6v to 12v
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=142301
Printed Date: 07 May 2025 at 4:21am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 6v to 12v
Posted By: Ted J
Subject: 6v to 12v
Date Posted: 09 Sep 2017 at 4:50pm
I just recently bought a CA from wiplowboy and it is an original 6v positive ground. The battery is on it's last legs and I want to change it over to 12v negative ground.
Besides flashing the genny, what else do I need to change? I know that I need to swap the leads on the ammeter and the bulbs in the lights to 12v, but what else?
Also, I remember years ago that my uncle who owned a Shell station just used to use a quarter and flashed the genny by holding it from one of the leads on the genny to the genny case. Anyone else ever heard of this?
Thanks in Advance guys,,,,,
Ted J
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"Allis-Express"
19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17
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Replies:
Posted By: Gerald J.
Date Posted: 09 Sep 2017 at 6:51pm
You also need to swap the primary connections on the ignition coil and add a resistor on the 6 volt coil or change to a 12 volt coil. With negative ground the + primary terminal goes to the ignition switch and the - to the points, just opposite of positive ground.
As for the generator if it is modern enough to have a voltage regulator it won't put out 12 volts. If it is a 3 brush generator it might when turned fast enough. Might require a smaller generator pulley to spin fast enough for 12 volts at most tractor engine speeds.
A modern alternator definitely isn't original but has better regulation that most all generators and that makes for better battery life when the battery is fully charged but never overcharged. The three brush generator generally has the field hooked to part of the light switch so the operator sets the current, high after starting and low after hours of operation. Going too long on high gets rid of the water in the electrolyte, not going long enough on high fails to fully charge the battery. Otherwise for a generator it can take a 12 volt generator with regulator to charge reliably, but the alternator with internal regulator is a half century bettery design and very much better on the batteries.
And its absolutely necessary to flash the generator before starting but after connecting the negative ground battery to make it build voltage of the proper polarity.
A coin ground the field isn't enough to flash the generator but could help with another coil bridgeing the cap between the B and A terminals on the regulator.
Gerald J.
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Posted By: Sugarmaker
Date Posted: 09 Sep 2017 at 9:18pm
Ted,
Congrats on the new tractor. I like to convert these to 12 volt with alternator, new wiring, key switch, battery, voltmeter, and lights. But that's just me. My D17 has been giving me problems with 12v generator. Its on the list to get changed to a alternator too.
Good luck.
Regards,
Chris
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D17 1958 (NFE), WD45 1954 (NFE), WD 1952 (NFE), WD 1950 (WFE), Allis F-40 forklift, Allis CA, Allis D14, Ford Jubilee, Many IH Cub Cadets, 32 Ford Dump, 65 Comet.
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Posted By: Pete from IL
Date Posted: 10 Sep 2017 at 6:47am
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If you like the look of an alternator then that would be the easiest and most reliable way to go. If you like the look of a generator then take yours to a local starter-alternator -generator shop and they can usually rewire it for 12 volt. You will also a new voltage regulator.
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Posted By: jaybmiller
Date Posted: 10 Sep 2017 at 7:21am
If you go alternator, use one of the CS-130 units. They are smaller than the old ,clunky GM ones, put out more power and do not require any tin cutting to fit them in.
On my D-14s, I was even able to use the original fan belt, just swapped the pulley off the generator.
If you use the tractor for short runs like me, an alternator is best as it recharges the battery better, faster than a generator does.Also since the regulator is built in, wiring is simpler.
Whatever you do , please, replace 100% of ALL the wiring ! Your tractor will be more reliable and YOU won't have to spend hours wondering what's the red wire that turns into green then white, actually doing !!! Get a kit from Steve at B&B or roll your own, but follow the colour code from an original diagram. THAT makes life a lot easier !!
Jay
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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Posted By: steve(ill)
Date Posted: 10 Sep 2017 at 8:40am
Sometimes a 6 v generator will work with a 12 volt regulator, if the old gen is in good shape. To "flash" a generator, you bypass the regulator.. So connect a wire to the "A" terminal of generator and touch the + battery terminal or "B" terminal of the regulator... What your thinking of with the quarter is touching the FIELD "F" terminal to ground, which does not polarize the generator, but bypasses a contact in the regulator and sometimes will make it "kick it" if stuck....... also a good way to test a generator and regulator.
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Like them all, but love the "B"s.
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Posted By: Ted J
Date Posted: 11 Sep 2017 at 3:55pm
Thanks for the clarification of that Steve. By saying "test a generator and regulator", do you mean just to see if they are working and charging correctly?
Looks like I'll be going the alternator route........ the 12v genny I had saved up is no good and I'd have to spend some extra $$ on another 12v regulator,,,,,so, I'm gonna put an alternator on it. I have some good CS-130s laying around from an auction, so I'll just have to build a wiring harness and find the little diodes that I bought a couple of years ago. Where'd I leave them??? Come to think of it, I don't need the diodes,,,,,that's for a magneto system,,,I think....
Change the light bulbs, change the leads on the ammeter and distributor and buy a new 12v battery and 3 ohm coil. Anything else?
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"Allis-Express"
19?? WC / 1941 C / 1952 CA / 1956 WD45 / 1957 WD45 / 1958 D-17
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Posted By: Dakota Dave
Date Posted: 11 Sep 2017 at 5:39pm
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If you have a distrubitor you need the diodes or it'll back feed power and not shut off. If you have a madneto you don't need them because magnetos are self generating and not connected to the power system.
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Posted By: Gerald J.
Date Posted: 11 Sep 2017 at 5:43pm
You can use a diode in the alternator excite start wire, or a resistor, or a lamp. The lamp will glow if the alternator didn't go to work.
Gerald J.
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Posted By: DougS
Date Posted: 11 Sep 2017 at 7:35pm
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I looked at the internal schematic of a CS 130 and the model with the "I" terminal has an internal resistor. I don't know if that resistor drops the voltage enough that you don't need a diode or not. You can give it a try without a diode and see what happens.
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