Re-engineering 6-12v

As long as we're playing my brain is longer than yours, Ive got one for the group. Why can't a step up transformer be used to run a 6v genny to charge a 12v battery? I prefer the original look of a genny, but the easy of a 12v battery. Can it be done, if not... why not?
AaronSEIA

You can install an inverter and then change that AC voltage back to 13.8 DC, but that would be both inefficient and expensive. It's best to just install a 12 volt generator or alternator.

CrestonM wrote: I've heard of a lot of 6V tractors (Mainly N series Fords) with "stealth conversions", meaning, like DSeries4 said, the 6V generators are re-wired for 12V, but still look original.

Yep, it's the same 6 volt generator, just re-wired on the inside for 12 volts.

I did some reading last night.  Transformers will not work on DC voltage.  They make something called a DC converter that would do the job, but they sound more expensive than having the 6v genny rewired.  Easy solution is to buy 12v ones in automotive applications.  It is otherwise impossible to get a 6v genny to charge a 12v battery, correct?
AaronSEIA

I have used 12V genniea from old Chevies. They are still available, reasonably priced, and need a real close look to determine it is an upgrade. I install the VR inside the tool box and have bolted the cutout relay on the genie to further disguise the upgrade,

Long ago my dad and I rewound a 12 volt generator to produce 24 volts for running a Command set transmitter in our ham station. We simply took all the windings from the field poles and the armature and replaced them with windings having twice the turns with wire of half the cross section. After getting the commutator turned it worked, but wasn't perfectly quiet so I moved out of my bedroom to the guest bedroom for the next 7 years while I finished high school and college because my dad liked to use the radio in my bedroom early mornings and I preferred to sleep. We didn't use a voltage regulator but with constant speed and mostly constant load the voltage regulation for filaments and relays was good enough. When I went to college and took the DC machinery course I learned we worked too hard. The voltage from a standard generator is directly proportional to the shaft speed with the field current held constant. So all it takes to get 12 volts from a 6 volt generator is to turn the shaft twice as fast. It won't take twice as fast if the field voltage/current is raised too, but the field core will saturate probably long about 8 or 9 volts but up to that point the voltage will rise faster than the speed.

Turning the generator shaft faster means with the stock pulleys its not going to charge at slow engine speeds, but if the generator pulley can be replaced with one smaller in diameter that will speed the generator. If the regulator puts 12 volts on the 6 volt fields they will run HOT. Heat is the enemy of winding insulation, insulation ages and deteriorates faster the higher the temperature and some will char if hot enough.

As for using a transformer, actually the voltage and current in each armature winding is alternating current, the commutator acts as a mechanical rectifier, connecting to each winding when the desired DC polarity is present. If the commutator was replaced by a pair of slip rings the output will be AC. My dad and rewound a couple surplus 24 volt generators to produce 120 volts AC replacing the commutator with slip rings. My dad had done that to a 1932 Dodge starter/generator when I was a year or two old based on an article in a magazine. i still have it. Then with AC output from the generator a transformer could raise (or lower) the voltage and it would have to be rectified to charge a battery. AC runs lights fine, but not ignition systems and direct battery charging.

6 volt systems have worked for a long time. The current SAE standards demand 12 volts negative ground. The modern limits of 6 volt systems are that 6 volt batteries are not common and the selection is very limited with the odds being that the lone battery on the store shelf has sat there for many months without being maintained and its not going to give good battery life when placed into service. Then its my experience (starting with a 6 volt car my dad bought new in 1954) that the 6 volt battery post connections need cleaning twice a year. That's because with 6 volts there isn't much tolerance for a poor connection to the starter. There's more tolerance at 12 volts. I claim 8 volts is just an attempt to give the connections more tolerance for cleaning. Many a classic 6 volt system with a cutout and a 3 brush generator requires the operator observe the battery (without anything but an ammeter that doesn't show the battery is charged with the varying voltage from the 3 brush generator) charge level and back off the charging current to keep from removing water from the electrolyte from over charging and so is harder on batteries. A voltage regulator is a step modern. And alternator (and one could be made for 6 volts positive ground, but you aren't going to find it at any parts store) with a solid state regulator is better for a battery with better control of the charging voltage and is a leap forward in battery care. Going to 12 volts allows using stock alternator or generator and allows for safe jumping with any handy vehicle. I like the original look but understand how much nicer 12 volt with an alternator is. I converted my 4020 years ago from 12 volts positive ground to 12 volts negative ground with an alternator and tripled battery life because the alternator really charged the battery. Its a work tractor with a MF loader so its appearance is a secondary consideration.

Gerald J.

Told ya lol

Then there's the best of both worlds....pricey but elegant
http://www.speedwaymotors.com/Early-GM-Powergen-One-Wire-Alternator-75-Amp,5867.html?sku=91067170-POL&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gclid=CNiYqJzoj88CFQVZhgodJpQByw


Edited by Bill_MN - 14 Sep 2016 at 4:37pm

My cheap WD45 conversion:

One used 12v generator - Free (given pile of used units, made a good one out of couple)
One bushing - a few bucks
One VR - 40?
Some wire, loom and connectors - already had - a few bucks
Bolts - less than a buck?

Mike










Edited by Skyhighballoon(MO) - 14 Sep 2016 at 5:25pm