Jump to content

6 volt /12 volt


Guest bradcrone36

Recommended Posts

Guest bradcrone36

what would be the pro and cons in changing a 1929 ton and half dodge to a 12 volt system ?

everything needs rebuilt as it is

Link to comment
Share on other sites

If you are going to rebuild everything, the 6 volt system worked fine when the truck was new.

Staying with 6 volt you do not need to worry about lights, gauges, ignition system, radio if it has one, and the list goes on.

IMO and many others, going to 12v is trying to cover up something that is worn out and needs replacement or repair.

The most important item is to be sure the battery cables are large enough and with good connections at each end.

Do no use 12v cables that you can buy at the local auto parts store as they are too small.

Link to comment
Share on other sites

Guest bradcrone36

with a new 6 volt battery it cranks and original battery wires seem to be good i am not familiar with 6 volt wiring seems like the positive on battery went to frame that is backwards to everything i know about modern wiring

Link to comment
Share on other sites

bradcrone36, many[most?] in that era were positive ground. Nothing wrong with that, and has nothing to do with voltage. If you can locate a starter/alternator shop in your area, have them rebuild what you can't.

As Larry said, the battery cables need to be larger than for 12 volt. O or OO size. The same shop that can rebuild your units can make them for you. Or perhaps a large truck dealer shop.As in Peterbilt, International, etc.

Ben

Link to comment
Share on other sites

Changing to 12 volts will cost a lot of money and work, probably the same or more as fixing your present system properly. The advantage will be, you have a modern system that does not necessarily work any better than the old one but parts are easier to get (a negligible advantage).

The disadvantage is, you spend a lot of money and work to reduce the value of your vehicle and reduce its authenticity.

As far as jump starting goes, you can jump start a 6V vehicle off 12 volts, I have done it many times without a problem.

If you do decide to hack your electrical system, do yourself a favor and save all the old parts you take off. The future owner who changes it back will bless you, and pay more for the vehicle than if you threw them away (although not as much as if you left them on).

Link to comment
Share on other sites

I don't know exactly what kind of electrics Dodge used in 1929, but as a rule old generators and starters can be rebuilt by any good auto electric shop, including the one in your home town. The cost is usually less than buying a rebuilt from the local parts store, and the quality superior.

If you have some unusual setup, there are specialists who rebuild the vintage stuff, at slightly higher cost. But once rebuilt will last a lifetime.

Link to comment
Share on other sites

There is another issue no one ever brings up. When they went to 12 volts, every manufacturer specified a different type of gear teeth on the ring gear and starter pinion, always finer or smaller teeth and more of them.

I believe this was because the faster speed of the 12v starter chewed up the old bendix and ring gear so they had to change them in the interest of reliability and long life.

I don't know if anyone has noticed fast or premature wear on 6v vehicles converted to 12v. If the gears got stripped or wore out they probably put it down to old age.

I would hate to have to replace the ring gear and bendix on a 1929 truck. It would be so much easier and cheaper just to fix it right and leave it 6v.

Link to comment
Share on other sites

No offence to you bradcrone36, or anyone else who has asked this question (lots), but I don't understand why people today get spooked by 6 volts and positive ground. Other than that it is the same as a 12 volt system. If it was good enough when the vehicle was built, it is good enough now. Make sure the system is in good shape and it will never give you a problem.

Terry

Link to comment
Share on other sites

It's been my experience that folks switch to 12 volts simply because they believe (wrongly) that 6 volts are problematic and inferior. They've heard horror stories of hard starting and dead batteries (and yes, 6V has its limitations) so they scurry around to "upgrade" the car without thinking about the real issue. If 6V was so inferior and such a hassle, why didn't the automakers convert earlier? It's not like 12V didn't exist. Rolls-Royce was using 12V in the teens and 20s and eventually went back to 6V. Is 12V really superior on a car without a lot of electrical accessories to run? Nope.

Add in the fact that all the hot rod guys and a majority of message boards will say that a 12 volt battery, GM 1-wire alternator and a Painless Wiring harness is the way to go to solve all your electrical problems, and everyone dutifully heads down that road without realizing that repairing the original system on a mostly stock car will deliver satisfactory results 99% of the time.

As we've all said time and time again, a badly maintained 6V system will be a headache, but fixing it is often no more difficult than cleaning your grounds and installing bigger battery cables.

