow and see if I can get the charging light to at least come back on.

Thanks,
 
Yup! The "pop" was something burning through and opening the battery circuit - either a failing cable, cable terminal or terminal connection. Clean and tighten the battery post clamps, the grounded cable connection to the frame and the cable to the starter switch.

If that doesn't fix it look for a bad cable. Often corrosion hidden under the insulation at a terminal is the culprit.
 
(quoted from post at 13:34:35 04/26/15) Hi guys!

I've been following some of the archived threads here for guidance in switching my old Farmall Cub Lo-Boy to a 12 V system with a 10SI alternator using the attached
diagram.

Everything has gone just fine, got the alternator mounted well, belts on, all wires run, and then I figured I should test the starter out to see if I could get it to
turn over. Pulled the ignition switch and the new "charging" or warning light came on (good). Then hit the starter. Nothing at all. Pulled the starting switch
apart about four times and thought maybe I had it just a little off somehow, but couldn't get any response. So I removed the starter switch and tried simply
connecting the (now positive) battery cable (that was connected to the switch) to the contact on the starter (normally under the switch) to see if it would turn over
that way.

"CLICK." (No crank.) And the charging light died. Now I don't get the charging light on at all and it seems even deader than before.

I've gone over the diagram about 17 times and I can't figure out what I've got wrong. Any suggestions?

Many thanks!
a190007.jpg
see you got batt power to the starter and batt power from starter to the ammeter but i don't see a wire from the ign switch to activate the starter solenoid?
 
The only wires that run to the starter are the one from the battery and the one from the ammeter. That's the way is'a always
been, and it has worked ok up until now. No other wires to the starter, and no other lug on the starter to attach one.

Am I missing something there?
 
Thanks! Will do. The ground strap from the battery to the frame is a new-ish looking piece (woven flat braid thing), but the cable from the batt to the starter is very old. I'll check it.
 
Are the starter contacts built into the starter, as in a mechanical lever that activates the starter? If so, there is no other wire, solenoid, or switch.

Sounds like just a bad connection at the battery, starter, or ground.
 
I went out tonight and cleaned up some connections, verified that I had 12V through the batt cable and the neg terminal had good conductivity to the metal of the engine.

I pulled the ignition switch and my new charging light came back on! (Whew!) Crossed my fingers, vice-gripped the batt cable end and wire from the ammeter together and touched them to the stud on the starter. "CLICK!" Just like before. Light went out and won't light again.

That light acts like something gets overloaded/heated and has to cool off or reset before it will light up again.


I cut the worst end off the batt cable and will go get a new end for it tomorrow. That should be the last of the questionable connections.
 
Sounds like the light acts like a to light of a fuse and pops as soon as you put power to it.
As far as i know that wire is to excite the genny windings,no need for a light there.
What is the purpose for the warning light anyway? you got the ammeter to tell if the genny is charging
 
Well, the light doesn't burn out, that's the odd thing. Time passes and when I try it again, it works just fine. As though something else in the circuit is acting
like a self-resetting circuit breaker.


The light isn't needed, exactly, but some resistance is required in that line. Some diagrams call for a 10 Ohm resistor instead, if you don't want to bother with a
light.

"The alternator warning light consists of small 12 volt lamp rated at about 0.2 amps. A #1815 bulb in a suitable lampholder (purchased at Radio Shack) works fine. A
#1813, #161 or #194 instrument/side marker bulb in a suitable holder will also work. Make sure the lampholder is NOT grounded - i.e. both lamp terminals are brought
out. (Note: If you don’t want to use a warning lamp, you can substitute a 10 ohm resistor rated at 2 watts or higher in place of the warning lamp.)"
http://www.yesterdaystractors.com/articles/artint195.htm
 
(quoted from post at 18:53:06 04/27/15) Without a light or diode, the engine will continue to run even with the switch off.
hat is why are prefer diesels, not much fancy electrics to worry about.
At least with the pre nineties diesels that is.;)
 
Why not splurge and buy a complete factory made cable? The replacement ends are not that great IMHO, mainly designed for quick fix. I would go with a #2 gauge or larger.
 
Well, some success!

I got a new end for my battery cable, cut the nasty tip off and reconnected.

Starter cranks! Yaay!

So, THANKS! The advice and encouragement is much appreciated!



Now if I can just get the starter switch to work right again...
 

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