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Looks like I should have read all the postings in this discussion befor I wrote the following but I'll leave it in anyway.

E= IR, IR Drop. The applied voltage has little to do with the voltage drop over the length of a wire. What is important is the I R drop. The loss along a wire is calculated by multiplying the current in amps times the resistance per foot in ohms. the result is the voltage drop per foot. Multiply the voltage drop per foot by the length in feet of the wire and you get the over all voltage loss. As the wire diameter goes up the resistance goes down and the voltage drop goes down. If you make the wire size smaller the resistance goes up and the voltage drop goes up.

P=IE The power needed to turn the motor over with the starter motor doesn't change just because you changed the voltage. The power is the power. It is the measure of the mechanical force it takes to cause the motor to turn over fast enough to start. I is the current in amps and E is the voltage in volts. You can see that to develop the same power with 6 volts as opposed to 12 the current has to be twice as much. This necessitates the need for the larger wire size for 6 volt systems as opposed to 12 volt systems.

I too think that the switch from 6 volt electrical systems to 12 volt systems was for economic reasons. With a 12 volt system all the wiring can be accomplished with much smaller wire including the internal wire of the starter and generator.

Another note: I have owned dozens of cars with 6 volt systems in my day and had no particular problems. The voltage was not really an issue. If you maintain the engine in good condition as well as the battery and charging system you will never have a problem just because the battery has 3 cells instead of 6. Most of the starting problems are a result of low compression or starter problems or a poorly maintained charging system. The carburetor is a good place to look to correct a hard starting condition. Take care of it and it will take care of you.

Bob

Thanks Bob.
I'm repeating your quote here so it won't be missed:

"I too think that the switch from 6 volt electrical systems to 12 volt systems was for economic reasons. With a 12 volt system all the wiring can be accomplished with much smaller... ".


Bob, i'm guessing you probably already know why a few of the the ca. WWII EC manufacturers used the 12v batteries instead of the 6v for more ECONOMIC reasons than just saving wire.

Here, we'll give the young guys on here a hint: Cosmoline.

Wasn't Cosmoline that preservative that everything was covered with to ready a ship for mothballs? I'm not sure what Cosmoline has to do with battery voltage.

Bob

G'day all, In response to Pack34, to my knowledge all of the Canadian RHD exports of US models to Australia were the same voltage as the US models. Fords manufactured in Australia such as Zephyr and Consul went to 12V in 1949, Chrysler products manufactured locally went to 12V in 1951, (Plymouth 1953). I would agree with Packard V8 that in terms of total worldwide production, there probably would not have been more than 10% which were 12V prior to the US changing in around 54/55 or so. It is getting very difficult to purchase 6V batteries in small Australian towns ( say less than 1000 people). The main demand used to be trucks which used two large 6V batteries. Now most appear to be 24 V with two 12v batteries. I was hoping that there would have been some book references detailing some of the history of vehicle electrical systems. Peter Toet

G'day all, Well I have located the article in the January 1954 SAE Journal entitled "12 Volts presents its case" . It was presented by S.M Terry of American Bosch Corp. and is Quote: Based on Secretary's report of Round Table_ 12 volt versus 6 -Volt Electrical System for Passenger Cars presented under the auspices of the SAE Passenger Car Activity at the SAE Summer Meeting, Atlantic City, June 10, 1953. end quote.
The opening statement is Quote: Ignition improvement is the main reason for using 12-v electrical systems in certain of today's passenger cars, particularly the ones with high-compression, 8 cyl engines. As far as lighting, battery, starter and generator, and accessories are concerned, 12-v systems are no better on the whole or they are at a disadvantage. end quote.
The two page article which I extracted in 1976 has suffered a bit in storage but i shall post it if i can figure out how to do it. The panel members who expressed the opinions in this article were :
C.W.Rainey, Panel leader, Ford Motor Co.
S.M.Terry, Panel secretary, American Bosch Corp.
L.E.Wells Electric Storage Battery Co.
H.L. Hartzell Delco-Remt Div, General Motors Corp.
C.R. Boothby Electric Auto-Lite Co
V.J.Roper General Electric Co
I.C Mackechnie Chrysler Corp.

A very interesting article. best regards peter Toet

Peter,

If you don't have a scanner, there is probably a photocopy store nearby that will have one. They can scan the article and put it on a disk for you. It would be really great to have a copy on the site. Very interesting stuff.

Otherwise, you could mail it to me in the states, but that seems extreme.

Cheers,


Tom

The statement u quoted FROM *** 1953 *** should be interpretted at best as only diplomatically prophetic of the industries 5-year plan to convert widely to 12v. NOTE that the definition of "diplomatic" means two faced.

At worse the statement is true but a gross misrepresentation due to ommissions or further explanation viz-viz the wire size reduction and cost savings to the mfg'er. They would not mention that because it is only advantagous to the manufacturer NOT the customer. The manufacturer does not need the SAE manual to make decisions. The manufacturers WRITE the SAE manual.

Written in 1953 citeing "high compression" engines????

The statement quoted is just a sales pitch to the world.

ok. I think we can answer the original question at the top of this post by even just approximate answers to the following questions:
1. Approximately what year range were the 12v cars sold in Oz????

2. Were cars sold as 6v prior to that year range ????
3. Were cars 6v AFTER the year range ???

4. What brand of 12v batteries were used in that year range of question 1 ??? (this question is not all that important to know but it mite help drive home a point).

Oldsmobile, as usual, led the way with 12V in 1953. Ford didn't change till 1956. I think several manufacturers had lead time to be ready with 12V batteries.

G'day all, especially PackardV8, My original question at the top of the post, as to why the US standardised on 6V has been answered by the SAE article, which I hope to post. In answer to your specific questions
approx year range for the 12V vehicles in Oz?: From at least 1932 to 1955, involving at least 26 Manufacturers, not counting the Australian versions of US makes mentioned in one of my previous posts
what cars were sold as 6V prior to that year range? I am not aware of any of these manufacturers changing from 6V to 12 volt prior to say 1946.
were cars 6V after that range? direct imports of US 6V models continued as long as Detroit made them. Volkswagen, to my knowledge, was the only make to stay 6V after say 56 and changed in around 1964?
what brand of 12V batteries were used in that year range in question? The major 12V manufacturers were, Willard, Exide, Chloride, Century and Lucas. I would image that there were also many smaller manufacturers. Best regards Peter Toet