Having tried to sort out a car converted to 12V by an amateur (he used only red wire in his new harness) I'll take a faulty factory 6V system any day rather than trying to reverse-engineer what some shade-tree mechanic figured was the ideal setup. Such conversions absolutely KILL resale values, too. I can fix a 6V system by looking in a factory shop manual. How do I diagnose, service, and replace parts on a setup some guy dreamed up at home? Oy.

Link to comment
Share on other sites

so... why did the manufacturers convert to twelve volt?

Power windows, power seats, power tops, air conditioning, radios and heater motors becoming standard instead of options, more powerful headlights, higher energy ignition systems, etc., etc., etc.

In short, more features needed more power. I suspect it won't be too long before we see new cars switching to 24V systems to accommodate the many electronic features they're cramming into cars today. 200 amp alternators take A LOT of energy to turn and when every drop of fuel matters...

Link to comment
Share on other sites

Power windows, power seats, power tops, air conditioning, radios and heater motors becoming standard instead of options, more powerful headlights, higher energy ignition systems, etc., etc., etc.

In short, more features needed more power. I suspect it won't be too long before we see new cars switching to 24V systems to accommodate the many electronic features they're cramming into cars today. 200 amp alternators take A LOT of energy to turn and when every drop of fuel matters...

Quite correct. Also, the high compression V8s that were coming into use at the time, demanded more moxie from the starter.

12 volt wiring, starters, motors, etc use about half the copper of their 6 volt counterparts. This was a considerable savings to the car makers given the high cost of copper wire.

Link to comment
Share on other sites

Only American RRs had 6 volt systems and then only at the end of production. This was only because they had complaints from customers finding it hard to get 12 volt batteries in the US. I've worked on both and found no difference in performance.

Link to comment
Share on other sites

so... why did the manufacturers convert to twelve volt?

The reason that the manufacturers changed to 12 volts is to save money. By using a higher voltage they could use smaller wires. It is as simple as that. MONEY.

In todays environment an additional bonus would be mass reduction with smaller wires, motors, etc along with the cost savings.

Link to comment
Share on other sites

Voltage is the "pusher" in an electrical circuit. Double the voltage and only half the amperage is required. Amperage requires larger conductors to carry the power which in turn builds heat. The higher the voltage, the lower the amperage and thus the conductor size. Consider our AC power grid with voltages exceeding 30,000 volts and how much "power" is transmitted thru those battery cable size wires.

Power(watts) = volts x amps .....ie: 30kv x 1 amp = 30 kw , thats alot of power for a 1 amp circuit.

Link to comment
Share on other sites

  • 2 weeks later...

New guy here.Just bought a 37 Plymouth. I was convinced that I needed to convert it to 12V. You guys just talked me out of it. Thanks.

Link to comment
Share on other sites

New guy here.Just bought a 37 Plymouth. I was convinced that I needed to convert it to 12V. You guys just talked me out of it. Thanks.

Good idea. Keep it stock unless there is a REAL GOOD reason to change it. Matt has hit it on the head... if it is stock the service manuals will help you find and fix problems. Just remember that with a 6 volt system wire size and good connections mean twice as much as in a 12 volt system. But with either system, if you maintain it properly it will keep you on the road and happy for many years. Both my 37 (6 volt) and 60 (12 volt) are reliable and fun machines. I would never think of changing either one from stock...

R

Link to comment
Share on other sites

I bought it on a 20% day and it wouldn't start.I was blaming the 6v.But my 2008 12v tractor wouldn't start either.What should I expect from an 80 year old car? In my warm garage it starts instantly.It doesn't have a heater and was thinking of adding one.12v would be easier.As it would in replacing the vacuum wipers.

Link to comment
Share on other sites

  • 4 weeks later...
Guest colt45sa

Larry, you are 'right on'. 6 volt systems need heavier cables on the battery than are commonly available. 6 volt systems also need 'clean' and 'tight' connections. Using a 8 volt battery is not the answer. I had a Studebaker with a 6-volt system that cranked over very slowly. Everyone said 'that's the way 6-volt systems are, you just don't remember'. Well I do remember. I went to a guy who understands automotive electric. He installed some heavier cables on the battery, cleaned and tightened many of the connections, and 'voila', the car cranked like it was a 12-volt car. Converting to 12 volts is a pita, and is totally unnecessary.

Link to comment
Share on other sites

Guest Al Brass

A good source for heavier cables is the truck industry. Plenty of ready made big cables there.

12V electric motors are smaller (lighter too), including starter motors and so less room is required.

