I want to convert my 1957 PV444 B16B to 12 volts using a "one wire" alternator. I know I need to change the coil and all bulbs. I think I will need to use a resistor to maintain 6 volt items such as horn, fuel guage, wiper and heater motors. Has anyone done this conversion? What type of resistor do I need (amps, ohms, etc) and where can I buy one? Do I need a seperate resistor for each item? Thanks in advance.

Thanks guys!!! Your information has been very helpful and I REALLY appreciate it. It's going to be so nice to actually see the road at night and have drivers behind me see those 50 cent piece size tail lights on my 444!!
Thanks again,
Bill

Hi Bill.
go to www.vintagecars.about.com.
in the search box type in CHANGING 6 VOLT TO 12 VOLT. To the right click the drop down arrow and select ON ABOUT.
Scroll down to article "6 VOLTS TO 12 VOLTS" URL is http://www.vintagecars.com/library/weekly/aa051201a.htm
Lots of good info plus some links to helpful services.
Have a good one.
Ray J.

Ray;

I looked around a both links, and don't see anything about 6 to 12V conversion. Please double check and repost links.

Tnx

Hi Ron.
Follow my instructions to Bill and after scrolling down to 6 volt to 12 volt, read the URL to make sure you have the right one and click on 6 volts to 12 volts and not the URL.

Ray J.

Hi Bill,
A resistor is a pretty wasteful way of dropping voltage, you might be better off trying to get hold of a step-down DC-DC converter (possibly available from electronics shops; I don't know much about car electrics so I don't really know where to get one with the necessary power rating). This will be a lot more efficient; you'll be able to set up 6V to supply everything that needs it rather than messing around making a potential divider.

Sorry I can't be more specific about where to get such a thing!

Brad

not that I've done this, but...

seems lots of places would offer 12v -> 6v step-down converters in the form of cigarette lighter adapters for Walkmans, Game Boys, and the like.

Of course, these might be only in the range of 500ma - 1 amp, but they might be of some use on items like the fuel gauge.

Guys;

12 to 6Volt power converters using highly efficient (>90%) switch-mode circuits with any significant power rating are rare if possible to find at all (those are just not voltage for which conversion is commonly required) and consequently way too expensive.

The whimpy little "12v -> 6v step-down converters" referred to by broken are MAYBE good for 1A, and in fact are not efficient switch-mode power converters (again, too expensive!), but simply linear regulators which waste just as much energy as a simple (and cheaper and more reliable) resistor would, and make JUST AS MUCH heat as that resistor!

My recommendations stand!

Cheers

Bill;

Calculate the value of resistance you need using Ohms law.

R=V/I ,(where Ris resistance in ohms, V is normal nominal operating Voltage of 6, and I is the current draw measured). Important: Power dissapated in the resistance MUST also be calculated, and the resistor appropriately sized to handle the load or else it will burn up. Calculate Power rating of resistor using another version of Ohms laws. P=I(squared)R, using the numbers you have, and have previously calculated.

Using dropping resistors is a terribly inefficient way of dropping the voltage to a load (mount resistors on undercarriage sheetmetal to help dissapate their heat). It works by actually wasting an equal amount of power that the load requires in heat...so you'll need that alt upgrade to keep up with the waste...but I recommend using a "two-wire setup which keeps the function of the AMP light. See: http://www.intelab.com/swem/altkit.htm

Another trick for splitting the voltage is to run two loads in series, allowing them to split the voltage between them, but this technique may ONLY be used if the two loads are the same (equal current draw means they will share the voltage equally).

Your best bet is to replace as many 6V loads as you can with 12V , and use dropping resistors on those which you absolutely must keep (gas guage maybe).

I have stock and sources for the resistors you'll need.

Cheers