Sign in to follow this  
bradcrone36

6 volt /12 volt

Recommended Posts

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

Share this post


Link to post
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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
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

Share this post


Link to post
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).

Share this post


Link to post
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.

Share this post


Link to post
Share on other sites
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.

Just be sure to turn everything off including the lights when cranking the engine. As Rusty says, it will work.

Share this post


Link to post
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.

Share this post


Link to post
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

Share this post


Link to post
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.

Share this post


Link to post
Share on other sites

(he used only red wire in his new harness)

I have run into that more than once. What were they thinking?

Share this post


Link to post
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...

Share this post


Link to post
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.

Share this post


Link to post
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.

Share this post


Link to post
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.

Share this post


Link to post
Share on other sites

The big diesel pick ups these days come with two 12 volt batteries.

It may very well be that cars will become 24 volt, Semi trucks use 24 volts in some systems.

Share this post


Link to post
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.

Share this post


Link to post
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.

Share this post


Link to post
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

Share this post


Link to post
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.

Share this post


Link to post
Share on other sites

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.

  • Like 1

Share this post


Link to post
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
Sign in to follow this