Al

Link to comment
Share on other sites

OK, you guys have beat the 6/12 volt debate to death. I'm in the 6 volt side of it by the way. The question I want to ask is why the switch over to negitive grounds in more modern systems. I believe I know the answer (I'm an electronics guy), but would welcome input from the experts. Anyone?

Link to comment
Share on other sites

Dodge used 12 volts for the first 10 years of production then bowed to peer pressure and went to 6v. An sure they put in as good or better system as before so you should have no problems except finding batteries and bulbs as the Dodge owners did in the early 20s on the so called better 12volt cars. Leave the cars as they came when new they ran ok or they could not have been sold!

Link to comment
Share on other sites

I have worked in the automotive/truck field for decades (ASE master tech, TIA commercial tire instructor, state and federal vehicle inspector, etc). I have operated both 6 volt, 12 volt, and the occasional big rig. My daily vehicle for decades was a 1947 Chevy truck switched to 12 volts. You can convert a 6 volt to 12 volt but will need to change all bulbs to 12 volt. All electrical gauges radio, and motors (generator, wipers, blower) would have to have resistors or be changed to 12 volts. A lot of vehicles from the 1960's and onward had their voltage dropped from 12 volt by resistors. You will have to drop the voltage via resister for the point system. You can keep your existing 6 volt starter without dropping the voltage. 12 volts will make it spin faster. The same goes with a 6 volt horn (12 volts will make them louder). The main thing to remember with 6 volt systems is that all connections need to be clean and wiring is thicker. A properly timed and tuned vehicle with 6 volts will be slower cranking (compared to 12 volts) but will operate fine. The changeover is fairly simple. The biggest advantage is much greater parts selection especially if you want to travel with the vehicle. For instance, see how many parts stores carry 6 volt batteries and how many choices they offer when compared to 12 volts. Another example is a 6 volt flasher versus the many choices for a 12 volt flasher

Link to comment
Share on other sites

Guest Al Brass
OK, you guys have beat the 6/12 volt debate to death. I'm in the 6 volt side of it by the way. The question I want to ask is why the switch over to negitive grounds in more modern systems. I believe I know the answer (I'm an electronics guy), but would welcome input from the experts. Anyone?

The main advantage in Negative grounding is the availability of accessories designed to operate on negative ground, like radios etc. A positive ground system requires accessories to be specially built to operate on this system. Otherwise, one system is no better than the other.

Regards

Al

Link to comment
Share on other sites

I find that even at my advanced age there is a lot I do not know. So, I have to ask, what is a "TIA commercial tire instructor?"

TIA stands for Tire Industry Association. They set the standards for anything tire related such as tire and wheel repairs etc. The repair industry, tire manufacturers, equipment suppliers, vehicle manufacturers, along with others meet to set standards. Basically anything tire related whether it is a scooter, motorcycle, passenger car, dump truck to even the big rigs to even earth moving equipment follows these standards. Twice a year TIA hold instruction classes where people from the field are trained in order to instruct techs in the proper techniques to diagnose tires and properly install, repair, and maintain them.

Link to comment
Share on other sites

Well, Al was the only person willing to take a stab at the question of why the auto industry went with the negitive ground concept. I think the mark was missed as aftermarket manufacturers are driven by what OEM's are putting in their new cars like 12volt negitive ground systems. The reason for a negitive ground system is of all things, galvanic corrosion. When electrons travel from a copper alloy to steel there tends to be less galvanic corrosion at the interface. It has to do with dissimiliar metals with one acting as an anode and the other a cathode. That's the way it was explained to me.

Link to comment
Share on other sites

Guest Al Brass

British Lucas, amongst other manufacturers, used a positive ground system for years and finally changing as late as the mid 60's when radios and heaters became common. I have never heard your theory before but I am not saying it isn't correct. I do know that positive ground systems work well and I have not seen any unusual signs of the galvanic corrosion you speak about.

Regards

Al

Edited by Al Brass (see edit history)
Link to comment
Share on other sites

I heard the galvanic corrosion explanation too, or at least the positive cable gets more corrosion than the negative. That is why they made the ground the positive, because it was easier and cheaper to replace a ground strap than the main starter cable.

For some reason this seems to be less prevalent on newer cars, the cables and connections don't get as corroded as the old cars.

Link to comment
Share on other sites

Guest Al Brass
I heard the galvanic corrosion explanation too, or at least the positive cable gets more corrosion than the negative.

Hi Rusty,

As I said earlier, this seems only to be someone's theory, it isn't so in practise.

Al

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...