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CA 6 volt or 12

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=127134
Printed Date: 17 Jun 2025 at 3:48am
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Topic: CA 6 volt or 12
Posted By: redowns
Subject: CA 6 volt or 12
Date Posted: 12 Aug 2016 at 8:20am
I recently purchased  a CA. I need a new battery. It has an 8 volt in it now. I was told 
I should put a six in it. Why did it have an 8?  Would now be a good time to go 12 volt
 and if so what all do I need? Also I need a new steering wheel where can I get one?



Replies:
Posted By: Trinity45
Date Posted: 12 Aug 2016 at 8:21am
I have two and converted both to 12 but that was my preference.


Posted By: Gerald J.
Date Posted: 12 Aug 2016 at 9:26am
It was made 6 volts. The 8 volt battery allows lax maintenance of battery connections. If there are lights they don't last as long on 8 volts. These days 8 volt batteries are not very common and the selection of 6 volt batteries are limited. Batteries sitting on the store shelf for months or years are bad purchases. The motor vehicle world along with tractors changed to 12 volts about half a century ago.

The original 3 brush generator has no voltage regulation, just some current limiting adjusted by the light switch also connected to the field circuit. Until the operator turns down the current sometime with the light switch, then 3 brush generator is guaranteed to overcharge the 6 or 8 volt battery leading to loss of electrolyte from being converted to a combustible mixture of hydrogen and oxygen in the optimum ratio for the beast bang if ignited. The most reliable way to tell the battery is being overcharged is detecting bubbling of the electrolyte. Don't use a match to provide light to see the electrolyte, the battery acid will eat your clothes and your skin when the battery explodes. Battery pieces will hurt where they hit.

The next generation of generators with a voltage regulator was a giant step forward in battery life maintenance.

Speaking of maintenance, the battery posts in a 6 volt system need to be cleaned twice a year whether used or not, there isn't enough voltage to tolerate slightly corroded connections. There is more tolerance with the 8 volt battery. !2 volt systems can run a couple years between battery post cleaning sessions.

To go to 12 volts for the best function, a small alternator with a built in solid state regulator will give the best battery life, but its obviously not original. For battery care its a new world. A generator can be found to fit wound for 12 volts or the 6 volt generator can be turned faster (needs to about double in speed to double the voltage) and connected to a regulator for a more original look.

Then for 12 volts any lamps will have to be changed, if there is an ammeter it will need to be 50 amps full scale for the alternator instead of the original 20 or 30 amps. The ignition coil (unless its a magneto) needs either a ballast resistor with the same resistance as the coil primary resistance or a new 12 volt rated coil. Some vendors on this forum do not trust the ballast resistors. My gas 4020 uses a 6 volt coil and originally used resistance wire to drop the voltage, but when I bought it ten or fifteen years ago, it had a ceramic ballast resistor that has worked more reliably than the wiring cobbles connecting it with a ScotchTap that went bad. It uses the 6 volt coil and resistor so that a special terminal on the starter solenoid applies battery voltage directly to the coil for better ignition when starting pulls down the battery voltage, which is worse with the skinny JD battery than most modern car batteries.

Going from 6 volt battery will also be likely changing polarity from positive ground to negative ground and probably need new battery cables because while a generator can work with either polarity, the vast majority of alternators are only made negative ground because that is the SAE standard since about 1963 and transistor radios are absolutely intolerant of reversed voltage. That also requires changing the primary polarity on the ignition coil and swapping the connections on the ammeter if present.

Not a trivial conversion, but not impossibly difficult, very detectable by the "correct police" at shows. Starting will be better (no need to change the starter), and battery life will be a lot better and the electrical system will need less maintenance like cleaning battery posts and connectors and adding water to the battery.

Gerald J.


Posted By: GregLawlerMinn
Date Posted: 12 Aug 2016 at 11:54am
Gerald hit all the highlites. My preference is to convert to 12V(+grd) due to availability of decent batteries and components. I have used the short 12V genneys from old Chevys and mounted the VR in the tool box to somewhat disguise the upgrade. If you intend to keep the tractor working; you may also want to consider upgrading it with the Petronix Electronic Ignition module and coil.

Check 1st with the vendors on this site for parts/kits; Steve at B&B is great to work with; as are the others

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What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC


Posted By: DougS
Date Posted: 12 Aug 2016 at 12:38pm
Originally posted by GregLawlerMinn GregLawlerMinn wrote:

Gerald hit all the highlites. My preference is to convert to 12V(+grd) due to availability of decent batteries and components. I have used the short 12V genneys from old Chevys and mounted the VR in the tool box to somewhat disguise the upgrade. If you intend to keep the tractor working; you may also want to consider upgrading it with the Petronix Electronic Ignition module and coil.

Go with negative ground if you switch to 12 volts. Sometimes you can special order positive ground 12 volt components and alternators, but positive ground is no longer the 12 volt standard.


Posted By: redowns
Date Posted: 12 Aug 2016 at 4:42pm
Thanks for the comments. Sounds like it would be best to convert to 12 volts.


Posted By: Dakota Dave
Date Posted: 12 Aug 2016 at 5:06pm
I have converted all my tractors to 12 volt neg ground. I also converted dads tractors. 6 volt will start them it's what the factory put on, If originality is most important to you. My tractors might sit for 6 months before I need it and I don't like to be fiddling around to get it going when I need it. I just put the batteries I take out of my diesel after five years and put in the tractors they'll usually go another five years before I touch them again.


Posted By: Gerald J.
Date Posted: 12 Aug 2016 at 6:31pm
Converting to 12 volts negative ground makes for  safe jumping with a modern tractor, car, or truck. 12 volts positive ground can be jumped safely but everybody trying it has to notice the tractor is positive ground or you can be out two batteries and the jumper cables. There can be an explosion that can be hard on clothes, skin, and hearing. A 6 volt battery should never be connected to a 12 volt battery unless through a resistor to limit the current or the consequences can be as bad as crossed polarity 12 volts.

Gerald J.


Posted By: TedBuiskerN.IL.
Date Posted: 13 Aug 2016 at 8:34am
I'm a purist and prefer the six volt system.  If you use the proper size cables, six volt needs a large cable to carry the amperage required to turn the tractor,  Size #1 minimum, six volts will turn your CA like a top, and be original.  I use six volts on everything that came as six volt, boosted compression WD45 included.  But that's just me.



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Most problems can be solved with the proper application of high explosives.


Posted By: Steve in NJ
Date Posted: 14 Aug 2016 at 7:27pm
Take a visit to our website. There's a lot of information there on 12V conversions, the do's and don'ts etc. We also have a "HOW TO" on installing an E.I. if wanting to go that route down the road. Lottsa' info to read on Alternators etc. We offer complete 12V conversion kits if interested.
Steve@B&B
bb-customcircuits.com


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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife



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